One again instead of focusing on school work and finals this week I have let my mind drift to bow making and here is the question I have for everyone... I use Smooth On EA-40 for everything and as I have become a slightly better woodworker I have started getting more creative with my risers. My latest riser requires 2 separate glue ups for the riser and then a final glue up for the entire bow. Has anyone had any problems with subjecting a EA-40 glue joint to 2-3 runs in the bow oven? I have not had a problem yet but I see how it could be a problem. Has anyone ever done anything like let all the riser glue ups cure at room temp. for 24hrs then doing a final cure when you cook the entire bow? Any advice or how others do this would help me get back to studying and stop thinking about this... that last part may be a lie but hope to hear some opinions.
Most of my multiple riser glue ups have been done without curing them in the oven (unless you count putting them in my truck cab when it's hot out). As long as your riser is clamped in some fashion- you won't have any problems with the glued being heated multiple times.
I bake my risers at 140 degrees and the bows at 180 degrees, even after multiple times in the oven I've never had a riser fail.
I would think one should bake the riser at a high temp. and then the whole bow at a lower temp? Bue--.
Alright, I now want to expand on this question... The Smooth on web site says "EA-40 Clear Epoxy is an unfilled low-viscosity epoxy adhesive that can be spread easily in thin films that are almost transparent after curing. Mix ratio is 1:1 by volume. When mixed 2A:1B by volume, EA-40 will achieve greater heat resistance and improved physical properties." currently I am mixing at a 50:50 ratio what do you do?
I've cooked several times on a riser, and I mix 50/50. No troubles.
I mix 50/50 and cure my risers 4 hrs @160-180 degrees. After glue up I repeat the same. Never had a problem. Once by mistake I cooked a riser 8hrs @210 degrees and it is still alive and shooting on the bow.
I have cooked them and not cooked them before glueup no problems either way.
smooth-on states that curing at room temps --then cooking improves the glues performance --i like to cure riser glue-ups at room temp then cure the whole bow at 165*-for 6 hrs--although the stuff is very forgiving