Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: mn_mike on October 22, 2012, 05:32:51 PM
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So, I bought a chinese desktop engraver machine (yes I know, I am cheap)
I bought for offline serial numbering for a part we run. Bought Mach3, got my serial macro to work great.
The problem is, I ran like 50 parts with extensive engraving on it and all of a sudden the "X" axis is not repeating. It some times moves .020" to .125" when I reference back to Zero. Basically cannot rerun the part on the machine if I need to drop the engraving depth.
I thought maybe the coupler on the stepper motor was slipping so I took it off, ground a flat on the screw and put a set of set screws in the coupler to clamp on the flats of the shaft. Ran it again, and with one run, it's off by .020"
So I guess I am asking for troubleshooting suggestions....
Could it be backlash?
Could it be the controller? (Is there a plug and play replacement board one would recommend for these units?)
Could it be the screw? (Is there something someone would recommend for a better screw system on this unit?)
Could it be the stepper motor? (is there better replacements here also?)
Any direction and insight would be great for those that have been playing around with these things.
I have an upgraded spindle coming (24K rpm), and would really be nice to nail down this lack of repeatability of this thing.
Thank you,
Mike in MN
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If it worked for engraving 50 parts it would seem like something is loose or an adjustment of the x axis components are required. Can you post some pics of the axis and maybe some info on the machine so someone can have a look and
offer advice.
RICH
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Trying again... (It keeps stalling when I try to post)
Here are 2 pics....(stalls while trying to attach)
http://www.cncbasics.com/pic1.jpg
http://www.cncbasics.com/pic2.jpg
Here is the link to the engraver... http://www.ebay.com/itm/CNC-ROUTER-ENGRAVER-MACHINE-DRILLING-MILLING-3020-q-/140562441574?pt=LH_DefaultDomain_0&hash=item20ba2ca566
I am wondering if maybe it's losing a signal here and there with the wiring also???
Thank you,
Mike in MN
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Try slowing the motors down. Look for internet connecting programs. Try searching post for lost steps.
More than one person has had to replace the blue box with a Gecko 540.
Hal
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Look for internet connecting programs.
Internet connection programs???
Try searching post for lost steps.
Post, the NC program?
Thank you,
Mike in MN
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Look for internet connecting programs.
Internet connection programs???
Try searching post for lost steps.
Post, the NC program?
Thank you,
Mike in MN
the only thing running on your control computer should be mach 3, no internet connection, no anti virus, no background tasks, not much of anything as they can interfere with mach.
You could also try setting your velocity and acceleration lower by half and see if that makes a difference.
On my machine I have to clean and lube frequently or I'll begin losing steps.
just a few suggestions, good luck finding the problem.
John
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Look for internet connecting programs.
Internet connection programs???
Try searching post for lost steps.
Post, the NC program?
Thank you,
Mike in MN
the only thing running on your control computer should be mach 3, no internet connection, no anti virus, no background tasks, not much of anything as they can interfere with mach.
You could also try setting your velocity and acceleration lower by half and see if that makes a difference.
On my machine I have to clean and lube frequently or I'll begin losing steps.
just a few suggestions, good luck finding the problem.
John
I do have a usb wi-fi adapter on it, but that's it.
I wonder if that will make a difference.
I will unplug it and give it a go tomorrow.
Thank you,
Mike in MN
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Measure the amount of backlash for each axis. I could not see any adjustments for it in the pictures.
RICH
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More than one person has had to replace the blue box with a Gecko 540.
Hal
I'll second this. Mechanically, these Chinese machines are OK, but the electronics are junk. If the motors are under 3.5A, put a G540 on it. It's the best $300 you'll spend.
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Windows XP Professional System Optimization Guide:
Try going through this file.
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So after much screwing around..
I noticed today that with the spindle running the steppers move a bit at rest.
You can feel the steppers ticking, shut the spindle off the ticking stops.
So I am thinking that there is noise coming from the spindle that is stepping the motors.
Hmmmm??? Don't know how to fix that, I am sure it's part of the control box where the noise is coming from versus the spindle itself.
Mike in MN
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If it has a VFD controlling the spindle then that is the most likely cause. VFD's can be noisy and the cheaper Chinese ones tend to be the worst. Shielding cables may help, having a line filter to the VFD may help. Trying to route motor and power wires away from low voltage signal wires (step/Dir etc) may help.
Hood
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Thanks for the reply...
I rewired the spindle cable and one axis cable with shielded wire and grounded the shield, still no difference.
I did find something odd which might be part of the problem...
If I unplug the parallel cable from the control box the ticking stops in the stepper motors. But if I replug it in the ticking starts again, if I then leave it plugged into the control box but unplug it from the computer the ticking continues. I am thinking maybe I have a bad parallel cable that is picking up the noise some how.
Because either way, when I stop the spindle it stops, so it definitely coming from spindle noise, and yes there is a built in spindle control board in the control box that is variable.
I don't have a different parallel cable to test right now, but I will keep it up to date for those that may have issue in the future.
Did I mention I ordered a Gecko kit this week? I will overhaul the whole thing when I get the kit, but I have some things that I really need to get done with the unit now. Looks like I just might be behind a bit.
Mike in MN
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From your description seems the noise is picked up in the control box and the culprit is the spindle control board inside the control box. The spindle control is generating noise and that noise is coupled to everything else inside the control box.
Shielding the spindle control board and associated wire runs may help.
RICH
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So just to followup....
Spent far too much money in the last week but....
Bought the Gecko 540, Power Supply and new servos and a water cooled 24k china spindle with VFD.
So after a week and my power supply being on the east coast I gutted the control box, left their power supply in there, wired in the Gecko, used the original servos (servos were in transit also) and had to design and mounting plate with a new designed spindle clamp. (Did I mention I own a cnc machine shop).
Mounted the spindle hooked it all together with a coolant pump and such and the darn thing actually runs good (after a re-calibration).
I am doing fine engraving on parts and I can rerun the engraver on the same part and there is no mismatch.
Oh, I rewired the whole thing with shielded cable and have it grounded.
When I get some time I will try to post pics of the modification.
The comment above was right, electrical sux on these machines, but the mechanics seem to be alright.
Mike in MN
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Happy all is working for you.
RICH