Date: Thu, 7 Mar 1996 00:04:01 -0500 From: JHocut@aol.com Subject: Taping Made Easy This is a refinement of the method for taping corners as called out in the plans, and I find it to be very easy with excellent results (far better than what I've done up to now). Measure the length of each edge/corner that will be taped, and layout these dimensions on a sheet of plastic side by side and/or lengthwise with a felt pen as desired to make the most efficient use of glass cloth. (3 or 4 mil visqueen works great). Take the final overall dimension and cut the glass cloth ( 2 plies bid @ a 45 for instance) slightly oversized. Weigh the glass, and prepare an equal weight of resin. Lay all the glass cloth on the plastic over the marks, pour your resin on the glass, and lay a 2nd sheet of plastic over the glass. With a 3 or 4 inch plastic putty knife (or similar), squeegee the resin to cover the entire surface of the glass. Since you have a "sandwich" it is very easy to move resin around in this manner and get all the glass wet out. Once all the glass is wet out, squeegee excess resin away from the glass with moderate pressure. You can get virtually all excess resin out of the glass like this. You can now very easily cut the glass tape to size with a "pizza cutter", paint a bit of resin on the area being taped, remove the top piece of plastic from a piece of glass tape and lay it in place. It's very easy to adjust it's position while there's still a backing of plastic, and when the tape is positioned peel away the last piece of plastic and peel ply. Wish I'd have figure this out a long time ago, someone may have even mentioned something similar and I didn't catch it. Jim Hocut Cozy IV # 448 Date: Fri, 8 Mar 1996 23:15:26 -0500 From: JHocut@aol.com Subject: Re: Re[2]: 2427 Epoxy >Wouldn't the lamps cause some hot-spots {un-even heating}? Yes, but I'm not going for perfection here, just trying to get the smaller layups cured without a horrendous electric bill. On the larger layups I just bite the bullet and leave the heat on. (I kind of like winter here in Georgia, temperature control is pretty easy - summer's going to be a bi___). I'd toyed with the idea of building an "oven" but got too busy creating fiberglass instead. > Anyone tried vaccum bagging? I know it will cost a bit more, but maybe > help with weight a bit and help with the "Blush" problems. Funny you should ask. I've vac bagged just about everything so far (I just finished chapter 6), with some pretty good weight savings over other weights I've seen. I did some X vs Y tests a while ago, and came up 18% lighter on the vac bagged parts (this does NOT mean that your completed plane will be that much lighter, since there are plenty of parts that can't get vac bagged). Jim Hocut Cozy IV # 448 Date: Fri, 29 Mar 1996 21:06:40 -0800 From: harvey3@ix.netcom.com (Neil K. Clayton) Subject: Micro in load-bearing layups? When you micro over bare foam and then place the first cloth layer, some of the micro seems to leech through the cloth and get mixed in with the pure epoxy. Doesn't this integrate some of the micro into a load-bearing layer and serve to weaken it? How can this leaching through be avoided, short of allowing full drying of the micro layer first?? Thx. Neil Date: Sat, 30 Mar 1996 09:08:54 From: JRaerocad@gnn.com (Jeff Russell) Subject: Re: (3)Micro in load-bearing layups? Neil K. Clayton writes >When you micro over bare foam and then place the first cloth >layer, some of the micro seems to leech through the cloth and get >mixed in with the pure epoxy. Try scraping a little harder to remove more micro slurry. You should only leave what it takes to fill the cut holes (cells)in the foam. Any more slurry left then this can give this problem. The larger the foam cell, the dryer the mixture of micro slurry needs to be. Hope this helps AeroCad Inc. Jeff Russell 1445 Crater Lane Yadkinville, NC. 27055 910-961-2238 E-mail: JRaerocad@gnn.com Date: Sat, 30 Mar 96 17:25:12 est From: "Larry Schuler" Subject: Micro in load-bearing layups? My understanding: The tiny amount of leaching is unavoidable, but not harmfull to the structure. The purpose of the epoxy is to hold the glass fibers in place to obtain full strength etc. from the glass, but that is all; the epoxy itself contributes very little to the structural strength. "IF" that is correct, the very small amount of micro won't affect the structure. I'm sure you will get other, more experienced responses...... Larry Schuler MKIV-#500 ______________________________ Forward Header __________________________________ Subject: Micro in load-bearing layups? Author: harvey3@ix.netcom.com (Neil K. Clayton) at INTERNET Date: 3/30/96 12:12 AM When you micro over bare foam and then place the first cloth layer, some of the micro seems to leech through the cloth and get mixed in with the pure epoxy. Doesn't this integrate some of the micro into a load-bearing layer and serve to weaken it? How can this leaching through be avoided, short of allowing full drying of the micro layer first?? Thx. Neil Date: Mon, 01 Apr 1996 14:41:04 From: JRaerocad@gnn.com (Jeff Russell) Subject: layups > Randy Smith Writes: > > I'm still using Safe-T-Poxy II so the color allows you to see the > air bubbles, but yes You pour more epoxy than a single layer. You > actually find that you use less epoxy than doing it in two separate > layers. What do you think happens when Triaxal skins are used on wings. This is 22 ounces of glass knitted in three orientations giving one total thickness of glass. Its like laying UNI in three plies and sewing it so it stays put. We wet it out with epoxy by ether poring or brushing as if its the same as UNI. Colored resin will always help in seeing if total saturation has been achieved. AeroCad Inc. Jeff Russell 1445 Crater Lane Yadkinville, NC. 27055 910-961-2238 E-mail: JRaerocad@gnn.com Date: Tue, 02 Apr 1996 21:16:48 From: JRaerocad@gnn.com (Jeff Russell) Subject: Triax or other Cloths Nigel Field writes: >Regarding Triax cloth, if you examine a piece closely you will >find lots of space between the fibre tows, much more than UNI. >These act like a sponge and soak up LOTS of resin. Repeat my test >in laying up two identical samples, one of triax and one three >plies UNI and then weigh and test them to destruction. See what >you get. IMO triax only saves time, and if you use the dry layup >method above it saves nothing. The only place you could use it is >on the wing top which call for three plies but the weave >orientation will not be the same as Rutan called for so the >tortional properties will differ. The bottom skin is two plies so >triax just adds lots more weight for nothing. Don't use it, its >arguably weaker and heavier than 3 plies of UNI. When we use Triax cloth, we always meter how much epoxy for the size cloth used. How do we do that?? Weight of Cloth = Weight of Epoxy. This will guarantee a 50/50 glass to resin count, about what is normal for a hand layup less vacuum bag job. We show in the composite workshops that we teach, how EVERY style of fiberglass has its best place for work ability. Biaxial is a poor choice for a hand layup maybe for a shearweb. Giving its airy composition and it does not like to make a outside bend, air is a bad problem here. If we were to use the same material in a mold. We could now vacuum bag to compress out the extra resin out. Biaxial cloth also likes to make inside bends. Hopefully you can see what I mean about (best place to use). Our molded environment lends the use to this style mostly because of vacuum bagging. A lessen we learned about knitted cloth instead of weaving was no cornstarch was used on the knitted cloth. cornstarch must be baked out of the glass so it will be able to except epoxy resin. When going through this baking process, the cloth losses about 30% of its strength per weight. If you had 9 oz of BID and 9 oz of Biax knitted cloth , I am told it like the 9 oz equivalent of BID (Biax is like going to S-Glass). We have NOT done any load test on these styles, but this is what Hexcel told us their test found. The use of Triax on the bottom skin of a EZ wing has been used on ALL Velocitys, and AeroCanards from day one. Why?? Stronger skin, better compression on the bottom side from crushing foam. Does anyone remember what Burt did and talked about at Big-O last year and the year before?? Skin delamanation on the wings larger than a quarter need to be repaired on ALL EZ's. On the Vari-EZ if this was found on top of the wing by the winglet, The airplane was grounded until fixed. Winglets come off rather quickly with this problem left unattended. Burt used a dime to tap on the wings to find the bad spots. Most were on the bottom of the wing were lifting to set the wing was a issue. I looked at LOTS of Longs