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Thread: Problems with GCC Spirit: Strange X/Y-axis behaviour

  1. #1
    Join Date
    Apr 2014
    Location
    Bonn, Germany
    Posts
    8

    Problems with GCC Spirit: Strange X/Y-axis behaviour

    Hi guys,

    I have not been here for quite some time, but am now meddling a little bit more with my GCC Spirit. I did experience bad engraving quality in two segments of the X axis caused by a badly worn guide rail (lines were not parallel in there places but slightly "wobbly", but fine in all other areas). I have purchased a new X axis guide rail and installed it in my laser. If I remember correctly then quite a handful of engraving jobs ran just fine, but then strange things started happening.

    Here is the prograssion of problems that I am trying to work out:
    The positioning on the X-axis was not consistent, so parts of the engraving shifted to the left or right evry slightly, making straght vertical lines slightly wobbly. This was not caused by too loose belts or loose optics, I checked that more than a couple of times. It got pretty bad after a time, with erratic shifting of the line starts from left to right.
    2017-04-23 12.30.21.jpg

    As I thought I had eliminated backlash and loose optics I interchanged X and Y motor, as they apparently are the same type. Everthing looked fine at first, but when looking more closely something was strange: Horizontal lines (as in the "Turbolift" text) now were not as thick as they were supposed to be. When decresing output resolution I found out why: It looks like there is a posisioning problem in the Y axis now, as the Y axis seems to move two lines at once, then one back, but not always exactly, so that one ends up with overlapping lines that remove too much of the material. X/Y seemed to be okay now. Hence my diagnosis: X motor malfunction (which I moved to the Y axis and the problems moved with the motor).
    I cleaned the encoder wheel without much success and ordered a new motor from a local distributor.

    After placing the old Y motor back to the Y axis and putting the new X motor in the X axis: No success. Still having the weird problem with the Y axis. This is what it looks like (lower engraving resolution):
    Problem2.jpg

    I have, again, checked belt tension and optics. I am out of ideas. And no, I have not turned on the "True Image" option by accident, which seems to do something similar (lasering every fifth or so line, then every fourth, then every third, etc).

    If any of you guys has an idea input would be very much appreciated. I think I know what I am doing, as I service Epilog machines almost on a daily basis. When nothing works I will try to take the whole X/Y axis system apart and put it back together again, in a "have you tried turning it off and on again"-fashion...

    Thanks in advance,
    Christian
    Last edited by Christian Schink; 04-27-2017 at 6:15 PM.
    GCC Spirit 40W
    Shenhui G350, 50W
    Experienced with servicing old and current Epilog Laser systems and older Universal Laser systems

  2. #2
    Pretty sure you have servo steppers like my GCC, and I'm about 99% sure of the problem:

    Your encoder disk(s) are dirty. Clean them, and all will be right with the world...
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE- make that FOUR now - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  3. #3
    encoder disk is within the black cap on the end of the stepper. This is my X stepper disk, and all that grit made my machine do exactly what yours is doing...
    be3.jpgbe4.jpgbe2.jpgbe6.jpg
    Not that hard to fix, pull the motor, remove the cap, find the right allen wrench and remove the disk, and clean it. I think I used Windex because I"m not sure how alcohol will affect the plastic disk...
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE- make that FOUR now - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  4. #4
    Join Date
    Mar 2009
    Location
    Cuernavaca, the eternal spring, Mexico
    Posts
    17
    I hope this helps Christian.. By the way, it's a great tip. Thak You
    Edu

    Laserpro Spirit 30w

  5. #5
    Join Date
    Apr 2014
    Location
    Bonn, Germany
    Posts
    8
    Thank you all for your input. I will try to work on the machine again either today and tomorrow and report back.

    Just to clarify what I did here, just in case this might help to isolate the problem for anyone out there:

    Trying to clean the encoder dics (I incorrectly referred to it as encoder wheel as I am not a native speaker) was one of the first things I attempted, at least that was when the motor was still mounted on the X axis. Heck, I even checked the graphite brushes (the spring-mounted graphite blocks that transfer current to the motor, located behind the circular scrwa-caps located on all four sides of the motor). At that point I only had problems with X-axis position consistency.

    I was then thinking "Maybe I will swap the X and Y motors, if the problematic one only needs to do single, little steps at a time, it should not be that bad. And as the Y motor never had much work to do, it should be in a better overall condition and therefore do fine on the X axis". Hence I swapped X and Y motors. After swapping I experienced this strange Y-axis behaviour in lines not being positioned where they should be. I then thought "Well, this might be the same problem, as the motor had positioning problems in the X axis in the first place".

