PM 728 Mill- Issues and upgrades.

I just went and measured the actual torque required to raise the head of my mill. I used a 5" lever arm on the shaft and measured just under 5 lbs of force to lift it. So this equates to 25 in-lbs or about 400 oz-in torque. That would be the upper limit of most NEMA 24s but a powerful one might work.
Robert
 
That is an excellent reminder. I did not figure in any inertia. Duh.
Robert
 
rwm said:
I just went and measured the actual torque required to raise the head of my mill. I used a 5" lever arm on the shaft and measured just under 5 lbs of force to lift it. So this equates to 25 in-lbs or about 400 oz-in torque. That would be the upper limit of most NEMA 24s but a powerful one might work.
Robert

I have gotten some input from others who have done this and they concur about the NEMA 34 with about 1000oz/in torque. I am confused about how to drive this? Those low power controllers on eBay are obviously designed for a much lower power motor. I would need a high power driver for this application. Outside of learning to program an Arduino is there an easy way to accomplish this? Could is use the controller you suggested above to provide logic input to a high power controller?
Click to expand...

Just to maintain continuity the italic text above is from a PM with Robert.

The stepper system normally consists of 3 main parts, the controller, the driver, and the motor. You can use any controller that outputs a 5 volt step & direction signal. The driver is the high power handling device that accepts the 5 volt input signals from the controller, and translates this into a high power 2 phase output to the stepper motor.

An example of a driver https://www.ebay.com/itm/LeadShine-...859435?hash=item3658f7a82b:g:AaMAAOSwzL9d4MWT

You will want to size the driver to the motor, the higher the voltage the better, but the maximum amperage output is the important number. You want the driver to be able to meet or exceed the motor rated amps. The amp output on all of the available drives is adjustable to match the motor, you can always adjust it down.
 
Jim- thanks for chiming in. I am now understanding this in much greater detail.

It looks like something like this would work for single axis control.
www.ebay.com

Motor Pulse Signal Controller Generator Stepper Motor Driver PWM Speed Regulator | eBay

Find many great new & used options and get the best deals for Motor Pulse Signal Controller Generator Stepper Motor Driver PWM Speed Regulator at the best online prices at eBay! Free shipping for many products!
www.ebay.com

The output of this would feed the driver.

Robert
 
Yes, that would work. I have some experience with those and the one thing to note is that you need to set the speed pot to zero or near zero before you press the go button, then turn up the speed. The output does not ramp up to the set frequency, but rather just applies the set frequency instantly, and at higher settings can cause the motor to decouple and just sit there and growl at you. Won't hurt anything, but the motor doesn't rotate under that condition. In other words, it tries to accelerate the motor faster than is mechanically possible.
 
And I realize you're kind of freestyling this, but if you were going with the end goal of CNC, why would you not use a conventional stepper driver? Keeping in mind I'm new to the CNC stuff, I am in no way criticizing...
 
Guns- I am glad you are commenting. I AM using a conventional driver module. This board would be the controller that would operate the driver. I do not want to spend the money or time on a 3 axis controller that requires computer input.
Jim- I can see that frequency issue! Also that module would be a little sketchy since it has no indicator (that I can see) to tell you which direction it was set to move! It needs a forward/reverse light. After looking around eBay it seems that most or these small boards have an integrated driver for small steppers. This was one of the few that have control only.
Robert

Edit: I just realized I could hack the board and add an led indicator on the direction output pin to indicated forward/reverse. Also the enable pin for that matter. This might be the ticket!
 
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Something like this might be better, you can add your own buttons and speed pot on a small panel.
www.ebay.com

DC 5-32V Stepper Motor Speed Controller Driver Servo PLC Control For Industrial | eBay

Input and Output: all input is optocoupler isolation, while output the negative pulse. The low level signal is valid. Start the motor and it will be in forward rotation again on and on. Then it automatically starts to reverse and won’t stop until it touches the REV limit.
www.ebay.com

Here is one I did a few years ago. Speed, For/Rev, Stop, and Run
1598722805066.png
 
Ordered! That's exactly what I want to do.
My Chinglish is a little weak though. By "public side" do they mean ground? By "forward limit" and "reverse limit" do they mean when those terminals are high that determines the direction?
Thanks for you help on this.
Robert
 
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