and Cozys and could see lots of these spots with just my eyes. The Velocitys did not seem to have this problem confirming what Danny M. told me that it took care of that flimsy skin problem with the Triaxial skins. We sell videos on how this method is used on our wings for $15.00 + shipping. If Triaxial cloth is not handled properly, it could take much longer to fix then the use of the standard UNI. So USER BEWARE. More to chew on AeroCad Inc. Jeff Russell 1445 Crater Lane Yadkinville, NC. 27055 910-961-2238 E-mail: JRaerocad@gnn.com Date: Tue, 09 Apr 1996 14:49:56 -0400 From: Nigel Field Subject: Re: Hard shell - Delam At 11:35 AM 4/9/96 est, Larry Schuler wrote in reference to 7781 glass: > > I ordered RA5277 BID and RA5177 UNI from Wicks...... > Is this the same stuff? > Larry, no its not. The 7781 is a fine weave 8.92 oz glass BID cloth I got from A Spruce, dont see it listed by Wicks. It looks like heavy peel ply and makes for a nice smooth layup needing little micro fill. If only it would bond better. Wicks seem to use different numbers RA5577 BID and 5177 UNI. I think its exactly the same as 7725 BID and 7715 UNI from Spruce. Ive used it from both suppliers with no problems. Perhaps someone else has run into this and could comment. Nigel Field Date: Mon, 15 Apr 1996 14:46:00 -0400 From: Dick.Finn@FNB.sprint.com Subject: Hard Shelling About 4.5 years back when I started work on my Mark IV a Cozy Classic builder, Jim Rios, came over and helped me with the first layups. he passed on some hints from aseveral Long-eze builders that relate to preparing the foam for glassing. I'll pass a few on for your edification and amusement. 1. Prepare the foam carefully. Sand with a long sanding block and vacumn carefully 2. Mix up some stiff micro and fill in any indentations, knicks, gouges, etc. Then go do something else for an hour or so while it sets up. 3. Mix up some more stiff micro and go over the above gouges again. Go away for another hour. 4. Mix up some thin micro and cover the complete surface to be glassed. 5. Hang the bolt of glass cloth over the workbench and pull out enough to cover the piece being glassed. Trim generously. This hurt plenty at first as it wasted some glass. After going back to measuring and cutting carefully to size then draping the glass over the piece in progress I found that I was being penny wise and pound foolish. You only waste a little glass this way but you make it easy to pull the fibers straight. The quality of the layup is greatly improved. 6. Mix up the epoxy in big batches (until you get toward the end of the layup). Dribble it over the glass fairly generously in the beginning. Squeegee it around. Don't pour it on in one place as that just results in pockets of epoxy rich cloth. I've been reading the comments on hard shelling and, like many others, have some concerns that the glass would only have a mechanical bond to the micro. This could result in the glass separating from the hard shell under certain circumstances. I'm not saying this would happen, just that it could and I don't know enough about the subject to take the chance. I am reminded of what happened to Steve Wittman when the fabric disbonded from his plywood wing after several years. I certainly hope I'm wrong as it seems a number of people have used the method. Anyway, I think the method I described would result in a mechanical bond to the foam and a good chemical band between the micro and glass layers. I've found that I get a very nice surface when following the method I described above. The above advice is guaranteed to be worth every penny you paid for it. Dick Finn Cozy Mark IV #46 DICK.FINN@FNB.SPRINT.COM Date: Fri, 31 May 1996 20:24:33 -0400 From: Jim Hocut Subject: COZY: Re: Vac. Bagging Sides At 04:27 PM 5/30/96 est,"Larry Schuler wrote: > I have just finished layout of fuselage sides; will also vacc bag as > much as I can. > > How did you do the longerons? I have been thinking about doing the > entire inside at on time (one shell at a time). > > Got any warnings or advice before I make same boo-boo's ? I only vac-bagged the first 2 ply overall layup on the fuse sides, not the longeron layup or the 6 ply layup at the aft end (notice I was polite and said aft and not a__). With 20-20 hindsight I wish I'd have done a little more planning ahead and did ALL of the layups at once, would have saved significantly more weight. I thought about it afterwards and decided that it wouldn't have been all that difficult. I only did one side at a time instead of both as called for in the plans. (I don't see how it would be remotely possible to vac-bag the sides any other way). I made my masonite forms oversized to allow plenty of room. As I recall, by using oversized masonite forms you'll have to do a little extra work with a tape measure to be sure that the pieces are oriented correctly with respect to the jigs (no big deal really). Naturally you'll have to seal the joints where the masonite is joined (unless you can come up with pieces longer than 8 ft.), I 5-min epoxied them together, and then sealed top and bottom with duct tape. I also vac bagged the fuselage bottom, that was a bit more interesting. I'm a bit brain dead right now though - just got back from being out of town all week and had to drive over 6 hours (CAN'T WAIT TILL MY COZY IS FLYING !!!!!!) - so will save my thoughts on this for another installment. Jim Hocut jhocut@mindspring.com Date: Sat, 1 Jun 1996 13:49:50 -0400 (EDT) From: Randy Crutfield Subject: COZY: Vacuum bagging the bottom When you have time, why don't you enlighten us on this. I did it the all night, old fashioned way as called for in the plans. This was one of those two people 8 hour, cussin', fussin' layups. My wife just left at one point and I thought she might have decided to leave for good. Finally a little after midnight, the layup was acceptable. At that point the energy and motivation had sunk to a low enough level that we went to bed, set the clock for 5AM and then put the bottom in place on the fuselage sides the next morning. Reading about it in the plans, it sounds so easy. I believe that after you put it on the sides you then hop under it and tape all of the joints, yeah right. This was another one of those layups that makes you wish that you could stand back and watch Nat work. Obviously I have a lot to learn, but I guess that it does get easier after you build a few planes. Thinking back about trying to get the cloth to laydown in those compound corners around the contouring, this seems like a great place for vacuum bagging. Randy by mta bnr.ca in /PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/; Relayed; Wed, 5 Jun 1996 10:48:15 -0400 by /PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/; Relayed; Wed, 5 Jun 1996 10:47:13 -0400 by /PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/; Relayed; Wed, 5 Jun 1996 10:47:00 -0400 Date: Wed, 5 Jun 1996 10:47:00 -0400 [/PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/;bcars735.b.148:05.05.96.14.47.13] From: "michael (m.j.) anderson" Subject: COZY: UNI Cross Threads Is it important to have the small cross threads on the UNIT cloth straight? I noticed on one of my layups that I had the main threads straight, but some of my cross threads were not. To my understanding the structural strength is provided by the main threads and not the cross threads. The cross threads are there just to hold the main threads in place. Is this accurate? Thanks, Michael Anderson mikej@nortel.com Cozy Mark IV #484 From: Marc J. Zeitlin Subject: COZY: UNI Cross Threads (fwd) Date: Wed, 5 Jun 96 11:04:03 EDT Michael Anderson asks: >Is it important to have the small cross threads on the UNI cloth >straight?....... No. >....... The cross threads are there just to hold the main >threads in place. Is this accurate? Basically, yes. UNI is used to provide strength and stiffness in ONE direction (hence the term UNIdirectional). BID is used tp provide strength and stiffness in both directions (hence the term BIDirectional). For BID layups, you should try to have ALL the fibers as straight as possible. For the UNI, only worry about the main fiber direction. For the spar cap layups, this is even more accentuated, since you REMOVE all the cross fibers. my $0.02. