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Thread: A machining conconundrum

  1. #1
    Join Date
    Jul 2011
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    418

    A machining conundrum



    I'm attempting to build a very low cost "commercial" tire grinding machine. This motor will be used to directly drive the tire. I had originally planned on grinding this motors shaft down to 3/32. After speaking with Bill Bugenis I realized the shaft on this motor is not hardened steel and is too soft for what I envisioned.

    I would like to reduce the instances and duration of time I touch donuts, hubs and set screws during assembly. The method I use to mount donuts requires a hub to be mounted to an axle during the gluing process. I'd like to leave the tire on the axle and just slide it into this motors shaft for trimming and the grind.

    I need to drill a parallel 3/32 hole in the center of this 4" x 1/2" motor shaft...
    I have; a decent large drill press, a wood lathe with a ton of runout, a great imagination.
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    Last edited by gotboostedvr6; 02-03-2018 at 05:26 PM.

  2. #2
    Join Date
    Jun 2002
    Location
    Northwest Ohio
    Posts
    122
    Tire Grinder to rough in shape

    Dremel Roto Tool or small Router mounted in a cross vise for axle. ( I used an old Sears electric die grinder)
    Small bench grinder with course grit wheel.

    Used this set-up for years when we made tires out of SBR
    Mike Blevins

    serfprod@yahoo.com

  3. #3
    Join Date
    Mar 2005
    Posts
    528
    Use the motor to power a shaft that runs in bearings & gear or belt drive it. What you are doing in introducing motor bearing play, end play & a ton of other issues into the equation.
    Why do I do this to myself?

  4. #4
    Join Date
    May 2002
    Location
    Kirkland
    Posts
    500

    just buy a unimat

    Quote Originally Posted by Wallbasher View Post
    Use the motor to power a shaft that runs in bearings & gear or belt drive it. What you are doing in introducing motor bearing play, end play & a ton of other issues into the equation.
    it's what Lee Gilbert has been using for decades for his commercial tires ?
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  5. #5
    Join Date
    Jun 2002
    Location
    Auburn,Wa
    Posts
    1,640

    tired

    All or not of these methods may work.

    Not knowing motor size or the diameter of the shaft there a few ways you can approach. One easy way would be center bore the shaft with an slight over sized 3/32 drill then drill and a tap dual setscrew thru the side. Then insert your 3/32 axle and knot it down with the setscrews. Only thing is drill has to be absolutely centered in shaft correct. You would do that by drill press but running the motor itself to achieve the center.

    Other ez way if you find a similar size collet or quick change drill chuck from dremel tap the shaft with treads that match the collet and attach thread on the collet. Depends again on the motor shaft size and rotation of motor depend whether you use the collet or a quick change chuck (or locking down to thread). Then you can attach a flat plate to motor to use a a surface to slide your cutting method or tool holder.


    The other version would be to use the motor with a pulley drive. Build a pillow block for axles somehow and use the motor to drive a parallel pulley.

    This would take alot more more work. If it was a large enough shaft on the motor The other method is to attach a grinder disk via threading use that motor to power a grinding setup mounted ridged then acquire a 3/32 shaft rc motor for you axle then tires attached. You can then attach to wide drawer slides to move the motor and tire towards the grinder. Even a cheap HF machining vice can be use to move and adjust the cutting distance from the grinder disk.
    Last edited by Slapshot; 05-12-2018 at 05:05 AM. Reason: tired of misspelling

  6. #6
    Join Date
    Jun 2002
    Location
    St Charles, Illinois, USA
    Posts
    2,299
    Best way to drill the 1/4" shaft for a 3/32" axle mount is to take the armature out of the black DC motor and chuck it up in the lathe and bore the hole in the center. Then cross drill a set-screw hole to hold the axle in place.
    l.d. kelley, M.A. Ramcatlarry@aol.com

    50 year pin 1959-2009
    Racing slot cars in America
    USRA 2009 member 0028, 2017 #404
    IRRA, ISRA/USA, Hardbodies 1/24 & 1/32
    retired raceway owner(for now)
    Omni/Cidex service center

  7. #7
    Join Date
    Jul 2011
    Posts
    418
    I ended up with this contraption. It cuts donuts in a second or two with no heating at all.

    I'll fill in the blanks over the next few days.

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  8. #8
    Join Date
    Sep 2011
    Location
    Long Island,N.Y.
    Posts
    898
    Cool set-up.

    I'm gonna' let you slide on the cold weld.
    Don't resist....VOTE !

  9. #9
    Join Date
    Jul 2011
    Posts
    418
    Yeah yeah..

    It's only holding about 3 pounds lol

  10. #10
    Join Date
    Sep 2011
    Location
    Long Island,N.Y.
    Posts
    898
    What grit is the wheel?

    Do you still do a final cut on a Hudy or does this set-up give you good enough final OD for racing ?
    Don't resist....VOTE !

  11. #11
    Join Date
    Jul 2011
    Posts
    418
    Matt Bruce made me a jig i used to center drill the motor shaft that spins the tire. It's just about dead nuts. I only use this grinder for initial cuts. Its capable of turning a hard wonder donut into dust in seconds. No smoke at all.

  12. #12
    Join Date
    Sep 2011
    Location
    Long Island,N.Y.
    Posts
    898
    Quote Originally Posted by gotboostedvr6 View Post
    Matt Bruce made me a jig i used to center drill the motor shaft that spins the tire.


    Matt Bruce is a very talented guy. His Retro fronts are 2nd to none.
    Last edited by oldweirdherald; 12-05-2018 at 06:58 PM.
    Don't resist....VOTE !

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