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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > Help sourcing hard to find parts for diy CNC build
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  1. #1
    Join Date
    Mar 2017
    Posts
    926

    Help sourcing hard to find parts for diy CNC build

    Does anyone know where I can find a 1/4" to 15mm motor coupling? I ordered some on eBay but the vendor sent me 9mm x 15mm couplings and then told me they don't have any 1/4" x 15mm ones in stock. I can't find any other vendors offering this size...

    If I can't buy them, is a diy coupling an option? It seems like it would be a simple case of finding the right size drill bits and adding a couple of set screws. Is there more to it than that?

    My other options would be using pulleys or using an intermediate shaft as I can easily find 1/4" x 12mm and 12mm x 15mm couplings but neither of those are ideal...

  2. #2
    Join Date
    Dec 2013
    Posts
    5717

    Re: Help sourcing hard to find parts for diy CNC build

    Build a 9mm x 1/4 bushing maybe? That's what I would do, a quick job in a lathe if you have one.
    Jim Dawson
    Sandy, Oregon, USA

  3. #3
    Join Date
    Mar 2017
    Posts
    926

    Re: Help sourcing hard to find parts for diy CNC build

    Someone just sent me an email with a place. If anyone else is looking for unusual size couplings, this is the place:

    NBK Japan MJC-30-RD 1/4 inch to 15mm Jaw-type Flexible Coupling


    Parts for larger ball screws can get really expensive.....

  4. #4
    Join Date
    Mar 2003
    Posts
    35538

    Re: Help sourcing hard to find parts for diy CNC build

    McMaster Carr 6408K series
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

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

  5. #5
    Join Date
    Mar 2017
    Posts
    926

    Re: Help sourcing hard to find parts for diy CNC build

    Quote Originally Posted by Jim Dawson View Post
    Build a 9mm x 1/4 bushing maybe? That's what I would do, a quick job in a lathe if you have one.
    Would you do that over making a direct coupling on a drill press? I.e. Drilling a 1/4" hole through a steel round bar and then enlarging the hole on one side to 15mm and then drilling small holes for set screws.

    I don't have a lathe although I have been thinking of buying a small one lately. It's one of those things I have a need for occasionally but it never seems to be enough to justify the purchase. I can't decide if those small benchtop models are good enough to be worth it...

  6. #6
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    Mar 2017
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    926

    Re: Help sourcing hard to find parts for diy CNC build

    Quote Originally Posted by ger21 View Post
    McMaster Carr 6408K series
    I keep forgetting about McMaster. I was just looking at their site again and they have a lot of interesting parts for a CNC build. I like the look of their "ultra flat heavy duty tables".

  7. #7
    Join Date
    Apr 2004
    Posts
    5728

    Re: Help sourcing hard to find parts for diy CNC build

    You can use a solid coupler if everything is really lined up perfectly. If not, rotation with a little eccentricity will snap the shaft off your motor. Here's more information about it than you probably want to read: Criteria For Power Transmission Couplings - SDP/SI You can get Oldham style couplers (the kind with a rubber piece in between) that fit inch or metric shafts from the same site; just order one from the inch catalog and one from the metric catalog - the rubber "spiders" fit both.
    Andrew Werby
    Website

  8. #8
    Join Date
    Dec 2017
    Posts
    77

    Re: Help sourcing hard to find parts for diy CNC build

    I'm learning as I go here, particularly from that website you just linked - it's great! So, correct me if I'm wrong on a technicality. The Oldham coupling is the type with full diameter slots that attach the inner element to the hubs. Whereas a jaw coupling is the one with an element that fills the spaces between alternating radial parts on the hubs. The term I've heard a lot is "spider coupling," but I guess that's ambiguous.

  9. #9
    Join Date
    Feb 2007
    Posts
    4553

    Re: Help sourcing hard to find parts for diy CNC build

    When searching eBay look for 6.35mm X 15mm, you will find many vendors.

    https://www.ebay.com/itm/D30L42-Flex...AAAOSwfxJZ6oN~


    Jeff...
    Quote Originally Posted by Goemon View Post
    Does anyone know where I can find a 1/4" to 15mm motor coupling? I ordered some on eBay but the vendor sent me 9mm x 15mm couplings and then told me they don't have any 1/4" x 15mm ones in stock. I can't find any other vendors offering this size...

