[abender]

Love all the builds on this forum! Recently made a video going over my process to make an epoxy granite machine base, check it out:

https://www.youtube.com/watch?v=4aBVAbfxLJw&t=2s

I built an aluminum skeleton into the frame to help increase the stiffness of the unit. Took a few tries to get everything right, but I really like the way it turned out.

[fostereast]

Great video! Thanks for sharing.

[abender]

Thanks, It was a fun build!

[burbingus]

That was really informative. Thanks for all of your work putting it together!

[Goemon]

Just a few things to add on epoxy granite. I have a lot of experience with epoxy and composites from my day job....

First, on the mold release, epoxy will not cure properly next to that mirror wax. That is one of the reasons for the poor surface finish in the video (with all the air bubbles). Adding a few layers of purple PVA mold release between the wax and the epoxy will solve the issue.

The other reason for those air bubbles is the way it was mixed. Those hand drill rotary mixers cause tons of bubbles like when you beat an egg. The resin should be gently mixed first (including any resin coloring) before mixing it with the sand and gravel (to make sure it is mixed properly). Any remaining air bubbles can be removed under vacuum at that point.

If you mix the resin and sand by hand (in small batches) and with heavy duty vinyl gloves, you can avoid mixing in additional bubbles. You can also feel the texture so you can make it as you want it. I like to add the resin slowly until it turns into a clay-like consistency.

You can't stick to rigid percentages of each ingredient, There are too many variables between resins and rocks. If it is too thick, add more resin. Too thin then add more sand.

You don't have to fill the mold in one go. It is actually better if you don't . As long as you don't leave more than a day or so between batches , it will all chemically bond together as if it was done in one batch. Curing too much resin at once is a recipe for excess heat which leads to bubbles.

On the mix, Home Depot sells premixed bags of sand, gravel and granite in the cement section. It was around $5 for a 50lb bag and it works perfectly for epoxy granite.

Regular room temp cure epoxy is not massively stable in high temperatures. It can become soft if left in the car on a hot day. Mixing it with sand /gravel helps a little but the best approach is to heat cure the resin or post cure. You can do this as a diy job by building a make-shift oven around your mold using sheet metal. You can then heat it with a plug in heat element from a BBQ smoker ($50 on ebay).

A tip for removing the mold walls. If you unscrew them, they can be easily knocked off with a hammer.

If you made it right, there is no chance of lifting it by hand. Buy a shop crane from Harbor Freight. Epoxy granite weighs a ton. Moving it can be dangerous .

Forget about drilling epoxy granite. I had to use a new drill bit for every hole. It is better to bolt face plates to the metal skeleton before adding the epoxy granite (like in the video), or adding tubes through the base walls for nuts and bolts.

Don't feel limited to just using epoxy granite over a metal skeleton. You can add any material you like to the design to achieve different properties. My base and fixed gantry is made with a carbon fiber shell filled with epoxy granite, steel bars filled with urethane foam, carbon fiber tubes (set in 3 directions), several kilos of carbon nanotubes (mixed with resin) and around three inches of carbon fiber strands (also mixed with heat cure epoxy). To say it is strong with excellent vibration damping is an understatement ....