MK2: moving gantry router for metal cutting - comments sought!

[Nick]

Interesting granite build.
The epoxy-granite is another story. There's the famous thread on cnczone with almost 5000 replies. But as far as I understand it, the most difficult part is the vibration for compacting. Vibrators are not cheap and not that easy to build and for good results they need to be tuned to the right frequency using inverters...

But a epoxy-granite cnc wouldn't be lightweight so it is out of the question for this build.

That cnczone thread is a mess... I have read through it twice and i'm not sure it is helpful. Ideally it should be vibrated and I was put off due to that thread before. But I have found you can get reasonable results with just compacting it with your hands/tools. If your very concerned about vibration I think something like this might be worth trying

https://www.amazon.co.uk/Nordstrand-...FCCYN1BBXNSFA0

The other discussion topic on that thread is about aggregate size, the members of the "cncecke" forum tend to use pre-mixed fullers approximated aggregate such as Silimix-282 with good results. If your interested there is loads of good information on these forums but you need to register and use google translate.

Filling the RHS section with epoxy granite or UHPC concrete would be a reasonable way of vibration damping. It won't add as much weight as you might think, for example the 160x80x1m section filled with EG would only add 25kg.

You would be using the RHS and just using the EG for dampening so you could use an easy flowing sand mix such as this one

https://www.adambender.info/single-p...e-Frame-How-To

I am currently making a mill from EG so i'm perhaps a bit biased.