Upgrading stepper motor for 80mm Spindle

This could be a hint for axial clearance, i. e. in the spindle axle. Bearing clearance can be radial but axial as well. You could measure it by pushing the axle into the spindle, with the dial gauge on it.

You are using the 80 mm mount, right? Did you check the bolts on the Z Axis’ ball nut, and those on the ball screw coupler too?

Anyway if you bought a spindle I would not give up that quickly. The loss of detail is not normal. And you also mentioned the advantages. Speed, and no ugly noise of sparks-emitting carbon-brush commutators on the home handyman’s consumer hand router…

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I would look at the spindle mount since you had to remove the 65mm mount and replace it with the 80mm. Mainly the lead screw to make sure there’s no play in it. The collar that clamps to the screw itself

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I will look into it thanks for the tip

Yes I used the 80 mm mount G penny 2.2 kw spindle. I will go over the details you mention where I can. Wondering if you think the nema 23 on the z is rated for a 15 pound spindle? Ive been told it is not, I understand onefinity did a lot of testing and state it is not an issue. I am also not doubting it could be something on my end either.
Thanks for the help

I am not sure how much you enjoy math, but here is a great video - Calculating Lead Screw Efficiency and Required Lifting Torque - YouTube - which shows the calculations for lead screw efficiency and lifting torque. The mass lifted and lead screw parameters used in the video differ from those on the 1F with your proposed 80 mm spindle. However with a ‘little’ math and the correct 1F leadscrew and spindle mass data, you should be able to calculate the stepper motor torque required to lift the spindle.

If you are still not daunted, Bosch Rexroth offers free configuration software for their products (but easily applicable and effective for any application). It is highly configurable and gives a great deal of information for those looking to size motors for their machines. Here is a video walk through of how to use it and some of the data it generates - How to Size Stepper Motors For A CNC Machine | .

The resulting data calculated from either of these above options may put your mind at ease as to the suitability of the current 1F stepper with your 80mm spindle.


Well I’m interested to see what happens with incremental upgrades.

I previously used a Shapeoko with a 2.2kw 80mm spindle so feel like the 1F should be able to manage it…

We’ll see.

Right now my problem is that the two set screws in the bottom of my z-Axis stripped (I had a brand new high quality hex wrench but I think they were just a little over torqued). Have to get these out and swap my new 80 mm mount in before I can do more testing.

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The 2 small set screws on the bottom do not need to be removed in order to change the spindle mount.

Did changing the micro steps in the z help or did you notice any changes from doing this? Wondering if I need to do this?

Honestly I haven’t noticed much benefit from increasing the microscopes in the Z direction. I have found more benefit on the X and Y plane.

Have you noticed any loss in detail with the larger spindle?

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No loss in detail that I can tell. I milled out some wood parts that mate up to the aluminum parts I made and everything went together just the same as is did with my 800 watt spindle. Reading through this thread there are a lot of thoughts going on but as I said earlier fellas, IN STOCK FORM THIS MACHINE HANDLES THE 2.2KW SPINDLE JUST FINE :+1:. 60-80 IPM is what I mill most of my parts at and this includes a lot of adaptive, boring and contour strategies.


Just finished milling this new fixture plate. 2.2KW spindle, stock steppers all around…and very accurate. Finish is smooth as silk. I hope this answers some questions :+1:



Have the spindle and big@ss™ stepper installed (still have to tram the spindle) and all looks fine so far.

Wired up spindle with breakout box and now have full spindle control via gcode.

Um, Dave?

The third step in the video you linked showed the exact two set screws I stripped as needing to be removed.

Ended up having to drill them out and it looks like they had some kind of thread locker on them.

Luckily I was able to remove them without stripping the threads and had some replacement set screws and all is well.

Optical illusion. Ran into shop to take that pic (my old head machine shop instructor at school would have a conniption if he saw me in my shop with open-toed sandals on…even if it is in my garage!)

Had one sandal partway off.


The actual set screws I thought you were referring to are the ones on the base of the Z-slider … not the ones that you are pointing to.

A few small test projects and so far everything seems working fine. No visible loss of detail that I’ve been able to detect.

Here is a quick video of it cutting a nimbus motorcycle logo into a piece of Zebrawoood:

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Hey Patrice,

this is mainly the shop vac that we hear, isn’t?

Is the spindle at how much krpm?

Yes, that is almost ENTIRELY the shop vac. The spindle is pretty darn quiet. I was at 17k I believe.


Hi - I’m trying to do the spindle swap and these damn 2.5M screws are stuck fast. @onefinitycnc are you glueing them into place? I have now also shredded the hex fitting. I really don’t want to drill them out. Does anybody have any suggestions (I thought this was the easy bit - oh boy)?