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Thu, 06 Jun 1996 23:53:00 -0400 From: Jim Hocut Subject: COZY: KEVLAR ??? I've been recruited to help a friend add some Kevlar layups on his boat. Can anyone make a recommendation as to a resin to use? Will any of the popular fiberglass epoxies work ok? (While this isn't directly related to Cozy's it will at least get me some experience working with kevlar in case I decide to add some to my Cozy in a few critical areas.) thanks, Jim Hocut jhocut@mindspring.com Date: Wed, 19 Jun 1996 07:38:42 -0400 From: william l kleb Subject: COZY: chapter 4 - air in the laminate i have laid-up the chapter three samples, the instrument panel, f22, and f28 without problems, but i ruined the seatback: after the lay-up was finished, i checked it carefully and saw no air bubbles or dry glass fibers. i put a sheet of peel-ply over the entire thing, adding just a little more epoxy. when it cured, it had air in the glass fibers covering around 20% by area. i rejected the part. i have since tried a test lay-up, adding lots of epoxy and using a lot of micro on the foam: it looks even worse. during this same period of time, i have laid-up the stiffners on the instrument panel without difficulties. help. (this seems to be the first question marc z posted when the list was getting started, but i couldn't find the answer.) [i am using safe-t-poxy I, and the humidity has been anywhere between 50 and 85 percent over the past month. this test lay-up was done with a freshly-opened batch of epoxy at 56% humidity and 80F. i use an epoxy pump which is kept around 85F.] depressed in hampton, --- bill kleb (w.l.kleb@larc.nasa.gov) 72 bellanca 7gcbc (citabria) 99 cz4 -> aerocanard From: Marc J. Zeitlin Subject: COZY: chapter 4 - air in the laminate (fwd) Date: Wed, 19 Jun 96 9:03:52 EDT bil kleb writes: >after the lay-up was finished, i checked it carefully and saw no air >bubbles or dry glass fibers. i put a sheet of peel-ply over the entire >thing, adding just a little more epoxy. when it cured, it had air in >the glass fibers covering around 20% by area. i rejected the part. I have found that if I add epoxy ON TOP OF the peel ply, I get air bubbles in the top epoxy skin, but it doesn't go into the main layup. I had this problem with the canard shear web (posted to the list about it long time ago) but found that I could scrape all the air filled epoxy off with a sharp chisel. Maybe this is what's going on (maybe not). I would recommend to NOT put epoxy on AFTER you've peel plied. The 2427 epoxy that I'm using seems to entrain air much more easily than do the other epoxies - I've seen postingsdescribing a lot of foaming during stippling (which I try to minimize) and air entrainment if you squeegee too much. Maybe you're getting some of this, although I don't remember this happening with the SP-I 15 years ago. >i have since tried a test lay-up, adding lots of epoxy and using a lot >of micro on the foam: it looks even worse. during this same period of >time, i have laid-up the stiffners on the instrument panel without >difficulties. Curious. You don't mention the peel ply technique here. My uninformed guess is that the peel ply is causing air on the surface, but not in the interior. Remember also that SOME air in the layup is acceptable. You may want to have your local EAA Tech Counselor inspect your parts (both the good and bad ones) and give you an opinion on whether they are truly rejects. Good luck. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Wed, 19 Jun 1996 08:51:41 -0700 From: Michael Antares Subject: COZY: air in epoxy Are you sure that it is air? I'm using the RAE epoxy so I can't comment on the others but I know that with mine (using a blue colored hardener) it is difficult to differentiate between air bubbles and variations in the color of the micro slurry used to fill the foam before glassing. The only time I actually have problems with entrapped air is when I try and push the pot life. Even with the slow hardener I try and use a batch within 5 to 10 minutes (lots of smaller batches). Keeping the viscosity down always helps (hair dryer). I think a lot of us made the mistake in the beginning of over-stippling; whenever possible I use the squeegee, on something like the bulkheads a brush would hardly be required--I stippled for hours on the bulkheads not knowing any better! Regards, 6077 Old Redwood Highway Penngrove CA 94951 707.664.1171 Finished through chap 14 except chap 13. Currently on 16, 17 and 24. Date: Thu, 20 Jun 1996 08:11:46 From: JRaerocad@gnn.com (Jeff Russell) Subject: Re: COZY: chapter 4 - air in the laminate William Kleb wrote: >I checked it carefully and saw no air bubbles or dry glass fibers. >I put a sheet of peel-ply over the entire thing, adding just a little >more epoxy. when it cured, it had air in the glass fibers covering >around 20% by area. i rejected the part. >I have since tried a test lay-up, adding lots of epoxy and using a >lot of micro on the foam: it looks even worse. during this same >period of time, I have laid-up the stiffners on the instrument panel >without difficulties. Try making sure your surry is not left to thick. Remove all but what covers the cells in the foam. Next, make sure you have micro and not Q-cells. Make some dry micro (about 1-2 oz) and leave a little epoxy in a cup to also cure. Check cures on both. If the dry micro is Q-cells it will cure with a much longer lag time. 24 hours or longer then your epoxy. If this is not a problem??? (Don't use Q-cell and Saf-t-poxy). Try not covering your hole part in peel-ply. It can trap air without vacuum bagging. AeroCad Inc. Jeff Russell 1445 Crater Lane Yadkinville, NC. 27055 910-961-2238 E-mail: JRaerocad@gnn.com Date: Mon, 24 Jun 1996 10:38:48 -0400 From: william l kleb Subject: COZY: chapter 4 - air in the laminate william l. kleb wrote [re: seatback bulkhead]: > > after the lay-up was finished, i checked it carefully and saw no air > bubbles or dry glass fibers. i put a sheet of peel-ply over the entire > thing, adding just a little more epoxy. when it cured, it had air in > the glass fibers covering around 20% by area. i rejected the part. thanks to all of those who replied to my request for help. it seems that the problem was my peel-ply technique. i laid-up a 2-ply uni test piece (10"x20") without peel-ply: it looks beautiful. however, i weighed down the center of the piece with a 2"x6" across the 10" dimension with a piece of saran wrap under it. in that region there was some air in the epoxy at the surface, but none in the glass fibers or within the layers. i have yet to figure out why my other bulkheads came out fine, since they were peelplied in their entirety. my current theories are: 1) the other bulkheads didn't have as large of acreage, so that air could more easily escape from the edges 2) the divinycell foam is much more porous (and thus more sensitive to poor slurry technique, eg, too thick, not worked in enough, etc) 3) i had used a hair drier on most of the other bulkheads to keep the viscosity low (ie, i got lazy on the seatback and didn't do this) thanks again, bil From: garfield@pilgrimhouse.com (Garfield) Subject: Re: COZY: Bulkheads Date: Tue, 25 Jun 1996 22:35:24 GMT On Tue, 25 Jun 1996 13:06:23 -0600 (MDT), "aka Mr. Radon" wrote: > I have found that 15 minute epoxy works real well in some places where >the extra time is really needed such as large pieces. I've also done >vacume bagging of all my parts so far and found that if you fill holes or >other imperfections with 15 minute micro the micro is not sucked up into >the fiberglass layups. We found this out the hard way on CU's Go-4 >project when we used 2410 micro to fill out a few holes, had to redue the >whole part. > >ROY Whoa, this is real important, and I wonder if I'm the only one confused by the above. Do you mean to say that the "2410 micro" was sucked up into the fiberglass when you bagged them, and left a void beneath; are you saying that the "15 minute micro" doesn't & that it's better. Could you say in more detail what happened and what was good and what was bad when you vacbagged the parts. I'm about to begin bagging everything, so my interest. I can understand if someone tried to fill imperfections with epoxy or wet micro and found that the epoxy was bled off by the glass, but why would the glass be "dry" in the first place prior to bagging. Do you mean to say you layed the dry glass over recently wet-micro'd surface and found it robbing the micro of epoxy. Inquiring minds want to know. manyTIA, Garfield Date: Wed, 26 Jun 1996 12:45:20 -0600 (MDT) From: Roy Grossinger Subject: Re: COZY: Bulkheads > > I have found that 15 minute epoxy works real well in some places where > >the extra time is really needed such as large pieces. I've also done > >vacume bagging of all my parts so far and found that if you fill holes or > >other imperfections with 15 minute micro the micro is not sucked up into > >the fiberglass layups. We found this out the hard way on CU's Go-4 > >project when we used 2410 micro to fill out a few holes, had to redue the > >whole part. > > > >ROY > > Whoa, this is real important, and I wonder if I'm the only one > confused by the above. Do you mean to say that the "2410 micro" was > sucked up into the fiberglass when you bagged them, and