Spare rear panel?

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

  1. Spoon Unit

    Spoon Unit Well-Known Member

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    At present I've just got a small cut of material under each foot, but I think I'll end up using a full sized piece in the final analysis just to make sure they're all even.
     
  2. wHack

    wHack Well-Known Member

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    Mine cracked as well even without threadlock. Seems they really shouldn't be tightened with anything but fingers.
     
  3. Kenneth Albanowski

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    I had threadlock (blue Loctite 242) attack my acrylic a different way -- I've used undoubtedly too much, and had it squeeze out around the ends of the extrusions. As has been mentioned, even the slightest amount does amazingly nasty things. Three of the corners of my electronics panel had cracks going between the t-nut hole and the edge of the panel in contact with the top/bottom plate and therefore touching just a little bit of the squeezed-out threadlock. (That 242 stuff is nasty, my 'calibration chunk of plastic' which was resting in all of those corners and touching a lot of loctite still has progressing cracks, has actual notches in the edges, and seems to be peeling itself part.)

    I'm now making sure to clean up the the threadlock (using isopropyl, not actually sure if that will remove what is causing the problem), and instructions to 'just use a small amount' are undoubtedly a good idea.

    I'm guessing the corners were particularly stressed due the thermal expansion (what's the relative coefficient between the aluminium and the acrlyic?) as this happened after a particularly cold night in the garage.

    I put a few drops of liquid acrylic solvent (MEK) in those cracks, and that seems to have helped, and I haven't seen them progress further, but I haven't really tried stressing them.

    Here in the US I haven't found an obvious source of the Loctite 425, I'd have started with it if I had some.

    Going back to other bits of the thread, I put self-adhesive felt pads under my rubber feet, just to make it easier to move the frame around during assembly without leaving skid marks on the table; clearly I'll need to remove those if the printer starts 'walking' once it is up and running.

    Orcinus, do you have a part number to suggest for the silicone washers?
     
  4. GiulianoM

    GiulianoM Member

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    I had the same thing happen with mine, I used generic 242 locker on the bolts on the ends of the extrusions and it seeped out and cracked the panels overnight.

    Once the threadlocker has cured, they shouldn't be a problem with the acrylic panels - but to fully cure most threadlockers require 24 hours.

    So an alternate method could be to apply threadlocker to the bolts, and let them cure overnight before installing.

    So what causes the acrylic to crack is the solvent in the threadlocker - once the threadlocker has cured, the solvent evaporates.

    Cured threadlocker on bolts can still be used, plenty of screws come this way with threadlocker pre-applied and cured.

    My printer frame was in my basement, which is insulated but not heated/cooled, so it stays at the same relative temperature.

    My panels cracked due to the solvent in the threadlock attacking the acrylic plastic, it's a known violent reaction.

    I'm not entirely sure that the Loctite 425 is safe, as I had radial stress cracking around the acrylic panel holes where I applied the 425.

    However I can't 100% attribute the cracking there to the Loctite 425 - I did notice a hazing effect on the acrylic as I tightened the bolts, so I backed off until the effect disappeared... But overnight the cracks appeared on all the holes.


    The PDF drawings specify that the panels are made out of acrylic, 5mm thick.. however I measured the thickness last night and it came out to 0.187" (3/16") or 4.76mm.

    I am wondering if polycarbonate would be a better material, most 3/16" stock reports to be 0.177" thick.

    24" x 48" x 3/16" panels are about $50 each, and you'd need two to CNC route the 4 panels.
     
  5. GiulianoM

    GiulianoM Member

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    Also, tell me I'm insane for considering carbon fiber panels as a replacement?

    ... I'm considering 5mm carbon fiber panels as a replacement.

    $118 for a 5mm x 500x600mm panel from Alibaba.
     
  6. blarbles

    blarbles Well-Known Member

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    Anyone have recommendations for companies in the USA that will custom laser cut plexi? I have an idea for changing one of the panel designs.
     
  7. GiulianoM

    GiulianoM Member

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    I'm going with 5mm carbon fiber panels!

    Placed an order from China for 5 panels of 5mm 500*600mm 3k glossy carbon fiber, it'll be here in about 2 weeks.

    2 panels for the rear, 2 panels for the sides, and 1 panel for the front.

    I plan to design a front panel to hold a PanelDue 7i, and have acrylic doors.. maybe from my cracked panels. :)


    Cost was $600 for 5 panels shipped, which is not bad considering the equivalent cost from USA suppliers is around $300 per panel.

    I bet if E3D were to buy custom sized panels at the required size, they could get them at a much lower cost in bulk.


    I have my CNC router and special CF cutting bits on the way.
     
    Spoon Unit and Paul Arden like this.
  8. Spoon Unit

    Spoon Unit Well-Known Member

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    Looking forward to seeing how that looks once installed.
     
