I recently bought a new nema 17 42mm x 48mm, I have StepStick A4988 drivers

it was ok for a few days but still skipping steps, and now it just skip on anything, adjusting current has no effect, motor just has no torque at all whatsoever, even with current adjust to the point just before it makes lots of noises and no movement, it still have no torque, I measured 1.2v at that point, but no torque, I can hold the gear with my fingers and it will skip, if I try to extruder, it just skip, nothing else happens, if I extrude with no hotend, it still skip sometimes, but if I gently hold the filament, it will skip.

is it the motor or is it a driver issue?

thanks

It's very hard to break a motor and very easy to break those pololu driver modules. It's the driver...

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

the spare driver is doing the same thing, I think I get a pololu drv8825 to replace it, do I need to change them all or can I just change the E driver to drv 8825, rest are a4988

Check the connector of the stepper cable and on the Ramps. They often provide bad contact.
Also the crimp-quality can differ a lot. Try to remove the wires from the housing and check/ solder these, too.

-Olaf

I've checked those this morning, they all good, just 10 mins ago I notice the bearing is jammed, I changed it out to a new one, now manual extrusion at 2mm/s feed rate no skip, if I was to hold the gear on the motor shaft, I can make it skip, not sure how strong they meant to be, if it was or wasn't suppose to skip if you hold the gear on the main motor shaft

p.s. I also loosen up the the screws by a quarter turn on the motor mount, extruder block is mounted together on the same screws, it seems if I fully tighten all 4 screws, it skips more,

I am using and printing another one of these at the moment, I have adjusted the model to align for my groove bearing instead of groove gear that it was made for originally, 6 layers down so far so good, no click, but only at 40mm/s max

Edited 1 time(s). Last edit at 08/31/2015 11:20AM by deaconfrost.

Sounds like the problem is on an extruder? You might also check and make sure the nozzle isn't partially clogged.

I'd try to drive a motor outside of your printer.
you might have mechanism issues.

Also, verify you have the wiring on the motor coils correct.
I've found different brands of motors use their own blue/yellow/red/green pairings.

Yes I have different color but they match up to diagram to pins. The part printed without a single click. I post up image tomorrow. The support came clean off easily and the part is very clean so it wasn't running too hot, these pla are rated 190 to 215c. I printed the part at 208c. Manual extruded 100mm without skip at 2mm/'s. Max print speed was 40mm/'s I will do more testing tomorrow

I also have a 42mm × 32mm stepper from the original set up that was use on direct drive on the x carriage was also doing the same thing as the new motor.

Edited 1 time(s). Last edit at 08/31/2015 07:45PM by deaconfrost.

Quote
bryanandaimee
Sounds like the problem is on an extruder? You might also check and make sure the nozzle isn't partially clogged.

Nozzle was checked and cleaned. I can push plastic through the nozzle by hand easily. Not really sure where the problem was but so far it's working. Finger crossed.

I have two identical direct drive extruders on my prusa. One works perfect, but the other skipped occasionally.
The reason was the drive gear wasn´t aligned perfectly with the filament. It is a MK8 grooved gear.
I loosened the grubscrew on the stepper shaft and the gear aligned itself ( was 0.5mm off )
Tightened everything and now it works flawless.

You indirectly experienced the same, when you loosened the screws on your extruder.
-Olaf

Edited 1 time(s). Last edit at 09/01/2015 02:36AM by o_lampe.

maybe my first message failed to post, or I did not ask the question correctly. In the latest reprap incarnation one of the pololu dr a4988 is used to drive two nema17 motors for the z axis. My question is; can two a4988's be wired in parallel to drive a higher current nema23 motor. Would i run into timing problems with current control function of the a4988? What I'm trying to do is build a 3dprinter/cnc mill/router, using more torque on each axis.

No you can't connect A4988 drivers in parallel to increase the current. But you can choose Nema 23 motors that have a current rating within the driver current spec and use a higher voltage to compensate. AFAIR the A4988 and A4982 chips are rated at 35V, and so are some 3D printer electronics boards.

Alternatively, use higher rated stepper drivers, but they will cost more.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Those little modules cost $5-6 each. If you could parallel two of them, you'd be in for $12. You'll need to keep spares on hand because they are easily broken, so now you in for $20-24

One of these, rated for much higher current (5A) is only $17 shipped : [www.ebay.com]

That's a chopper driver, pretty much the same thing as a A4988 on steroids. There's a better option- a DSP based driver that allows higher microstepping ratios, suppresses resonance, etc. (runs silent!). I use these: [www.sainsmart.com]

All these things are easy to drive- they have opto isolators on their inputs. You just give them step/durection/enable from the controller board.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

... I'm using the RASP128 drivers on my RADDS boards for the RepRap-style machines - they are developed as Pololu-plugin-replacements and can support until 2.2Amps continuous current.

Here are some infos around them - [www.dr-henschke.de]

I'm actually developing a comercial paste-bot with 2A-NEMA23-steppers on toothbelts for X+Y and spindle for Z ... and driving them with only 500mA(!) with 250mm/s for X+Y without step losses

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I don't know what's the effect, but for another reason, my bed couldn't keep above 100c for abs during print, I upped the voltage on psu to 13.5v not bed is holding 110c during print, extruder stepper also stopped skipping, printed out a small gear, large gear, extruder block at 0.2mm layers at 40mm/s speed, not a single click... trying 60mm/s on the idler.

Be careful about turning up power supply voltage. Its power rating does not increase with the voltage but the load does. It is very easy to exceed the power supply's rated output power and as a result kill the supply. If the bed resistance is 1 Ohm, the bed will use 144 W at 12 V and will use 182W at 13.5V. Other powers will likewise increase.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

thanks for the info, I would guess I will need a new psu soon, before I went near the psu, it was set by factory, but it wasn't giving 12v to begin with after few months of usage, it measured 11.8v when it is doing nothing, when under load, it dropped to 11.1v, I turned it up to 12.3v and a month later it dropped, so its been dropping since day one. that might be where all my problem came from

I think I will get this

12v 33a 400w psu