Spare rear panel?

Discussion in 'Getting Started' started by orcinus, Aug 8, 2019.

  1. orcinus

    orcinus Well-Known Member

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    Mine's still holding up okay.
    The electronics panel has a slight beginning of a crack on the very edge where it mates with one of the aluminium profiles.
    But that's it.

    I do have them extremely loosely tightened + the silicone washers seem to take away some of the bite/force too.
     
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  2. kswaid

    kswaid Member

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    Add me to the cracked panels club. I assembled the panels finger tight using a screwdriver type hex driver and did not use threadlock on any of the panel screws. After assembling the chassis it sat for an entire work week and when I started work on the electronics today I noticed that every single panel has at least 1 corner with large cracks. The only way I could imagine that these panels were stressed at all was during all the flipping or reorienting of the chassis for installing different parts.

    I have never experienced unblemished acrylic that cracks this readily.

    IMG_20191219_210849561.jpg IMG_20191219_210900923.jpg IMG_20191219_210912151.jpg IMG_20191219_210924541.jpg IMG_20191219_210935360.jpg IMG_20191219_210950944.jpg
     
    #82 kswaid, Dec 20, 2019
    Last edited: Dec 20, 2019
  3. Ben Kay

    Ben Kay Well-Known Member

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    Mine are spreading too now....think it's maybe room temperature swings day/night. Also think it would have been wise to maybe have rubber washers under the screw heads to allow for some expansion. Shame.....I'm kinda hoping a new electronics panel design is released though to suit Hemera's and duet 3's eventually, I'm holding out for that.
     
  4. blarbles

    blarbles Well-Known Member

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    Make sure they are really rubber and not neoprene. I have a friend who is a plastics materials expert who said the neoprene might have an adverse reaction with plexi.
     
  5. MikeL

    MikeL Member

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    First Post, so don't want this to sound too negative, I'm loving the machine and have just got some multi-material prints starting to take shape I'll post up some photo's as soon as I get a moment.

    That said, I've joined the cracked panel club. Built my machine last week, no threadlock near the panels and mouse like torque (having already read this thread.) I even put the smooth side of the washer against the sheet for fear of stress risers!

    Came back to the machine the next morning and was rather sad to see the electronics panel had cracked from the bottom right corner. The side panel has also cracked in the same corner. The others don't seem to be affected so far.

    It's out in the workshop so I can only think the thermal cycle overnight killed it. I've never worked with acrylic before, is this normal ?



    ~
    Mike
     
  6. mhe

    mhe Well-Known Member

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    Mine started to crack too a while ago, I'll replace them with something other than acrylic, probably machine some from MDF or similar. Should also resonate less, hence be quieter.
     
  7. yngndrw

    yngndrw Well-Known Member

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    I've had the same issue with no Loctite on these bolts. I wonder if its from moving the printer after working on it, it's quite heavy and the frame isn't cross-braced so it flexes as you lift it.

    At least the electronics panel hasn't cracked - That would be a mare to replace. Pictures attached.
    20200112_224751-1612x907.jpg 20200112_224626-1612x907.jpg
     
  8. kswaid

    kswaid Member

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    I think you are right on the mark about it being from moving the fame. My panels were all fine until I started lifting and rotating the frame to install electronics. The corners are also exactly where you would expect failure to occur first from this type of loading. The tolerance stackup on my unit also resulted in many of the panel fasteners basically bearing against the edge of the holes in the acrylic, so there wasn't enough clearance for anything to deform at all. If I get new panels I might just try going down a size on the fasteners and using rubber washers to allow some compliance and ensure all loading is carried by shear at the clamped interface instead of bearing against fasteners.
     
  9. Frostie2k

    Frostie2k Member

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    On my DIY Motion System i only use Aluminium Plates because the Acrylic sheets on my previous cheap china Printers always break after a while.

    Foto 14.01.20, 18 13 19.jpg Foto 14.01.20, 18 21 16.jpg Foto 14.01.20, 18 21 22.jpg
     
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  10. mhe

    mhe Well-Known Member

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    That is not a bad idea. Why did you not leave the bottom closed though?
     
