Looking into making a rotary bed for my OMTech K40. I’m pretty sure the stock controller runs on 24VDC but many of the beds I see for sale seem to specify 12V for their motor as well as the various DIYs I’m looking at.
I could unplug a motor and test it myself but you know, I’m lazy. What voltage NEMA17 should I be shopping for?
OK, quick research shows the NEMA17 spec itself calls for 12V. Does that 24V controller put out 12V for the steppers?
More on that 12V specification: That basically means that 12V is the max voltage you can put across the coils without limiting current; if you put 12V across the coils they will pull the maximum rated current.
You’ll want a motor with a similar specification to the Y motor in your K40 if you are using the Y controller on the control board. This is because the current limiting will be set by a resistor that is soldered to the board. If you have trouble figuring out the specification for your existing Y motor, feel free to post a picture of the back side of it with the writing visible and readable.
(There are other configurations besides re-using the Y axis; some folks have a control board with a separate A axis for the rotary where the rotary motor can have a different configuration for current because it’s using a different stepper driver chip.)
gonna get a picture of one of the existing steppers. more to follow
so much for that. jammed my camera in there every which way and I can’t see any sign of a label on any face of either motor. between the two of them I think I saw every face, so I’m not going to go so far as to remove one
yeah, the ones I see spec for other rotary beds all seem to be 0.9° also. and if that’s not right I think I can adjust it in K40 whisperer
You have to adjust Y step ratio for the radius of whatever you are cutting anyway, so the resolution of the A stepper doesn’t really matter that much, and 400s/r (0.9°) motors typically have lower torque than 200s/r (1.8°) as far as I know. Current matters more.
That makes it reasonably likely that another 1A motor is reasonable for your A motor hooked up in place of your Y motor.
Do note that you should never connect/disconnect motors under power — it can kill the driver to do that. You probably wouldn’t anyway, but if you plan to swap out whether the Y driver is connected to the Y stepper or the A stepper, I just wanted to make sure you knew not to try to hook something up that would let you swap while power was turned on.
From what I recall, my X motor was ~1A and my Y motor was .8A or something like that and I figured it was because of 2 reasons.
1-The 24V in the LPS was pretty weak so they kept the stepper motors low power
2-the X axis takes more strain while engraving and the Y axis generally moves less.
If you want to beef up your 40 watt laser pop a VMS controller in to it LX4s is the one you want to run a full motorized bed with autofocus functionality. It will not only run your bed but totally turbocharge every function of your laser, increase the speeds dramatically and give you superb results. I run that board on a 100 watt laser but it will work just as well on a40,50,60 and even a150 tube. It doesnt seem to have a limit.
With a motorised bed you should be using a stepper motor with a planetary gearbox unless you are just using 3mm wood on top, that stepper gets a lot of wear on it without one.
Here’s a good one but you will need a controller like above to run it at 24 volts, If you decide to use an electric motor instead then use a separate PSU and not the LPSU, as it’s not powerful enough to run the laser and 3 steppers.