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  1. #321
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    Re: David A's New 2x3 Bench Top CNC

    Just finished reading this thread front to back, it looks like you enjoy turning conventional ideas on their head . I will take up your invitation to steal a few features.

    Regarding the rotating ball nut :
    The AC bearings fitting the ball nut body, was that simply a happy coincidence ? That seems unlikely. How did you manage to get that fit ?
    Anyone who says "It only goes together one way" has no imagination.

  2. #322
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    Re: David A's New 2x3 Bench Top CNC

    Quote Originally Posted by cyclestart View Post
    The AC bearings fitting the ball nut body, was that simply a happy coincidence ?
    Thank you for your satirical support, cyclestart, I appreciate it.

    As stated in my posts, you are more than welcome to 'steal' any features for your personal use.

    As to the bearing/ball nut fit, I hope you understand that I can not divulge certain
    details on the ball nuts as I might run that at some point as a commercial product.

    Btw, I like your signature.

  3. #323

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    Re: David A's New 2x3 Bench Top CNC

    Hey David I was just curious if you drilled out the ball screws for the set screws, or do you think that they will hold? Not trying to create more work for you but I just figured I'd throw it out there and maybe save you some frustration down the road.

    Dan

  4. #324
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    Re: David A's New 2x3 Bench Top CNC

    Dan, just four 1/4" set screws on a serrated shaft, no drill outs.

    Just think that a belt pulley is held in place with two, much smaller, set screws on a polished shaft.

  5. #325

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    Re: David A's New 2x3 Bench Top CNC

    Quote Originally Posted by davida1234 View Post
    Dan, just four 1/4" set screws on a serrated shaft, no drill outs.

    Just think that a belt pulley is held in place with two, much smaller, set screws on a polished shaft.
    On mine it's a keyed shaft with set screws, that's why I was asking since I've seen some guys who don't have the keyed shaft have issues with it slipping and then thinking that they're losing steps. Like I said I was just throwing it out there. Do you have any more progress pics?

    Dan

  6. #326
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    Re: David A's New 2x3 Bench Top CNC

    I like it when you throw things out there.
    Can only improve things.

    I am done posting of what I had done previously.
    From now on, it will be as I progress. Not as frequent.


    I am now breaking in the ball screws a bit,
    then will run the ClearPath tuning software.
    And then run some speeds manually.

    Of course, all with videos. Just hang in there.

  7. #327
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    Re: David A's New 2x3 Bench Top CNC

    Quote Originally Posted by davida1234 View Post
    Thank you for your satirical support, cyclestart, I appreciate it.
    Glad to see you read that in the spirit intended, I have high respect for people capable of thinking outside the box.

    As to the bearing/ball nut fit, I hope you understand that I can not divulge certain
    details on the ball nuts as I might run that at some point as a commercial product.
    Okay, that's fair. If any production run happens please post to this thread.
    Anyone who says "It only goes together one way" has no imagination.

  8. #328

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    Re: David A's New 2x3 Bench Top CNC

    Quote Originally Posted by davida1234 View Post
    I like it when you throw things out there.
    Can only improve things.

    I am done posting what I had done previously.
    From now on, it will be as I progress. Not as frequent.


    I am now breaking in the ball screws a bit,
    then will run the ClearPath tuning software.
    And then run some speeds manually.

    Of course, all with videos. Just hang in there.
    Ok cool glad you aren't taking it the wrong way, I'm just trying to help out if I can based on previous experience. And I'm looking forward to to the videos, I'll be sure to subscribe to your channel. I think the router is going to turn out to be a great machine.

    Dan

  9. #329
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    Re: David A's New 2x3 Bench Top CNC

    Hey David, I am enjoying reviewing your progress. Can't wait to see the final product!!

    Thought I would throw out a question to see your thought process: Why did you decide to go with belt drives on your ballscrews instead using a direct coupling?

    I have seen opinions on both and personally use direct connections through flex couplings. Of course, I only went this route because I spent a number of years working on machine tools as a field rep, so it's the design that I know.

    Thanks in advance, Chris

  10. #330
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    Re: David A's New 2x3 Bench Top CNC

    Thank you, Chris.

    I am not quite understanding your question. I use powered
    ball nuts. The servos spin them, the ball screw is fixed. How
    would you drive a rotating ball nut with a direct coupling?

  11. #331
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    Re: David A's New 2x3 Bench Top CNC

    Quote Originally Posted by davida1234 View Post
    Thank you, Chris.

    I am not quite understanding your question. I use powered
    ball nuts. The servos spin them, the ball screw is fixed. How
    would you drive a rotating ball nut with a direct coupling?
    Ahhh. That makes a little more sense. I guess I learned a couple things this morning. 1. Don't post when really tired before going to bed. 2. Don't skim over pics and just look at the thumbnails. Oh well, such is life...

    Like I said, I built my first one based on what I know and with cheaper materials just to learn and play. Now, I want to rebuild it into something better. So, I'm looking over everyone else's machines and trying to see pros and cons of each design. You had said that you have played with your design for quite a while before actually putting it together. Just curious why you used this design and what you think are the benefits to it...

  12. #332
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    Re: David A's New 2x3 Bench Top CNC

    If your doing anything on the pulley shafts, setscrews keyed or not, I always use Blue Loctite on the screws. PS if you use Red it takes heat to loosen!!
    Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router

  13. #333
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    Re: David A's New 2x3 Bench Top CNC

    Quote Originally Posted by wmgeorge View Post
    If your doing anything on the pulley shafts, setscrews keyed or not, I always use Blue Loctite on the screws. PS if you use Red it takes heat to loosen!!
    Very true and wise advise.
    I let Loctite dry on the screw so that
    nothing gets on the shaft. Did it once.....

