New SO3 Z-Axis

Assembly questions and answers for the Shapeoko 3 CNC Mill
Posts: 244
Joined: Tue Apr 15, 2014 6:31 pm
Location: SVE - Mesa, AZ

Re: New SO3 Z-Axis

Post by woodworkerbob » Mon Jul 31, 2017 2:27 am

Could you post a link to the z axis assembly you are using?

Shapeoko 3 - #13, dust deputy, precision collets, limit switches.

Posts: 271
Joined: Tue Jan 06, 2015 4:34 am
Location: no where near the end of the rainbow

Re: New SO3 Z-Axis

Post by LTEPM » Mon Jul 31, 2017 3:34 am

zamp wrote:
It now takes 1012.5 z steps to move 1 mm on the new z. Compare that to about 40 steps per mm for the x, y, and old z. If I try to move the new z much faster than about 500 mm/min, then the z moves pretty roughly and I think I'll lose steps. At 500 mm/min the z movement is nice and smooth. I didn't actually try the z anywhere between 500 mm/min and 550 mm/min but 500 was smooth and 550 was rough. I might be able to push the z just a little but faster. than 500 mm/min.

You can try to change the ratio on your pulleys to reduce the amount of steps per mm.

Curious How this compares to the Z steps per mm on the SO2.

Posts: 44
Joined: Fri Jan 02, 2015 8:54 pm

Re: New SO3 Z-Axis

Post by zamp » Mon Jul 31, 2017 3:49 pm

This is the one I bought and have been writing about in this forum thread: ... 2749.l2649

The seller also has a web site with similar z-axis assemblies at, but I don't see this exact same assembly there.

I could probably change the z belt and stepper and leadscrew pulleys, but I'm not yet sure if the slower z will be a problem when I'm cutting. The z certainly homes quickly enough for me.

Posts: 44
Joined: Fri Jan 02, 2015 8:54 pm

Re: New SO3 Z-Axis

Post by zamp » Sun Aug 06, 2017 10:58 pm

I finally cut a couple of jobs. Sorry it took so long, but I had to be at work last weekend while fiber optic cabling was relocated and reterminated. Also, I'd done so little work with CAD and CAM before and too long ago that it too a while for me to come back up to speed.

Super brief summary: I'm very happy with how the SO3 cuts now that I have a leadscrew Z on it, and I don't notice slowness of the Z for the two simple 2.5D jobs I ran.

First job was just re-running an old May, 2015 gcode file for a single stepped hole for a threaded insert. The job ran just like it did in 2015 and the 19mm MDF I put the hole in accepted a threaded insert just like it did back then. 1/8" roto-zip style bit, speed of 2 on DeWalt router.

Second job was to draw a circle, diamond, square test and run that. I'd not run one of those before. Drew a 90mm circle on top of a 100mm (on a side, not diagonally) diamond, on top of a 150mm square. Used CamBam to generate toolpaths and gcode. 1/4" bit. gcode file was 1308 line long including about 10 comments. Used bCNC to run job. 28 minutes and 4 seconds to run job. DeWalt router started at speed 1 which cut OK but ended up at speed 4 which cut smoother.
IMG_1743.JPG (37.18 KiB) Viewed 1411 times
Square drawn side lengths: 150mm
measured lengths: 150.13, 150.17, 150.21, 150.18

Diamond drawn side lengths: 100mm
measured lengths: 100.37, 100.05, 100.47, 100.13

Circle drawn diameter: 90mm
measured diameters: 90.27 (width), 90.12 (height)

Final note: If I ever start running jobs with tons of Z moves, I'll probably want to speed up the Z, maybe by using a stepperPulley:leadscrewPulley ratio other than the 1:1 that was supplied by the vendor. I'd probably try stepper:leadscrew of 1:2 and see how that went.

It took me a little more than 2 years to finally be able to trust the SO3, though that would have taken much less time if I'd worked at it steadily and especially if I hadn't let the SO3 sit unused for more than a year. Mine is an early bird unit, serial number 42. Along the way I've added cable management (drag chain), replaced a couple of broken v-wheels, installed a limit switch kit and then redid it with fabricated aluminum mounts instead of the 3D printed mounts, upgraded the X and Y to 9mm belts, installed a Suckit mount and shoe, replaced the z plate with the new, stiff style instead of the original flat and floppy unit. And finally replaced the entire Z axis with an eBay leadscrew model.

At some point I'll probably install a 1.5kwatt spindle and configure GRBL for spindle on/off and speed control. I'm also thinking of adding a tool length probe (a fixed-location, bed-mounted microswitch), assuming I can figure out how GRBL and bCNC deal with that. But first I'll be using the SO3 for a job I've been waiting on: milling the back panel for connectors for a PiDP-8/I ( PDP-8 "clone" and milling a dotcom style front panel for a MOTM-650 MIDI interface (that MIDI interface is a musical keyboard and computer interface for an analog music synthesizer).

Posts: 44
Joined: Fri Jan 02, 2015 8:54 pm

Re: New SO3 Z-Axis

Post by zamp » Wed Aug 16, 2017 2:47 pm

I emailed the seller of this Z-axis assembler and let them know I'd modified it to install on a on SO3. The seller replied:
We have a spacer kit for our Z axis when customers need to mount them on a SO3. It's 25$ for this kit, the kit consist of a spacer plate and some screws.
I have no other details on that spacer kit. The seller is cnc4newbie -a-t- gmail -dot- com .

Posts: 2
Joined: Fri Jul 28, 2017 1:59 pm

Re: New SO3 Z-Axis

Post by fiero1 » Wed Sep 27, 2017 1:42 am

Nice to hear it is working out for you!
Is there any reason why you couldn't swap out that 3/8" screw for one with less threads per inch to help
with slow z.
Something like this? ... ght-60896/


Post Reply