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Thread: Debate of the Day: Experimental Chain Tensioner

              
   
   
  1. #51
    Empulse R #24 frodus's Avatar
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    Quote Originally Posted by Stevo View Post

    What I really really need to find is a 520 sprocket adapter for the 7/8" keyed electric motor shaft. Nobody makes a solution AFAIK.
    I have 10t 7/8" for 520 in stock:
    https://www.emf-power.com/product/10...for-7-8-shaft/

  2. #52
    Senior Member Stevo's Avatar
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    Quote Originally Posted by frodus View Post
    Thanks for your support Travis. I think it would be too small for my liking. I was editing my post above^^^ while you posted this, so you probably didn't see the context.
    I did find, ordered and received a 14t JT sprocket for an idea I have. I'm drafting up a sprocket adapter for these 7/8" keyed Motenergy shafts. My idea was to be able to get an over the counter model specific sprocket and use it on the adapter. The problem is I only found 2 sprockets that I thought would work. This sprocket that I just got is for a BMW G450X dirtbike. It fits nicely on the shaft and only a keyway needs to be cut out. The problem is that the sprocket's center splines need to be a much larger diameter in order to be mounted to an adapter. My idea wont work because the sprockets will have to be proprietary and made to order, which defeats the purpose of my original idea. The only larger sprocket spline diameter I could find was for a Honda RC51, and that would only give 2mm of meat to play with, not enough.

    I can use the BMW sprocket by cutting a keyway, then welding it to a 10t Martin, which I just happen to have in my garage.
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
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  3. #53
    Empulse R #24 frodus's Avatar
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    Can you machine down a #50 sprocket (530 chain size) to what you need?

    www.surpluscenter.com has some under "Power Transmission"and "finished bore sprockets"

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    520 is good enough for Superbikes and probably MotoGP as well, so go with that instead of the wider chains. Of course, that presumes you get a good 520 chain, Regina actually makes 6 different 520 chains in their "GP" line of chains for racing, and other 520s for lower level uses.

    cheers,
    Michael

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    Can't you buy some sort of adapter made for the shaft, bore the center out of a sprocket and weld the two together? I've retoothed rear aluminum sprockets by turning off the teeth and boring out the new sprocket and welding them (intermittently) at the join.

    Carbide will cut through the case hardening on the steel sprocket. You can also fit the two together and drill holes at the border between them and put close-fitting steel pegs in the holes to take the drive loads and then weld everything up if you want a little more security. Another way to do that is to cut a wavy "sine wave" pattern on both pieces so the weld isn't taking the loads, just holding things together.

    If you've got room leave a shoulder on the adapter for the sprocket to mate against to help keep it running true.

  7. #56
    Senior Member Stevo's Avatar
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    I agree with you Michael. Switching my 530 chain out to 520 on my VFR probably shaved off a few lbs in unsprung weight. The difference in strength is arguably minimal. I'm actually kinda surprised nobody else on here has started a discussion regarding the lack of available sprockets for these motors. 520 is probably the most common chain size used on motorcycles. 530 the next most common.
    What I've done in the past is use a cutoff disc and slice a sliver off of a Martin #50 sprocket, then grind the teeth profiles all by hand. It works. It's cheap. It's also a PITA.
    Not to mention that the surface hardened heat treat is ruined when you do this. The heat treat will probably be ruined if I weld a sprocket onto a Martin also. Is there no other better options available to us?
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
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    Sprockets aren't rocket science, you've just got to find a place willing to make them at a price and quantity you can afford. For big production numbers sprockets are hobbed or shaped, but I've seen mention of places doing BMX/MTB stuff that just CNC sprockets (I suspect aluminum) on a mill. I've got software that will generate a DXF of different pitch/tooth count sprockets and I've got 520 x 14-18T DXF already on hand (those are actually just 5xx curves, I extrude them as thick as needed for the xx width). I've attached various 219/415/428/5xx dxfs.

    Use at your own risk!

    If you need a hand with the CAD I can probably assist a bit.

    cheers,
    Michael
    Attached Files Attached Files

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    A bit of Googling found ANSI 50 taper lock sprockets starting at 15T

    https://www.rainbowprecisionproducts...ocket-ansi50#1

    and they use these bushings

    https://www.rainbowprecisionproducts...lock-bushing#1

    It looks like $26 gets you a 15T with a 7/8" bushing.

    cheers,
    Michael

  10. #59
    Senior Member Stevo's Avatar
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    I've seen the taper locks before too, but they are still sized 530 and not really a solution .

    Your other suggestion of CAD design help may work with Aluminum. They will probably need to be replaced more often. But we could collaborate and design a prototype sprocket and adapter pairing to have it cnc'd somewhere. Are you game?

    Sent from my Pixel 2 using Tapatalk
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
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    530 needs 1/8" turned off one face to turn it into 520. That doesn't touch the hardened surface on the teeth where the rollers ride and would be much easier to do than making sprockets.

    An aluminum chain sprocket (as opposed to an aluminum belt sprocket), especially one with too few teeth per the chain manufacturers recommendations, coupled with the torque of an e-motor, sounds like a bad plan to me. Every stress cycle on aluminum brings it that much closer to fatigue failure. Rear sprockets get away with it by having a lot more teeth engaged but even so an aluminum rear sprocket won't last as long as a steel.

    I'm willing to assist you on the design but modifying a decent sprocket/hub that someone else already makes in quantity is probably going to be a much cheaper and faster to realize solution, as well as a better one for longevity. You could buy a sprocket and hub and put the sprocket in a lathe (or on a mill table) and have it thinned in 10-15 minutes. It is what I'd do if I were going to run a chain.

    On these keyed shafts I hope the hubs are a tight reamed fit. A hub that also had a taper lock on the shaft (like an ER or 5c collet) strikes me as a good idea if you can't clamp the sprocket on tight enough with a nut/bolt to keep it from moving back and forth under load reversals causing fretting.

    cheers,
    Michael

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