Well this is embarrassing......

Michael_Omiccioli · February 16, 2016, 4:56pm

Well this is embarrassing… Over the holidays I upgraded my ShapeOko2 to an Xcarve and I must say I am seeing better results. I did notice that the Z Axis movement was different. I chalked this up to switching to the ACME lead screw which is 12TPI. Well guess what I forgot to do? Change the travel setting for the Z Axis. The old setting was 1.25mm per rotation. I calculated the ACME screw to be 2.11mm per rotation.

However I am not totally sure I am right. The TinyG uses a travel per rotation. I did some measurements and it seems right my isolation cuts seem to be better because the Z head is traveling less per rotation.

Can anybody confirm?

raykholo · February 16, 2016, 5:05pm

Working on the math now. What micro stepping setting are you using?

Michael_Omiccioli · February 16, 2016, 5:07pm

8 since the all the NEMA17s that cam with the ShapeOko2 were 200 (1.8) with 8 for micro stepping.

raykholo · February 16, 2016, 5:11pm

So your old value was 1280 (right?) and your new value should be 755.79

That’s a substantial difference. Based on your pcb milling results I’m not sure on how you broke through all the copper if you weren’t going down far enough.

Colleen_McGuire · February 16, 2016, 5:37pm

By upgrading do you mean you switched out all the mechanical pieces? Wondering if I should do the same.

Michael_Omiccioli · February 16, 2016, 5:39pm

Actually the original micro stepping per step was 4 so it calculated to 640.

Changing 2.11mm/Rotation and micro stepping per step to 8 gives me 758.293 or 15% reduction in the plunge depth?

Which I think is what I need. But again the TinyG ask for the mm per rotation not micro steps per step. So I think the 755/758 number is right.

The team at Inventables say the number should be 188.976 which comes in at 2 micro steps per step if using the GRBL controller.

Michael_Omiccioli · February 16, 2016, 5:46pm

Colleen,

I purchased the ShapeOko2 to Xcarve upgrade. It came with a better Z Axis Gantry and better X and Y axis plates. The X axis gantry plates center the weight better and all in all more rigid and stable. I notice an improvement. The motors, rails and gears stay the same. The Z motor is inverted and driven from a belt instead.

raykholo · February 16, 2016, 5:48pm

189*4= 756 so we’re at the right value.

The exact pitch is 2.117 so use the value with decimals I provided above.

Michael_Omiccioli · February 17, 2016, 2:04am

Made the adjust as suggested and looks good. Thanks for the confirmation.

raykholo · February 17, 2016, 2:09am

Most certainly. Can you mill another board? I’d like to see if there’s a discernible difference.

Michael_Omiccioli · February 17, 2016, 2:18am

Sure I will mill one in the AM, I am curious how much it improves. I can tell just from the Z moves there is a difference.

Michael_Omiccioli · February 17, 2016, 2:03pm

I posted a quick video of the 3 boards I milled while adjusting the micro stepping. Check out and let me know what you think.

raykholo · February 17, 2016, 2:24pm

Started out great and only got better. Awesome results.