View Full Version : Wandering Y-axis

Dan Hintz
01-22-2009, 8:13 AM
When I ran a job several days back on some anodized aluminum, I was slightly annoyed the job wasn't printing where I thought it should. The X-axis was fine, but the Y-axis appeared to be about 1/8" lower than what was on the screen. I was in a rush, so I tweaked the file and ran without issue.

The next day I noticed the pointer was about the same distance down in the Y-axis when it was at 'home'. Well, that explains it. So I adjusted the carriage until it was at the proper home position and thought "Problem solved", but I kept an eye on it. Sure enough, over multiple jobs it had slowly worked its way back down.

Anyone seen something like this before? It doesn't appear to be skipping steps and gives a very clean engraving, but something is obviously amiss with the Y-axis mechanicals.

Mike Mackenzie
01-22-2009, 12:59 PM

Check the couplers that connect the Y axis shafts to the Motor, You can also check the drive gears that are on the opposite ends of the drive shafts just check to see if anything came loose.

Dan Hintz
01-22-2009, 9:51 PM

I believe I have found the culprit, though I thought the machine would be able to take care of it. I lined it up while the machine was on by hand-turning the Y-axis stepper shafts. When I turned the machine off, the Y-axis moved down 1/8". If I pushed the carriage back up by hand (while still off), I could feel some elastic tension pushing back against me. It was the air-assist tube :(

Two things are running through my mind, though... why doesn't the machine pick up on the carriage not homing every time (looks like it only checks the homing sensors on boot-up and assumes the steppers don't lose steps, a poor programming decision, IMO), and what do I do about it?

I probably won't get an answer for the first question, but a useful one for the second question would probably resolve the issue. Are these tubes cut to exacting lengths at the factory, or are they eyeballed by the person installing it? I think trimming off about 1/2" of tube would resolve the issue and still leave room to hit the max Y position, but I'm worried about going too short and having it kink while in the min Y position.


Mike Mackenzie
01-23-2009, 1:12 PM

Let me check and see what length they should be. I will get back to you. Also you can re-home X&Y through the UCP.

Dave Johnson29
01-23-2009, 6:30 PM
It was the air-assist tube


Not sure of the layout of your laser, but could you hook a light rubber band to the back section of the tube to pull it out of the way a little. If you are like me, I very rarely use more than about 6" or 8" of travel in the X and Y so the back section of tube could tethered without much harm.

Dan Hintz
01-23-2009, 9:12 PM

The tube is attached to the left side of the carriage beam and "rolls up" as the beam moves up and down the Y-axis. It always remains parallel with the beam along the left side of the table. When the carriage beam is at the top of the table (farthest from the front), most of the tube is "unrolled"... the small bit of loop that takes the tube from running along the side beam and onto the carriage beam is what rubs up against the wall of the machine.

If the tube was less rigid, the "loop" would collapse a bit and this wouldn't be an issue. I'm tempted to remove the tube, cut it back 1/2", and put it back in.

Dave Johnson29
01-24-2009, 8:16 AM
I'm tempted to remove the tube, cut it back 1/2", and put it back in.

Hi Dan,

Is the tube any special material? I have not seen one so I am guessing on what it might look like.

Back in my model helicopter days we used silicon fuel lines. They were super soft and very flexible. Maybe check out an RC store and make your own tube.

Scott Shepherd
01-24-2009, 9:37 AM
Don't me making anything special or spending money. This is a brand new machine and under warranty. Call ULS and get it resolved. Their tech support will solve the problem in 24 hours or less and it'll be fixed per their specifications. Maybe it is cut too long and maybe it's something that's being missed in quality control. If you never tell them, then they can't fix it for others. If you tell them, then they can research the problem, stop it from ever happening to anyone else.

Give them a call, you paid for the service, use it.

Dan Hintz
01-24-2009, 11:28 AM
Scott, I plan to call them this week, but my 8-5 sometimes prevents me from dealing with stuff in the middle of the week... posting here isn't as much of a problem. I'm now running into an issue with the rotary calibration, which I'll post in another thread in a moment.

