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  1. #1
    Join Date
    Apr 2011
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    27

    rotating lead nut design

    right im designing a machine out of MDF.
    instead of having a rotating lead screw, im wanting to have a rotating lead nut
    ive made a design, but im not sure if it will work. or if its too much.

    any ideas on what to improve my design?
    would it be better to have the bearing in one piece of mdf? so just one nut as well.

    ive also missed a collar off, which mounts to the nut, so the thrust bearing is in between the collar and the MDF.
    Attached Thumbnails Attached Thumbnails rotating nut idea.PNG  

  2. #2
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    Apr 2009
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    5516
    Quote Originally Posted by homer93 View Post
    right im designing a machine out of MDF.
    instead of having a rotating lead screw, im wanting to have a rotating lead nut
    ive made a design, but im not sure if it will work. or if its too much.

    any ideas on what to improve my design?
    would it be better to have the bearing in one piece of mdf? so just one nut as well.

    ive also missed a collar off, which mounts to the nut, so the thrust bearing is in between the collar and the MDF.
    How are you going to accurately attach the nut to the pulley?

  3. #3
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    Apr 2011
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    27
    i started to think of that just before. tbh i dont really know.

    another design i had was a round nut and a pully fit over it, with a cap head or grub screw to tighten it onto the screw. with thrust beariings between the nut and MDF.

  4. #4
    Join Date
    Jun 2010
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    0
    You could get one of these timing gears: and set screw it to the nut (if the hole was big enough for the nut to fit in). I've seen bigger pulleys on this site, just needed to find a similar one for picture.

    A machine is only as accurate as the tools used to build it. "CNC = Computer Numeric Control - or on some days - CNC = Can Not Control" Imagineering

  5. #5
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    Apr 2011
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    yeh that was my other design. i can get a pulley and machine the diameter bigger.
    but with the size of nut i have found i cant get a bearing onto the nut and be in the MDF.
    is it possible to get a really long nut?

  6. #6
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    Jun 2010
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    Quote Originally Posted by homer93 View Post
    is it possible to get a really long nut?
    Maybe something like this?

    [ame="http://www.amazon.com/SteelWorks-Corporation-11846-Threaded-Coupler/dp/B000H5WZB0/ref=sr_1_5?s=industrial&ie=UTF8&qid=1304035341&sr=1-5"]Amazon.com: SteelWorks Corporation 11846/70106 Threaded Rod Coupler Nuts NC: Home Improvement[/ame]
    A machine is only as accurate as the tools used to build it. "CNC = Computer Numeric Control - or on some days - CNC = Can Not Control" Imagineering

  7. #7
    Join Date
    Apr 2009
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    149
    I am currently working on a rotating lead nut design. The design has been tested successfully and I am currently working on the patent. Except for one custom milled part, everything else can be user built. Extremely simple. I am looking for a machinist able to work in aluminum or steel. I'm just currently out of money and time to pursue this project on my own. There are a lot of people looking for a product like this, but without help it will be a long time before I can make this available. You will need to sign a non-disclosure agreement. Anyone interested?

  8. #8
    Join Date
    Jun 2009
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    251
    You will need AXIAL bearings for that, and you can find cheap ones used in car front wheels, although i wound not suggest using that method since it is quite complicated to make it work with no backlash and no play and for that you would need some type of adjustment to have some preload on the bearings. To date i have seen only one industrial machine use that type of movement and it was on a GEISS 5 axis 2.5x2x1.5 meter work envelope ( to bad the owner doesn't want to sell it since it is rusting outside and it is missing the control board and the spindle, i offered 1500 euros for it but no go).
    Also i have seen one DIY here on the forum that uses that but it doesn't mention anything about how he went about building it.
    Regards,
    Tom

  9. #9
    Join Date
    May 2010
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    290
    http://www.hossmachine.info/images/z...%20%282%29.jpg

    http://www.hossmachine.info/images/c...ed_800x461.jpg

    Hoss uses this design for the z axis of his machine. It's pretty simple.

