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RigidOko

Discussion in 'CNC Mills/Routers' started by SecretSpy711, Oct 16, 2017.

  1. SecretSpy711

    SecretSpy711 Well-Known
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    Rijad likes this.
  2. SecretSpy711

    SecretSpy711 Well-Known
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    Working on re-designing the Z axis. There are some aspects of the CNCnewbie units that I don't like, so I now plan to make my own using probably 20mm profile linear guide (same as used on X and Y), and 3/8 leadscrew (using the excess cut from my Y screws possibly).

    Haven't decided whether I want to go for the full 4 bearing setup, or use 2 of the long variety bearings.
     
  3. SecretSpy711

    SecretSpy711 Well-Known
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    Also reconsidering my bearing setup to capture the leadscrew. The bearing blocks I bought from servocity are looking pretty wimpy.

    Here's the bearing blocks I bought for the X axis:
    1/2" Bore, Face Thru-Hole Pillow Block

    I believe it uses this bearing:
    http://www.product-config.net/catalog3/output/82052925/specsheet.pdf. Static load rating of 71 lbs, and I have 2 of them. Should theoretically be enough but I'm more worried about the fact that they are so thin and I am not planning on turning down my leadscrew

    Considering something more like this, and I wish I had seen it sooner:
    1/2" Two Bolt Flange Bearing UCFL201-08
     
  4. Marshy

    Marshy New
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    Hi secret spy what program did you design the machine in?
     
  5. SecretSpy711

    SecretSpy711 Well-Known
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    Creo
     
  6. SatMike

    SatMike Well-Known
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    Would you be interested/willing in sharing your build files? I've been piecing together the components to make a very similar system, and would love to take a closer look at your plates and potentially use them as a starting point.

    Thanks.
     
  7. SecretSpy711

    SecretSpy711 Well-Known
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    Sorry for the delay, I hadn't checked the thread in a while since I haven't been able to work on this recently. I will see about posting files when I get some time.

    The Z axis long-version bearings and rail just arrived, so I can make some more progress soon. I was waiting until after the holiday bills had passed before buying the motors and drivers, then the machine will be mostly complete. I also still need drag chain, a motion controller and Mach3 software. I was also considering getting some more extrusions for the base instead of mounting it directly to my wood torsion box.
     
  8. Andreas Bockert

    Andreas Bockert Veteran
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    This does look very slick! The red is awesome.

    Could you show more of your Z-axis?
     
  9. SecretSpy711

    SecretSpy711 Well-Known
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    sure, I'll take some pictures when I get home. CAD might be easier since I can hide parts. Basically it's the reverse of many designs here. The Z rails are bolted to the back of the Z plate, and the linear bearings are mounted to the X carriage plate. So the entire Z plate and motor move up and down. This makes the Z axis taller overall, but more rigid. Thanks to Florian Bauereisen for that suggestion.
     
    GrayUK likes this.
  10. Andreas Bockert

    Andreas Bockert Veteran
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    Uuuh... mind... blown...

    I would love an explanation for how it becomes more rigid.

    You might just have caused a redesign on my side. Can’t wait to see your solution.
     
    #10 Andreas Bockert, Sep 19, 2018
    Last edited: Sep 19, 2018
  11. Andreas Bockert

    Andreas Bockert Veteran
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    Ok, so, please help me think this through correctly.

    One benefit is that you can let the "rail side" move below the X-beam. This would at the allow you to mount the router higher up (and make it easier to attach a second mount for the router if desired). It should also give the possibility for a lot more travel along Z.

    I can also see a benefit to the rail blocks being mounted symmetrically w.r.t. the X axis. At least in my case, this would be approximately the case anyway.

    The big drawback would be the added weight that the stepper needs to move...
     
  12. SecretSpy711

    SecretSpy711 Well-Known
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    Here's a view looking at the back of the Z axis. You can see the rails bolted to the plate which act like stiffening ribs. The 2 bearings and short piece of 80/20 that holds the lead-nut (actually 1"x2") bolt to the X carriage plate. Since I only have 2 bearings here instead of 4, I am using the "long" versions which are about 3.5" compared to the standard length (about 3") everywhere else on by build. I am using a piece of 3/8-8 4-start leadscrew (0.5" travel/rev), and the Z carriage *almost* falls down when power is removed from the motor, but not quite. A small spring, or a slower leadscrew would fix that.
    rigidoko_z.jpg
    There is a flaw in this design that I've found, which is this: if there is enough force in the Z direction, the piece of 80/20 could potentially slide up and down, causing lost steps. It is mounted using sliding T nuts. You can barely see those T nuts here:
    IMG_20180919_192025.jpg

    That means I need to really, really make sure that these 4 bolts are tight, and if that's not enough then I might bond the piece of 8020 to the X carriage plate or try to machine a different lead-nut bracket that doesn't use sliding T nuts.
    IMG_20180919_192102.jpg
     
  13. SecretSpy711

    SecretSpy711 Well-Known
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    I also have several sets of holes on my Z plate so I can mount the router clamps at various heights.
    IMG_20180919_191954.jpg
     
  14. Andreas Bockert

    Andreas Bockert Veteran
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    Did you cut the mounts as well?
     
  15. SecretSpy711

    SecretSpy711 Well-Known
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    Yes, on my old machine, very slowly.
     
  16. Andreas Bockert

    Andreas Bockert Veteran
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    I'm considering milling new router mounts. Right now I'm considering if I should go with 1/2" or 3/8".

    Did you use 3/8" or 1/2"stock? Do you find them rigid enough?
     
  17. SecretSpy711

    SecretSpy711 Well-Known
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    They were from 1/2" stock but the piece they were made from was bent a little, so they are probably more like 0.45" now since I faced it first.

    3/8 should be fine if they are spaced apart. If they are close together go thicker.

    What I don't like about these mounts is that the mouting holes are behind the router, so I can't remove the mounts unless I first remove the router. (They were originally made to fit a Shapeoko 2's Z plate and I cannibalized them for the new machine.) Also, tramming is difficult with this arrangement, and tightness of the clamp affects the tramming. I plan to re-design these mounts at some point.
     
    #17 SecretSpy711, Oct 13, 2018
    Last edited: Oct 13, 2018
  18. Andreas Bockert

    Andreas Bockert Veteran
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    Ok,
    Thanks for the info. My idea is to use 2 mounts. Each held by 2 m5s from the front. Especially with tramming in mind. It feels like I would like to have more screws in the mount but I’m guessing that this is newbie overbuilding talking.

    I think I’ll use 1/2”.
     

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