Machining vermiculite

Does anyone have any tips for machining vermiculite block? I have no idea where to start for feed and speeds or tool material type.

This is something which no one has yet asked about or mentioned doing, either here, or on the old Shapeoko forums, nor on reddit on /r/cnc or /r/hobbycnc.

Do you have a product link?

Does the manufacturer have guidelines on how this material should be worked?

I suspect it would be similar to cutting/machining brick — would it be okay to use a coolant on the material? Or would that stain it?

What sort of cut do you need to make? How accurate does it need to be?

I want to make custom moulds for glass casting.
I have read it can be worked with woodworking tools. I
t is less dense and much more crumbly than brick.

I have a Nomad3 so coolant could be challenging but I could rig something up if it was needed.

I can’t find and material specifications.

If it can be cut w/ woodworking tools, then I’d start w/ the hardwood feeds and speeds from Carbide Create – they’re quite conservative — then adjust per:

It’s a silicate, (so basically sand). I have to imagine it’s going to wreck regular steel or carbide tools pretty quick. You could use a grinding process with a diamond coated bit as you would for etching/engraving stone.

I think I would consider using the CNC to cut a model or pattern, and casting the vermiculite around the pattern to make a mold for your glass…

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Yeah, I knew it was going to be hard on steel tooling but wasn’t sure if carbide might be tough enough. My volume is very low so I might take the hit on tools. As it is a granular material I am not going to get a sharp/smooth finish so blunt tooling maybe OK anyway. I have a couple of carbide end mills with really tiny chips which I could experiment with.
I appreciate the suggestion about casting the material but I don’t know if I have the resources to do that and don’t want to invest in much for my very low quantities.

I would be careful cutting vermiculite because it may contain asbestos. Here is a link you may be interested in EPA Doc

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