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Bed goes down not up at beginning of print - solved


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Posted · Bed goes down not up at beginning of print - solved

Hey all,

I did a search but couldn't find a similar thread, if one exists could you please point me to it. But the jist of it is my Ultimaker original auto homes fine. But as soon as the print starts, the bed moves down and never comes up and the print head starts to print out to open air. Sometimes the gap will be 1/4" but the last couple of times I've replicated it it's been 2" or 3". I don't think it's the switch because the auto home height is fine, and using pronterface I can jog up and down the z axis just fine. I've also made sure the coupler was nice and tight. I've tried this with the ulticontroller, and attached to the computer, and different print files, and same result each time so I am out of ideas. Any thoughts? If I didn't describe this clearly I can upload a video to show what I mean and the gap.

Thanks,

John

 

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    Posted · Bed goes down not up at beginning of print - solved

    Quite a strange behaviour... a video indeed might help to get a better understanding. However, you already did some important checks. Sounds as if mechanics (motor and end switches) are fine.

    Which slicer did you use for gcode generation? Do you use the default firmware or a custom version?

    As a shot in the dark, it sounds to me as some strange gcode problem with a missing z-coordinate for the first print command.

     

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    Posted · Bed goes down not up at beginning of print - solved

    here is a dropbox video (~5mb) of the machine doing an autohome, and then trying to start the part. https://dl.dropboxusercontent.com/u/4115151/test.mp4 I'm using a fresh install of Cura and I'm using the default marlin firmware. The aprt I've tried printing is the default robot as well as a small superman logo. Does the same thing on both.

     

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    Posted · Bed goes down not up at beginning of print - solved

    Can you post the first few lines of the gcode here - up to and including the first few G1 commands.

    BTW, your head is assembled wrongly. The nozzle should be tight up against the heater block, and there should be more open space above the heater block before the PEEK part.

     

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    Posted · Bed goes down not up at beginning of print - solved

     


    ;Generated with Cura_SteamEngine 13.12
    M109 T0 S220.000000
    T0
    ;Sliced at: Mon 10-03-2014 13:01:18
    ;Basic settings: Layer height: 0.2 Walls: 1 Fill: 10
    ;Print time: #P_TIME#
    ;Filament used: #F_AMNT#m #F_WGHT#g
    ;Filament cost: #F_COST#
    ;M190 S70 ;Uncomment to add your own bed temperature line
    ;M109 S220 ;Uncomment to add your own temperature line
    G21 ;metric values
    G90 ;absolute positioning
    M107 ;start with the fan off
    G28 X0 Y0 ;move X/Y to min endstops
    G28 Z0 ;move Z to min endstops
    G1 Z15.0 F9000 ;move the platform down 15mm
    G92 E0 ;zero the extruded length
    G1 F200 E3 ;extrude 3mm of feed stock
    G92 E0 ;zero the extruded length again
    G1 F9000
    ;Put printing message on LCD screen
    M117 Printing...
    ;Layer count: 169
    ;LAYER:0
    M107
    G0 F4500 X91.77 Y93.49 Z0.30
    ;TYPE:SKIRT
    G1 F2400 E0.00000
    G1 F1800 X92.59 Y92.83 E0.02471
    G1 X93.50 Y92.36 E0.04886
    G1 X94.46 Y92.09 E0.07218
    G1 X95.20 Y92.03 E0.08970
    G1 X95.75 Y92.02 E0.10278
    G1 X96.08 Y92.02 E0.11054
    G1 X96.13 Y92.02 E0.11169
    G1 X96.90 Y92.02 E0.12961
    G1 X97.28 Y92.02 E0.13854
    G1 X97.60 Y92.02 E0.14623
    G1 X98.01 Y92.02 E0.15578
    G1 X98.34 Y92.02 E0.16349
    G1 X98.74 Y92.02 E0.17304
    G1 X99.07 Y92.02 E0.18072
    G1 X99.48 Y92.02 E0.19027
    G1 X99.80 Y92.02 E0.19796

    Thanks for the heads up illuminarti, I've been having problems with the plastic coming out irregularly so I'll fix it shortly.

     

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    Posted · Bed goes down not up at beginning of print - solved

    The gcode looks ok...

    It's a bit hard to tell from the video, because the camera moves... but at the part when the head is moving over to the middle of the bed to start printing.... it looks like the z-axis motor is spinning: I see the coupler turn fast. But the bed doesn't seem to move at all, or maybe even goes the wrong way?

    Which is it?

    I suspect that the issue is just that your z-coupler is loose where it connects to the z-screw, and its spinning without moving the bed properly.

     

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    Posted · Bed goes down not up at beginning of print - solved

    Yes the bed is moving, but it is moving in the wrong direction. The spin of the coupler also coincides with the direction of the bed so it is definitely being told to do that. I've triple checked the coupler and that is not any play in it that I can find, as I initially suspected that.

     

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    Posted · Bed goes down not up at beginning of print - solved

    That is so damn strange - it turns the wrong way.

    I would say it's the DIR bit form the arduino but then it wouldn't home either. Or the limit switch is stuck but then it would just stay at 15mm off the platform instead of moving *farther*. This is bizarre.