left a void > beneath; are you saying that the "15 minute micro" doesn't & that it's > better. Could you say in more detail what happened and what was good > and what was bad when you vacbagged the parts. I'm about to begin > bagging everything, so my interest. I can understand if someone tried > to fill imperfections with epoxy or wet micro and found that the epoxy > was bled off by the glass, but why would the glass be "dry" in the > first place prior to bagging. Do you mean to say you layed the dry > glass over recently wet-micro'd surface and found it robbing the micro > of epoxy. Inquiring minds want to know. > The reason behind the 15 minute epoxy is that by the time you have finished setting up your layup the epoxy will have thickened enough so that if there is air under the epoxy and you draw the vacume the micro will not become entrained into the glass. We/I only use the 15 minute stuff for gaps that are large like 1/16" where two pieces met. I did this for my fire wall, I used the excess .25" foam from the landing gears to cover the inside of the fire wall which I later cut out. Made a real nice layup, but before I had some large gaps where the foam met to firewall. Small pin holes can easily be covered with the micro slurry using 2410 or 2427 epoxy, there isn't enough volume epoxy or air wise to create a problem. Even if a little micro is sucked up into the glass fibers it isn't a very large concern as long as it isn't a whole lot, see Nat/Rutan's criteria on air. Hope this helps explain the reasons behind the method. ROY Date: Fri, 12 Jul 1996 12:50:06 -0600 (MDT) From: Roy Grossinger Subject: COZY: Vacuum Bagging Last night I did the 2 30 degree layups for the two sides. I'm vacuum bagging everything to this point and spent a little extra time setting up these two parts to do at the same time using a very large vacuum bag. However to prevent alignment problems I will attach the stiffeners tonight. My time was 2.5 hours to do the whole layup and bag. My sister, who is a doctor helped. (She's fast and very accurate!) I was concerned about the depressions for the control stick, the glass just wasn't laying down, but when we pulled the vacuum, WOW! I was able to pull 23" Hg on the layup, which is good at our altitude 5,400'. I was worried since I screwed through the plastic when I secured the masonite to the jigs. If anyone out there wants I can give them ideas on how to layup the two sides at once like Nat shows in the plans. Also since the bag is secure and reusable, I should be able to bag the 4 plys on top and the 6 plys in the back too. I haven't weighed any of my parts yet, but will post them as soon as I do. Do you have any weights to compare these to Mark? I noticed your link on the WEB is empty. ROY ============================================================================= Roy H. Grossinger- ME grossinr@rastro.colorado.edu Cozy Mk IV #503; Chapter 5 ROY_GROSSINGER@Radon-hq.ccmail.compuserve.com CU's Go - 4; Hull Layup "A man's destiny is his character" | ___ | http://bechtel.colorado.edu/~grossinr |---------(>-<)---------| http://www.abwam.com/grossing / ~~~ \ o/ \o Date: Fri, 12 Jul 1996 13:05:43 -0600 (MDT) From: Roy Grossinger Subject: COZY: Vacuum pumps If anyone is looking at getting a cheap vacuum pump look at estate sales. I originally bought, for a few dollars, a refig. compressor. I had to route the exhaust outside and install a cooling coil over the case. The pump ran very hot. Normally the oil and coolant circulate to cool it. After doing 10 bags or about 50 - 60 hours of operation the pump seized. In the meantime I found a high volume vacuum pump from an old coffee factory. They were expanding and had an auction. I picked up this vacuum pump for $5.00 that will pull 23"Hg up here and has a flow rate of 35 liter per minute of air at 10"Hg. Its a nice pump when you have a leak. Also I found that if the refig pump turned off and I wasn't around (I put my pumps on a timer for 5 -6 hours) air would get sucked through the compressor and into the bag. I only allowed this to happen once and had to redue the test part I was working on, oil vapor was sucked in. With the other pump I'm not worried since it is oil-less. So if you use a ref. compressor, be very careful. ROY Date: Sat, 13 Jul 1996 21:05:51 -0700 From: wkasty@ix.netcom.com (william g kastenholz) Subject: COZY: Epoxy Pump ratio To all of you builders using epoxy pumps. I purchased an AR-100 pump in May direct from the company. I told the seller that I was using 2427 epoxy and the pump came setup 44/100. On the epoxy can the instructions tell you to mix the epoxy 44/100 by weight. I talked to Wicks and they checked the volume ratio to be 47/100 which is what I have used and I believe to be correct. My layups appear to be of good strength as I begin chapter 5 work now. Bill Kastenholz wkasty@ix.netcom.com Date: Sun, 14 Jul 1996 21:59:00 -0400 From: Jim Hocut Subject: Re: COZY: Vacuum Bagging Roy Grossinge wrote: > ...... I was able to pull 23" Hg on the layup,..... 23" Hg is HIGH!!!! I started out at around 16" and had to back down to around 10 because of excessively dry layups. Maybe Jeff can comment on this also, since he must have about as much experience vac bagging as anyone. Jim Hocut jhocut@mindspring.com Date: Mon, 15 Jul 1996 08:17:01 From: JRaerocad@gnn.com (Jeff Russell) Subject: Re: COZY: Vacuum Bagging Jim Hocut wrote: >23" Hg is HIGH!!!! I started out at around 16" and had to back > down to around 10 because of excessively dry layups. Dry layups in vacuum bagging come from air comming into the bag from a poor seal, or letting off the pressure to soon before it's hard and the part is allowed to bring back air in. Think of it a a loaf of bread that was stepped on and it came some what back up from being flat. Not good in this case. (Keep it flat untill its hard) We pull up to 27-29 Hg with no problem and only 10 Hg on wing cores because thay will crush. AeroCad Inc. Jeff Russell 1445 Crater Lane Yadkinville, NC. 27055 910-961-2238 E-mail: JRaerocad@gnn.com Date: Tue, 16 Jul 1996 12:08:05 -0400 From: DFinn7971@aol.com Subject: Re: COZY: 2427 curing In a message dated 96-07-14 22:22:20 EDT, jhocut@atl.mindspring.com (Jim Hocut) writes: << I printed a listing of resin and hardener weights for different size batches and stuck it to the wall behind where the scale resides >> Good idea, after getting started on layups in the past only to find I've forgotten something I made up a pre-layup checklist and keep it taped on the cover of my epoxy pump box. I don't have it handy but I include things like: - Check to make sure peel ply removed, - Sand surface, - round edges -- Fill epoxy pump containers - Get out squeegee and brushes, - Layout saran wrap - Lay out waxed paper, - etc. all items do not apply to each layup but it did serve to make me think about everything before getting started. On several occasions it saved me from some really dumb mistakes. As a side item, I also include: - Go to the bath room - Get a soda with a straw - Check the time, if it is in the evening ask yourself if the layup be completed without getting too tired so as to make some really stupid mistake. Dick Finn Cozy Mark IV #46 DFINN7971@AOL.COM Date: Tue, 16 Jul 1996 22:58:05 -0400 From: StetsonE@aol.com Subject: Re: COZY: 2427 curing In a message dated 96-07-16 12:10:11 EDT, Dick writes: > As a side item, I also include: > - Go to the bath room > - Get a soda with a straw > - Check the time, if it is in the evening ask yourself if the layup be > completed without getting too tired so as to make some really stupid mistake. > I would also add: Put a clean stirring stick in your back pocket. That way you have something to scratch your head, face, or whatever, when your hands are covered with epoxy. For some reason, the only time I get an irresistable itch is when I have epoxy on my hands! Stet Elliott stetsone@aol.com Perpetual Long-EZ Builder Date: Wed, 17 Jul 1996 08:58:03 -0700 From: Michael Antares Subject: COZY: My Peel-ply lesson (fwd) What follows is not a peel-ply lesson but is related. I am using RAE epoxy and not 2427 but I assume it probably is the same with the 2427. I found early-on that even though the epoxy seems to still be well within its pot life and hasn't started to visibly gel, I would find it very difficult or impossible to thoroughly wet out the glass, the result being a lot of small white specks in the cured section, if I went over 15 or 20 minutes of pot time--this using even the slow hardener. Of course as you gain practice you naturally work faster and faster but I am now very careful to mix up smaller batches and use them quickly, especially with 80 degree summer days. Michael 6077 Old Redwood Highway Penngrove CA 94951 707.664.1171 Cozy#413 Finished through