Z axis moves in the wrong direction

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xmishka
Posts: 2
Joined: Fri Jul 20, 2012 7:28 am

Z axis moves in the wrong direction

Post by xmishka » Fri Jul 20, 2012 8:24 am

Hi,

So I finally got my ShapeOko kit assembled after weeks of it sitting in the garage. Everything seems to work except for I am having an issue with my Z axis. After assembling I ran some test commands to make sure everything was working ok. X and Y axis don't have any problems. Z axis command sometimes go the wrong way.

G91
X10 X10 X10 X10 - All commands move in the same direction
X-10 X-10 X-10 X-10 - All commands move in the opposite direction of the above
Y works the same way.

Z10 Z10 Z10 Z10 - Some move up some move down.
Z-10 Z-10 Z-10 Z-10 - Some move up some move down.

I tried printing Hello_World_ShapeOko using a sharpie and it just ended up getting smashed.

I am running the grbl08_basic GRBL code from the guide on the site. I ran the Z axis with a drill a few times to smooth it out so it doesn't bind. I tried changing the speed on the Z axis. I tried messing with the pots a bit (I didn't change them much since I can't find any docs on how to set them). I am not sure what else I could do. Could it be a defective GRBL shield or motor?
Any help is appreciated.

Thanks,
-Victor

aldenhart
Posts: 132
Joined: Tue Apr 10, 2012 2:17 pm

Re: Z axis moves in the wrong direction

Post by aldenhart » Fri Jul 20, 2012 11:33 am

Victor,

Please contact us at the Synthetos address and let's diagnose if this is a grblShield problem or not. If you would, go to the synthetos.com website and post a note to the grblShield support forum topic.

Thanks

Alden

vios
Posts: 46
Joined: Sun Apr 22, 2012 12:00 pm

Re: Z axis moves in the wrong direction

Post by vios » Fri Jul 20, 2012 3:07 pm

xmishka,

It does happen to me. Same z axis go up and down.
I've got that fix after found out some of the wire (molex connector to the driver board) not sit firmly.
Try to check again the connector and make sure all the wire connect firmly.

aldenhart
Posts: 132
Joined: Tue Apr 10, 2012 2:17 pm

Re: Z axis moves in the wrong direction

Post by aldenhart » Fri Jul 20, 2012 6:50 pm

The other things I'm aware of that could cause this behavior is if there is a manufacturing flaw in the circuit board that allows the direction signal (DIR) to float, or if the power output to one axis or the other is not working. Either of these cases could cause an axis to turn erratically. I have seen this on boards I have hand-soldered, but we have not seen this on production assembled boards (like the Inventables and the ones we sell on our site), but it could happen. All production boards are tested for proper motion in both directions on all axes, but it's possible that something could have shaken loose in transit. So I wanted to diagnose the board if this was happening. But I agree with vios, start with the connector and make sure those are solid.

xmishka
Posts: 2
Joined: Fri Jul 20, 2012 7:28 am

Re: Z axis moves in the wrong direction

Post by xmishka » Fri Jul 27, 2012 4:53 am

So I ended up going on the synthetos forum and did some troubleshooting. It looks like it is the motor itself. Here are the steps I followed:

1. Swapped X/Z connectors and tried running the X axis through the Z channel and Z axis through the X channel (after making some settings adjustments)
Result: The X axis channel on the Grbl shield had the same issue when trying to drive the Z axis motor but the Z axis channel on the Grbl shield did not have any issues driving the X axis motor.
2. Tried changing the $2 and $3 settings to various values
Result: This did not help.
3. Made sure I had the Z axis mod on my Grbl shield (https://www.synthetos.com/wiki/index.ph ... r_Shapeoko)
Result: Had the mod.
4. Checked all the connections - Checked resistance between the pin the back of the Grbl shield and the wire on motor side of the connectors.
Result: Connections are all good - All connections had equal resistance (0.02 ohms)
5. Checked for binding
Result: The Z axis bolt was easy to move by hand and I don't feel any binding.

I am hoping I can get the motor warrantied since it seems to be defective. I just need to figure out if there is one and how to go about doing so or try to find the same part number online.

Thanks for your help guys.

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