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Anti-Backlash nuts for 1/2 inch lead screws?

Discussion in 'CNC Mills/Routers' started by Jacob123, Aug 6, 2019.

  1. Jacob123

    Jacob123 New
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    Hey everyone. I am upgrading my workbee to 1000mm x 1500mm. Planning on using 1/2 inch lead screws to combat the whip with such a long screw.

    Does anyone have a good source for 1/2 inch antibacklash nuts? I have found several online but none of them will be able to mount to the gantry.

    I would just machine my own out of delrin, but i moved into an apartment a few months ago and my machine had to be completely disassembled. Now I will (finally) have a basement again, but i dont want to set up the machine and calibrate it just to machine the antibacklash nuts and then do it all again.
     
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
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  3. John Davies

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    The best i have found for my modified Shark CNC is from DUMPSTERCNC.COM. They work very well. The ones I use are 2 start 1/2" 8TPI but there are lots to choose from.
    John
     
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  4. sharmstr

    sharmstr Master
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    Techincally the ones I used aren't anti-backlash but pair them up and they work great.
     
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  5. Jacob123

    Jacob123 New
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    Great build Sharmstr!! That thing looks super solid.

    I'm not sure I understand how 2 regular nuts will help with backlash. Do you mind explaining to to me?
     
  6. sharmstr

    sharmstr Master
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    Sure. The mounting holes for them are enlongated so you can adjust the spacing between them. When they start to wear, you can just spread them apart more slightly. Same concept as a backlash nut. The backlash nut has an adjustable gap. There are threads on either side of that gap. When the threads start to wear, you use the grub screw to increase the gap, thereby taking out the slop. Make sense?
     
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  7. sharmstr

    sharmstr Master
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    In the build video below, you'll see that the Workbee uses two nut blocks on the Y for the same reason. If you look closely, you'll see the oval holes he's using.

     
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  8. Jacob123

    Jacob123 New
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    Ok it makes sense now. Thanks for explaining.

    It seems like i can just elongate the existing holes in my plate for the current nuts. Is that right? Or do the holes on the new nuts not line up with the current holes?
     
  9. sharmstr

    sharmstr Master
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    No, they dont. Go back to my build and you'll see how i lined up and the drill guide i made.
     
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  10. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    You might contact the seller to see if you can get the nuts without the mounting holes pre-drilled as it would be fairly easy to tap your own holes in the plastic where you need them to be.
     
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  11. sharmstr

    sharmstr Master
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    Good idea. But if i remember correctly, the holes on the plate are too close together so you'd end up hitting the 1/2" threads in the block. Unfortunately Im 500 miles away from my machine atm. If you're not in a hurry i can check on Tuesday when Im back.
     
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  12. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Based on 20mm c/c on the 5mm screws there should be 15mm clear between them. Missing a 12.7mm screw shouldn't be an issue unless the lead screw is noticeably off center.
     
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  13. Jacob123

    Jacob123 New
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    Thanks to both of you for all the help.

    I am going to buy some delrin and make my own nuts. Will save me 25 dollars and I'll have enough to make a few replacements as well.
     
  14. Jacob123

    Jacob123 New
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  15. sharmstr

    sharmstr Master
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    I cant answer that. But will the nuts fit inside the c-beam? If not, you'll have to run them on the outside which would be more work.
     
  16. Jacob123

    Jacob123 New
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    Mounting it outside the cbeam wouldn't be too difficult, I think.
    But i think I'm just overthinking this. I generally don't like to upgrade anything twice, which is why I was thinking of just going with ballscrew instead of upgrading to a larger lead screw and then to ballscrew later on.

    But It seems many people have no issues with lead screws, so that's what I'm going to go with.
     
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