BTW, this was a demo machine, so while I still have a warranty on it, it's not fresh from the factory.

Rodne Gold
01-24-2009, 12:11 PM
Do you have an option in your driver to tell it to start all jobs from home?
If you use relative or start from the last position the head was in , you could well have a positioning error of some sort.
I don't know the machine at all but if it has some sort of positioning encoder like a strip or shaft encoder , this could be dirty and causing errors.

Bjorn storoien
01-24-2009, 2:32 PM

i will have to check what driver version i am at today but there is a button for homing after every job in the newest drivers.

i have also had probs with the rotary


Dan Hintz
01-24-2009, 5:33 PM
Bjorn, The problem with the rotary turned out to be user error.

Rodne, I'm not sure if that options exists, but even if it did I wouldn't want to count on it. It's definitely an issue with the air assist tube bumping against the wall, I just haven't decided how to approach a solution yet.

Scott Shepherd
01-24-2009, 10:16 PM
Dan, they have extended hours for service. Don't wait to call Paul, call the factory. They will handle it. They are open from about 6 in the morning until later at night, so you should be able to call then once you are home and at the machine.

John Ness
01-28-2009, 11:49 PM

I have an Epilog and have had similar problems with the Y axis. The Y axis would move down 1/4" everytime you shut off and restarted the machine.

It turned out to be the main controller board. I had to replace three in only a little over a year.

You might want to see if that might be your issue too.

John Ness

Dan Hintz
01-29-2009, 7:42 AM
Thanks, John, I'll check it out. I was going to call ULS tech support while I was stuck at home yesterday (our street was a virtual skating rink, so I wasn't about to try driving), but I ended up working on my workshop some more. The good news is another full day of work and it will be completely insulated :) The bad news is I now have fiberglass jabbing into my hands and arms :( I really despise that stuff.

Mike Mackenzie
01-29-2009, 4:50 PM

Sorry for the delay in getting back to this if I measured ours the length of the hose on the barbs is 12.5 inches long. If you cut this hose cut small pieces off at a time 1/4 inch and try it. If you cut too much and it is to short then you will have to replace it.

Dan Hintz
01-29-2009, 9:57 PM
Thanks for checking, Mike. I was finally able to drag myself away from work and call tech support. Friendly, prompt, listened to my problem, etc. The tech listed the tube as 13", so he's sending me a couple of feet of tubing to cut my own from.

Don't know why I didn't think of this until now, but a simple (non-destructive) test would be to remove the tube from one end and see if the carriage beam still shifts downwards... :rolleyes:

Dan Hintz
02-26-2009, 5:52 PM
I forgot to keep this one updated...

So a new tube was shipped to me a couple of weeks back. Once the old tube was out, the rubber was obviously less supple than the new one, and the curve/roll in the tube when the optics were at home was pretty permanent. In went the new tube...

...and it has done the same thing for the last two weeks :( It's not the tube after all. With the machine off, I can push the bar all of the way to the back of the machine, but when I release it the bar moves towards the front about 1/4" as if it were pressed against soft rubber.

Tech support went through the standard textbook tests (is the carriage bar straight, does it catch on anything elsewhere, etc.), but in the end they sent me back to my rep <sigh>. I have a call into him now, so I'm hoping he gets back in touch with me soon as this is getting frustrating.

My take on the problem? If the air assist tube's rubber was stiff and semi-permanently malformed, the belts can be, as well. My best guess is the carriage bar wasn't perfectly at home when the system was left dormant for a long period of time. Whatever made the air assist tube harden also made the belts harden. The belts now have a malformed spot in that location, which causes the bar to roll back to the malformed spot. This is speculation on my part.

Back to reality... when looking at the belts, they have a 1" long shiny spot on them about 1" back from the bar, the exact point that would be wrapped around the toothed rollers when the carriage is near the back of the machine. Tech support totally dismissed this as even a possibility, but I'm not so quick to ignore it, particularly since they weren't able to resolve the issue.

