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  1. #1

    Join Date
    Dec 2018
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    9

    Question Dual drive ballscrews?

    Hi everyone,

    I have recently finished my EMCO retrofit project with UC300eth and I am very satisfied with the result so far
    As my next project I would like to do a complete build of a bigger CNC machine, mostly for aluminium and wood.
    I am looking for something like the Dual drive ballscrews CNCRP is using for their Benchtop Pro series. I would be very grateful if you could tell me if these are custom made or if I could buy these directly from a manufacturer?

    Kind regards,
    Tom

  2. #2
    Member
    Join Date
    Jul 2018
    Posts
    1376

    Re: Dual drive ballscrews?

    Hi Tom - Can you explain the dual drive ballscrew a little better? They use a std precision ballscrew in their ads? for their Z. The XY use R&P. Do you mean two nuts for the drive screw in Z? Peter

    PRO4824 4' x 2' CNC Router Kit | Avid CNC | CNC Router Parts

  3. #3

    Join Date
    Dec 2018
    Posts
    9

    Re: Dual drive ballscrews?

    Thank you very much for your reply!
    I mean the Benchtop Pro Series (Benchtop PRO 2424 2' x 2' CNC Machine Kit | Avid CNC | CNC Router Parts). Especially the Components used for the X and Y axis.
    I found out that these are called "Ball Rail Tables". Bosch Rexroth has them for example but they are really expensive

  4. #4
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    Join Date
    Jul 2018
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    1376

    Re: Dual drive ballscrews?

    Hi Tom - Link explains better Ta. The dual means the gantry is driven on each side vs using a single central drive. That model uses lead screws not ball screws. Some routers of that size use a single central drive under the table to remove cost of extra motor and parts. As machines get bigger however the central drive has issues so they move to the two drive arrangement.

    Look up BST motion for ball screws.

    https://bstmotion.aliexpress.com/store/314742

    Lead screws us a bronze or plastic nut and require some way to remove the nut backlash. Either split nuts, two nuts or springs. Leadscrews are cheaper then ball screws. ballscrews are more accurate then leadscrews and use ball bearings in a matched thread to drive. This needs less effort as the balls roll and the balls can be preloaded to remove the backlash. There are also double nut arrangements for even more accuracy. Ballscrews are available from many sources ex USA. Rexroth is a premium brand hence a premium $$$. Look around for budget ballscrews I think you will find these perform better and last longer then leadscrews. But others can direct you to suitable suppliers. Are you in US of A? I'm in Australia so know sources here but BST have been good to deal with...Peter

  5. #5
    Registered
    Join Date
    Feb 2005
    Posts
    809

    Re: Dual drive ballscrews?

    The AVIDCNC benchtop pro uses ballscrews on all axis.

  6. #6

    Join Date
    Dec 2018
    Posts
    9

    Re: Dual drive ballscrews?

    Yes, like nlancaster said, the benchtop pro uses ballscrews. The linear guideways and the ballscrew are one unit like this product from rexroth: https://www.boschrexroth.com/en/us/p...ll-rail-tables
    These look like easy to use axes for cnc but I could not find a cheaper alternative with good quality.
    I am located in Austria (no kangaroos only kuhlimuhs )

  7. #7
    Member
    Join Date
    Jul 2018
    Posts
    1376

    Re: Dual drive ballscrews?

    G'Day HL - We are lucky lots of Kangaroos, some in my backyard and lots of cows across the road. I presume kuhli muhs are cows via a quick search. Yes sorry looked at wrong model pro uses screws. Keep Making.. Peter

  8. #8
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    Feb 2005
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    809

    Re: Dual drive ballscrews?

    happens peteeng

  9. #9
    Registered
    Join Date
    Nov 2013
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    852

    Re: Dual drive ballscrews?

    Hi,
    the big determinant in price is whether the ballscrew is rolled or ground.

    Rolled ballscrews are typically rated at 50um per 300mm but up to 25um within one revolution, this is C7 spec.
    Ground ballscrews start at C5 and are rated to 18um per 300mm but only 0.7-0.8 um per revolution.

    As you can see its the cyclic accuracy (accuracy within one revolution) is very different.

    For a C7 (rolled) ballscrew and support bearings and 1m long you might pay $200USD.
    For the same size C5 (ground) ballscrew and support gearings and 1m long you might pay $1500USD.

    BIG difference in price.

    Craig

  10. #10
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    Nov 2013
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    852

    Re: Dual drive ballscrews?

    Hi,
    I lucked out and got these babies (three screws) second hand off Ebay for $1000USD including shipping to New Zealand. They are ground C5 with medium preload,
    ie no backlash. If they are second hand I fail to see any sign of wear, they are perfect in every regard.

    Careful and patient reading of Ebay can result in such gems.....but you have to be patient.

    Craig

  11. #11
    Registered
    Join Date
    May 2010
    Posts
    5

    Re: Dual drive ballscrews?

    I built my own using CNC Router parts linear rails and Z axis using ball screws. Here is a pic. I just made some adapter plates to stand it off enough. Wish I had a better side shot. I still might have the file template I made if you are still wanting to go this route. Not sure if you have already built it or not since this post is from December.

    Shane



    Attachment 442974

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