chap 14 except chap 13. Currently on 16 and 24. Date: Sat, 20 Jul 1996 23:29:51 -0400 From: StetsonE@aol.com Subject: Fwd: COZY: Upper Longeron layups In a message dated 96-07-17 11:57:36 EDT, mantares@a.crl.com (Michael Antares) writes: > To add a suggestion: I have found in several instances that I could get > glass to do what it did not want to do on its own by using strong thread. > The thread, or the groove that it leaves, is completely invisible. This > worked for me especially when I did the NACA scoop. It doesn't work to well > on concave! curves but then you can't have everything... > Another idea I've put to use when glass wants to lift in a corner and draw in air is to cover the area with a piece of Saran wrap and then work the air out. The Saran wrap prevents the glass from drawing air back in. Also works well on outside corners that weren't rounded enough prior to glassing. Of course, this works only to keep the glass down and the air out. It doesn't address the possible loss of strength in making the glass conform to a small radius. Stet Elliott stetsone@aol.com Perpetual Long-EZ builder --------------------- Forwarded message: From: mantares@a.crl.com (Michael Antares) Sender: owner-cozy_builders@hpwarhw.an.hp.com Reply-to: mantares@a.crl.com (Michael Antares) To: cozy_builders@hpwarhw.an.hp.com Date: 96-07-17 11:57:36 EDT To add a suggestion: I have found in several instances that I could get glass to do what it did not want to do on its own by using strong thread. The thread, or the groove that it leaves, is completely invisible. This worked for me especially when I did the NACA scoop. It doesn't work to well on concave! curves but then you can't have everything... Michael, 6077 Old Redwood Highway Penngrove CA 94951 707.664.1171 Cozy#413 Finished through chap 14 except chap 13. Currently on 16 and 24. From: Paul.Krasa-1@pp.ksc.nasa.gov (Krasa, Paul) Organization: Kennedy Space Center, FL Date: Mon, 29 Jul 1996 10:25:35 -0400 Subject: FW: COZY: Shoulder Support BID Orientat Paul Stowitts states >... it doesn't seem to matter much as BID seems to give >pretty good strength in all directions. Not true. Composite materials made from clothes can only carry the load in the direction of the fibers, thus the fibers need to be in the direction of primary stress. A quasi isotropic layup will approximate strength in all directions. In the region of the shoulder support, the direction is less critical since the purpose of the BID is reinforcment which keeps the sholder harness from pulling out. I alternated 45s with 90's which will disipate the load in four directions instead of two. More expensive clothes such as a four, six, or eight harness satin will allow "nesting" which is alternating the cloth faces such that the fibers lay into each other, but we do not use this process on any of the canard aircraft that I know of. Some people think that this process will give you a stonger part, but since I've not conducted physical testing I won't make that claim yet. Paul Krasa Long EZ 214LP !---*---! Date: Mon, 29 Jul 1996 16:04:14 -0400 From: CozyBldr@aol.com Subject: Re: FW: COZY: Shoulder Support BID Orientat In a message dated 96-07-29 10:31:17 EDT, Paul Krasa writes: <... it doesn't seem to matter much as BID seems to give >pretty good strength in all directions. Not true. Composite materials made from clothes can only carry the load in the direction of the fibers, thus the fibers need to be in the direction of primary stress. A quasi isotropic layup will approximate strength in all directions. >> Paul, if I were to take your statement at face value, I would assume then that loads not in line with the fibers of a BID layup would cause an immediate failure of the part. This obviously isn't so. With BID, loads not directly in line with the fibers are going to pick up a component of the strength of both sets of fibers. Keep in mind, a load placed in line with one set of fibers in BID will get no additional support from the other set of fibers. My main point was where the plans do not specifically call out BID orientation, the part does not appear to be critical or there is enough strength at any orientation to be sufficient for its purpose. Paul Stowitts From: Paul.Krasa-1@pp.ksc.nasa.gov (Krasa, Paul) Organization: Kennedy Space Center, FL Date: Tue, 30 Jul 1996 09:16:05 -0400 Subject: Re: COZY: Shoulder Support BID Orie Not true. Composite materials made from clothes can only carry the load in the direction of the fibers, thus the fibers need to be in the direction of primary stress. A quasi isotropic layup will approximate strength in all directions. >> Paul Stowitts says, >>Paul, if I were to take your statement at face value, I would assume then that loads not in line with the fibers of a BID layup would cause an immediate failure of the part. No, the load is transfered to the fiber by the matrix material. Test coupons cut from a BID layup orientated with the fibers will be stronger than test coupons cut with the fiber oriented at 45 deg. >This obviously isn't so. With BID, loads not >directly in line with the fibers are going to pick up a component of the >strength of both sets of fibers. Keep in mind, a load placed in line with >one set of fibers in BID will get no additional support from the other set of >fibers. This is true to a point, the way the load is transferred into the composite will determine the load sharing between the different orientation of fibers in the BID. An orthogonal load applied at the surface to failure will cause a composite to fail in shear between the layers of fibers. A load applied in the plane of the fibers and oriented in the direction of the fibers will fail in tension; and a load applied in the plane of the fibers, but not oriented in the direction of the fiber will initially fail when the fibers shift in the direction of the load as the matrix material fails, then fail in tension. All out of plane failures caused by a nonorthogonal load will be a combination of shear, tension, and matrix failure. >My main point was where the plans do not specifically call out BID >orientation, the part does not appear to be critical or there is enough >strength at any orientation to be sufficient for its purpose. I agree, and my point was that composite materials are not isotropic materials. I think my nickel has just about run out. Paul Krasa Long EZ 214LP !---*---! From: Epplin_John_A@90.deere.com Date: Tue, 3 Sep 96 09:41:15 -0500 Subject: COZY: Chapt 6 Bottom Laups One reason for two layers of UNI layed up +- 45 deg is to keep from having a bump formed by an overlap. Butt the edges of the UNI, do not overlap. This will not affect the strength of the finished lay-up. The two layers should be 90 deg. to each other and 45 deg from the principle direction of the part. If you try this with BID, you will have a bump caused by an overlap a discontinuous structure if you do not overlap. Hope this helps. John Epplin, building carry through spar still. je25272@hpmail1.90.deere.com From: Paul.Krasa-1@pp.ksc.nasa.gov (Krasa, Paul) Organization: Kennedy Space Center, FL Date: Thu, 05 Sep 1996 12:42:34 -0400 Subject: COZY: vacuum bagging Recently I was on a Berkut builders homepage and read that the flight structures are all vacuum bagged. Does anyone know how much wieght this will save, if there is any structural degradation or enhancement, and what is the bagging schedule? Since the wings and the canard are very simular to other canard type airplanes then this process should work for everbody. I looked in this years topics list and didn't see anything on the subject, but I have not checked last years topics yet. Paul W. Krasa Long EZ 214LP !---*---! Project Status: Closing up the wing roots. I think this is my last layup! Date: Fri, 06 Sep 1996 00:38:51 -0400 From: Jim Hocut Subject: Re: COZY: vacuum bagging I "bagged" most everything that was practical up thru fuselage construction (ch 8 ?). This included all bulkheads, the inside layups on the fuse sides and bottom, and a few other items I can't remember at this late hour. My assembled fuse weighed in at about 76 or 77 lbs, vs. about 85 lbs for a couple other builders that have listed their weights. I (my projdect) would have been a couple of pounds lighter except for repairs I've had to make along the way. So up to this point, I've saved about 10% in weight. My guess is that by bagging the canard and wings my total savings will be about 35 to 40 lbs. Strengthwise the parts seem to be about the same. I did a little bit of testing a few months ago, and the strengths were nearly identical except that the bagged parts exhibited catastrophic failure about 5 - 10 % before the non bagged parts. I don't think these results show a significant difference, probably within the limits of experimental error. In case nobody has noticed it before, I'm rather interested in the physical properties (srength) testing aspect of this. In case there's anyone around who hasn't seen my plug before, I'd love to supply some sample parts if anybody could spare a little time and has access to some decent test equipment. Jim Hocut jhocut@mindspring.com From: Paul.Krasa-1@pp.ksc.nasa.gov (Krasa, Paul) Organization: Kennedy Space Center, FL Date: Fri, 06 Sep 1996 08:34:51 -0400 Subject: RE: COZY: vacuum bagging Hi Jim, I'll take you up on your offer to test a set of test coupons. I have access to an Instron 1125 and an Instron 4507 tensile tester with the appropriate test fixtures for composites. Give me a call @ (407) 867-6015 during normal business hours or beep me any time at (407) 953-0402. We will need to talk about the appropriate shape for the test samples. If every thing works out we'll post the results for everyone. Paul Krasa Long EZ 214LP !