DIY CNC Milling Machine From Scratch

**Lee Roberts** · 02-07-2014

Originally Posted by charlieuk

I would be very carfull filling anything like that with that much epoxy and when it cures it can produce a huge amount of heat and contained in a metal tube you could have a small disaster on your hands. If you do want to do this make sure it is extremely slow curing and if anything put some bags of ice around it to keep the heat down and only do a little at a time.

Thanks for the heads up Charlie, is it really that bad?

.Me

**charlieuk** · 02-07-2014

Originally Posted by Lee Roberts

Thanks for the heads up Charlie, is it really that bad?

.Me

depends exactly on the epoxy but yes especially in warm temps, if you left a cup of epoxy to cure on its own you would be surprised how much smoke it can make! its a exothermic reaction so when if heat starts to build its a chain reaction and just gets hotter and hotter and will quickly turn into a smoking and bubbling mess. Ive never had flames but have heard of it. It all so doesn't make any different if you have some sort of filler mixed in with the epoxy so less actual resin to fill the space it will still have the same effect. As i said small quantities a bit at a time in a cold temp is your safest bet.

**Ger21** · 03-08-2014

Originally Posted by charlieuk

depends exactly on the epoxy but yes especially in warm temps, if you left a cup of epoxy to cure on its own you would be surprised how much smoke it can make! its a exothermic reaction so when if heat starts to build its a chain reaction and just gets hotter and hotter and will quickly turn into a smoking and bubbling mess. Ive never had flames but have heard of it. It all so doesn't make any different if you have some sort of filler mixed in with the epoxy so less actual resin to fill the space it will still have the same effect. As i said small quantities a bit at a time in a cold temp is your safest bet.

You don't want to fill it with just epoxy, as that won't dampen anything. You want an epoxy-sand mix, with ~10-15% epoxy. You need a thin, slow setting epoxy to get enough working time. The sand will keep it from getting hot.

I've mixed up a cup of epoxy sand, and it doesn't get hot at all. A cup of plain epoxy, on the other hand, will exotherm and get very hot in only a few minutes.