Pm25-mv Conversion Planning

I think the error output works in a away that the commanded steps from the controller are then commanded by the servo drive, then the drive counts the steps from the encoder, if they don't match or it doesn't do it
 
Just a comment on the Automation Technologies servo systems. We are using their 600 oz servo on our CNC router which works great though we are using a high end driver by another company. We initially used the encoder they sell. Their encoder is a single ended unit and we had a number of issues with noise causing position errors. We switched to a US Digital differential encoder which is much superior. I think the AT encoder is more suited for applications like vending machines vs precision CNC.
 
SRX,

Did you order a kit from arizonavideo for the mounts and ballscrews?

General question, why can't we use the factory screws? Are they too fine of a thread for the stepper motors? Would it be and option to gear them and not drive them with the stepper directly?

I am planning on getting a PM25MV here shortly so I am just trying to gather some information.
 
There are a couple of very good reasons to use ball screws in place of the original acme thread lead screws. One is the turning effort on the ball screw is much less, reducing the power lost in moving the table. Another is reduced backlash. Ball screws are by design low backlash devices, which improves overall accuracy. It is possible to do CNC without using the ball screws, but on a mill the size of the PM-25, the Chinese ball screws are well worth the cost, in my opinion. Automation Technologies sells the kit for $189 for the G0704.
 
it has nothing to do with the pitch of the screw, in most cases, you will be ordering ball screws of the same pitch, as said above it has to do with friction, ball screws are something like 90% efficient, acme screws (factory) require a lot of torque to turn, and would wear out quickly from the repeated higher turning speeds of CNC systems, and then you also have backlash, now, acme screws can be had that are close to backlash free, but they are both expensive, and require an even higher amount of torque to turn, because both the nut and the screw have much tighter, closer fitting tolerance. even then, they still wont hold up like ball screws to the higher speeds of CNC.
 
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