Sherline Lathe Project

Short Description

With the 6040 becoming operational and the Grizzly being rebuilt, we don’t have much use for a 3rd mill, the Sherline won’t make a good mill without significant investment, and its current limitations shouldn’t necessarily make it a bad lathe. It was originally a lathe so I plan to turn it back into a lathe.

Initial State

  • The Sherline was set up as a mill with a vertical axis.
  • There’s a lot of backlash in the X axis (to avoid confusion, the axis that goes left/right when looking at the machine, or to/from the lathe spindle)
  • There is only one spindle belt, there was a prior harvesting of the lathe belt to replace the broken mill spindle belt
  • The Y axis (forward/backward when looking at the machine) has a little bit of backlash, but far less than the X axis.
  • The Potentiometer for the lathe spindle is missing. Ideally this should instead be controlled by the controller
  • The Y axis motor has a broken pin
  • We actually have lots of tooling and accessories (such as boring bars, etc)

Problems to overcome

  • Spindle speed control should be controlled by the controller so dynamic speeds can be utilized.
  • Tool holding, there’s only one tool holder, a future improvement would be to make an automated tool turret, the Y axis bed is quite large so right now a lot of tools could be mounted in individual tool holders.
  • Work holding, there’s no chuck I could find, determine if we have collets that could work
  • Swing over Y axis bed is quite short. Tools probably will need to hang over the edge, probably not that bad, but make sure there’s nothing else to be done.
  • Coolant (seems the machine is fairly well set up for coolant, might be nice to set it up at least as an option.
  • Shield – Before getting it working as a lathe, it seems prudent to build an enclosure to prevent accidental flying objects.

Questions to anyone who knows

  • What’s the state of the computer and controller? Would it be better to use a GRBL board or use the current setup?
  • Anyone know of any concerns that I’m missing?

Work I’ve done at the time of this post

  • Opened headstock cover to assess spindle
  • Swapped mill spindle belt back to lathe spindle belt
  • Obtained new drawbar for boring bar (though it requires some fudging so I’ll seek a better one still)
  • Removed milling UHMW plastic milling attachment to assess bed.

Next work I’ll do

  • Determine how the missing spindle potentiometer could be controlled via a controller
  • Clean the machine (lots of swarf and dust bunnies)
  • Remove mill Z axis
  • Relabel axis to be the more common lathe coordinates
  • Take measurements and photos


Lots of :heart: to those who have traveled before me on this machine. If this runs contrary to anyone’s desire for this machine, please let me know and I’ll stop and/or undo any work I’ve done.



I like this a lot, and I agree that we don’t have much utility for it as a CNC mill right now. A CNC lathe would be neat.

Keeping in mind that it’s been almost 5 years (!) since I’ve touched the thing:

Do you have pictures or more info on how it’s wired up?

Unless something has changed since I last looked at it, I think the current computer/controller combo is fine for now. When the computer inevitably dies due to conductive dust / filthy coolant ingress, we can see about replacing the controller with something that doesn’t need a parallel port. Right now I believe it’s Good Enough™ and effort should be focused elsewhere.

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Thanks for your input, it is valued.

I’ll try to get it minimally viable first then see if we can task out improvements.

Since I like build logs, here’s my update for this morning:

I did some more investigation to get used to the machine, I started removing the z axis but it looks like I have more to go than anticipated and may require disconnecting the x axis ways to take it off.

I made some connector cables for the speed controller but now I’m considering using the mill speed controller instead since it is known to be working and is nice and enclosed.