Stepper motor for the PM-25MV Z-axis power feed?

J

javaduke

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Sorry, folks, I know it's been discussed before but I can't find any specifics. So I'm thinking about making my own Z-axis power lift and I'm planning to use a stepper motor with ZK-SMC01 (or 02) controller, which gives me an ability to move the head up and down and also adjust speed, which may come handy with power drilling and boring operations. The only thing I cannot figure out is which motor should I use. So far I'm thinking about this one: https://www.amazon.com/Torque-Stepper-Motor-425oz-Router/dp/B00PNEPW4C - is it good enough, or is it an overkill? I'm not sure how to figure out if it will be powerful enough to move the head up (down is obviously not an issue :))
Any thoughts?
 
The only way to know for sure is to measure the torque required using a spring scale or bathroom scale and some sort of lever arm so you can
get a baseline reading in foot/pounds
The other option is to just buy a big honking motor and hope it's strong enough or gear it down if it isn't
 
A torque wrench on the shaft might be better to figure it out. The beam style let's you see how much you are applying, and maybe see the stick slip.

Next up is how fast you want. A high power motor with the correct gearing will move it faster than a low power one (again, set up with the right gearing).

Your mounting details may make a belt or gear reduction a nice way to get the drive into where you need it.

Sent from my SM-S911U using Tapatalk
 
Agree with the other posts - measure it! Use the largest cutter you expect to use and bore into the hardest material you expect to use. Convert the force reading to torque, then back-figure that into whatever ballscrew/worm gear setup is used, and presto.
 
That 425oz should be plenty strong enough. I used some of those on my now dismantled CNC mill drill project.

www.hobby-machinist.com

Homemade vertical mill drill

Well, I guess I'm gonna try to make myself a mill for cheap. I found this column on Craigslist for $80. And I ordered this spindle I can power with a VFD I already have. And I'm going to get one of these cheap x-y milling tables. And probably look for a really flat piece of C channel...
www.hobby-machinist.com www.hobby-machinist.com

Are you planning a full CNC conversion or just the Z-axis feed?

It’s a slippery slope….

Hopefully I’ll be offering up my now unused components for sale here soon.

John
 
For now I'm not planning any CNC conversion, all I need is to move head up and down, but being able to adjust the speed. Going forward I may go all the way CNC, so I ended up buying a Nema 34 motor. Now I'm looking for a way to mount it on the column, looks like the mounts are not available separately, only as a part of a CNC kit.
 
Weldingrod1 said:
A torque wrench on the shaft might be better to figure it out. The beam style let's you see how much you are applying, and maybe see the stick slip.

Next up is how fast you want. A high power motor with the correct gearing will move it faster than a low power one (again, set up with the right gearing).

Your mounting details may make a belt or gear reduction a nice way to get the drive into where you need it.

Sent from my SM-S911U using Tapatalk
Click to expand...
The problem with using a torque wrench is you are talking about oz-in. rather than ft-lbs. I ran smack dab into the problem when I was dealing with measuring required torques on my lathe and milling machine. My Tormach CNC uses a 770 oz-in. stepper on the z axis but it is driving a ball screw rather than an Acme thread. You can use a 1/4" breaker bar and an appropriate spring or digital scale but you need to ensure that the pulling force is always perpendicular to the bar

The way that I got around this was to machine a pulley and wrap several turns of cord around it Pull on the cord with an appropriate scale. The force is always perpendicular to a line from the center of the shaft to the tangent point on the scale so true torque is being measured and is simply the radius of the pulley X the measured force. An additional benefit is that you can measure the force over a continued pull so you can measure stiction effect as well as running force.
 
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