  9. GiulianoM

    GiulianoM Member

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    I think it's going to look spectacular!

    But looks are secondary, the CF panels will be all about the stiffness.

    Also will be adding handles to the side panels :)

    Not sure if I'll make them cut outs or just mounting holes for some aluminum handles... Which I could also CNC.
     
  10. Spoon Unit

    Spoon Unit Well-Known Member

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    Would be interesting to actually have a measure of stiffness with those panels and with the supplied panels. Without a measurement, you only have an assumption. For $600, you might have even been able to just go for Alu waterjet-cut? Surely the stiffness in that case would be superior?

    The nice thing about the acrylic is the ability to see into the enclosure. PC could do the same without the same threadlock issues potentially, but I'm not sure about stiffness comparability.

    Handles instead of cutouts I think. Probably two per side so you can enlist help. Seem like some connectivity to the base and top panel would be good?
     
  11. orcinus

    orcinus Well-Known Member

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    Bear in mind that CF will completely block the WiFi if you intend to cover the rear as well.
     
  12. orcinus

    orcinus Well-Known Member

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    For what it's worth, silicone washers and no thread lock seems to work just fine for me so far.
     
  13. GiulianoM

    GiulianoM Member

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    I'm using the Duet Ethernet.. but if I were using the Duet WiFi, it now has an option of an external antenna.

    Could have gone for aluminum panels, but the rear electronics panel is specced for 5mm thick, so you'd have to either use a undersized thickness or mill it down. The gap between the Z extrusion and the rear extrusions is 5mm.

    Also full aluminum plate is HEAVY.. and the printer is heavy enough, and I can still lift it.. handles would make it easier.

    In any case, I am not sure I trust acrylic or PC for structural parts, there's a reason RepRap frames aren't much made of acrylic any more.
     
  14. orcinus

    orcinus Well-Known Member

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    Yeah, I wouldn't go for aluminium either, printer's heavy enough as it is.
    It's not so much about lifting as about whatever you put it on.

    I used to keep my BigBox on an Ikea Alex (wide) drawer unit.
    Now that I've put my Toolchanger on it, I'm seriously worried about the casters every time I roll it around.
     
  15. orcinus

    orcinus Well-Known Member

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    Thing to note - I haven't noticed any change in print quality with or without the side panels in place.
    As long as everything is tightened, I don't think they contribute much to... well, anything, except to hold the spools in place.

    I don't know, maybe it's because I haven't got the panels themselves tightened down too hard.
     
  16. GiulianoM

    GiulianoM Member

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    I had some thoughts of setting up a digital indicator up against the edge of the top plate, and seeing if it deflects under heavy movements.

    Maybe an indicator that has a max/peak measurement.

    My acrylic panels are installed even though they're cracked, so I'll probably complete the build and test it as-is before I replace the panels.

    It will take me some time to set up before I can cut the new panels anyway, the CNC router kit just arrived today.
     
  17. wHack

    wHack Well-Known Member

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    Be careful with that. Isopropyl alcohol attacks acrylic as well. It is actually really sensitive stuff.
     
  18. Killercds

    Killercds Member

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    Avoid isopropyl and alcohol based chemicals on acrylics and similar materials, as is easily causes "spider-web" style cracking
    My experience with that comes more from PC water cooling components
     
  19. Kenneth Albanowski

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    At least I know how fast the isopropyl evaporates... anyone know how long the 242 takes to completely evaporate the solvent, and/or otherwise cure? About a week after I assembled the main frame, I'm getting continuing cracks as well, I've got more corners coming off, one panel that wasn't even mounted at the time has a side peeling away, and it looks like the Loctite was getting drawn up between the acrylic and framing, as it's gone blue in places.

    One panel that I solvent welded the corners back on to seems fairly stable, I guess I'll just dismount all the panels, weld the corners, and leave the frame to cure... a while. Shoot, I don't think I can get the electronics panel out without undoing all of the Z-Axis or removing the belt.

    I guess I need some real specific advise: how do I neutralize this 242 loctite? Just time and air, soap and water, let me know... I hope the acrylic stabilizes, if not, and this is a permanent rot, these panels may be toast.

    E3D, I'll gladly keep all loctite away from this thing in future, but I'm wondering the wisdom of suggesting threadlocker at all, or at least anything with that particular chemistry.

    I had some Threadmate VC-3 that I was planning to use as a pre-coat on any further screws that might need locking, someone let me know if that's equally evil. (Their site says its an MEK base, that sounds relatively safe as it's used to weld acrylic in the first place, but at this point I'm wondering if it's going to melt the PCBs or something.)


    20190913_215503.png 20190913_215443.png
     
  20. Spoon Unit

    Spoon Unit Well-Known Member

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    They did change the advice after a number of panels showed these issues and the instructions now specifically state not to use threadlocker at acrylic interfaces.
     

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