---*---! Date: Fri, 06 Sep 96 10:11:37 est From: "Larry Schuler" Subject: Re: COZY: vacuum bagging Jim Hocut wrote: >I "bagged" most everything that was practical up thru fuselage construction >(ch 8 ?). This included all bulkheads, the inside layups on the fuse sides >and bottom, and a few other items I can't remember at this late hour. Jim, I have been doing a good deal of vac bagging also; am beginning chapter 6. How did you do bag on the fuselage bottom? >Strengthwise the parts seem to be about the same. I did a little bit of >testing a few months ago, and the strengths were nearly identical except >that the bagged parts exhibited catastrophic failure about 5 - 10 % before >the non bagged parts. I don't think these results show a significant >difference, probably within the limits of experimental error. This is news. Everything I had read prior to beginning this project indicated a strength improvement..... "IF" this 5 - 10% holds true throughout, wouldn't the operational envelope need to be changed (ie. lower G spec etc.)? Was stiffness affected? (I get concerned about flutter.) >In case nobody has noticed it before, I'm rather interested in the physical >properties (srength) testing aspect of this. In case there's anyone around >who hasn't seen my plug before, I'd love to supply some sample parts if >anybody could spare a little time and has access to some decent test equipment. Keep us posted on results...... Larry Schuler MKIV-#500 Date: Sat, 07 Sep 1996 12:20:40 -0400 From: Jim Hocut Subject: Re: COZY: vacuum bagging Larry Schuler wrote: > How did you do bag on the fuselage bottom? It was a little bit of extra work, but not bad. Lay the bottom in place like the plans show. Instead of building a "frame" to hold the shape of the fuse bottom stretch a string or other straight edge across the length of the fuselage as a reference. Take measurements of the distance from your reference to the fuse bottom every 6 inches, which will give you a chart from which you can cut a jig similar to the ones for the fuse sides. I made 3 such jigs, one on the centerline, and one on each side a few inches in from the side. The rest is very similar to making the forms for the sides. > This is news. Everything I had read prior to beginning this project > indicated a strength improvement..... "IF" this 5 - 10% holds true > throughout, wouldn't the operational envelope need to be changed (ie. > lower G spec etc.)? I had also heard about a strength improvement, but in the one set of tests that we did there was definitely not an improvement. When you think about it a little bit that makes sense, since it's glass fibers that give strength, and there are the same number of fibers in both instances. (Strength to Weight ratio would be greater though, since I saw a 17% decrease in weight). As for the 5 - 10 % decrease before catastrophic failure like I said, that's not much of a difference considering that we only ran one sample and that we were using somewhat crude equipment. > Was stiffness affected? (I get concerned about flutter.) Stiffness was identical in both cases. A plot of force vs. deflection for the two parts were absolutely the same. With Paul Krasa's offer to test some samples on real live lab quality equipment maybe we can expand our database of knowledge. Jim Hocut jhocut@mindspring.com Date: Thu, 12 Sep 1996 23:20:35 -0400 From: Jim Hocut Subject: Re: COZY: vacuum bagging Larry Schuler wrote: > > Just wondering if you had any mating problems when you floxed the > bottom in place? Did it turn out accurately enough? No mating problems at all, turned out darned near perfect (for once!). > > Also what are your thoughts about doing the outside bag? I'll believe it when i see it. I generally try to avoid statements such as "no way", but in this case I just don't see how it can be done (short of making a mold). I sure wasn't able to come up with any ideas that were workable. Jim Hocut jhocut@mindspring.com Date: Tue, 24 Sep 1996 08:52:14 -0400 From: william l kleb Organization: NASA Langley Research Center Subject: COZY: chap 3: stippling This is a multi-part message in MIME format. --------------1CFB3F54FF6 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit in reviewing the rutan/melvill composite construction video, i noticed a small thing: mike says brush stippling is not the dictionary definition where the brush would complete leave the surface between jabs, but that it should be a fairly gentle motion, with the brush never leaving the surface. --------------1CFB3F54FF6 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename=".sigeaa" --- bill kleb (w.l.kleb@larc.nasa.gov) 72 bellanca 7gcbc 9! cz4 -> aerocanard --------------1CFB3F54FF6-- Date: Sat, 12 Oct 1996 15:55:28 -0400 From: COZYMK4@aol.com Subject: COZY: Poor-mans vacuum bagging I use saran wrap on top of peel ply to get a drier layup without air bubbles. I dont' know where I first heard about this technique, but I have done a lot of parts this way and find them as good or better than regular parts. I will do a regular lay-up, like last night, on the outboard winglet side and then place pee-lply on it. The peel-ply won't wet out completely but then I cover the part with saran wrap and overlap joints by about one inch. Then, with a round wood-handled awl, I can start in the center and roll out all of the airbubbles toward the edges. This also milks out the resin rich areas toward the edges or into the more resin poor areas. I find that the furthest edge ends up with the excess epoxy and acts as the seal to prevent air entry. This edge is usually the one that is trimmed after cure. Rarely do I need to lift the saran wrap to place a few drops of epoxy onto a dry area. Usually a good squeege job in adavance prevents this. I do the rolling work with gloves off and the awl has never touched epoxy. A hole in the saran wrap is easily seen as an air source that spreads raiply along the fibers, but can be patched with a little piece. I haven't done any weighing or real testing of parts but I have been really proud of the smooth texture, complete lack of bubbles, and possibly lighter layups. When I brush on pure epoxy later, the clarity of the layup can be seen. This technique also allows me to peel-ply more layups with out worrying about dry layups under the peel ply. Nat had recoomened peel-ply whenever practical for reduction in sanding time and / or damage later. I spent an additional 15 minutes with the saran wrap and awl handle over what would have been a finished layup with imperfectly wet out peel-ply on this winglet. I am ready and waiting for any reasons why this technique is wrong, bad, poor, etc. ;-) Kevin Funk CozyMkIV #90 Date: Sat, 12 Oct 1996 16:12:59 -0400 (EDT) From: mahan@digital.net (Fred I. Mahan) Subject: Re: COZY: Poor-mans vacuum bagging Kevin said: I use saran wrap on top of peel ply to get a drier layup without air bubbles. I am ready and waiting for any reasons why this technique is wrong, bad, poor, etc. ;-) Kevin: Your technique looks spot-on to me. It's one of those simple, "why didn't I think of that" techniques. Wish I'd thought of it when I built my Long-EZ. I will use it in the future when a layup is too small to vacuum bag. Thanks! Fred in Florida Long-EZ N86LE Defiant 5% mahan@digital.net Carpe Diem Date: Sun, 20 Oct 1996 06:36:20 -0500 From: mbeduhn@mail.snider.net (Mark Beduhn) Subject: COZY: Plastic over peel ply After reading the recent posting regarding covering peel ply with plastic, I decided to try it and see how it worked. I did it on a large layup (wing) and it worked great! Rather than Saran wrap, I used a butt roll of stretch film that I got from work, but essentially it is the same - just wider and more clingy. After doing the layup, wetting out the peel ply and putting the plastic on top, I rolled the entire surface