    If I can't buy them, is a diy coupling an option? It seems like it would be a simple case of finding the right size drill bits and adding a couple of set screws. Is there more to it than that?

    My other options would be using pulleys or using an intermediate shaft as I can easily find 1/4" x 12mm and 12mm x 15mm couplings but neither of those are ideal...
    Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.

  10. #10
    Join Date
    Mar 2017
    Posts
    926

    Re: Help sourcing hard to find parts for diy CNC build

    Quote Originally Posted by jalessi View Post
    When searching eBay look for 6.35mm X 15mm, you will find many vendors.

    https://www.ebay.com/itm/D30L42-Flex...AAAOSwfxJZ6oN~


    Jeff...
    Not many. Just a few and at least two of them don't have what they are advertising. I ordered from them and, as I said, one sent me the wrong size and then said they didn't actually have the 6.35mm x 15mm. The other just cancelled my order and said they didn't have it. For reasons I will never understand or accept, both vendors are still advertising the same 6.35mm x 15mm coupling that they don't have...

    The link you posted is a vendor in China. I don't order anything direct from Chinese vendors. They take forever and I have zero trust left for any vendors over there. Too many bad experiences.

  11. #11
    Join Date
    Mar 2017
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    926

    Re: Help sourcing hard to find parts for diy CNC build

    Quote Originally Posted by awerby View Post
    You can use a solid coupler if everything is really lined up perfectly. If not, rotation with a little eccentricity will snap the shaft off your motor. Here's more information about it than you probably want to read: Criteria For Power Transmission Couplings - SDP/SI You can get Oldham style couplers (the kind with a rubber piece in between) that fit inch or metric shafts from the same site; just order one from the inch catalog and one from the metric catalog - the rubber "spiders" fit both.

    I assume that is why some use flexible couplings. I wondered about that as it sounded like a recipe for backlash.

    My emergency diy coupling will be my spare straight shank tool holders. I have some with a 1/2" shank so I could just buy the right size collet to create an appropriately centered coupling for odd sizes.

    I might have to do something diy for my new Z axis ball screw. I misread the specs and accidentally bought a 38mm screw with a 63mm barrel ball nut.... Somehow, I don't think anyone expected to drive it with a nema 23 with a 1/4" shaft....

  12. #12
    Join Date
    Nov 2007
    Posts
    1

    Re: Help sourcing hard to find parts for diy CNC build

    Quote Originally Posted by Goemon View Post
    Does anyone know where I can find a 1/4" to 15mm motor coupling? I ordered some on eBay but the vendor sent me 9mm x 15mm couplings and then told me they don't have any 1/4" x 15mm ones in stock. I can't find any other vendors offering this size...

    If I can't buy them, is a diy coupling an option? It seems like it would be a simple case of finding the right size drill bits and adding a couple of set screws. Is there more to it than that?

    My other options would be using pulleys or using an intermediate shaft as I can easily find 1/4" x 12mm and 12mm x 15mm couplings but neither of those are ideal...
    I have bought 14mm couplers from RoverCNC.com. Good quality and reasonable prices. Several sizes available. John A.


    Sent from my iPad using Tapatalk

  13. #13
    Join Date
    Feb 2007
    Posts
    4553

    Re: Help sourcing hard to find parts for diy CNC build

    Purchase these and drill the 10mm side out to 15mm, it's easy to accomplish as long as you shim the gap before drilling.

    https://www.ebay.com/itm/3Pcs-6-35x10mm-CNC-Stepper-Motor-Jaw-Shaft-Coupler-6-35mm-to-10mm-Flexible-Jaw-S/222894434020?hash=item33e58b26e4:g8sAAOSwUQlas9e0


    Jeff...
    Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.

  14. #14
    Join Date
    Nov 2011
    Posts
    137

    Re: Help sourcing hard to find parts for diy CNC build

    I have ( I think there called) lovejoy couplings on mine stepper side is 1/4,acme thread side is 7/16.Comes with a set screw for each side and a very solid rubber connector between then the perfect answer for a motor that is not perfectly aligned with the rod,when I installed mine I pushed the acme lead screw tight with a bearing and I have about a 1/2 space on the outer side so if i need to tighten it up I can...gets rid of backlash......they com in different sizes real cheap got mine from Granger.....

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