New PM-728V-T Mill

[Tio Loco]

@jimrk I don't really have an interest in a CNC conversion, but I would like to add a power feed to the Z axis. My mill setup is a bit of a stretch to reach and use the hand wheel comfortably.

Would you be so kind as to share specifically which ClearPath NEMA 34 motor you selected for your Z axis? If my understanding is correct, using the ClearPath motor and a suitable power supply, I can build a simple controller using an Arduino (or other microcontroller) in conjunction with a rotary encoder. Am I missing something there?

Also, could you share your thoughts on your inline mount instead of a geared mount replacing the hand wheel? I'm assuming it is related to replacing the lead screw with a ball screw?

For my application, I'm assuming that the stock lead screw will be fine since it will be a 'manual' setting and gravity will compensate for backlash.

 

[rwm]

Tio- I am trying to do this also. I really don't want to learn how to program and arduino just to do this. Is there a simpler way that still uses a stepper?
Robert

 

[jimrk]

@jimrk I don't really have an interest in a CNC conversion, but I would like to add a power feed to the Z axis. My mill setup is a bit of a stretch to reach and use the hand wheel comfortably.

Would you be so kind as to share specifically which ClearPath NEMA 34 motor you selected for your Z axis? If my understanding is correct, using the ClearPath motor and a suitable power supply, I can build a simple controller using an Arduino (or other microcontroller) in conjunction with a rotary encoder. Am I missing something there?

Also, could you share your thoughts on your inline mount instead of a geared mount replacing the hand wheel? I'm assuming it is related to replacing the lead screw with a ball screw?

For my application, I'm assuming that the stock lead screw will be fine since it will be a 'manual' setting and gravity will compensate for backlash.

The ClearPath I used is CPM-SDSK-3432S-RLN ($387)

Have you checked what Priest Tools has?

I don't see it listed on his site but I would guess about the same cost of the other ones ($299). The site also has installation docs so you can see what he is doing.

 

[AlanB]

A stepper motor would probably be a better choice for a simple motorized Z axis (it is a long reach for the crank), the servo is expensive and when turned off has little holding torque. They both require step pulses and a direction signal. A small microcontroller can easily convert the two quadrature signals from an encoder knob to step and direction, or generate other pulse sequences from buttons, toggle switches, etc. similar to a power feed.

 

[Tio Loco]

@rwm That's the problem, there are so many ways to approach this problem, but for steppers or servo motors something is needed to generate the pulses and direction and the Arduino is a very affordable and relatively easy solution. DroneBot Workshop has a couple of tutorials addressing this approach:

Stepper Motors with Arduino - Bipolar & Unipolar

Learn how to control bipolar and unipolar stepper motors with an Arduino using drivers like the ULN2003, L298N and A4988.

dronebotworkshop.com

And more to the point of this project:

Using BIG Stepper Motors with Arduino | DroneBot Workshop

Learn how to use a large stepper motor with a microstep driver and an Arduino. We’ll add a potentiometer to control speed and a push button switch to change direction.

dronebotworkshop.com

My concern at this point is getting a motor with enough torque and precision to do the job.

@jimrk Thanks for that. Looks like a very affordable solution assuming that it is the same price as his other power lifts. My concern there is with accuracy. Ideally I'd like a jog wheel control that would allow me to set the head as precisely as I can currently with the hand wheel and from his videos, I'm not sure that is possible. It seems like more of a 'big picture' movement system. I know, picky, picky, picky.

@AlanB Thanks for the input. I had just been reading about the ClearPath motors and their claim to significantly more power and torque vs. similar sized steppers, but hadn't considered holding power. I'm not sure how significant that would be if I did something like the Priest Tools design, where the manual hand wheel stays in the equation as the manual wheel is sufficient to hold the head in place once set, and particularly after the head is locked.

I sincerely appreciate any and all additional input on this project. I don't mind the lather, rinse, repeat development model for little stuff, but this has the potential to get expensive if not done correctly the first time.

