Large Format Epoxy Granite Gantry CNC - Looking For Feedback

Hi All,

I built a CNC router with elevated rails in 2012 out of aluminium profiles. I still use it today and it works ok. I can cut wood and aluminium, but it is not stiff enough for aluminium and not fast enough for wood. Back then I made it 1.5mx2.2m which is just an unpractical form factor. My workshop is to small for that. So I made it half as wide. The raised rails are a very convenient way to make the gantry stiffer and to keep the rails clean. They also make it harder to access the cutting surface.

So now I learned a bit about the good and bad things of CNCs, and I plan to build a new one. My plan is to make it 2.5m long and 1.2m wide. That way it can be positioned nicely along a wall of my workshop. The gantry will be very long, so it won´t be in the way very much and I can still use the CNC as a work bench. The work space will be a little over 2 x 1m. The weight of the base will be 590kg.

I plan to add a few styrofoam (xps) cores into the base. That way I can use less epoxy and reduce the overall weight. In the front and the back, those styrofoam boxes will form little shelfs to store the electrics and tools. So they don´t always lie around on the cutting table.

Let me know what you think about this! One concern is if I should use Epoxy Granite or Concrete since 100kg of Epoxy cost about €1000 alone.


This is a tour of my workshop including my current CNC at around 13:00min.
https://www.youtube.com/watch?v=S1CnfRxpGjA

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I've often wondered about the practicality of using of light-weight concrete as part of a CNC machine. Foam concrete is used in the building industry but is not easy to make in your own back yard. One option I considered is to use small polystyrene beads (as sold to make those incredibly impractical bean-bag chairs) as all or part of the aggregate in ordinary concrete. We're not looking for anything like the strength required to build a road bridge and this stuff might well provide effective vibration deadening with a high bean content at a fraction of the weight.
As with many of my best ideas, I have had the bag of beans tucked into the roof of my shed for years but have never actually got round to using them.

Kit

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Originally Posted by Max Maker

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This is a tour of my workshop including my current CNC at around 13:00min.
https://www.youtube.com/watch?v=S1CnfRxpGjA

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Thanks, I always enjoy workshop tours for the ideas I can glean from them.

In this instance, how to solve the sliding mitre saw space problem! :-)

Unless you want to do angle cuts. you will still have to move the saw forward unless you make quite a big hole.

A sliding table with a strong locking mechanism to bring the saw forward may be a better solution.
Makita saws have a carrying position at 45 deg that makes the saw a lot more compact. You may not need to make a hole.
I guess most saws have the same parking feature.

I made a 1300x675mm working area router with the gantry being the long 1300mm axis. It works well, however I wonder if the length of your gantry is pushing things.

Also, the ends of your gantry look like a weak spot.

I'm interested to see how this works out.

What i think is it will be good if you read my second build log , look at signature. My advice is build the gantry like mine and make bed from 14cm UPN like i did , there is nothing cheaper and stronger than that. When welded to the bed, it acts like 10cm solid block of steel...

If you build the gantry exactly 1:1 like i did it, it will weight around 300 kg and will be ridiculously stiff . You should worry more about your Z i think. About the overhang and so on... Of course if you encase the spindle like i did, would be the best action. The way i did my gantry and my Z= same like double gantry and spindle in the middle, if not even better.