Epoxy cure time

[DC]

I use West 105/205 epoxy for my boo backing and splicing. It cures hard in 6-8 hours and reaches max strength in 1-4 days. I'm wondering if it's strong enough after overnight to start tillering. By strong enough I mean is there any chance the epoxy may be creeping a tad and contributing to "set". I've made a dozen or so of these bows and I've never had any problems but they have all taken a bit of set and I've wondered if I some of it is the glue creeping. It's easy enough to wait a couple of days but I'd rather not if I had my druthers. Maybe one of you guys that make laminated or glass bows have more insight into this than me. Do you jump right in to tillering the next day or do you wait for max strength? Do you have any evidence that it creeps in the early portion of curing if stressed?

[bradsmith2010]

im guessing it would,,

[Buckeye Guy]

temp varies time greatly
west should have a table for finding what you want to know

[willie]

dc

epoxy just gets slowly harder until it reaches its max hardness, doesnt kick off or cure suddenly like some others. your concern is warrentented, but I would think that if the lams were slipping then you would have something that looks like set because the relaxed limb parts would be reoriented, so that could mean the belly was actually not overstrained, and the bow could be reshaped with reverse slipping if done in time.... the "fg" pros use a hot box for a reason

all about time and temprature as buckeye guy sez

[DC]

I got the info in the first post from their site. There is nothing about if it will creep in the first few hours. I'll wait a couple of days. Better safe than sorry. I just thought someone on here might know.

[simk]

i think its all about temp/management when using epoxy. i dont know your specific products but most epoxies can be cured on higher temps in a few hours in a heat box. on room temp they need much longer. little too cold makes big difference in time. if your temp/time-management is unprecise better safe than sorry seems a good strategy.

[bassman]

2x

[Badger]

  I used West Systems when I was first starting out over 20 years ago. For some reason none of the glass bow builders use it and I am not sure why.

[PatM]

Because by itself it's not really a bonding epoxy.  It's all purpose leaning towards being used to wet out fabrics mainly.

[avcase]

I used West Systems Epoxy for the first time after experiencing a number of failures with a newer batch using my old standard epoxy. The West epoxy worked out very well.  I used some moderate heat (140-150 deg F) to achieve a full cure in a few hours. The bow did eventually fail, but it was due to a shear failure through the core material and not a bonding failure.  The bow was a pretty extreme flight bow design, so the core failure was not a surprise.

With epoxy, I haven’t had an issue with the glue joint creeping under load. It seems to either delaminate completely, or hold.  I have had issues with tightbond 3 glue joints creeping, especially if I don’t give the bow generous time to cure and lose the moisture introduced. It is easily detected when this happens because little ridges can be felt between the laminates at the tips where the laminates slid a tiny bit relative to one another.

Alan

[DC]

It is easily detected when this happens because little ridges can be felt between the laminates at the tips where the laminates slid a tiny bit relative to one another.

Alan

That's a good tip. I've never felt that on my bows so I guess I'm good. This one has had three days now.

[willie]

Because by itself it's not really a bonding epoxy.  It's all purpose leaning towards being used to wet out fabrics mainly.

you are referring to the the base resins of course. even though the boatbuilding companies market specialty adhesives formulated with thickeners, the boat builders usually buy a base resin in large quantities and mix their own additives for thickening as the job dictates. a bow building shop would not need to buy in such quantity, and therefore would typically prefer to buy something preformulated to their needs.

I have experienced creep with less than fully cured epoxy. Inconsistent cure times occur when the mixing proportions vary too much, and getting the correct proportions become more difficult when using small amounts measured by volume or in containers that retain unmixed portions on the container walls. my results improved when I started mixing by weight.  use a piece of saran wrap to cover a  gram scale. and mix a generous amount that will not find you scraping the container for that last little bit, and of course, mixx well, then mix again. a little cabosil is worth having around if you buy enough for different jobs

[PatM]

Yes.  It is easy enough to customise the mix with thickening agents and even adding a bit of G flex to the mix but you can just buy the finished product.

 West 610 is great stuff for bows.

[bownarra]

An email for a datasheet will do it I'd also contact their tech department for any specifics not mentioned in the datasheet.
Glass bow makers don't use West epoxies because EA40 is essentially perfect for glass bows. Why jump ship and test other glues with potentially fairly large amounts of money and effort to test it out. I've tried using various other epoxies on glass bows all with varing degrees of regret at not using EA40. It takes some beating and Smooth-On  know it Hence the price/profit margin.

[PatM]

   However Smooth On  started putting out bad batches which made a bunch of people jump ship. 
  There really is plenty of very good epoxies out there.