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Rotor Winding Tooling

Discussion in 'The Garage' started by Jim, Jul 22, 2018.

  1. jetmechmarty

    jetmechmarty What should I put here? XS650.com Supporter Top Contributor

    I acquired a rotor many years ago from a friend on the Micapeak email list. It was well under 5 ohms. 18 years on it, so far.
     
    Jim and gggGary like this.
  2. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Making the winding form was straightforward. All I had to do was make a new inner piece. The rest of it worked just fine.

    form3.jpg


    Cranked out 500 turns.

    500 turns.jpg

    Wrapped in fiberglass tape just like the XS coils (didn't get a pic) and pressed it back together.

    pressed.jpg

    It's not splined like the XS rotors, so I made a punch mark when I took it apart. Wound up nailing the alignment, so balance should be pretty close.

    punch mark.jpg

    Was shootin' for 3.8 to 4Ω... nailed it:D

    3.9 ohms.jpg

    I'll let the JB Weld harden overnight and finish putting it together. The taper on the hole turns out to be identical to the XS taper, so balance and runout tooling will work for this rotor.
     
  3. Superjet

    Superjet XS650 Guru Top Contributor

    I like the punch marks for alignment. Sometimes its the simple things similar to this that help greatly!
     
    Paul Sutton, Mailman, 59Tebo and 2 others like this.
  4. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Which CB750 is this for? The DOHC 750 from '79 up, or the SOHC CB750 built up till '78?

    The DOHC 750 and 900 have a big following now, they'll always be looking for rotors.
     
  5. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    I believe it's for the DOHC750 Scott.
     
    mrtwowheel and Paul Sutton like this.
  6. 59Tebo

    59Tebo 59Tebo Top Contributor

    Hey, Jim, you've got quite the cottage industry in the works there. A "side job" that could pay for all your other projects (and keep you off the streets at night! :wink2: ). Catalog all you winding forms and tooling, keep detailed notes (i'm guessing you already have), and you'll have built the "better mouse trap" the world beats a path to your door for.... :twocents:
     
  7. Mailman

    Mailman Hardly a Guru Top Contributor

    You sure do nice work Jim! :thumbsup:
     
    59Tebo, gggGary and Jim like this.
  8. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Sweet Jim!
    Those DOHC STATORS were fragile, bump the RH crank cover and plan on a new stator.
     
    Paul Sutton, Jim, Mailman and 2 others like this.
  9. Grumpy32

    Grumpy32 XS650 Member

    Jim is correct Scott, that rotor is for the DOHC Honda 4's. It was used on the cb750's, 900's, and 1000's, yrs 1979-83.
     
  10. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Slip ring looked pretty rough to start with...

    slip ring.jpg

    Much better now. All back together. As with the XS rotors, there's a slight increase in resistance when it's assembled. I'm guessin' there's a bit of inductive reactance going on when the iron core is pressed together. Still... 4.1 Ω is pretty close to what the guy's on the CB site said was preferred. According to them, the book calls for 4.5 Ω, but their years of experience has showed them that 3.8 to 4 Ω makes for a better charging system. 4.1 will do.

    4.1 ohms.jpg

    Runout is good, but I can't check the balance because my balance shaft is too light for this much heavier rotor. I'm currently epoxying extra weight to it.
    Please stand by...:er:
     
    Last edited: Jan 16, 2020
  11. Grumpy32

    Grumpy32 XS650 Member

    Excellent!:) I'm standing by...
     
    Paul Sutton and Jim like this.
  12. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Thought something was odd. Went back and looked at the pics. Yesterday was 3.9 Ω and 4.1 Ω today... but in both cases, the coil was already in the rotor. Hmmm.... different temps maybe? Just rechecked it...

    4.0 ohm.jpg

    Guess we'll call it 3.9 to 4.1... depending on how I hold my tongue. :umm:
     
    TwoManyXS1Bs, Mailman and gggGary like this.
  13. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    All my meters drift down slowly for about 3-4 seconds before they settle when ohming rotors.

    "Temperature Coefficient of Copper. The Temperature Coefficient of Copper (near room temperature) is +0.393 percent per degree C. This means if the temperature increases 1°C, the resistance will increase 0.393%. ... The wire resistance will go up 0.00255 ohms (10 degrees * 0.00393 per degree * 0.0649 ohms = 0.00255 ohms)."
     
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  14. gggGary

    gggGary I'm listening, change my mind XS650.com Supporter Top Contributor

    Temperature Coefficient of Copper. The Temperature Coefficient of Copper (near room temperature) is +0.393 percent per degree C. This means if the temperature increases 1°C, the resistance will increase 0.393%. ... The wire resistance will go up 0.00255 ohms (10 degrees * 0.00393 per degree * 0.0649 ohms = 0.00255 ohms).
     
    59Tebo and Jim like this.
  15. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Yeah, mine too. All my readings are after 20-30 seconds.
     
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  16. Machine

    Machine Race the wind Top Contributor

    20200117_123540.jpg
    A fresh Jims rewind rotor , ready to spin forever !
    -R
     
  17. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Honda CB750 rotor balanced, clear coated and ready to ship. :D

    CB rotor done.jpg
     
  18. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    I've had this iron since my Air Force days... and I retired in 94. I guess we can say this tip gave it's all.

    iron.jpg
     
  19. ReycleBill

    ReycleBill Part Time Tyrannicide XS650.com Supporter

    Is it easier to count turns or simply use up a measured length of wire? The end result will be the same.
     
    Jim likes this.

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