Tweeks - my replies are inline<br><br><div class="gmail_quote">On Mon, Dec 31, 2012 at 3:52 AM, Thomas Weeks <span dir="ltr"><<a href="mailto:tweeksjunk2@theweeks.org" target="_blank">tweeksjunk2@theweeks.org</a>></span> wrote:<br>
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<p style="margin:0px;text-indent:0px">First, why do people use fiberglass on the body tubes on high power rockets?</p><p style="margin:0px;text-indent:0px"> </p></div></blockquote><div><font color="#000099"><font color="#cc0000">Main reason is to create a stronger </font><font color="#cc0000">airframe, </font></font><font color="#cc0000">Under extreme G loads, cardboard can buckle and even fold over. Another advantage is that the tubes won't ding or crush during transport and it makes it easier to get a smooth finish - without spiral seams.</font></div>
<div><font color="#cc0000"></font> </div><div><font color="#cc0000">I built my workbench with drawers that are 50" apart so i can but a rod or even a rail segment between them and glass a tube. In the past I build a rotisserie and still have the motor, gears, belt, pillow blocks, etc. I made the frame out of 2X6 but would like to get some 80/20 aluminum to make one with. I only used it for adding a finish layer of epoxy and preventing drips.</font></div>
<div><font color="#cc0000"></font> </div><div><font color="#cc0000">I've only used West Systems or other higher quality/non hobby shop epoxy. I haven't looked for a local source but I know severaql places to get good quality epoxy at a good price.</font></div>
<div><font color="#cc0000"></font> </div><div><font color="#cc0000">West Systems calls for acetone for diluting epoxy and that's what I've used in the past. I've also never tried to glass tubes less than 3" so you done good if you got a 2.</font><font color="#cc0000">56 tube glassed. Biggest pain for me was getting the glass started straight. I started using a thin strip of double sided tape. This lets the glass get lined up straight and keeps it from moving.</font></div>
<div><font color="#cc0000"></font> </div><div><font color="#cc0000">Weight of glass depends on what you are glassing the larger the tube the heaver the glass. Start with veil cloth or 2 oz cloth for under 3" tubes. For 4" tubes i use 4oz, and 8oz for larger sizes. I usually use a single piece and do 2 layers. I also take between 1/2" to 1" of the weave that would be along the long side of the tube to p</font><font color="#cc0000">revent them from coming lose while laying up. This also helps to fair in or taper the end of the glass seam. </font></div>
<div><font color="#cc0000"></font> </div><div><font color="#cc0000">West Systems has some good reference material for cure times, additives, diluting, etc. They also discuss the different cure stages and this is very helpful. Trimming the ends should be done while the epoxy is in the leather stage when it can easily be trimmed with a sharp knife. I would rather not try to document everything here but i am happy to help anyone. One final tip I heard is that if you spill any epoxy on the carpet, mop up what you can and then use baby powder to soak up the rest from carpet fibers. Otherwise you will have a huge problem.</font></div>
<div><font color="#cc0000"></font> </div><div><font color="#cc0000">Hope this helps some</font></div><div><font color="#cc0000"></font> </div><div><font color="#cc0000">Bob</font></div><blockquote style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid" class="gmail_quote">
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<p style="margin:0px;text-indent:0px">Well, after reading how other flyers who have launched my same "LOC Hi-Tech"rocket on full J motor but have seen them shred when passing mach-1 -- I I decided it best to go ahead and glass my new 2.6" (diameter) bird:</p>
<p style="margin:0px;text-indent:0px"><a href="http://www.rocketryforum.com/showthread.php?36225-LOC-Hi-Tech-shred-J350" target="_blank">http://www.rocketryforum.com/showthread.php?36225-LOC-Hi-Tech-shred-J350</a></p>
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<p style="margin:0px;text-indent:0px">Well, not being that experienced with fiberglassing myself (having only done it one other time), I was looking for some really good tutorials on youtube and surprisingly didn't come up with that much. So I juts proceeded with what little I knew. Wow.. I learned some hard lessons/tips that I'll share further down.</p>
