Stepper motor power feed question

[lagweezle]

I was not aware of the possible damage I must have missed that in my research but it does make sense. Since the stepper will generate electricity when being turned by hand.

Same here! I was aware that all motors are terrible generators when you turn the spindle, but it hadn't occurred to me that the drivers might suffer damage. Glad I read that in caution in Sherline's documentation. I'm guessing some driver circuitry would be fine, but those are likely ones built with some extra electronics specifically to handle that scenario.

 

[Garryloy]

I will design the "off switch" circuit to disconnect the motor so it cannot back feed the driver in manual mode.
Thanks

 

[Driveslayer45]

I was thinking the same thing. It would have to be easy to turn on and off. It also needs to disconnect two wires, one from each pole of the motor....

 

[intrepid]

I will design the "off switch" circuit to disconnect the motor so it cannot back feed the driver in manual mode.
Thanks

I'm interested in installing a stepper on my LMS mill for the simplicity like you. The direct drive will also save some room. Do you have a link to the motor you plan to use? Thanks.

 

[Garryloy]

I have selected the stepper I want to use, but I have not bought it yet:

1 Axis Stepper CNC Kit 4.5Nm(637oz.in) Nema 34 Stepper Motor & Driver - 1-DM860T-34HS31 STEPPERONLINE

1 Axis Stepper CNC Kit 4.5Nm(637oz.in) Nema 34 Stepper Motor & Driver - 1-DM860T-34HS31 - Single Axis CNC Kit - This CNC kit included: 1 x Digital Stepper Drive 2.4-7.2A 18-80VAC or 36-110VDC for Nema 34 Motor 1 x Nema 34 CNC Stepper Motor 4.5Nm (637o

www.omc-stepperonline.com

Here's my reasoning:
1) it may be overkill for your application but I'm using it on a RF-31 with the original leadscrew, so I want plenty of torque. I don't plan to go ballscrews and CNC.
2) The torque of these motors overlap the frame sizes, and I could use a smaller diameter nema 23 for less cost, but it would be a lot longer. I wanted the shortest motor I could get that, with the shaft in line with the leadscrew, the body would not project above the plane of the table.
3) To me my mill is worth the investment of a good power feed (I think the off the shelf models available are simply a poor adaptation of an existing product designed for another machine application). I think I have solved the number 1 disadvantage of a round column mill and my machine meets all my needs. I will design a very robust compact mounting scheme using 3D solid modeling.

One more comment. Beware of shipping costs.

 

[Driveslayer45]

Using a nema 23 with 427 oz of torque i find if I try to start the motor turning too quickly it will stall, even with no cutting load. If I start slowly and turn up the speed as I go it's not an issue