with an inking brayer (4" wide rubber roller). I started in the center and worked to the outside pushing out all the bubbles. This layup had absolutly no voids or dryspots. My other layups tended to lift in areas causing quarter sized voids (areas not bonded well to foam). BTW, I also hardshelled the cores. Mark Beduhn Cozy MK IV #494 finished skinning wings, now working on ribs and ailerons. Date: Tue, 22 Oct 1996 16:42:49 -0400 From: william l kleb Organization: NASA Langley Research Center Subject: COZY: knife trimming Tom Riley wrote: > I never liked the knife trim technique and always wait > for cure then trim with a hacksaw and file. i never liked either, until i learned a tip (from s hall who most likely learned it from j russell, who most likely learned it from ...) at the composite workshop at sun n' fun this year: simply use the same hair-drier that you use to lower the epoxy viscosity to aid in wetting-out layups/peelply to heat-up the excess glass/epoxy and the knife blade. trimming is nearly as easy as regular knife trimming. i have successfully used the "heated" knife-trim technique even after extended periods (weeks). i have found that i _cause_ delaminations if i am not careful doing any of the other post-cure trimming methods, eg, hacksaw, file, dremel, etc. however, with knife-trimming you should be careful not to "pull" the knife away from the foam while trimming. a slight downward* motion (towards the foam side) while trimming along an edge works well. simply trimming along the edge tends to bunch-up the glass if the knife is dull or the epoxy isn't quite to "knife-trim" stage. the slight downward motion alleviates this problem. *downward if the foam is laying flat and the glassed side to be trimmed is on the top. i definitely prefer the dust-less method of "heated" knife trimming to losing sleep (having to wake-up in the middle of the night to knife-trim) or delamination. i suppose the fein detail sander with cutting attachment might be a superior method, but i haven't figured out how to buy that yet. ;) --- bil kleb (w.l.kleb@larc.nasa.gov) 72 bellanca 7gcbc 9? cz4 -> aerocanard Date: Thu, 24 Oct 1996 09:54:33 -0700 From: Chris van Hoof Organization: C van Hoof - Architect Subject: COZY: knife trim Hi to all, my 0.02c on knife trim. Knife trim in this workshop only happens if the area to be trimmed is easily accessible, is timed not to lose sleep, generally the next morning, with a sharp knife - we cut only on the downward stroke and try not to disturb the part material (bend the cutoff away etc) However, we seem to do this very little so the alternative method used is , to let the part cure as much as poss. and then trim with a toothless blade in the jigsaw (you call it sabre saw i think) - found these blades in the hardware store on the specials shelf - they did not sell at all - its a Black & Decker part - superficially it looks toothless but closeup shows a fine abrasive edge, this seems to "heat" the part being cut and goes thru like a butterknife... they don't last very long - a blade cuts thru 5 layers (top of fuse. at longeron) for about 5 yards before its done/kaput. The lenght / time of use is of course proprotional to the amount of push administered. chris with Cozy #219 in chapter 8 Date: Thu, 31 Oct 1996 17:07:00 -0800 From: berkut@loop.com Subject: Re: COZY: Builder Tips >I've found it works best if I peel the clear plastic off the back and keep >the paper attached while I carry it over to the plane. It is real easy to >simply lay the strip in place, lightly stipple it down and then peel off the >paper. I then complete the stippling process and virtually always peel ply. > >Maybe this will be of value to some of the newer builders. > >Dick Finn >Cozy mark IV #46 >DFINN7971@AOL.COM We use aluminum foil instead of paper. It doesn't absorb resin, and when yo try to make a tape curve in 3D it will crinkle and take on the new shape, while the glass conforms. We often squeegee the foil and "squirt" excess resin or air out from under, then pull off the foil while it's still wet. -- Czech Sikhs! Richard Riley "The important things are always simple. The simple things are always hard." See the Berkut at http://www.berkut.com Date: Thu, 31 Oct 1996 10:06:18 -0500 From: DFinn7971@aol.com Subject: Re: COZY: Builder Tips In a message dated 96-10-31 05:00:11 EST, Rego writes: << Plastic bags flat on a table makes a nice wet out platform for tapes etc.( Ernie degovia, cape town ) >> Rego, An additional thought on wetting out tapes. I got ahold of a roll of plotter paper. I lay my two inch wide straight edge on it and draw parallel lines 2" apart for use as a template to cut out the strips. I then unroll some clear plastic food wrap that I bought at a restaurant supply store to use as a base for the layups. I cut a width of glass wide enough for all the strips (placed side by side. In other words, if I need five 2" strips I cut glass about 12" wide (10" for the strips and 2" extra to ease laying things out). After laying up the glass on the plastic I place the plotter paper template over the top and lightly squeegee it on. I can then cut out the strips by simply cutting along the lines on the plotter paper. I've found this yields nice tapes with minimal waste. I've found it works best if I peel the clear plastic off the back and keep the paper attached while I carry it over to the plane. It is real easy to simply lay the strip in place, lightly stipple it down and then peel off the paper. I then complete the stippling process and virtually always peel ply. Maybe this will be of value to some of the newer builders. Dick Finn Cozy mark IV #46 DFINN7971@AOL.COM Date: Thu, 31 Oct 1996 10:49:42 -0500 From: "David R. Kuechenmeister" Subject: Re: COZY: Builder Tips - Glass Tapes I've had very good success with using plastic wrap to make up the two inch tapes. One thing that shouldn't be overlooked is that these tapes are a very good way to use up scraps of cloth that just won't fit anywhere else. Just make sure the seams where you butt the pieces together don't line up from ply to ply. I think this is obvious, but not mentioned; it is a good idea to wet the area where the tape goes before it is applied and stippled. There doesn't need to be bunches of epoxy there, just enough to keep the area from being too dry. Regards, Dave Kuechenmeister Long-EZ #779 (770)528-7738 Atlanta, GA Date: Thu, 31 Oct 1996 10:52:57 -0500 From: HighPlane@aol.com Subject: Re: COZY: Builder Tips--template for tapes >>After laying up the glass on the plastic I place the plotter paper template over the top and lightly squeegee it on. I can then cut out the strips by simply cutting along the lines on the plotter paper. I've found this yields nice tapes with minimal waste. I do much the same thing, but with the cut lines pre-marked on a square of peel ply, which I lightly squeegee onto the layup I'm going to cut into tapes. That way, I've already got the peel-ply positioned, and can pretty much stipple the tape and peel-ply into place (with some minor adjustments) at the same time. From: Epplin_John_A@hpmail1.90.deere.com Date: Thu, 31 Oct 96 10:27:30 -0600 Subject: Re: COZY: Builder Tips - Glass Tapes I have a sheet of Melamine for the top of my cutting table. = I tape butcher paper over this, mark the tapes, usually several at a time with a fine felt point pen. Then cover with clear food wrap and tape this down, could use wax paper here if this is to be the last layer applied. Lay up the required layers and squeegee each layer out. You can easily see the markings through the complete lay-up. Cut on the lines and pick up the tapes, paper and all and press in place. Squeegee to remove trapped air. Strip off the paper, clear film and all. Peel ply if desired. For cutting, use a roller cutter from the fabric store. You have to dismantle these to clean, don't get acetone on the plastic handle, it will go away. After you use these cutters once, you will want to throw away any scissors you have. The Melamine is sacrificed in this operation, however it will last probably through at least one Cozy. John epplin Mk4 #467 Date: Thu, 31 Oct 96 11:50:44 EST From: MISTER@neesnet.com Subject: Re[2]: COZY: Builder Tips Dick Finn wrote: "I then unroll some clear plastic food wrap that I bought at a restaurant supply store to use as a base for the layups." I like to use aluminum foil instead of plastic wrap or waxed paper as a base for lwetting out the bid tapes. It works especially well for corner taping. I lay the glass up on the foil, cut it to the width I want, place the tape glass side down, squegee over the aluminum foil, remove the foil, then peel ply. Bob Misterka N342RM Date: Fri, 1 Nov 1996 13:50:02 -0500 From: DFinn7971@aol.com Subject: Re: Re[2]: COZY: Builder Tips