having trouble will steppers binding on new build

Hi everyone,

please excuse me for being a complete noob to this. This is my first 3d printer anything. I have built my printer using gadgets3d electronics kit. [gadgets3d.com]

I have nema 17 steppers rated for 2A.
I am using 1/4-16 acme lead screws. The motors bind or stall when traveling at any real speed. I am using marlin firmware. here is a video of the problem. [www.youtube.com]

this happens even with the motors disconnected from the lead screws. (no a weight issue or design problem)

any help would be greatly appreciated. getting this worked out will set me up to start my first print. YAY!

you are pushing the motors faster than they can go. first reduce acceleration, second reduce speed. see if problem goes away.

if problem is still there, then you got a wire mixed up somewhere.

also what voltage are you working with. all my lead screw machines run at 19v-36v. higher voltage allows current to flow when there is a lot of resistance in the winding .

Edited 1 time(s). Last edit at 03/07/2014 01:20AM by jamesdanielv.

You should have read up on it a little more at only a 16th of an inch per turn travel it's going to be very slow. I have built one using ballscrews and I would say for the X and Y you need at least 5/8 of an inch per turn. To obtain reasonable speed and for higher speeds you need more than 5/8 of an inch possibly up to an inch and a quarter per turn. Check out my old posts you'll see the one I made

cnc dick is correct, let's back it up with some calculations:

For most stepper motors, you're looking at about 1000 RPM (17 RPS) max unloaded speed (very optimistic). That translates to 27 mm/s for 1/4-16 screws. Pretty slow, especially considering that you would have trouble even reaching 1000 RPM in the first place. And that's only if you can step it that fast. A 16MHz Arduino maxes out at about a 16kHz step rate. With a 200 step/rev motor at 16x microstepping, that's a max speed of 5 RPS (300 RPM) or 8 mm/s. You would have to drop down to 4x microstepping (or less) to be able to reach the maximum (theoretical) motor speed of 1000 RPM. An increase of motor voltage will also help eek out higher stepper speeds.

Edit: Anyone feel free to correct me on my calculations and assumptions. It's entirely possible that I made a mistake

Edited 1 time(s). Last edit at 03/07/2014 12:08PM by NewPerfection.

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Sounds about right. I can reliably drive my 5mm pitch ball screws at 1750 rpm using 16 microsteps. However the steppers are on a 68 volt power supply and a 200Khz driver. So this setup is just going to be slow.

Ouch. Well I really appreciate the help. While I am pouting, what would you suggest?
I am thinking revamp x and y to a belt drive instead.
Gearboxes are not cost efficient and lead screws with a 20mm pitch or higher are way too large for my setup.
I don't see replacing my controller and adding a huge power supply as an easy option either.

Seeing the numbers for the stepper and arduino really help though.
Thanks again.

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aye_b_red_beard
While I am pouting, what would you suggest?

Go ahead and run your printer as-is, you will just have to reduce the maximum speeds and accelerations that you run your machine at. You can print at slow speeds (20 mm/s or less) for now, which should produce acceptable parts, with maybe some oozing issues due to slow travel rates.

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aye_b_red_beard
I am thinking revamp x and y to a belt drive instead.
Gearboxes are not cost efficient and lead screws with a 20mm pitch or higher are way too large for my setup.

You are right that gearboxes would not be a good way to go, not least of which because they introduce complexity and backlash into the system. You can get reasonably small lead screws with over 20mm pitch, but they aren't cheap. See: [trinitylabs.com]

There's a reason that most all RepRaps are belt driven

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Belt drives for you sound like the way to go besides the belts and the pulleys and obviously the mechanical pieces you have to make will be the only cost. It's kind of a shame that you didn't look close enough there has been people out there using lead and ball screws building printers not that many of us of course but we've had good luck. The most recent one is aluminum reprap would lead screws here on the reprap forums. There has been units sold some not working too well the illuminatis for one example it was basically because of shoddy construction and not being able to keep up with orders. But anybody that has ever dealt with it would've told you about the thread pitch

Edited 2 time(s). Last edit at 03/07/2014 08:53PM by cnc dick.