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alan corder
09-02-2017, 4:38 PM
Hi, I have a G Weike LC1390 dual head laser. I’m using Lasercut 5.3. I have been using it for a couple of years now with no major problems.

Today I was cutting some parts and all was OK until I went to cut another part and suddenly things went a bit strange with my Y axis.

While the X axis is fine, the Y axis now only moves half way and every thing is only half the height it should be. The heads return to the datum just fine but when trying to move the head to the front of the machine using the cursor buttons the head again stops halfway.

I’ve switched off and on again numerous times and reloading the configuration file and lasercut and it’s made no difference, the gantry still stops half way between the back and the front of the machine and everything still comes out half the height it should. Checking the setting in laser cut all appears to be as it should. I’m at a total loss as to what to do next. Any help would be greatly appreciated.

Mike Null
09-02-2017, 4:53 PM
Are you able to manually move the gantry all the way to the front stop position?

I mean by hand not with the arrows.

alan corder
09-02-2017, 5:16 PM
Hi, I can but it's quite hard to move and I had to force it, not like when the machine is switched off. After I'd moved it to the front, when I tried to move the head to the back of the machine again using the cursor keys it stopped half way again and wouldn't go to the back until I pressed the datum button.

Mike Null
09-02-2017, 5:23 PM
I'm not familiar with your machine but I wonder if there isn't something binding such as a gear, pulley or some impediment. My first thought was the motor but since it operates adequately to move halfway on the axis it's probably ok. We have a lot of members who have similar machines so I'm sure a few of them will chime in with some ideas.

alan corder
09-02-2017, 5:29 PM
I had that thought but it's now cutting half size on the y axis, the right shape but only half the height. If I try to cut a 12" square it comes out about 12 x 6. The x axis is fine. I'm totally stumped!

Dave Sheldrake
09-02-2017, 6:20 PM
DON'T move the axis by hand

If you do it with the machine turned on it will damage the steppers, if you do it with the machine off the steppers work like a generator and will damage the step drivers.

It sounds like a scale factor is set in the machine settings (you can auto scale in the settings)

alan corder
09-02-2017, 6:48 PM
It's as if half the bed can't be used anymore and everything is squashed into the other half.

Rich Harman
09-03-2017, 6:54 AM
if you do it with the machine off the steppers work like a generator and will damage the step drivers.

I've never damaged a stepper driver, and I move them by hand frequently. Not just lasers but routers, 3d printers, mat cutters, mills and robots. I move all of them by hand - some of them require being moved by hand.

Michael Henriksen
09-03-2017, 7:17 AM
Normally the stepper drivers have diodes to protect them but if you are able to move the stepper fast enough to generate a high voltage you might be able to damage the driver. If you move things slowly there shouldn't be an issue.

John Lifer
09-03-2017, 10:17 AM
Move slowly with machine off and it should be ok. Don't push fast and no current should build up.

Jerome Stanek
09-03-2017, 1:29 PM
Had someone come into my shop and pushed the Gantry to the end and it blew a driver. Lucky it there was a fuse on it. Gecko 203

Bill George
09-04-2017, 8:31 AM
He posted the same question over on CNCZone and I gave him the same answer he has gotten here? I have moved stepper motors all over the place, with the power off and slowly and never had an issue. If you are concerned, unplug the motor.

alan corder
09-04-2017, 9:14 AM
I have an update!

I tried the laser cutter with another computer and the head now moves the full depth of the bed, y axis. However, the cutting size is still the same, x axis is fine but the y axis is still half size. Where do I go from here?

Bill George
09-04-2017, 10:09 AM
I have an update!

I tried the laser cutter with another computer and the head now moves the full depth of the bed, y axis. However, the cutting size is still the same, x axis is fine but the y axis is still half size. Where do I go from here?

Ahh, you said you used the keypad meaning keypad on the controller and it did the same thing..... why would changing computers make any difference?

alan corder
09-04-2017, 10:28 AM
i have absolutely no idea, that's the problem.

Matt McCoy
09-04-2017, 11:19 AM
I would check to make sure your software/driver configuration settings are correct first. If so, inspect movement of the gantry and the optical path to ensure everything is tight and functioning properly. With the power off, you should be able to move the laser head freely across the bed. As mentioned, don't force anything and do so slowly. Then check connections from the controller to the Y stepper, both physically and with a multimeter. After these are eliminated, you might try swapping the X and Y steppers to determine if the motor is shot.

alan corder
09-05-2017, 1:03 PM
The mechanical side of things seems to be unaffected by the problem. motors work OK and gantries move freely. I'm beginning to think it's software related, possible the motion driver card, MPC6515.

I have noticed another symptom. if the head is moved towards the front of the bed, Y axis, where it stops becomes the new datum. The X axis is not effected.

alan corder
09-07-2017, 3:52 PM
I’ve fixed it!!! It turned out to be one of the dip switches on the Y Driver board had set itself to the down position instead of up. I never even gave it a thought as I’ve never touched anything inside the cutter.


Many thanks to you all for spending the time on my problem.

Kev Williams
09-07-2017, 5:53 PM
ghost in the machine ;)

Ian Stewart-Koster
09-08-2017, 9:54 PM
I wish my solution was as simple... The Y asix moves erratically, as if it is resisiting impulses to move. (ULS M300)
The stepper is fine. I swapped it out- no difference.
The wires to the stepper are fine. I swapped them out- no differemce.
There is no drive card or board- it comes off a single motherboard with everything on it.
There's no clear software fix or cause I can find, suggesting it may be somehow electronic, in the motherboard...

Last time it did this, unplugging & replugging everythng fixed it for 6 weeks, then a second ditto, make it last 3 weeks, then back to its tricks.
Now, the undo it and do it up again makes no difference.

alan corder
09-10-2017, 7:58 AM
I wish I could help. Good luck!

Kev Williams
09-10-2017, 12:59 PM
Ian, have you checked power supply output voltages? Cleaning the connections could have been a temporary bandaid to help with a low voltage situation. Bad connections can cause a low-volt issue, had that happen with the GCC, cleaning all the connectors fixed it right up. (all my volt outputs were fine)...

You also have a display with no text, same machine? That was the first thing to go when my connection problem cropped up... I'm thinking bad power supply maybe...

Ian Stewart-Koster
09-11-2017, 8:53 AM
Thanks, Kev- that's a good point- checking the voltages- but I'd thinking potentially dirty terminals sound more like it.
I'll check it next time it plays up.
For right now, it's suddenly OK again.

The power supply on the newer VLS-400 is brand new, so I'll have that as a spare- if they're compatible- but in the case of the ULS M-300, the power to the steppers comes off the motherboard directly. And the X axis is quite OK. It's not from a power supply directly- and the power IN to the motherboard is a single standard 4-pin PC power connector, like the old ones for CDs and Hard drives.

But a dirty connector is a feasible exscuse for the erratic behaviour- and the console LCD panel came back to life after sitting quiet for a week. :)
______________
The chinese Golden laser 130w has been earning its keep- spent all day lasering 15 and 20mm acrylic with 3M-468 DS tape underneath.
It's a bit of a chore stopping the tape from catching fire though, travelling at 99% power (which is 80% of tube max), and 2 mm/sec. speed in the 15mm, 1.3mm in the 20mm thick.