  10. #10
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    Apr 2011
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    27
    i decided not to bother with my first idea.
    used the other easier idea.

    i made a 3D model of it. but in still having problems finding a long lead nut.
    with what the parts ive been able to find i can buy there is like 1 or 2 mm being held by the bearing in the MDF.

    if i could find a pulley that i could screw onto nut which had a flange it would be easier. i would have more area for the bearing to dit on then.

    there is two thrust bearings in the design. one uses some washers, which is the smaller one. the other one is just between the pulley and a metal plate. do i need the washers here or not?
    thanks
    Attached Thumbnails Attached Thumbnails 1.PNG   2.PNG   3.PNG   4.PNG  

    5.PNG   6.PNG  

  11. #11
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    Mar 2011
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    Quote Originally Posted by tjskcnc View Post
    I am currently working on a rotating lead nut design. The design has been tested successfully and I am currently working on the patent. Except for one custom milled part, everything else can be user built. Extremely simple. I am looking for a machinist able to work in aluminum or steel. I'm just currently out of money and time to pursue this project on my own. There are a lot of people looking for a product like this, but without help it will be a long time before I can make this available. You will need to sign a non-disclosure agreement. Anyone interested?
    You realize that my 1970's Bridgeport boss uses this design. Good luck with that patent...

  12. #12
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    Apr 2011
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    27
    does that include the one i just did?

  13. #13
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    Apr 2009
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    5516
    Before you go and patent yoru idea, there are TWO THK 20-04 rotating nuts on eBay now... I believe they use an ISO bolt pattern for the pulley.

    It's really not a complicated thing to make, just complicated to make WELL with DIY tools (unless you have a mill or lathe or both.) You would just take a piece of bar stock, turn the ID to fit the leadnut (or ballnut), then turn the OD for a flange and two AC bearings; then thread the end for a locknut. The flange would be drilled and tapped to accept a pulley. The bearings would be mounted to a plate, like a fixed end bearing, and the motor as well, with a pulley to turn the nut. Adding too many parts means more potential areas of backlash.

  14. #14
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    Jun 2009
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    251
    Quote Originally Posted by louieatienza View Post
    Before you go and patent yoru idea, there are TWO THK 20-04 rotating nuts on eBay now... I believe they use an ISO bolt pattern for the pulley.

    It's really not a complicated thing to make, just complicated to make WELL with DIY tools (unless you have a mill or lathe or both.) You would just take a piece of bar stock, turn the ID to fit the leadnut (or ballnut), then turn the OD for a flange and two AC bearings; then thread the end for a locknut. The flange would be drilled and tapped to accept a pulley. The bearings would be mounted to a plate, like a fixed end bearing, and the motor as well, with a pulley to turn the nut. Adding too many parts means more potential areas of backlash.
    Very well explained, thank you very much.
    B.Th.W. i missed the part about patenting it, and i can chime in, good luck with that since there are so many similar designs already patented and in use. I mentioned somewhere I, again 'I' have seen only one LIVE that i could touch and play with ( also walk on the table since it is over 3.5 meters tall ), but i have seen many on the net that use that same principle.
    It was one the first ideas that came to mind when i started a bigger cnc a year ago, but i found out that having 40mm lead screws has a nice side effect: you can use two bearings on one side and leave the other end free. To explain it easier here are some pics of what i made using all thread and some NSK industrial assemblies i found at a junk yard.
    On the first pic you can see a piece of wood that has chamfered places for bearings on both sides so there are two bearings one on each side folowed by two nuts on each side so i can preload the bearings and fix them in place, but you can not see the other side on the second picture. The third pic shows what is normally a ball nut ( in my case two more nuts adjusted for minimum backlash and the forth pic shows the other end of the all thread. I have this setup working for nearly a year and i have it tuned to about 0.02mm backlash. Luckily i use it rarely and i am aware that is not an 'be all end all' solution but it will take me about 20 minutes to change everything when the backlash goes bigger since inevitably it will when using all thread.
    The last picture shows the 40mm NSK ( yes 1.5" ) ball screw and nut as they were fitted on a huge mill ( the X table weighted over a ton ) and i can do 250 rpm with no whip, i did not try anything faster since i don't need it.
    Regards,
    Tom.
    Attached Thumbnails Attached Thumbnails 20110501_002.jpg   20110501_003.jpg   20110501_004.jpg   20110501_005.jpg  