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<p style="margin:0px;text-indent:0px">But first.. </p>
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<p style="margin:0px;text-indent:0px">MY QUESTIONS:</p>
<p style="margin:0px;text-indent:0px">Q: Anyone here have any good tricks-n-tips or HOWTO videos, links, etc they would suggest?</p>
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<p style="margin:0px;text-indent:0px">I still have some specific rocket glassing questions on:</p>
<p style="margin:0px;text-indent:0px">* the recommended use of alcohol for thinning the epoxy</p>
<p style="margin:0px;text-indent:0px">* what weight of glass-fabric to use</p>
<p style="margin:0px;text-indent:0px">* when to use > 1 layer</p>
<p style="margin:0px;text-indent:0px">* can you glass a plastic nose cone? (if so, how?)</p>
<p style="margin:0px;text-indent:0px">* final finishing tips (top coat? sanding/wet sanding, etc)</p>
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<p style="margin:0px;text-indent:0px">MY TIPS:</p>
<p style="margin:0px;text-indent:0px">A few fiberglassing tips (aka lessons) I have to share after learning them the hard way today are:</p>
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<p style="margin:0px;text-indent:0px">1) Epoxy Cure Time is Critical:</p>
<p style="margin:0px;text-indent:0px">BE SURE to check the set-time of the epoxy BEFORE you start mixing and applying the epoxy and glass fabric. Never use 5min epoxy. 15 is ill advised. Use 30 or even 60 minute for more time to do a good job! I decided to use up the last of my old 15-minute epoxy today for this project, and BARELY rushed and got it all smoothed out before it setup on me. </whew!> I had t oadd more alcohol TWICE to keep it from prematurely setting up on me! I later used finishing epoxy on another part of the rocket, but I hear that "West System" is the best epoxy to use for nice HP rockets:</p>
<p style="margin:0px;text-indent:0px"> <a href="http://www.westsystem.com/ss/" target="_blank">http://www.westsystem.com/ss/</a></p>
<p style="margin:0px;text-indent:0px"> (Bob?)</p>
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<p style="margin:0px;text-indent:0px">2) Set Up A "Glassing Station":</p>
<p style="margin:0px;text-indent:0px">Set up a nice glassing station like this, as it helps immensely:</p>
<p style="margin:0px;text-indent:0px"> <a href="http://www.facebook.com/photo.php?fbid=3602061510552&l=706a387e07" target="_blank">http://www.facebook.com/photo.php?fbid=3602061510552&l=706a387e07</a></p>
<p style="margin:0px;text-indent:0px">Once you have the epoxy mixed, glass fabric half applied, body tube balanced on a broom stick, and epoxy starting to gel... it's too late to try to set something up. ;) I found that I could use the box that the vendor shipped my rocket in, as it was juuust the right size. :)</p>
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<p style="margin:0px;text-indent:0px">3) Alcohol for Smothing out Bumps:</p>
<p style="margin:0px;text-indent:0px">As you finish hte last few inches of glassing a BT, quickly start turning your work looking for bumps, lumps, globs and stray glass threads before it gets too tacky to fix them! Wet your gloves liberally with alcohol and "smooth" the surface, rub off any lumps or bumps, work out air bubbles and ensure the ends of body tubes are wrinkle free.</p>
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<p style="margin:0px;text-indent:0px">4) Rotate Piece Until Set:</p>
<p style="margin:0px;text-indent:0px">Keep turning your project until it has mostly gel or set. Otherwise, you can get pooling and drips (that will need to be sanded off later) nad lopsided coverage. I have heard of people reprovisioning motorized rotisseries for this purpose.</p>
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<p style="margin:0px;text-indent:0px">Anyone else?</p>
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<p style="margin:0px;text-indent:0px">Tweeks</p>
<p style="margin:0px;text-indent:0px">p.s. I know that fiberglassing is a specialized area of knowledge for Bob (who just rolled back into town).. so I am half hoping that he'll share something useful. :)</p>
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