PM1022 Bench Lathe CNC Conversion

In 2020 I started the CNC conversion of a Precision Matthews 10" lathe. This machine is for the winter shop in Brenda, AZ. Space is tight so a 10" lathe is about the largest that would fit.

Selection of the lathe came down to either a Grizzly or Precision Matthews 10" lathe. These are both relatively inexpensive Chinese machines. I could not find a lathe of better quality without going to German or Swiss machines, which were way out of my price point. An intermediate quality would be great (maybe Taiwanese) but was not obtainable. The Grizzly machines, at first glance, are a better candidate. You can get one version with a 3-phase motor and VFD. The Grizzly machines don't have an X axis feed which would be very desirable if used manually, but if converting to CNC it just gets taken out. However, I chose the Prescission Matthews for two features. First, the cross slide has T-slots to hold tooling. Second, the spindle chuck mount is a form of quick release rather than using threaded on chucks. I figured these features can't be changed or added after the fact, but a new motor with VFD is a fairly easy conversion. So it was the PM1022 for me.

There are several build logs for CNC conversion of the Grizzly machines. I could not find similar for the PM1022. The machines are very similar but, mainly due to the cross slide X feed mechanism, not the same. Great information though if you're doing a similar conversion.

I used ball screws on both X and Z axes. I really wanted to use double ball nuts for both but there's no way they would fit for the X. In fact it's hard to get a single ball screw to fit for the X. The picture below shows the ball screws sitting next to the stock lathe.

After a lot of thought and designing I came up with the configuration below. The model shows the full assembly.


Updates & Tooling


A picture of the completed conversion is below. Well it shows all the mechanicals only lacking the spiral springs as they had not arrived from China at the time of the picture.

This is a condensed version of the build. A more complete build log is available on the CNCzone forum. It documents all the rabbit holes that were explored.