Recommendations: CNC "machine"

[sako243]

I thought I'd appeal to the collective knowledge here - to see if anyone has any experience with / recommendations for the following: a CNC "machine" that can take ~A3 on the bed, needs to have a Z axis height of a few inches. I don't actually care whether it's a mill, 3D printer, router etc.

All I'm actually interested in is the XYZ movement - I'm doing some R&D which involves scanning a sensor node across a surface - the separation from the surface is crucial and small. XY resolution / accuracy is less important (in fact it's a non-event) but I ideally need close to or better than 10um resolution, and more importantly repeatability, in Z. I'm after the mechanics more than anything else - driving the lead screws / ballscrews with stepper motors will be trivial enough.

I'm umming and ahing over building one from scratch but the time involved makes buying something (even if part of it's thrown away) as a basis much more appealing. E.g. a 3D printer / router / mill and then basically just remove the head and replace with my custom sensor.

Budget is flexible (can claim VAT back as well), willing to spend more for something that's more versatile, e.g. if it could be used for milling aluminium / laser cutting etc., then would be willing to spend more as then it can be used outside this particular project.

 

[Ali]

Some of the older Roland machines had the option to fit these Piezo scanning heads - I had some good results with them. I could probably lay my hands on a smaller one if you wanted to modify it, but they never did anything A3 size.

https://www.pdi3d.com/Roland_ZSC_1_p/r-zsc-1.htm

 

[sako243]

Unfortunately the A3 size is again a pretty hard requirement (can be a fraction smaller, but not by much).

Perhaps I should clarify on budget - it would be nice if it were in the ball-park of £1k or less - if it was more expensive it would have to offer a lot.

 

[MattH]

One of the cheapo Chinese 6040 type units may do.
You might have to go with servos with 10000cpr encoders to get the resolution or retro fit 1mm or better leadscrews.

 

[MattH]

Or you could buy my smaller laser cutter which we no longer used due to an upgrade

 

[sako243]

One of the cheapo Chinese 6040 type units may do.
You might have to go with servos with 10000cpr encoders to get the resolution or retro fit 1mm or better leadscrews.

I was wondering when you might chime up .

That's along the lines of what I was thinking but I suppose was ideally after a specific machine recommendation.

Or you could buy my smaller laser cutter which we no longer used due to an upgrade

Specs? Potentially interested.

 

[MattH]

Same as this one:

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/253160232868

 

[sako243]

Whilst I nice looking machine I don't think the Z-axis looks beefy enough to support the sensor head with enough rigidity (they're of the order of 4" square) for what I need. If it's working then I'd be loathe to cannibalise the machine for that purpose. Thanks for the suggestion though.

 

[Ali]

I don’t think the Z axis on a laser cutter would have the accuracy you might need for point probe scanning...they’re just designed to lift the (heavy) table up and down to focusing height.

 

[sako243]

Just to keep people in the loop current candidate is:
https://www.ebay.co.uk/itm/3-Axis-M...525402&hash=item41f4c3f0d2:g:lHgAAOSwdBRZfuZl

Easy win would be swapping out the stepper drivers for the TMC2660-PA chips which increases the micro-stepping provided that's not going to provide too much vibration.