Cheap CNC Mill ?


Sep 2, 2018
Hi J,

I just noticed your thread and that there was a comment about converting the PM 940M to CNC. If you decide to go that route you may want to look at thread. Where ptrotter has been making the conversion. He essentially has completed the conversion and it sounds like he pretty much got a good job and machine. We have become friends as we try to help each other out. He may have gone a little over board at the beginning by stripping the machine of all of its paint etc, but it does look nice now.

I purchased one of the last PM 940M CNC VS machines that PM sold and have used it over the last couple of years. I do not machine often, but wanted to get started. Since, I live in Pittsburgh I thought it would be good to purchase locally, and have found the folks to be very helpful. More recently, I upgraded my old SB lathe by purchasing a PM 1440GT lathe from PM and one of these days I will post my info on its variable speed/VFD conversion.

I think all of these inexpensive Mills have their own set of problems. The 940M is no exception. I am still learning, but my feeling after talking to ptrotter about some of my problems I am wondering about the consistency of quality between machines. His seems to be more mechanically accurate than mine. Maybe it is just luck or maybe there was a significant difference between the manual vs CNC version. While the basic machines are similar they are not made quite the same. It is a heavy machine and I think the head with the 1.5KW motor is both good and bad. Good for heavy cutting, bad for control and positioning. I ask Trotter to weight his while he had it apart and he found it to be about 275#s, which is similar to what I had estimated. I have not rebuilt the machine like others have done. After I remounted the control box on the side of the column rather than the back etc, mine is still pretty much just like it came. Out of the box, I will say the Taiwanese lathe seems to be a much better built machine than the Chinese Mill.

Anyway, if you decide you might want to go the PM940M conversion route and you want info or just to talk about it maybe I can help. I am sure that I will learn some things as well. By the way, I am not a machinist, the 940M is really the first mill I have owned or even operated, so I am still learning. I am a scientist by education and practice, but am now, mostly, retired.

I see you live in Freeport, NY. While I have lived in Pittsburgh for many years, I spent many years working for E. K. Research Labs. in Rochester. I last lived in Webster on the lake. While I do not miss the weather, I do miss the lake view!



Dec 21, 2020
Thank you Dave, for your advice.
I also am still very much in the learning stage. I have such a limited budget, it may be a while till I have all the funds necessary for such a purchase.
I also need to sell a few machines to create more space in the basement workshop.
The basement has a low ceiling in places, which prohibited me from getting a BP, hence the g0755 was purchased awhile back.
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