    That was when I ordered a new motor from a distributor. I put the motor which was on the Y axis before back in place (it was doing fine there until I started meddling with the machine) and installed the new motor on the X axis. And boom: Still a problem with the weird positioning in Y and I cannot really see whether X is okay or not. This is about when I lost it yesterday...

    Thanks again, I will report back.
    GCC Spirit 40W
    Shenhui G350, 50W
    Experienced with servicing old and current Epilog Laser systems and older Universal Laser systems

  6. #6
    Join Date
    Apr 2014
    Location
    Bonn, Germany
    Posts
    8
    I think I have solved the Problem. I will try to outline what I thought might have been wrong and explain how I found out why each hypothesis was, in the end, not the solution to my problem.

    1.) As there seemed to be a connection to movement on the X-axis before, double-checking of all mirrors and mounts (for the umptieth time) was done. A loose mirror or lens might cause problems at higher engraving speeds as small vibrations in the optical system lead to a displacement of the beam and hence can produce a multitude of interestingly lookign problems. Evenrything seemed to be fine. I still swapped all optics for new ones.

    2.) I thought a motor was at fault, as the problem seemed to have moved from X to Y when I swapped X and Y motors (left/right problems before, line consecutiveness after).
    When ordering and fitting a new motor in the machine there still were problems in either X or Y, with no clear pattern associated with one of the three motors in whatever position. I also checked both "old" motors for dirt in the encoder system, but everything seemed to have been sealed well, no dirt whatsover. In the end, when seeing extreme problems with lines not being engraved consecutively, but rather in a "skip two, fall one back, skip two.."-fashion i stuck a longer piece of adhesive tape to the gear on the Y-motor to better visualize motor movement for me and was surprised: even stepping after each line, no back-and-forth motion. Oookay, motors will most probably not be the cause of the problem.
    Spirit Encoder.jpg
    Encoder before cleaning (I still disassembeled everything)

    3.) Maybe some of the rollers have worn out. Swapping those out for brand new ones on both sides of Y and on the X-rail. I could not feel any up/down play on the X-rail, which indicated to me that the rollers should have been okay. Worn out rollers usually result in uneven lines from left to right, resulting in either banding or a "foggy" engraving, depending on the resolution and material. After putting everything back together: No improvement. Well, at least the rollers and rails have been cleaned once again. Rollers were ruled out as the cause of the problem.

    4.) As by now I started to go slightly crazy I suspected either the PC and/or data transmission to the laser. I moved the laser to a different power circuit than the air filtration system, tried a different laptop, still similar problems. I had a very hard time getting the driver to work on several laptops, as printjobs seemingly are sent to the laser (they are transfered and disappear from the job queue, but do not show in the control display of the laser. Any tips for that?

    3.) As I replaced the linear guide on the X-rail about two months back, I just completely disassembeld the whole X-axis assembly again, alhtough everything seemed to be fine. I did not know what else to do anymore. There was no obvious play in any of the components and there were no strange noises pointing towards a problem. When putting everything back together I saw something that I might have overlooked the last two times when taking the right assembly off the X-Rail: The connection where the reducer (the part with the bigger gear on the top [with the belt to the motor] and the smaller gear on the bottom driving the X-belt) connects to the bearing on the bottom part of the rail IS POSITION SENSITIVE. The reducer has a slit, just like a screw. and in the bearing there is a protrusion that can fit into this slit. If both do not align correctly and fit to each other, assembly is still possible without any obvious play in the components, and all screws can be tightened completely. When the protrusion of the bearing fits in the slit on the reducer, hoever, the complete assembly clicks just an absolutely minute fraction of an inch deeper into the bearing. For me it made no obvious difference in stability, but after reassembly everything seems to be fine now.
    Spirit-Solution1.jpgSpirit-Solution2.jpg

    I still see minor (but regular) left-right issues, but this was the first test engraving after putting everythign back together and should usually be solved by varying belt tension and/or using the image tuning slider in the driver.

    Spirit-After1.jpg

    Maybe this helps someone else, I have spent about 20-25 hours trying to figure out what the problem was here. I still do not understand completely why this should have resulted in a problem loking like a defective Y-motor rather than manifesting in a left/right problem...
    Last edited by Christian Schink; 05-07-2017 at 9:19 AM.
    GCC Spirit 40W
    Shenhui G350, 50W
    Experienced with servicing old and current Epilog Laser systems and older Universal Laser systems

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