Stepper motor sizes


Needing some help with motors.

I have an enco 110-1351 metal lathe (13x40) that had Amtek DC servo motors (Photo attached) on it which stopped working with the breakout board.

I wanted to replace with a stepper motor and well I ordered the wrong size cause they don’t move the X and Z axis haha! Oops.

I had done a bunch of reading on other forums and people were saying 230-280 in-oz of torque to move a 12x36 lathe.

So I figured I’d get the “QSH6018-86-28-310
1460-1084-ND STEP MOTOR HYBRID BIPOLAR 4.17V” which was rated for 439 and be good.

These didn’t work out. Anyone have an idea of what I need? I attached photos of lathe.

Breakout board is a DB25 1R5AM
Drivers I put a photo up of too.




There’s no way of knowing from this side of the screen how much torque would be required–it’s a thing that will vary with adjustment, lubrication, temperature, phase of the moon, and probably a few other things.

It shouldn’t be hard to measure however, given a hanging scale or some test weights. Multiply the length of the lever arm (e.g. handwheel radius) by the amount of force required to move it, and you’ll have a torque figure.

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Thanks Rick.

2 issues. I don’t have a hanging scale and no hand wheels haha.

I’m also a horse trainer by trade. It’s been 13 years since I did anything really in depth with this type of math.

Is there any way I could be “over torqued” on the machine?

I was thinking of getting one of the 1275 in-oz motors for the X axis and a fella near me is selling a near new 1700 in-oz motor?

Only question would be a driver for them that supports the amount of V required for them?

I did the best I could with using indrasize application by rexroth. Looks like my Zaxis would need 4.3 Nm of effective torque just to move the slide/tool post/and X-axis attachment (X-axis is all attached to the Zaxis slide).

Scales of the sort used for weighing the fish one just caught start under $10 at StuffMart.

Improvise something. A locking pliers or pipe wrench would do, provided that one uses some shim stock or a rag or the like to keep from marring the shaft.

Well it’s not exactly rocket surgery… Just multiplying two numbers together.

Yes and no. Any actuator capable of delivering enough torque could potentially do the job, but there’s a reason that people don’t tighten the screws on their eyeglasses with an impact wrench…

They exist. The one pictured above may well do the job. In an application of this type current is more the quantity of interest, as that’s where torque comes from. If one wanted to spin the motor quickly, then a higher-voltage driver may be called for.


Thanks Rick.

I will pick up a scale in the next day or two and get some numbers.

Not sure why no other place used a photo like that and explained it like you did but definitely not hard to find haha!

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Okay, I did some measuring with the fish scale.

Z axis is about 6lbs 8oz to rotate 1.75 inches off center of axis.

X axis is about 1lbs 6oz to rotate being 7.5 inches off center of axis.

By my calculations then:

Z is 182 oz-in to move
X is 180 oz-in to move

Which, doesn’t make much sense to me as the 439 oz-in motor could barely move the X axis and couldn’t move the Z axis at all.

So what I do wrong? Haha

The torque figures mentioned would appear to be within the capabilities of a QSH6018-86-28-310 motor under rated operating conditions. Check the configuration switches on your driver unit and verify that an appropriate output current setting is selected.

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Thanks Rick I will take a look!