    I think it's a feedrate of 9000 issue. So try this. Connect pronterface back up and set the feedrate to 9000 for your Z moves. Home Z axis then move to Z15, then Z0

    G1 Z15 F9000

    G1 Z0

    Try that a few times. It's supposed to go up and down. If it's doing it wrong (going up and up) then maybe check the DIR bit coming from the Arduino next. Maybe the signal is open or flakey or weak.

    X driver

     

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    Posted · Bed goes down not up at beginning of print - solved

    Hey gr5, thanks for the info and sorry for the late reply, I left my machine at work and only now got back to it. So I tried your lines and now the machine has gone full bonkers. I tried the initial commands

     


    G1 Z15 F9000
    G1 Z0

    and it went down both times, with the second command being it went down a about 2 inches and then back up half an inch. Then I tried to autohome and it went up a hair and then went all the way down hitting the bottom zstop. it didn't stop at that point so I had to pull the plug. When i restarted it and tried to home again, it did the same thing, went all the way down. If I send manual commands or try to jog the z axis via pronterface it'll respond to that correctly. How do I go about checking the DIR bit? I'll try swapping drivers and see what happens.

     

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    Posted · Bed goes down not up at beginning of print - solved

    hm so I tried to home and got the bed stuck all the way at the bottom. After some tinkering I got it reconnected in pronterface and got the z axis to move back up, I pressed the -z button to bring it up 10 mm and it went about 5mm, made an odd noise and went back down 5 mm. Now either direction on pronterface causes it to go back down. This is after I swapped drivers FYI. So I'm out of ideas.

     

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    Posted · Bed goes down not up at beginning of print - solved

    I'd check your endstop connections. If you have a continuity tester or multimeter, check whether the z endstops are behaving correctly.

     

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    Posted · Bed goes down not up at beginning of print - solved

    Here is another new idea :wink: :

    Connect your z motor with the x-axis on the Ultimaker Arduino shield. Make sure the z stage is somewhere in the middle of the two end switches.

    Then try to move the motor in both directions, e.g.

    G91 (for relative positioning)

    G1 F9000 X15

    G1 X0

    If the motor skips reduce the speed (e.g. F4500 or even less). If this tests works (means the z stage drives in both directions) then its a broken DIR bit for the z axis (as gr5 said).

    Make sure, you switch the z motor back to the z axis afterwards before something really bad happens... ;)

     

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    Posted · Bed goes down not up at beginning of print - solved

    Since I couldn't figure out how to test the endstops with my multimeter I tried Dim3nsioneer's suggestion, and lo and behold some results... So after switching the x and z motor I can move the bed just ifne but when I use the z axis on pronterface (which is now connected to the x axis) the x axis only moves in one direction regardless of whether I press up or down on pronterface. So I'm assuming this means it's a broken DIR bit on the z axis... how can I fix this? Do I need to replace my board? my arduino? could I resolder this?

     

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    Posted · Bed goes down not up at beginning of print - solved

    Swap the x and z end stops as well - otherwise you haven't really proven anything.

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    Posted · Bed goes down not up at beginning of print - solved

    Switched the end stops as well and the same results.

     

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    Posted · Bed goes down not up at beginning of print - solved

    Finally you should swap the drivers of the x and the z axis in addition to the swaped motors and end switches. Skip it if you swaped exactly these two drivers before.

    If the result is still the same, time has come to submit a ticket with this information to Ultimaker...unless someone else has a mind blowing idea...

    I think, the problem may be something like a bad solder point on one of the boards...

     

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    Posted · Bed goes down not up at beginning of print - solved

    Yep already swapped the drivers, looks like I am throwing out a support ticket...

     

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    Posted · Bed goes down not up at beginning of print - solved

    It's the DIR signal. I sent you the schematic in post #8 above. It's intermittent so probably a bad solder joint or bad connection on the arduino. I would just put a solder iron to the pad where the signal connects to the arduino and where it connects to the servo driver.

    Or it could be a bent arduino pin. Or a bad arduino. Arduino's are very cheap. Something like $20 including shipping in USA (I assume you are in USA if you have baseball in your name) so why not buy a spare Arduino now?

    Of course you can ship the PCB and Arduino back to UM for a new one but more fun to just fix it yourself.

    Full schematics:

    The circuit diagram, and board layout are here:

    http://reprap.org/wiki/Ultimaker%27s_v1.5.7_PCB

    There is a zip file at the top. It contains the "brd" file which is the layout. Also the "sch" file which is the schematic.

    Both files can be opened by eagle software which is free:

    http://www.cadsoftusa.com/download-eagle/

     

     

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    Posted · Bed goes down not up at beginning of print - solved

    So I took a look at your files there gr5 and I was able to trace my DIR pin for the Z axis and on the Ultimaker board it wasn't even soldered... So a few seconds under the gun and it seems to work much better now. I spent more time taking apart the machine than I did troubleshooting or fixing it! Thanks for the help guys.

     

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    Posted · Bed goes down not up at beginning of print - solved

    Aren't you glad you didn't send it back and wait a week for a new board? :)

     

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    Posted · Bed goes down not up at beginning of print - solved

    So I took a look at your files there gr5 and I was able to trace my DIR pin for the Z axis and on the Ultimaker board it wasn't even soldered... So a few seconds under the gun and it seems to work much better now. I spent more time taking apart the machine than I did troubleshooting or fixing it! Thanks for the help guys.

     

    Congratulations on your self-fix! You might want to give Ultimaker some short feedback as they probably will be interested to check why quality control of this board failed.

     

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