    20110501_006.jpg  

  15. #15
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    Apr 2009
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    5516
    Quote Originally Posted by tommylight View Post
    Very well explained, thank you very much.
    B.Th.W. i missed the part about patenting it, and i can chime in, good luck with that since there are so many similar designs already patented and in use. I mentioned somewhere I, again 'I' have seen only one LIVE that i could touch and play with ( also walk on the table since it is over 3.5 meters tall ), but i have seen many on the net that use that same principle.
    It was one the first ideas that came to mind when i started a bigger cnc a year ago, but i found out that having 40mm lead screws has a nice side effect: you can use two bearings on one side and leave the other end free. To explain it easier here are some pics of what i made using all thread and some NSK industrial assemblies i found at a junk yard.
    On the first pic you can see a piece of wood that has chamfered places for bearings on both sides so there are two bearings one on each side folowed by two nuts on each side so i can preload the bearings and fix them in place, but you can not see the other side on the second picture. The third pic shows what is normally a ball nut ( in my case two more nuts adjusted for minimum backlash and the forth pic shows the other end of the all thread. I have this setup working for nearly a year and i have it tuned to about 0.02mm backlash. Luckily i use it rarely and i am aware that is not an 'be all end all' solution but it will take me about 20 minutes to change everything when the backlash goes bigger since inevitably it will when using all thread.
    The last picture shows the 40mm NSK ( yes 1.5" ) ball screw and nut as they were fitted on a huge mill ( the X table weighted over a ton ) and i can do 250 rpm with no whip, i did not try anything faster since i don't need it.
    Regards,
    Tom.
    If I saw 1-1/2" leadscrew whipping, I'd probably run!

    Check out blurrycustoms, their tables feature hollow-shaft servo motors, pretty cool (and probably expensive) design... and I believe they can be ordered as well...

  16. #16
    Join Date
    Mar 2003
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    35538
    Quote Originally Posted by louieatienza View Post
    Check out blurrycustoms, their tables feature hollow-shaft servo motors, pretty cool (and probably expensive) design... and I believe they can be ordered as well...
    Going from their G540 Ironman router to the hollow shaft servo setup looks to be about a $20,000 upgrade. It's not really the same machine, though, as the PCX version is made of a composite stone material, and looks to have a 3HP spindle as standard equipment. But $26,000 for a 20"x30" machine?

    I've never seen anyone with one of their $5000 machines. I doubt I'll ever see the $26,000 one.
    Gerry

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    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  17. #17
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    Apr 2009
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    5516
    Quote Originally Posted by ger21 View Post
    Going from their G540 Ironman router to the hollow shaft servo setup looks to be about a $20,000 upgrade. It's not really the same machine, though, as the PCX version is made of a composite stone material, and looks to have a 3HP spindle as standard equipment. But $26,000 for a 20"x30" machine?

    I've never seen anyone with one of their $5000 machines. I doubt I'll ever see the $26,000 one.
    They have an ultraman on ebay now I believe, with a 5hp columbo spindle, for 33k... I think their bench mill is 26k! I could get a used Haas mini mill for that price...

  18. #18
    Join Date
    Jan 2005
    Posts
    67

    8020 rotating lead nut

    here is a rotating nut design that is easy to mount
    Attached Files Attached Files

  19. #19
    Join Date
    Aug 2013
    Posts
    8

    Re: 8020 rotating lead nut

    i cannot open your pdf file.

  20. #20
    Join Date
    Jan 2007
    Posts
    209

    Re: rotating lead nut design

    I have rotating nut on my designed and built CNC machine.

    Here's the build thread: https://www.cnczone.com/forums/cnc-w...gineering.html

    Since converting from R&P I'm really happy with the rotating nut setup. The main bits including the nut was purchased from Hiwin.

    It works very well but is more expensive that other methods. Conversion on my machine was a $3k upgrade over R&P costs for 2 8 foot screws and 1 3 foot screw with nuts. Nuts were much more expensive than the shafts due to their complexity. You also need to come up with pulleys and an attachment method for the nut and servo/stepper with timing belts. Mine runs on 1hp servos and I'm dual driving my gantry x-axis.

    Also the motors are traveling on the gantry vs standard ball screw with rotating screw so you have more gantry mass to deal with. Not an issue I'm worried about with my design but some designs might suffer.

    Difference is night an day in accuracy over R&P. I was getting best case +/-0.004" with R&P with lots of fiddling and compromised feed rates. With Rotating nut I'm getting typically +/-0.0005" when cutting harder materials like Corian, and aluminum plate with no fiddling needed.

    Andrew

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