 

[rwm]

Tio- Thanks for that link! That explains a lot.
However if I understand it correctly, using an Arduino to control this is way over kill! Why can't I just use a variable pulse generator to supply the PUL input and use mechanical switches to activate the direction and enable? That would be a very minimal effort. Perhaps I am missing something here?
Robert

 

[jimrk]

@rwm That's the problem, there are so many ways to approach this problem, but for steppers or servo motors something is needed to generate the pulses and direction and the Arduino is a very affordable and relatively easy solution. DroneBot Workshop has a couple of tutorials addressing this approach:

Stepper Motors with Arduino - Bipolar & Unipolar

Learn how to control bipolar and unipolar stepper motors with an Arduino using drivers like the ULN2003, L298N and A4988.

dronebotworkshop.com

And more to the point of this project:

Using BIG Stepper Motors with Arduino | DroneBot Workshop

Learn how to use a large stepper motor with a microstep driver and an Arduino. We’ll add a potentiometer to control speed and a push button switch to change direction.

dronebotworkshop.com

My concern at this point is getting a motor with enough torque and precision to do the job.

@jimrk Thanks for that. Looks like a very affordable solution assuming that it is the same price as his other power lifts. My concern there is with accuracy. Ideally I'd like a jog wheel control that would allow me to set the head as precisely as I can currently with the hand wheel and from his videos, I'm not sure that is possible. It seems like more of a 'big picture' movement system. I know, picky, picky, picky.

@AlanB Thanks for the input. I had just been reading about the ClearPath motors and their claim to significantly more power and torque vs. similar sized steppers, but hadn't considered holding power. I'm not sure how significant that would be if I did something like the Priest Tools design, where the manual hand wheel stays in the equation as the manual wheel is sufficient to hold the head in place once set, and particularly after the head is locked.

I sincerely appreciate any and all additional input on this project. I don't mind the lather, rinse, repeat development model for little stuff, but this has the potential to get expensive if not done correctly the first time.

I forgot about the holding power of the servo. I do need to remember to lock the Z or it can/will drop. On the good, the servo it will raise the head even when locked. With the crank left in place it should not be a problem. Being an old guy and shrinking I understand making life easier is good. I have an X3 with the Z crank on the base it's still a PITA.
Cheap/easy might be just take the hand wheel off and hook up a drill to the shaft. Height could be an issue still but just putting it out there.

 

[AlanB]

There are many ways you could generate a step and direction signal for a stepper or servo. Probably the best model of what is wanted here is a CNC Pendant or MPG. These tend to generate serial or USB outputs that need to be converted to step/direction. This would be a good job for an Arduino or a Raspberry Pi. Overkill is probably not the right way to think about using these components. They are low cost tools that can make a very simple solution. Raspberry Pi boards start at five bucks and some Arduinos are much less. The real question is what does one want for a user interface. Perhaps a knob so you can rock the position back and forth. Maybe a rate control to reduce the amount of twisting needed to move farther. How about some constant rates for slewing slow or fast, like jog speed and direction. A small micro board could do these things with less hardware and less effort than a bunch of chips (the way we used to do it). So instead of a pile of parts it's just one small module, a couple of wires and a bit of code. But you can do it many different ways. With the micro you could change your mind without having to redesign hardware. And learning something new is always fun!

 

[rwm]

You know....the drill on the shaft is not a bad idea.... That's the kind of simplicity I am looking for here. Unfortunately the shaft is too large for my hand drill. I may make an adapter.
For computer guys who already know Arduino or Rasp Pi its pretty easy to throw that solution out. I do not want to spend the time getting up to speed on that. It would take more effort than you think.
Can somebody shoot down my idea of using a 555 timer with a potentiometer and a couple of switches?
Robert

 

[jimrk]

You know....the drill on the shaft is not a bad idea.... That's the kind of simplicity I am looking for here. Unfortunately the shaft is too large for my hand drill. I may make an adapter.
For computer guys who already know Arduino or Rasp Pi its pretty easy to throw that solution out. I do not want to spend the time getting up to speed on that. It would take more effort than you think.
Can somebody shoot down my idea of using a 555 timer witcoh a potentiometer and a couple of switches?
Robert

could try a tweak on the handwheel to make a 'nut' and use a socket on the drill.