Thread: CNC Accuracy - Chasing your tail!

I am assuming .04 is mm? If that is the case that equates to 1.6thou, don't know what material your spoil board is and what construction your CNC router is, but in my (admittedly uneducated) opinion that isn't bad at all.

Over what distance can you consistently get that accuracy?

G'day Glenn

Like you say, it all depends on what you're cutting... The machine I've just finished building downstairs in the workshop is probably +/- .2mm over a 1200x800mm table, but I only plan on doing 2d on it. More than acceptable for what I want!

The machine I do most of my work on which is a Roland EGX600, I use to an accuracy of >0.5 thou. Every now and then, I'll re-true the surface to to make sure it's good, then put a 'finger' style clock over it so make sure. That gets me to an accuracy of .001mm (or less, depending on my eye sight at the time) - but considering the accuracy of the machine in the specs (0.01mm from memory) it's probably being a bit pedantic.
The reason for the stiff accuracy is for engraving on anodised aluminium... It's not very thick, so I need spot on depth control over the 600x400 surface. Otherwise, the engravings are all over the place.
If you're looking for 'dead-flat'.. I doubt you'll achieve it, at least, not for long because of humidity, temperature changes, material expansion factors; etc, etc, etc...

Thanks, good to get a reality check on it. sorry, yes thats mm. and the cnc is made from ally plate and extrusion so its faily rigid. Spoil board is ply (but fully supported by the extrusion)

the cutting area is approx L 1100 W 500, so from say one corner to another it will be a max difference of .04mm

Thanks Glenn

Thanks John - that helps put things into perspective! and your definitely right, a lot of other factors come into play that are out of our control, i was just over thinking things!

I think I'll push on and get back to what I'm meant to be doing rather than fluffing around with the machine!

Cheers
Glenn

Ours has a 2 x 3.5 m bed, and MDF spoilboard which is susceptible to humidity changes etc.
I'd be happy with 0.15mm bed height variation or 1/6 of a mm.

Lesser variations can be simply caused by dust!