Epoxy and heat

RocketQ

RocketQ

It's Not Rocket Science
Silver Member
Any one have some thoughts on the strength of epoxy once it is heated after cure? If you sweat a pin out does the new epoxy have as much bite into the stuff that got hot as opposed to into wood? Something I was pondering on my way into work this morning.
 
I'd think that if you were to go through the motions of re-drilling/tapping the hole, the new bond would be very close to the original's strength. Basically, the purpose for re-D/T is to accurately clean-out the hole of the wasted epoxy. The residual of the original that has permeated the wood hasn't penetrated too deeply before it set-up and may have been partially protected by the insulating properties of the wood itself. It's important that you only use the minimal amount of heat that you need for the job. NEVER remove a pin with heat that's set in phenolic. The phenolic will expand and you run the risk of splitting whatever is encasing it.

FWIW, I remove pins/inserts that are set in wood quite often and haven't experienced any problems. When they're set in phenolic, it's a different story. These must be bored out. Carbide tooling is your friend.
 
Thanks...
I just was thinking about it. Never did any testing on what the heat does to the epoxy after it has cooled and reset.
 
I only have limited experience with taking pins out. Everytime I plugged redrilled and tapped. I would imagine if you heated the pin and took it out then let the cue sit overnight. You could run a tap back throught to clean out as much of the old stuff as possible. Then new epoxy with new pin. That's how I would approach it.
 
Epoxy

Once you heat the epoxy hot enough to release, it it shot. If you reinstall the pin, you had better do a really good job of cleaning out the old epoxy.
It has no sturctural strength. Some structural epoxies release/breakdown at some surprisingly low temperatures. You can usually find it out if you dig deep enough in the specifications.
 
That's what I always thought. I've heard of heating epoxy in the microwave to help it cure but I wouldnt try it. Defeats the purpose of the long setting epoxy.
cutter said:
Once you heat the epoxy hot enough to release, it it shot. If you reinstall the pin, you had better do a really good job of cleaning out the old epoxy.
It has no sturctural strength. Some structural epoxies release/breakdown at some surprisingly low temperatures. You can usually find it out if you dig deep enough in the specifications.
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dave sutton said:
That's what I always thought. I've heard of heating epoxy in the microwave to help it cure but I wouldnt try it. Defeats the purpose of the long setting epoxy.
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Based on experience with speed-setting high strength epoxy (typically 4 hour set time, 24 hour cure time, at room temp) for golf clubs, you can accellerate the set time considerably with little heat, and you lose little shear strength as a result. We're talking about increasing the temp to perhaps 40C (100F) to get a set time of 45 minutes (rather than 4 hours) with perhaps a 10% - 15% reduction in shear strength (still WAY higher than fast-set epoxy strength). We used a string of christmas lights with a 7 watt bulb under each club head, not much heat but a great benefit in time. Just a data point for what it's worth.

BTW, these same epoxies break down at about 300C iirc. When broken down it turns into an opaque white powdery/crumbly mess, and I don't think it would be good to try to re-glue anything to that crap.

Dave
 
I have been searching on this and have found little information. I am using West system with 205 hardener. As all epoxies are not created equal. If heat melts the cured epoxy in the wood wouldn't the best practice be to bore larger than the deepest thread, plug, drill, rebore and tap? Just picking brains here.
 
Studied an adhesive specification book thicker than Webster's dictionary, my days making custom fitted sets of golf club , no brainer ... My take is the slower the cure the stronger the bond because the catylist at quicker set times causes the material to have less elasticity and therefore more brittle ... CA glues and fast cure epoxies under electron microscope look like broken glass when failed ,where the slow cure epoxies exihibit much less of the fracturing... Heat destroys the integrity of the molecular bond , so don't glue to old epoxy because the bond will only be as strong as the old epoxy ... I've replaced many pins and a little glue left behind don't hurt ... But using a heat gun to speed up cure will weaken bond by making it more brittle ... Hope this helps a little ...:cool:
 
Eric Wynne said:
Studied an adhesive specification book thicker than Webster's dictionary, my days making custom fitted sets of golf club , no brainer ... My take is the slower the cure the stronger the bond because the catylist at quicker set times causes the material to have less elasticity and therefore more brittle ... CA glues and fast cure epoxies under electron microscope look like broken glass when failed ,where the slow cure epoxies exihibit much less of the fracturing... Heat destroys the integrity of the molecular bond , so don't glue to old epoxy because the bond will only be as strong as the old epoxy ... I've replaced many pins and a little glue left behind don't hurt ... But using a heat gun to speed up cure will weaken bond by making it more brittle ... Hope this helps a little ...:cool:
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tap tap tap
rep point to you sir.
 
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