So I figured out what NOT to do with a stepper motor-

If you ever open one up and pull the armature, resist the urge to, or otherwise avoid, sticking it to steel surface, such as your laser's cabinet. I did that tonight, by accident, didn't think much of it until I put it back together and found I have a totally useless stepper motor now. No torque, nearly all the resistance is gone.

I'm guessing the act of it sticking to my laser's cabinet de-magnetized it. Not fully, but all it does now is skip around and squeal at anything faster that 30% speed. And there's no way to slow down the initial high-speed acceleration at every change, so it's pretty much useless...

Next up- Can anyone answer me this question: I'm holding in my hand a Moons stepper, type 23HY4402-01N, with a date code 18/8/12 which I assume means mfr'd last August... NO where on the internet, including Moons website, or any of the many Moons PDF catalogs from around the world I've downloaded, can this part number be found. Not even close. The only info I can find at all is that the 23 is the frame size, the HY means it's a hybrid 1.8° 2 phase motor. No other info.

This motor was brand new yesterday, it was to replace the motor mentioned above, which is the original X-axis stepper on my 15 year old LS900 Gravograph laser. The original, for some time now has been VERY LOUD, mostly due to the bearings being totally devoid of lubricant, partly due to the motor always being extremely hot to the touch, idle or running. The Moons motor was installed, it ran okay, very quiet like it should. However, it was engraving funky, lots of backlash issues, which I tried to adjust out while engraving a half dozen rowmark ID plates. After running those plates I did other stuff for about 3 hours. Afterward I needed to make a miniature square with some measurement markings, was going to use the 900 to make it. I checked the stepper just to see if it was getting as hot as the original. It was ice cold, and the whole machine was non-responsive. I shut down, turned on, and the screen greeted me with the dreaded 'motor over temp' message. This message only shows up when one of the steppers has fried innards. So whatever's been making the original stepper very hot, fried this new stepper within a few hours...

Trying to eliminate the noise within the old motor is why I tore it apart, and then screwed it up. So now my LS900 is dead, and I want to find some other stepper options. There's no labeling on the original, Gravograph says that motor isn't made anymore. I'm sure I can find a suitable stepper, but without any info as to voltage, amperage and torque, I don't know what I'm needing. FWIW this is the 3rd stepper replacement- first was Gravograph's go-to replacement for the original, but that motor didn't have enough torque, it skipped badly. Second motor was Identical to this Moons, and we burned it up too, BUT, while testing it after wiring it to make sure we had the wires correct, we got a bit of a spark- The machine ran okay for a few minutes, then the motor just died. We assumed then that the spark caused the problem. Yesterday we wired up a new plug to fit the motor, no sparks or any other drama, it ran, sat, and just died...

sometime tonight I'm going to check voltages, resistance and continuity from the controller to the stepper. The old stepper shouldn't be getting so hot, and the new ones should obviously not fry themselves within hours.

If anyone has idea of a stepper than might work I'm all ears! (78mm is the absolute max frame length btw)

Sounds a bit like when I burned a servo and and later drive card on our cnc router.
In your case, can you swap drives to test them? I know x is usually lighter gauge than y, though.
Sounds like a fault in the card.

I would suspect the motor driver.

I was suspecting the driver too, based on the fact the original started getting more noisy the longer it sat. I didn't get a chance to check any voltages, but, my Gravo rep called this morning to tell me he was digging the X stepper out of an old 'parts' machine he has and was bringing it over. I told him the same thing, old stepper was getting noisy and thought there was something fishy with the driver. He said he didn't think so, and hopefully we'd find out after putting this stepper in, which is identical to my original. He also explained why I couldn't find a replacement Moons stepper, it's because it's a proprietary stepper they make only for Gravograph, which is supposed to be the replacement for their lasers. Upon examining the 'new' used motor, it's label states it's a 4 amp motor. My machine was a 'last-year' machine before they made some major changes, a big one was moving from serial/parallel connection only to USB and I'm assuming ethernet connection. This required a re-designed controller, and it could be the steppers and/or drivers were changed in the voltage/amperage department. So my rep is presuming the Moons replacements aren't compatible with my machine, even though they work fine in other machines he's put them in.

So we swapped in the identical replacement. And wow- I didn't realize this machine ever ran that quiet. The last 3 replacements, while quiet, weren't this quiet. The only noise is the 'swish' of the rail bearings. And it engraves great. Well, sorta great, I haven't tensioned the belt yet, it's a bit loose, and the backlash alignment is at least 3 steps out of whack. But it's been in sitting idle for over 3 hours, and like before it's hot, but not so hot I have to remove my fingers, but almost ;) -- By this time the last 2 Moons steppers had already self-destructed.

I just did another test run, other than I still need to adjust the belt & backlash, it's perfect.

So our assumption is the driver is fine, and Gravograph needs to find different steppers for my machine's vintage.

This pic tells the story, it's 3 engravings morphed into one photo. The engravings are of the same exact text and settings.
On top is what the Moon's produced fresh out of the box, and this is one of the better ones as I'd adjusted backlash.
In the middle is the nonsense my original stepper was doing, but the serial number and date line engraved okay...
Bottom is the exact same as the top, done with the identical replacement...
Attachment 412902
-the Moons stepper produced wildly erratic text thickness, IMO the engraving is terrible...
-my original, even screwed up, where it engraved normally bested the engraving quality of the Moons by a ton-
-the identical replacement, for the most part, very consistent. It's a bit choppy but adjustments should help with that :)
I'll be giving it the acid test, I have a ton of work for it!


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Good news!

One reason steppers run very hot is that they are often driven with constant current, so they constantly dissipate power even when standing still and essentially no torque is required to hold the gantry in place. Epilogs did this with the old rotaries and got the motors so hot you often times couldn't touch them after a while.

A good possibility for not finding info on that motor part is that it could have been custom made/marked for the OEM. Sometimes that simply means the OEM paid to have a custom part number, sometimes it means the wire color/length is different than what the motor manufacturer normally uses, sometimes it means a different connector was used, and sometimes it means something like custom wire sizes or windings. If you have a good motor, you can meter out its connections and determine the winding configuration and impedance. Knowing that, the frame size, step angle, and operating voltage, you can get a couple custom made for not much more than off-the-shelf.

I would for sure work to get another one in place if you can.... Might fail next month, might be never, but if parts are iffy......

So far this used one is working flawlessly, and if the drive cogs are any indication of actual usage, my original stepper must have a million more miles on it than this one, it still has nearly square teeth, the old teeth look like inverted "V"'s... ;) - I don't remember the last time the engraving looked this clean. This machine's still on the original rail bearings, that have never been lubed...

But I would like to get a spare stepper, they do go bad, I've changed out quite a few over the years. My burning up 2 'factory authorized replacements' within hours of install isn't going un-noticed, Gravograph engineers are going to inspect them, hopefully they'll come up with something...

If you search for Servo Motor Repairs they talk about many repairs they get is because someone opened the motor and it lost it's Magnetic Ability. In my old Navy Training they talked about a Magnetic Keeper Jig when opening the motors... I am betting the Stepper you mentioned that lost it's ability would have still lost it if it had not stuck to the Laser Case.

They make jigs to re magnetize the Servo and Stepper Motors.