Does blacktoe meet its specification?

[kousha]

Hi there,

I need a machine that is able to cut plastic at a resolution of 50microns.

Blacktoe claims to meet that specification. Now does it in reality?!

Thanks

[jckstrthmghty]

Hi there,

I need a machine that is able to cut plastic at a resolution of 50microns.

Blacktoe claims to meet that specification. Now does it in reality?!

Thanks

I think what you are reading is a bit misleading.

It's probably true the resolution of the motors with the drivers will give you 50 microns of resolution however that is only part of the equation for accuracy. Other factors like backlash, accuracy of your drive mechanism (chain in this case), calibration of your machine, and deflection (flex) all must be taken in to account. Chain drive is probably the least accurate means to drive your axis and the design itself lends to deflection.

I'm not going to say it's not capable of doing the job but I will say there are other options that will yield more accuracy for a similar price.

[louieatienza]

50 microns is about .002". My guess is that the chain would have more than that in play, and the frame (mdf or plywood) can flex at least that much. Plus not sure if their v-bearings are dual row or single row.

[michaelthomas]

I can safely say, "No it will not hold .002" on anything". It will not hold .002 in air.

Chain is perhaps the poorest method of motion. I built one with chain.....I saw that it wasn't great, then rebuilt it with belts. The belts were much better, as long as you were doing light work.

You cannot tighten the chain very much, or the drag overcomes the steppers power very quickly. So, you either have a saggy chain......where the gantry see saws on the slack and draws closer to the side with the most chain hanging or you tighten it down and miss steps constantly.

You can tighten belts extremely tight without inducing much drag......but 9mm belts will stretch under a modest load. Cut balsa, or take light passes and its OK.

I would look at something with a ballscrew. I don't know what is out there as a kit......so I cant be of much help, there.

The blacktoe copy I built was very good for light work that was not dimension critical. It did a fine job for 3d work as well.

Look on the Build your CNC forum and search for posts by michaelthomas......you'll find the build on my machine. I think it was titled DIY Blacktoe.....sort of.

It will absolutely NOT perform to your specs with either chain or belt.