Hi, Thanks again for the information.sammer wrote:This is where the "read more" comes in.Bloefeld wrote: It appears to me that Forrest is no longer making QCM and I certainly could not find any information on it from their site. They make coatings now.
Thanks a ton for your insight. I am hoping to come up with a superior formulation that I can make cheaper than what everyone is paying and pass the saving I get by buying in big quantities onto the home build group.
Cheers,
Bloefeld
Forrest recently acquired QCMs epoxy division.
The reason you can't find anything online is it's still too new.
I've tried a couple QCM formulas and find them too thick with out warming them up.
I've had great success with West systems epoxies as they are less viscous and wet out way quicker ( but twice the price of QCM)
I work in my basement where the temp is a constant 12c
Vacuum does not produce enough pressure to push epoxy into the fabric.
QCM will pretty much just puddle on top. I've tried this.
You have to get your glass wetted out completely or you end up with dry glass. Granted I can only heat to around 140f.
Most of the bubbles I get in my layup come from trying to push the epoxy into the fabric.
I gave up using a squeegee or spreader and now use my hand as it doesn't cause the cavitation.
I would love a 300-500 cps epoxy. Something that flows like water into the fiber. Wet out would be so much quicker and more complete.
Not to offend,
I do believe you are an epoxy expert, I also believe you know a shit ton about composites.
But build a ski in your home, in a reasonable amount of time and investment, go ski on it for a couple days, then come back and tell us what works best.
Can't wait to see the product.
sam
Maybe I should phone Forest. Among the last posts on the topic of QCM was they people at Forest said they would not be continuing with QCM and that was that. Their site reflects that and thus my not unreasonable assumption that they were selling off the last of their stock and it would not be or was not commonly available.
With all due respect, your opposition to vacuum is unfounded. Almost all wind blades are made by vacuum infusion. I mean hundreds of millions of tons of glass and resin used each year and every day to make blades up to 60 meters long.
I have made thousands of balsa cored panels 14 feet by 7.5 feet by 4.5 inches thick in the past 5 years with vacuum infusion.
Vacuum, even when pulled on pre-wetted cloth is the easiest way to get great resin/fiber ratios; crucial in making strong and durable parts.
You should read my previous post a bit more closely about using epoxies designed for compression molding. With your ability to heat to 140 degrees, just spreading the epoxy on the top of the glass and not worrying over much about trying to squeeze it in is exactly what you should be doing. Then put the whole thing under 40 to 45 lbs (in your temperature case) and the epoxy will wet-out the resin completely. Again I recommend a good post cure heat if you can build a hot box. At 140 the epoxy is not coming close to its Tg (Glass transition temperature) and is not fully curing. I would at least leave them in the hot press for a week or so.
I have done some compression molding, not enough to be an expert, but we were using 90,000 centipoise epoxy and it still wet out the fabric. We used a lot of pressure and heat too, but our goal was to make the part in less than 5 minutes and to tolerances in the 0.005 range. We failed.
Have you tried rollers to spread your epoxy and get rid of the bubbles.
http://www.fibreglast.com/category/Supplies_Tools
Fiberglast has loads of good stuff too.
I understand where you are coming from. My goal is to build a better ski than I can buy. I have some ideas about fiber direction and types that will be unusual.
I believe that I should probably build a heated press and a hot-box to get as close as I can to perfect cures.
I no longer have my Skunk Works, so I will have to rebuild a lot of my jigs and test fixtures to get me going. I will have to park my old Honda on the street and take over my garage to do this, or go nuts and rent some space.
When I have read as much as I can from this site, and torture good fellows such as you for information ;-) I will then build some skis. So I see this happening next fall with testing in December. Then I will keep doing iterations until I get it right.
Let the pressure and heat do the work for you on your wet-out. Weigh the epoxy and resin to make sure you get less than 40% resin weight. Then make up a pair the way you normally do, but don't pound in the resin, just spread it evenly. Heat them as much as you can or for as long as you can. Cross-linking will continue for a really long time. Do this and I am sure you will get a better feeling ski and at no cost.
When I get my epoxy thing sorted out I will sent you a couple of gallons to try and see what you think.
Thanks for all of your help, you have made me think a lot about the entire ski building issue and have given me some great advice. I appreciate it a lot.
Cheers,
Bloefeld