20mm screw. I milled the nut but it is not needed. I have a 25mm screw but it really just looked too big. I cut a little off of it and will be using it for the Z.
The X and Y will be powered by a 900 oz stepper. I have been running one on my IH for about a year and it works fine. I have also been running a 900 oz on the Z and it works OK but a bit more power would be nice. The Z is heavy so if you use a stepper a 1200 oz 7A would be best. I'm going to run a Clear Path servo but I might try the stepper just to see how it works. I do have a air spring for the Z not for lift but mainly to stop the head from dropping when the power is turned off. Something like this. www.automationtechnologiesinc.com/products-page/nema-34/nema-34-high-torque-stepper-motor-1200-oz-in-12-single-shaft-with-flat I do wish I could find one that had 7A current, It would have lower inductance than the 6mH that the 1200 has.
Hi Steven. Both will work. The stepper will only give about150 IPM if you run 75V or so and the servo will go faster. None of this is a problem for this type of mill. Most people will run the Z around 100 IPM. The servo will be quieter. You get a higher peak power output from a servo because you can run them closer to full power where with a stepper you need to have at least 40% extra power so you don't loose steps. I have run the brushed DC Gecko drive drivers and servos for years and the steppers work as well or better in some ways. I have yet to run the CP servos so I will have to wait and see.
Have you decided on what motors you are going to use on X,Y, and Z? I am getting ready to order steppers for my PM940 and I am undecided on what size I am going to use on the Z, as you know there is a lot of different opinions. Mine are going to all direct drive. Any info you are willing to share on your electronics choices would be appreciated.
ArizonaVideo99, Would you have the dimensions of the z axis slide mount that you would be willing to share. I am not asking for your design dimensions only the dimensions of the stock mount. I am only asking because I am out of town visiting family and I have an opportunity to build my mount for my 940M conversion at a friends shop and I have not measured it myself yet. I can give you specific dimensions that I would need but I am pretty sure you know which ones. By the way I ordered 900 and 1200 oz motors like you suggested. Thanks for any help you can provide.
Arizonavideo, Thank you for your advise. Ordering the electronics for this conversion is causing me the most difficulty as I am a complete novice on steppers and servos. I am trying to learn from others and not waste money on parts that have already failed real life conditions. If you have any other recommendations on electronics, or any other aspect, I would appreciate your input. I should be ordering my electronics by the end of the week and even deciding on where to purchase them is confusing.
I like you idea of reversing the orientation of the fixed end to the non drive side. Other then reducing the stepper motor stick out did you have some other reason to do it that way?