  11. Frostie2k

    Frostie2k Member

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    The first time I wanted to build the Sysem original.
    But I'm going to make a new base plate that will also get thicker. I think this will make the system a little stiffer if it is on an uneven surface.
     
    mhe likes this.
  12. dc42

    dc42 Well-Known Member

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    Recently I set about getting the bed level. The height map showed that it had a slope along the X direction, and a twist. I solved the slope by adding 0.6mm thick washers under the support screws on one side. The apparent twist turned out to be caused by the uneven bench surface, which caused the frame to twist such that the two Y rails at the top were not quite parallel (one fell a little from back to front relative to the other).

    So I agree that using the TC on an uneven surface is a problem. To solve it, I suggest the following:

    1. Add a length of 3030 extrusion at the front just above the base plate, to stiffen the base. I think this would be more effective than using a thicker base plate. Perhaps add another at the back too.
    2. Instead of five feet, use just three: two at the back (because there is more weight at the back) and one centrally at the front, underneath the added extrusion.
    3. If that isn't sufficient, either add diagonal bracing or use stiffer (non-acrylic) side panels.
     
    #92 dc42, Jan 15, 2020
    Last edited: Jan 15, 2020
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  13. mhe

    mhe Well-Known Member

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    I asked about stiffening the frame with profiles during E3D's Toolchanger livestream (Greg and Sanjay) and they almost told me off for even daring to suggest that it wouldn't be stiff enough, but there we have it... :p
     
  14. MikeL

    MikeL Member

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    I do like the idea of a bar at the front.

    Thing is the panels should be the things adding a huge amount of torsional stiffness right?

    The problem is they can't do that if they self distuct or we are not tightened them up because we are scared of cracking them.

    Anyone looked at dibond? I can't seem to find 5mm thick though, at least not in quantities I'd want.

    PC?

    Mike
     
  15. Nibbels

    Nibbels Well-Known Member

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    If we want to have the sides more stiff:
    We could maybe cross the panel sides +-45° using a steel cable and then stretch it to the force we need to have all sides quadratic.
    Like a bikes wheel.

    Could such be a solution?
    https://www.amazon.de/Seilwerk-STANKE-Rankhilfe-Spannschloss-Bügelformklemme/dp/B071YHY68B/
    https://www.amazon.de/Ring-Lifting-Edelstahl-Gewinde-Verschluss-20/dp/B07BHK16JD/
    https://www.amazon.de/Beschichtete-...nium-Europäische-Standard/dp/B075WVP4S8/?th=1
    The shown parts are help to think about the proposed solution, I did not search things that would fit our aluminum extrusions!
     
  16. yngndrw

    yngndrw Well-Known Member

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    The term "not fit for purpose" could be used to describe the provided panels. To be honest, if I were to be re-making them myself, I'd strongly consider getting them cut from metal. Perhaps a sandwich made of 1mm aluminium, 3mm delrin and 1mm aluminium would work out cheaper, easier to source and just as strong / rigid?

    I was thinking of how to add a diagonal brace as David suggested from 6030 extrusion but the electronics panel gets in the way of that. I think the wire could be a good option although the spool holders do also get in the way. The extrusion is 30 series so the EU30 t-nuts should work.
     
    #96 yngndrw, Jan 18, 2020
    Last edited: Jan 19, 2020
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  17. Frostie2k

    Frostie2k Member

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    Replaced now the Bottom Plate with a 10mm Aluminium Plate, adds a lot more torsion stiffnes.
     

    Attached Files:

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  18. Omnimuller Inc.

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    Finished the build of the Toolchanger 3 Days ago, and I have a total of three hours of printing time on the machine. No threadlock was used anywhere near the acrylic panels, and the Screws are barely fingertight. Noticed the cracks today when I removed the rear Panel of the machine to add a transparent Wifi-Interface to my Duet2 Ethernet board.

    And before anyone makes the comment: The machine is not actually standing on a wooden floor, those are tiles in wood optic, the tiling is not even two years old, and perfectly flat across the area the machine is standing on.

    As request by Mister Holloway, here are pictures of the cracks:
    c1.JPG c2.JPG c3.JPG

    Curiously enough, they have only developed int those lower three corners, and the rear Panel also seems fine until now
     
  19. yngndrw

    yngndrw Well-Known Member

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    Adding an angle bracket in the middle of the joint between the side panels and the bottom plate should make the whole thing a lot stiffer too.
     
  20. Omnimuller Inc.

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    By the way, has anyone already made CAD-models of the Panels and is willing to share them, just in case some of us wanted to make replacements from different materials?

    I know it is a trivial task, but it would still be nice to have it as a resource
     

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