Dienqtran,
For your model airplane wing design, check out season 8, episode 5 of how its made on the discovery channel (the model jet episode). They discuss the procedures for bonding wings and the design of flaps in the initial layup that are trimmed post cure. You should be able to find on...
Why not try making a reusable bag from silicone instead of a normal vacuum bag. The brushable silicone from smooth-on works real well. Brush a few layers over your mould and you have a vacuum bag with the exact contours of your plug. Since you are doing wet layup you don't have to worry about...
Thank you to each of you for your suggestions. I was hoping to not have to work with a polyester or vinyl ester due to the color, the styrene smell, and the mekp catalyst. I am doing infusion so viscosity is a concern. I have been searching for a solution for about 6 months. This week I was...
Ingear,
Try the silicone from Smooth-On. They are at www.smooth-on.com. I have used the silicone that they specify for moulding as well as their dragon skins 10 minute. The ten minute is colorless and quite elastic but does run a little bit. The material for mould making is green and more...
Hello Everyone,
I am looking for a room temperature curing epoxy that will not degrade in the 160 to 220 deg F temperature range. Something in a colorless epoxy with a viscosity less than 700 for RTM. I have been using several of the 2:1 epoxies and they have been working well for other...
Chris,
I have a couple of countersinks in my mould where I put screws to mount the part. I will sometimes get a few bubbles at the top of those, but fortunately I drill those out. I figure it may be bubbles from not degassing the resin and since the countersinks are the high points they end...
I would like to thank Chris for starting this thread and everyone that contributed because you led me on a path to some discoveries about my techniques. My setup is very similar to the one that Chris initially described with the exception that I use a 12 CFM pump connected to a resin trap with...
I had one more insight to try. After infusing and clamping off the infusion tube try elevating the tube so that it is higher than the part. If you clamp so that some resin is in the tube after clamping and you don't have an air leak the bubbles will migrate to the top of the resin in the tube...
We seem to have a problem. That everyone is facing so it might be best to try to apply some scientific testing to this. I would propose some systematic testing to try to pinpoint the problem. Here is a rough idea of what I am thinking:
Bubbles caused in the resin/epoxy matrix could be caused by...
A good resource to these problems is Resin Transfer Moulding for Aerospace Structures by T. Kruckenberg and R. Paton, ISBN 0 412 731509, Chapter 13 page 438 "Defect Formation"
Chris,
Glad you figured it out. It may just be a problem with vacuum vs mass of the epoxy in your part. Trying to relate this to some avenue of science to explain what you are seeing would be nice but beyond the scope of this forum. I did not shoot my part with the degassed epoxy as it took...
Chris,
I believe I have the answer for you. I use a similar epoxy to the one you described. I have made hundreds of parts without experiencing the problem you are having...guess what...I don't degas the epoxy.
I tried a test today and degased the epoxy..and guess what happened? The epoxy was...
Chris,
I would suggest going back to basics to determine a few things first. 1) Figure out if you are vacuum boiling the resin. To test this I suggest doing a traditional wet layup.
Try This.
1) Layout your tacky tape perimeter and cut the appropriate vacuum bag to fit.
2) Cut a few layers...
B.E.,
I was wondering right after I submitted the post if you were referring to using two layers of vacuum bags. Neat idea. I wonder if it wouldn't be easier to vacuum the outer bag and use positive pressure to infuse. Probably a whole different set of problems with that as well. Thanks for the...
Chris and B.E.,
First, good luck Chris with the new setup. Make sure you keep some resin on the backside of the feed tube clamp after infusing. It helps seal off air. Timing the clamp off is important. With practice you will learn to clamp a little early to let the resin wetout and the vacuum...