  14. #334
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    Re: David A's New 2x3 Bench Top CNC

    Quote Originally Posted by Outlawtaz View Post
    Just curious why you used this design and what you think are the benefits to it...
    Thank you Outlawtaz.

    The short answer would be that I just was curious.
    I don't know if there are any benefits or drawbacks.


    Following are my personal thoughts and relates only
    to the lower-cost equipment we generally use here:

    Option #1:
    If you put a servo on a CNCRP drive, you get additional
    speed or, with lower gearing, torque. All happening at the
    pulley side.

    The final gear side, pinion with pressure spring on the rack,
    stays the same. Some noise, wear and minute cogging.
    Protruding servos. Weight of servos on carriage.

    Option #2:
    A direct rack drive with a gear box and pinion is expensive
    for a good gear box. Can select appropriate speed/torque
    combination. Requires perfect gear mesh or pressure. Some
    noise, wear and minute cogging. Protruding servos.
    Weight of servos on carriage.

    Option #3:
    With traditional ball nut and screw application, everything is
    happening at the nut/screw side. With xx05 nuts, you get
    more torque, with xx10 nuts, you get speed. Just two fixed
    ratios. Less noise, wear and almost no cogging. Speed limit
    due to whipping and/or larger screw inertia. Possible
    backlash in coupling. Protruding servos.

    Option #4:
    With a powered ball nut, everything is happening at the
    nut/screw side as well, not the pulley. Less noise, wear and
    almost no cogging. With xx05 nuts, you get more torque, with
    xx10 nuts, you get speed. Limited speed/torque combinations.
    Less inertia than #3. No whipping but possible harmonics noise.
    Weight of servos on carriage.

    From all four options, #4 seemed the least explored to me. I
    prefer ball nuts over rack drive, so I wanted to see what's possible
    in that setup.
    .

  15. #335

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    620

    Re: David A's New 2x3 Bench Top CNC

    I like it and it has my wheels turning on converting my machine. Initially I was thinking about switching to the traditional style ballscrew setup. I'm not a fan of my current rack and pinion drive assembly that my machine came with. It's noisy and since the rack isn't perfectly flat and parallel it doesn't mesh perfectly and it's only a matter of time before it starts to wear. Your set up looks like it could be a relatively easy conversion on my router. Thanks for the ideas and let me know if you're going to be selling the parts for the rotating ball nut. I'm sure I can fabricate and adapter to make it work with my router.

    Thanks,
    Dan

  16. #336
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    Re: David A's New 2x3 Bench Top CNC

    Dan, let's see first how it performs before you tear apart your machine.....

  17. #337
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    Quote Originally Posted by davida1234 View Post
    Thank you Outlawtaz.

    The short answer would be that I just was curious.
    I don't know if there are any benefits or drawbacks.


    Following are my personal thoughts and relates only
    to the lower-cost equipment we generally use here:

    Option #1:
    If you put a servo on a CNCRP drive, you get additional
    speed or, with lower gearing, torque. All happening at the
    pulley side.

    The final gear side, pinion with pressure spring on the rack,
    stays the same. Some noise, wear and minute cogging.
    Protruding servos. Weight of servos on carriage.

    Option #2:
    A direct rack drive with a gear box and pinion is expensive
    for a good gear box. Can select appropriate speed/torque
    combination. Requires perfect gear mesh or pressure. Some
    noise, wear and minute cogging. Protruding servos.
    Weight of servos on carriage.

    Option #3:
    With traditional ball nut and screw application, everything is
    happening at the nut/screw side. With xx05 nuts, you get
    more torque, with xx10 nuts, you get speed. Just two fixed
    ratios. Less noise, wear and almost no cogging. Speed limit
    due to whipping and/or larger screw inertia. Possible
    backlash in coupling. Protruding servos.

    Option #4:
    With a powered ball nut, everything is happening at the
    nut/screw side as well, not the pulley. Less noise, wear and
    almost no cogging. With xx05 nuts, you get more torque, with
    xx10 nuts, you get speed. Limited speed/torque combinations.
    Less inertia than #3. No whipping but possible harmonics noise.
    Weight of servos on carriage.

    From all four options, #4 seemed the least explored to me. I
    prefer ball nuts over rack drive, so I wanted to see what's possible
    in that setup.
    .
    #4, servos and xx05 screws may give better speed than xx10 screws with steppers.

  18. #338
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    Re: David A's New 2x3 Bench Top CNC

    That's what I have here, numbers are slightly
    better for servos and can go even higher.

    1204's (not xx05) with servos give about 450 ipm @ 3,000 rpm

    1610's with steppers give about 400 ipm @ 1,000 rpm.

  19. #339
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    Re: David A's New 2x3 Bench Top CNC

    .
    Before I do the final install of power ball nuts
    and drive line, I am going to tram the Z-axis.

    All Z ball bushings freshly greased, Z-slide
    balanced by the springs. Just having some fun:

    https://youtu.be/M9y08NVXCC0

  20. #340
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    Re: David A's New 2x3 Bench Top CNC

    Hey David,

    Thanks for the reply and thanks for sharing the knowledge. I think it's great that you are taking the road less traveled. I will definitely have to go back and reread all your posts in detail.

    Another question: how many hours would you expect the belts to hold repeatability/tolerance before stretching and having to be adjusted?

    I've always wondered this, not necessarily for your design specifically, but for all machines that use a belt drive system. The machines I worked on as a tech used belt drives on alot of the rotary axes and I had to adjust them a couple times a year to ensure repeatability. Granted, that was production runs but I've always been curious if it smaller machines / smaller belts would degrade at about the same rate.

    Thanks again and good luck on the test runs!!

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