Update. (just some thoughts and observations, mostly notes for myself)
I have been carving oak and mahogany. Last night I was powering through oak with a 1/4" at over 120 inch/min no problem, I probably could have gone much faster.
I am getting lazy. No longer concerned with tuning the feed and speed for best results as even my generic “ballpark” settings seem to work well.
The project I was doing had a huge toolpath file. Too big for my little table to load into memory.
So I started looking into ways to shrink file size.
The first was to reduce the number of decimal places…
For what I was doing I decided to try limiting it to 2 decimal places (instead of 4). I figured 100th of a mm is more than accurate for a decorative wood carving. But that did get me thinking about resolution and accuracy.
It turns out you want to run micro stepping for smother motion and quieter motors, but you might not want to rely on the added resolution of the “in-between” steps. You want to set up your limits and values based on the single step resolution. In practice this is pretty easy.
The Z axis uses a 8mm screw. 200 steps is a full revolution that moves 8mm. So each step is 0.04mm.
So in calculating depth of cuts just make sure everything is divisible by 0.04mm
I work in metric so this is super easy. Depth of cuts get changed from 6.35 to 6.4 or 6.2 etc.
I use VCarve which is supposed to be able to run a constraint on number values generated for g code, but I am doing something wrong because it is not actually doing it.
You can also set the number of decimal places for each axis in the post processor. And that does work as expected.
I have updated my X axis to also use a 8mm screw. But the Y axis still uses a belt (this lets me have a Y axis longer than 1000mm - which is the longest a 8mm screw can go)
My single step resolution on my Y axis is
3mm per tooth, 20 tooth per pulley, 200 steps per revolution
(3*20)/200 = 0.30 mm/step
Z = 0.04 mm/step
X = 0.04 mm/step
Y = 0.30 mm/step
So the various axis single step resolutions don’t match and don’t divide well into each other.
But I found a Gear Ratio 15:1 Planetary Gearbox Nema 23 motor and a 40 tooth pulley that will fit.
3mm per tooth, 20 tooth per pulley, 200 15 steps per revolution
(340)/200*15 = 0.04 mm/step
So if I wanted too I could swap out the Y motors (they should fit the same just with some longer standoff bolts and spacers) and pulleys and match the single step resolutions on all axis.
The question is would I want to?
It is nice from a design standpoint but so far I have not noticed any resolution issues with my style of carving.
Of course adding the mechanical gearing would increase the torque significantly on the Y axis, which is much more prone to slipping than the X or Z. But upgrading to a Z controller would also accomplish that with the higher motor current.
This is something to look into. I will need to keep a eye on the carve quality as see if resolution is actually an issues.