Scott Shepherd
02-26-2009, 9:03 PM
Dan, don't get pushed back to the rep, make them fix it from the factory standpoint.

I'm not sure if he's still there, but I spoke to Paul last week and he was going to be at the ARA show, so there's a good chance you might not get a call back really quickly. He may have it all covered, but in case you didn't hear much, I thought I'd let you know what I knew, and that was he's out of town at the show. Might be home by now, I don't know, but thought I'd throw it out there.

I'd step up the chain a notch in tech support and get it resolved. No reason to wait for the rep and I'm not sure why they would tell you that. That's a very unusual statement for someone in tech support to say, in my opinion.

Rodne Gold
02-27-2009, 4:01 AM
Dan , cant you re align the belts , ie take em off and shift em a few inches?
Hows the belt tension?

Dan Hintz
02-27-2009, 9:42 AM

Thanks for letting me know... I forgot the show was going on and I should have assumed he would be there. This isn't ultra time-critical but I do want it diagnosed and repaired before warranty runs out (no more nightmare stories of people spending a year trying to get a problem resolved).

The first time I called several weeks back the gentleman I spoke with was top notch. He listened to my problem, had me check a few things, then said my suggestion of installing a new tube was easy enough to check and seemed like a good next step, so next-dayed a new tube to me. That was good service and a great first impression.

I hate to say it, but yesterday's call reminded me more of what I have come to expect from a company like Harbor Freight trying to resolve an issue with a $50 nail gun. You could hear him going through the check list in front of him (to me, a service guy worth his salt would know the basic checks, like checking for axis alignment, by heart). It seemed he only asked the other guys in the office if they had heard of something similar because of my polite insistence in exploring all avenues. My suggestion of warped belts as a possibility (especially considering the hardened air assist tube) was immediately considered illogical and dismissed, something I don't expect an open-minded tech to do. You simply can't rule out things like that.


I was thinking along the same lines, but the belts are not continuous... they're one long strip that's stapled/clamped at the ends to make a loop, so there was no leeway to rotate them a few inches. If I could have done that, it would either prove my theory or eliminate the belts as the cause, a test worthy of an hour or so of wrenching.

Update: My rep's tech guy just called (I think they're still in LV at the ARA). He would like me to check the homing sensor... there's a possibility the metal flag that interrupts the photo sensor has bent slightly (evidently there's not much leeway there). If it's bent, it's probably hitting the sensor itself, which would cause the 1/4" of bounceback I'm seeing. I won't get a chance to check until this evening when I get home, but I'm crossing my fingers it's that simple.

Dan Hintz
03-06-2009, 12:40 PM

The homing sensor was fine, so on to the next step. Paul emailed me a more recent version of the Control Panel driver which appears to have resolved the homing problem. I won't be able to say with 100% certainty until I've had an opportunity to run the system through its paces this weekend, but it certainly booted to the correct home position on several attempts.

On a side note... it seems Paul is the first line of defense should anything go wrong with my system, not ULS tech support proper. This is in stark contrast to what I'm used to where the salesperson is only concerned (rightly so, IMO) with the actual sale and any after-sale support is taken care of by someone else. Fine by me, I know the guy and feel comfortable working with him. That said, my last call to ULS tech support left a bad taste in my mouth... too unprofessional for my tastes considering the cost of the product.

Scott Shepherd
03-06-2009, 9:27 PM
Dan, we're lucky in that respect. Paul is a walking encyclopedia of knowledge of the industry. He always seems to know why things were done and how they did it, so it makes him an excellent resource for us, since you can describe extremely detailed minute issues and he fully understand you, and fully understands why it's happening like that. He also seems to have an excellent communication channel into the factory and if he can't help you, he will make sure he finds out the answer and he'll come back and explain the who/what/where of it all.

We're lucky to have Paul in this region. He certainly understands and knows his product.

Dan Hintz
03-07-2009, 10:15 AM

Remind me to discuss this with you during our meet in May... there's a bit more to my story than I'm saying here.