In a message dated 96-10-31 12:15:56 EST, MISTER@neesnet.com writes: << I like to use aluminum foil instead of plastic wrap or waxed paper as a base for lwetting out the bid tapes. >> I think the aluminum foil would work better then the plastic wrap. Its stiffer and would peel off easier. I find that I often have to pick at the plastic wrap to pry loose a corner. In some cases on the long strips, it tears and I have to start over. Dick Finn From: Lee Devlin Subject: Re: Re[2]: COZY: Builder Tips Date: Fri, 01 Nov 1996 13:25:54 MST Dick wrote: > In a message dated 96-10-31 12:15:56 EST, MISTER@neesnet.com writes: > > << I like to use aluminum foil instead of plastic wrap or waxed paper as > a base for lwetting out the bid tapes. >> > > I think the aluminum foil would work better then the plastic wrap. Its > stiffer and would peel off easier. I find that I often have to pick at the > plastic wrap to pry loose a corner. In some cases on the long strips, it > tears and I have to start over. Instead of aluminum foil or the .5 mil saran wrap type food plastic, I recommend the clear polyethylene sheeting available at home improvement centers that comes in 3 or 4 mil thickness. It's cheaper per square foot than either aluminum foil or food wrap. You can find it in the paint section. Typically, it comes in rolls that will fold out to 20x25'. I use it to prepare all my corner tapes. Here's a posting I made on this subject about a year ago. It was in the topics95 'layups.txt' file. >From: Lee Devlin Subject: Pizza cutter and corner tapes Date: Tue, 28 Nov 95 9:07:50 MST Randy wrote: > One thing that caught my eye was a cutting wheel and the large thick > plastic mat that was graduated with all sorts of measurements and angles > that were used to cut the fabric. The wheel resembles a pizza cutter and > is VERY sharp. Does anyone have any experience using these tools to cut, > oh say,...fiberglass? I understand that you can buy different style > wheels to make wiggle cuts, or pinking cuts. Not having ever cut any > fiberglass, I was wondering if I should get my wife one for Christmas. :-) Yes, I have one and find it useful for cutting corner tapes. The method I'm about to describe is a variation of the one Nat describes except it uses polyethylene (not wax paper) on _both_ sides and a pizza cutter. A similar technique was described here some time ago using wax paper on both sides and created a huge discussion about the evils of wax paper. Cut some clear 3 or 4 mil polyethylene big enough to lay under and fold over the amount of fiberglass cloth that you need for tapes. Pour out epoxy on the polyethylene, lay the 2 plies of BID down in it and then fold the polyethylene over the top as well. This creates a sandwich of fiberglass and epoxy inside the polyethylene. Use a squeeqy to distribute the epoxy. Even vigorous squeeging will not disrupt the fibers and you can get excess epoxy out of the tapes by squeegying it away from the cloth if needed. Using a magic marker, draw parallel lines on top of the polyethylene with the correct spacing and slice it into strips with the pizza cutter. The strips now have a protective cover on both sides which makes them easier to handle for final fitting and trimming. Then peel one side of the poly off, put the tape in place, and peel the other poly tape off of the back. Lee Devlin Date: Sat, 02 Nov 1996 13:04:13 -0500 From: Paul Burkhardt Subject: COZY: Electric blankets We had a garage sale last weekend and my wife had an old electric blanket she was selling. It didnt sell and as an afterthought I thought It might make a good "layup warmer" during the cold winter months coming upon all (or most ) of us. I'm thinking of just placing some plastic wrap over the sticky part and laying the blanket over it. I wish I had thought of this when I did my wings. Has anyone else used this method? Any thought, concerns? Paul Burkhardt From: "James E. Marker" Subject: COZY: Aero Poxy & Micro Balloons (Questions) Date: Thu, 28 Nov 1996 14:08:45 -0500 I finally ordered the "Moldless composite sandwich construction" kit from Wicks and now I have two questions... 1) The microballoons were not sealed up and ended up everywhere in a nice thin dusting. Will this hurt the glass or the foam? I vaccumed it up, but it still seems to be everywhere. Should this warrant sending it back? 2) Instead of RAE slow (like in the picture) I got Aeropoxy PR2032/PR3660. Is this epoxy ok to use? Or...will I just make my confidence layup only to have it break too easily? P.S. The only difference between chapter 3 of the Cozy plans the moldless composite construction kit seems to be in making one repair. You still build the bookend and the confidence thing-a-bob. But in the moldless composite construction book they have you break (or cut) your confidence thing-a-bob and repair it to show how good the repairs are. ========================================================================== Jim Marker - jemstone@csra.net - http://www.csra.net/jemstone COZY Mark IV - Serial Number 0581 - Building Chapter 3. http://www.csra.net/jemstone/cozy.htm Date: Mon, 02 Dec 1996 17:52:33 +0000 From: Jnik Subject: COZY: Re:Aero Poxy& Micro balloons (SNIP) > >2) Instead of RAE slow (like in the picture) I got Aeropoxy PR2032/PR3660. > > Is this epoxy ok to use? Or...will I just make my confidence layup only > > to have it break too easily? > > I've never used the Aeropoxy, but again, for the practice layups, I can't > imagine that it makes any difference at all which laminating resin you > use. The idea is just to get used to the techniques of mixing and > spreading, and checking for wet-out and air bubbles. This is almost > identical no matter which epoxy you use. I'd also be very surprised if > there was a substantial difference in the layup strength after curing. > > Just make sure that when you actually begin building, you get the epoxy > you decided you really want to use. > > -- > Marc J. Zeitlin Email: marcz@an.hp.com I disagree slightly with the above statement. Different epoxies have somewhat different properties, such as viscosity, ability to wet out a layup etc. I think that if you are going to practice, you should practice with the stuff that you are eventually going to use. May not be a big difference, and any practice with any kind of epoxy is worth while, but why get used to two different systems. I have used three different epoxy systems in the past and I had to adjust to each. John Meernik From: Marc J. Zeitlin Subject: COZY: Aero Poxy & Micro Balloons (Questions) (fwd) Date: Mon, 2 Dec 96 16:59:19 EST Jim Marker wrote: >1) The microballoons were not sealed up and ended up everywhere in a nice >thin dusting. Will this hurt the glass or the foam? I vaccumed it up, but >it still seems to be everywhere. Should this warrant sending it back? For the bookend layups and other practice layups that you're going to do, this is not a problem - you're just getting used to the ideas of laying up foam, micro, glass, and epoxy. In the future, try to keep your microballoons double bagged in plastic, and be _real_ gentle with them. On "real" structural layups, it's a good idea to brush off and vaccuum everything _really_ well before applying the microballoons, just to ensure that the micro actually contact the foam, and not dirt and crud. I will say, however, that on the porous foams, the micro has _always_ stuck well for me, even if the underlying foam was, how shall we say, less than pristine :-). >2) Instead of RAE slow (like in the picture) I got Aeropoxy PR2032/PR3660. > Is this epoxy ok to use? Or...will I just make my confidence layup only > to have it break too easily? I've never used the Aeropoxy, but again, for the practice layups, I can't imagine that it makes any difference at all which laminating resin you use. The idea is just to get used to the techniques of mixing and spreading, and checking for wet-out and air bubbles. This is almost identical no matter which epoxy you use. I'd also be very surprised if there was a substantial difference in the layup strength after curing. Just make sure that when you actually begin building, you get the epoxy you decided you really want to use. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Tue, 17 Dec 1996 21:17:38 -0500 From: INFINITY Aerospace <72124.347@compuserve.com> Subject: COZY: Filler Hi to All, >Bill Kelb wrote:< >maybe the filler poses a durability problem in areas like the landing gear cover or the landing brake?< I use a little flox mixed in with the filler (I usually use Polyfair F-26) on all airfoil leading edges, and around access doors, speed brake, etc., to toughen up possible high impact areas (from bugs, rain, luggage, etc.). FYI, this idea came from Roy Bailets of Bailets Composites. HTH. Infinity's Forever, JD