Shapeoko 3 Z-Axis stepper skipping

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stuarttaylor00
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Joined: Mon Oct 19, 2015 4:06 am

Shapeoko 3 Z-Axis stepper skipping

Post by stuarttaylor00 » Sat Jan 09, 2016 11:07 am

Hi guys, I'm having a few issues with my Shapeoko 3 (#1095).

It started with the machine not cutting all the way through on a profile cut, instead of a 12mm deep cut it only made a 6.5mm cut (material is plywood). I did some investigating and it turns out the Z-Axis stepper has lost almost all of it torque. It is so bad that I can stop the stepper moving with two fingers if I hold the pulley and move the Z-Axis in 1mm increments. it feels like gear teeth skipping when it happens.

I've flicked an email off to support but thought I'd check here if anyone has any information or experience with this? It seems like the stepper isn't receiving enough power or something like that.

Any help would be greatly appreciated, I am just getting the Hang of the SO3 and want to keep progressing!

Cheers
Shapeoko 3 #1095 - Aluminium wasteboard, homing switches, Modified Z plate, Makita 700 router
Flashforge Dreamer Dual extruder 3D printer

2013 Ducati 848 Evo ;)

madhatter
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Location: WA, USA

Re: Shapeoko 3 Z-Axis stepper skipping

Post by madhatter » Sat Jan 09, 2016 8:04 pm

Could it be the toothed gear is slipping on the stepper motor shaft? Did you file/grind a flat in the shaft?

Make a slash across the entire gear face and shaft end and see if the shaft is turning inside the gear.
SO3 #0054
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WillAdams
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Re: Shapeoko 3 Z-Axis stepper skipping

Post by WillAdams » Sun Jan 10, 2016 12:12 am

Losing steps due to insufficient belt tension?

I has to use a pry bar to get mine taut enough.

Documented the note I was getting here: http://www.shapeoko.com/forum/viewtopic ... 075#p53075
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

stuarttaylor00
Posts: 36
Joined: Mon Oct 19, 2015 4:06 am

Re: Shapeoko 3 Z-Axis stepper skipping

Post by stuarttaylor00 » Sun Jan 10, 2016 12:34 am

Thanks for the response guys, however I have proven it is neither the belt slipping or the toothed gear spinning on the shaft:
I slackened off the z-axis belt and when I hold the toothed pulley on the motor shaft it still slips, that eliminates the belt tension (I also used a flat head screwdriver to tension the belt during assembly)

I then used a sharpie to draw a line on the end of the toothed gear and the motor shaft, these lines stay in the same place in relation to each other while the motor is slipping: this proves the gear is secure on the shaft (mine came with the flat machined on the shaft already)

Thanks for the suggestions, I feel the issue is low power to the stepper or the stepper itself isn't working as it should.

During running the stepper gets warm to the touch, but not hot, do I don't think the issue is heat either.
Thanks again guys :)
Shapeoko 3 #1095 - Aluminium wasteboard, homing switches, Modified Z plate, Makita 700 router
Flashforge Dreamer Dual extruder 3D printer

2013 Ducati 848 Evo ;)

richb
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Joined: Thu Dec 01, 2016 7:08 am
Location: Mechanicsville VA

Re: Shapeoko 3 Z-Axis stepper skipping

Post by richb » Thu Dec 01, 2016 4:21 pm

Did you ever resolve the z-axis stepper skipping issue? I have the same problem on my new Shapeoko XXL. I have marked the motor pulley, shaft and belt and none of those are slipping. All stay fixed in the same relative position to each other. I have also reduced the spring tension which seems to help. But I have now also experienced run-away plunge with a 3-flute bit, which seems to indicate the motor is also too weak to hold up the spindle. The problem might be insufficient power to the motor from the controller. So, how did you resolve this?

WillAdams
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Re: Shapeoko 3 Z-Axis stepper skipping

Post by WillAdams » Thu Dec 01, 2016 5:25 pm

Rather than the motor being too weak, it's more likely that the pulley is skipping on the belt due to insufficient belt tension --- I had to use a small pry bar to get mine set, but you have to be careful not to bend the stepper motor shaft:

http://www.shapeoko.com/wiki/index.php/Shapeoko_3#Belts

my notes on this at: http://www.shapeoko.com/forum/viewtopic ... 075#p53075 but the wooden shim idea is probably better: http://www.shapeoko.com/forum/viewtopic.php?f=37&t=8249
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

richb
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Re: Shapeoko 3 Z-Axis stepper skipping

Post by richb » Thu Dec 01, 2016 6:22 pm

But my mark on the belt stays lined up with the mark on the pulley. So the belt is not skipping or slipping around the motor pulley.

WillAdams
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Re: Shapeoko 3 Z-Axis stepper skipping

Post by WillAdams » Thu Dec 01, 2016 7:06 pm

Mystified as to how all these parts could stay lined up, but the motor only could get out of synch --- I'd suggest putting in an e-mail to support@carbide3d.com w/ all these details, referencing any previous communications with them, and including your serial #.
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

DocN
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Re: Shapeoko 3 Z-Axis stepper skipping

Post by DocN » Thu Dec 01, 2016 7:53 pm

I had an issue with my CNC lathe conversion, where one stepper, while powered up but idle, could relatively easily be turned by hand.

I wish I could say definitively what the issue was, but I know for a fact it was electronic. I could swap leads between the two steppers, and the "weak hold" issue followed the one controller. I ordered another controller (I'd bought the control setup and enclosure used but supposedly known-good) and when it came in, before installing anything, I powered up the system again to double-check. This time both steppers held solidly, and I was able to take some test cuts with ease, using the manual jog feature.

I still do not know what caused the issue in the first place, nor what happened to cause it to "fix" itself. But it was very definitely due to the electronics, not the hardware. (IE, belt tension, skipping teeth, etc.)

Doc.

richb
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Re: Shapeoko 3 Z-Axis stepper skipping

Post by richb » Fri Dec 02, 2016 7:24 pm

Did some more testing to try to diagnose the Z-axis issue losing position on my Shapeoko XXL. I am using the Makita router. Removed the bit and placed a digital shipping scale under the router. Connected the machine and using the jog feature in Carbide Motion lowered the router in 0.1 mm increments onto the scale. The Z axis skips consistently at around 27 lbs of force. This is with the Z springs removed. The skipping sounds like a clunk. My marks show that the belt is not slipping on the motor or stationary pulleys. In fact, I find that I can move the Z axis position simply by pulling up or down on the router with my hands when the machine is turned on and at idle. If the standard springs are installed the maximum force would be even less, especially in the lower positions.

Has anyone else measured the maximum Z force available on their machine?

I also spoke to Apollo today and he is unsure of the cause. Wants some pictures of pocketing operations before sending out a replacement controller board.

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