One of my carbon fiber shanks came out floppy. The other was fine.
I’m redoing the floppy one.
I used a scale to mix epoxy and hardener for the good shank the first time, but not the bad one. So I made sure to measure out again for the replacement.
I also used quite a bit more epoxy for the successful shank than the failed one. I went generous with epoxy again for the replacement.
Definitely need to get those ratios correct for epoxy.
There are other resins where you use a base resin and then a catalyst. In those cases, the ratio can drive the reaction speed, but aren’t as critical for a proper cure.
Another thing that can cause those issues is insufficient mixing. Also a good idea to have a second, clean mixing cup. Pour your two parts together into one cup and mix thoroughly. Then, pour that into the second clean up and mix again. That prevents issues where you have unmixed buildup on the walls that gets integrated later when you’re scraping out resin.
As far as excess resin, you generally want to go the other direction. Hand laid up composites will always have more resin than ideal from a strength standpoint. You’ll get better performance the more you can reduce the excess resin.
Great tips! I appreciate the mixing.
I’m optimistic I got mixing right…by manually stirring and scraping with a popsicle stick for five minutes straight. I probably overdid the amount of epoxy, but I did end up squeezing a lot out to the sides by pressing on the stack once laid up. Hopefully what’s left when I trim edges is mostly fiber.
You would be amazed how much some of that unmixed stuff will stick to the walls of the cup.
With wet layed up composites, it is pretty much impossible to get enough epoxy out. Once you get the air bubbles out so there aren’t dry spots, get everything out you can.
I decided to buy some more generic cork sheet for filling from Amazon. But this time, I went with thinner ¼” sheet, and also with peel-and-stick backing.
I have found that I’ll need to double up and sand down for some areas. But overall, just being able to peel and stick was way more convenient.
