[welshtom]

Hi all

I have a small CNC machine which i use to cut mainly sheet alu.
Recently I've been dabbling with engraving with it and I am pleased with the results.

however unlike my normal cutting this requires a true flat surface, especially as I plan to engrave over a 500x500mm area.

I have been getting quotes for a 540x540mm piece of MIC6 Aluminium which I figured would be the best type to use.

My question is thickness, would 10mm suffice?

I have 3 support struts underneath this piece at equal spacing that would run the full length of the piece

Would 10mm keep its flatness across these gaps? Or would I be better with 15mm or 20mm?

Thanks for any help.

Tom

[Perfect Circle]

The thicker the better, for staying rigid & flat.
"you can always have too much"

[ger21]

Place a piece of MDF on the bed, and surface it flat with the machine.

[welshtom]

We've been using MDF/Hardboard for our general work cutting patterns in aluminium mainly.

Thats fine but only for so long as we use a coolant which does get soaked up.

Within 1 or 2 engraving jobs the wood is unusable. It needs to maintain a high degree of flatness for large engraving jobs.
a 0.5mm rise or fall across a half a metre bed is disasterous

This is why we are changing to a metal solution just for engraving, with a view to be able to take this bed on and off as we need to

I think 10mm will suffice, its works out approx 50% extra for double thickness though so it its tempted to go 20mm and be "safe"

[DSIF]

MIC6 aluminum is cast and blanchard ground. Usually flat within .005". I would anchor it and machine it flat for use as a fixture.
Dan

[welshtom]

Hi

This is why we picked it, for its cast nature and flatness.

Can anyone answer my question thought?

Would 10mm be sufficient

Tom

[DSIF]

Tom-follow your instincts. 10mm is very thin for a fixture. The thicker fixture will provide better results. Plus,as it wears, you can resurface it. I would use 25.4mm(1.0").
Dan