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Serious Bed Homing Problem

Discussion in 'Troubleshooting' started by adikted2astro, Jun 25, 2019.

  1. adikted2astro

    adikted2astro Active Member

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    Ok I need some help. I've posted about this before and I thought I could manage the issue, but it keeps getting worse. Here's what happens....I'll begin the day just fine and start printing meshes (this happens with all my prints now). But as the day goes on, it seems like either the printer is changing the offset by itself, or when the bed homes, it doesn't always home the same way (z-axis) every time. Sometimes it's 0.2mm off, sometimes it's 1mm off, sometimes it's 0.5mm off (these offsets are always positive, from the actual z-offset point to the bed). It has no discernible pattern whatsoever. I've moved my homing position into the middle of the bed so there's no problem with edges. I've replaced my IR sensor, I've cleaned my IR sensor(s), nothing seems to help it out.

    When I do my z-offset AND when I home the bed before every print, I do it the exact same way, with the exact same bed and hotend temps. I thought maybe it was because I had glue stick, or hairspray on the bed (I have a glass bed) that was interfering with the IR sensor, so I do everything on a pristine, clean glass bed every time. I've cleaned and greased the z-screw, I've cleaned and greased all of the X/Y, and Z rods/bearings; there are no more variables to consider. Sometimes what might help is reflashing the firmware and starting from scratch, or doing an M502, M500 to clear the z-offset and then do that again. But no matter what I do this keeps happening. What's weird is that I guarantee when I come in tomorrow morning it will do just fine, maybe even for 2 or 3 mesh prints, then it will start offsetting again. I can never, ever just start a print and let it go and feel confident it will do what it's supposed to do. Even a 0.2mm offset ruins the entire print. I always have to visually check that it is homing properly by issuing a G28, then a G1 Z0. 2 hours ago it was fine, 1 hour ago it was offset by maybe 0.3mm, and just a few minutes ago it was offset about 1.2 mm. Like I said, it's a crap shoot and it's getting worse. To the point that I can't even calibrate my mesh anymore. Has anyone had this problem, or does anyone know of something I can try? I'm seriously desperate because I've got prints piling up and no way of completing them.

    Somebody please, please help. My sanity is at stake here...............what sanity I have left anyway.
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    try putting something like painters tape over the glass bed -- see if that helps. The IR sensor may be the root cause, but the tape may help.
     
  3. PJA

    PJA New Member

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    Interesting, We have an issue with the gantry in the X direction, sticks and grinds and has to be reset, I clean grease etc. and hey have been zero help trying to fix it, not sure what to do?
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Sadly, if it is a bad bearing, that is more of a job to replace ...
     
  6. albert3d

    albert3d Member

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    If you need bearings, I got a set of these to replace all of mine on my second-hand R2 that came with a couple of broken ones. Work well and I think the same ones are used in the R2 and C2.

    https://www.amazon.com/dp/B00DMFQ5TA
     
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The C2 is 6mm, I think the R2 is 8mm (but I don't have one to confirm with)
     
    #7 mark tomlinson, Jun 26, 2019
    Last edited: Jun 26, 2019
  8. albert3d

    albert3d Member

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    Interesting, my R2 and C2 both have 8mm rods on the sides and 6mm rods for the middle going through the extruder assembly.
     
  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Mine is 6mm all around :)
    Consistency <sigh>
     
  10. adikted2astro

    adikted2astro Active Member

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    Honestly, if I have to use painters tape, then there really is no need for a glass bed. I use the glass because that's what I like to print on; it is amazing. I hate using painters tape and I don't like using BuildTak, but if I have to choose between the two, then BuildTak it is. The problem with it is that when I'm done printing on BuildTak, I literally have to use a hammer to take my prints off. And it's not because I'm smashing in the first layer. It happens no matter what. It's the primary reason I chose glass.

    Also, I tried asking Robo for another IR sensor, but they told me to go to Partsbuilt. The problem is they don't have them, so what am I to do? The only course of action is to ditch the glass and hope that was the problem, or install a MUCH better IR sensor, or even a touch sensor.
     
  11. adikted2astro

    adikted2astro Active Member

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    Also, I just turned it on and started a new mesh print.......problem isn't there, like I said. But by the end of the day I'll be screwed. However, I have some hope.
     
  12. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Email PartsBuilt. They will probably source the replacements for you -- they have been very responsive when I reached out to them. They may not have them "now" but they might have them "soon" if you ask :)

    They were even souring a replacement for the R1/R1+ beds (good luck to them). It is a small shop (family run).
     
  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    You might also be able to simply darken the glass in the autoleveling landing zones (black magic marker).
     
  14. adikted2astro

    adikted2astro Active Member

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    Yeah, they already told me they don't have it and they can't find a source for it. I'll just have to wait. I might try that black marker idea. For now, it's working, so we shall see..........................
     
  15. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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  16. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    I think one of the issues is the IR board is poorly designed and made, I don't know for sure, it is just a guess on my part. At some point I am going to try to play with sensorless homing, but of course that requires a swap of the mainboard and the use of Trinamic TMC2208 or the new TMC2209 drivers. That would essentially eliminate the IR board completely. It should be a cheap upgrade!

    Maybe someone who is in good with PartsBuilt.com could suggest they offer an upgrade kit, that kit would be a all-in-one board, maybe like this one, https://www.aliexpress.com/item/33042554065.html, together with a wiring harness, like the kind Schoche makes for cars, it doesn't replace the existing harness, it just adapts the more standard JST connectors to the connector that Robo/Foxconn used on the R2/C2 then a flash drive with new firmware with sensorless homing already set up. Some small 3D printed board mount that screws into the same holes as the original mainboard and has proper mounting holes for the new board. They might have to include a power socket on a pigtail as well as a USB on a pigtail to complete the kit. Easily sellable as a printer upgrade. It would be faster, print quieter and use a current firmware rather than the outdated firmware Robo uses.
     
  17. albert3d

    albert3d Member

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    The IR board Robo put in these is a derivative of David Crocker's IR Board that Mark linked to on the Filastruder site. They changed some components on it and the board layout. Who knows what kind of QC was around all that. Would be great to look into just making an adapter for it to fit on the fan shroud at the same height using the true IR Board from DC/Duet.

    Waldo, does sensorless homing work for Z? I thought it was only X and Y. I do agree a nice adapter board to allow an easy changeover to some common boards will be great for when things fail down the road with the priority Robo board.
     
  18. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I'd take a S.W.A.G. at "none" ;)
     
  19. adikted2astro

    adikted2astro Active Member

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    I have no idea what this means.............. :) just making fun

    I think I will go ahead and replace this IR sensor once I have the time. I want to print a new fan shroud to use larger fans for cooling so maybe I can integrate the Filastruder sensor in that design so that it's a somewhat drop-in replacement. These sensors are not that complicated, but in my experience (other than the one on the R2), they are surprisingly accurate. Does anyone have experience with a touch sensor at all? I don't, so I'd be interested to see if maybe a touch sensor is a better way to go for this glass bed. I assume it may not be as accurate, but I don't know for sure.
     
  20. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    You mean like a hall effect BLTouch? You would need to route a new set of wires that carry +5v because the signal wiring aren't enough for a BLTouch.

    I posted my suggestion on that flaming piece of hell like social network FB, maybe someone can champion it.
     

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