Options to stiffen the frame?

Discussion in 'Motion System' started by W1EBR.Gene, Feb 2, 2021.

  1. W1EBR.Gene

    W1EBR.Gene Well-Known Member

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    I removed my acrylic panels so that they can be replaced. I had cracks at many of the holes in the corners of the panels which might have been caused by slight flexing of the frame. I don't have a setup for the printer that is both flat and stiff so I think improving the frame rigidity will prolong the life of the side panels and the consistency of the results.

    I noticed that the bottom aluminum sheet flexes slightly if I lift the printer up with a finger under the bottom sheet. When I place a 30x60 extrusion along the outer edge of the front of the bottom sheet a gap is visible at the midpoint of the extrusion between the sheet and the extrusion which I can close by slightly lifting the sheet, so ...

    What do people think about placing 30x60 extrusion along the four bottom edges of the lower aluminum sheet and bolting the sheet to the extrusion and to the supporting posts in the corners? I know it creates more possible ways to misalign the frame, but it should also stiffen the lower aluminum plate. The front to back extrusions would sandwich in the electronics panel. I realize that an "X" shaped reinforcement between the posts would work the best but the front and back aren't great locations for an "X".

    Any ideas before I start cutting and drilling? Thank ahead of time!
     
  2. W1EBR.Gene

    W1EBR.Gene Well-Known Member

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    This is what I came up with:
    frame.jpg 20210212_133621.jpg
     
  3. Joe Pomo

    Joe Pomo Well-Known Member

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  4. dc42

    dc42 Well-Known Member

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    I was looking at putting a piece of 6030 extrusion along the bottom front, and replacing the front two feet by a single foot in the middle. This is because when the TC is placed on an uneven surface, it distorts the frame and this is evident as an apparent twist in the height map.
     
    #4 dc42, Feb 15, 2021
    Last edited: Feb 19, 2021
  5. W1EBR.Gene

    W1EBR.Gene Well-Known Member

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    @dc42 , I read your previous post with your idea. What I noticed is that the bottom aluminum plate flexes slightly with less than the weight of the printer pushing on it. If you put a finger under the middle of the front edge and lift the printer slightly, you'll see the plate flex. It also flexes front to back. I decided to reinforce both directions. The printer is heavier now but has a very rigid feel to it when you pick it up. Also, I lifted a front corner off of the table and reran bed mesh compensation and the plot looks the same as when it sits flat.

    I used (2) 1 meter long pieces of 30x60, (4) 60mm inside corner gussets and (6) 30mm inside corner gussets. The two 60mm gussets used in the front need to have one channel tab removed from the bottom to fit properly.
     
  6. Sandini

    Sandini New Member

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    Nice work! I took a similar approach where I used the bottom sheet metal plate as a template and drilled holes through the table it sits on (phenolic resin lab table). Ran bolts and washers through the underside into the 4 posts and z-axis.

    I had run the machine for quite some time with the side and farthest back panel off for initial testing. Adding in the acrylic sheets made a noticeable difference. I'd say if you want to take it another level up on rigidity, replace the acrylic with cast aluminum plates but I think that may be overkill for the system.
     

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