Its the inductance.

The 570 has 2uH and almost all the smaller ones are higher so at the same voltage are slower.

A little extra power lets you run the ball nut tighter and end bearings and often you have tight spots in the ways to get past.

So from a cost stand point you can just run the 570 at 3A or 4A and they make less noise and less heat over a 390 oz with higher inductance.

The break point is 50V. The 80V driver are more money so you save some by staying at 50V.

Quote Originally Posted by NIC 77 View Post
So I spent a few minutes on this

https://motion.schneider-electric.co...-control-ip20/

Above is the part # data sheet from the first EBay add I posted a link to. The same data sheet I posted earlier. So this is for "MDI1" It says for

Control Type = Programmable Motion Control
# of I/O = 4 I/O points, programmable as sinking outputs or sinking and sourcing inputs
Logic Range = Inputs and outputs tolerant to +24 VDC, inputs TTL compatible

And then below is the data for "MDM1"

https://motion.schneider-electric.co...on-input-ip20/

Control Type = Step/direction input
Control Method = Clock and direction inputs
P1 Connector Options = Power & I/O Flying Leads, Pluggable, Wire Crimp

So good call guys. Looks like you need to pick the correct one.

I'm pretty good at looking at torque vs speed curves and doing the math with inertia and lead, etc., but I can miss things on the electronics side. Certainly, the feedback from RCaffin, and jfong, was appropriate, so again, good call guys.



Roger, are you saying that Schneider Electric MDrive is older technology with a dying product line? Or is this a general statement referring to something else?

There are many reasons why you could have different control inputs. Their target market could be factory automation for some models, for example, move a beer bottle over, wait for it to be filled, move it back.

It was my understanding that the MDrive was a step up from traditional steppers. These are "smarter" steppers with built in drivers optimized for the motors. From what I've seen in videos, you can't loose steps on these motors, they will adjust the speed if the load is too great. If the OP can find an appropriate model on EBay, I think that would be a good choice.

As far as why they aren't widely used, I think it is because unless you find a great EBay deal, they are alot more $$$ to buy direct than a traditional setup.

Correct me if I'm wrong.





I don't think 150 oz to 300 oz is a little small for this kind of application, but that would only hold true if the inductance was low and they could hold torque over a long speed range. Obviously, the ones you have looked at don't do this, and at speed they don't have what is needed.

Really, you're looking at less than 100 oz in that is needed at final speed for a small mill. The initial torque at low speed doesn't matter, you won't use it. Of course, this depends on the lead you are using. That's why I mentioned the MDrive as being a potentially good choice. It has low torque but a fairly flat curve to a high RPM. The ballscrew inertia and motor inertia are low, and at accelerations 0.2G and below, not much torque is needed as far as I can tell, unless my initial look has missed something.

I don't see the OP ever using anywhere near the 570 oz in at low RPM on X and Y, however with a low inductance, and at 50V, I absolutely do not in any way disagree that this could be an excellent overall choice based on performance at higher RPMs.

Do you have a torque vs speed graph for comparison to other options?

Really, not disagreeing with you in any way, just pointing out that it is only the torque available at top end speed that bears relevance, which I'm guessing you know well, but the OP might be questioning. If you disagree, let me know.

As far as the discussion about encoders is concerned,

Well, I wouldn't bother with it, so I agree with Ger21 on that, but as 109jb has stated perhaps it's not much money, and if you want to do it, well, why not.

I don't see alot of value added, but.....some interesting points all around.

Certain jfong has a good insight into how electronics work, far better than mine. Really, all of the interested parties' comments are from people whos opinions I value based on other threads I have read or participated in.

I was thinking, didn't Jim Dawson say he had some kind of linear encoder in his machine with his custom control software? Probably not relevant, but interesting nevertheless.

I really wouldn't worry about encoders on steppers, but if the price isn't prohibitive, well you could, and if you can find a deal on a "smart" stepper like an MDrive, well, you could do that instead, or, you could just get the steppers that arizonavideo said, and those have proven to give a good result.