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  1. #16
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    Oct 2011
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    Quote Originally Posted by nadroj View Post
    Do you have a universal mill?
    Yes - that's my mill in the video I linked to...

    If it is only a speedo drive then probably something like some 4140 or similar would be good enough, as there is not really any power being transmitted. (Elan beat me to it)

    There is not really a way around the universal mill issue for helical gears, as part of the deal is that the table gets set over to the helix angle. If you could gear the D/H to your table drive, you might be able to do something by tilting the head, but you would still need a universal dividing head. Most people only have a semi-universal head though - way cheaper, but without the gears or drive train on the side. The gears are just to get the ratio, so nothing special. The ones on my set up are all ones I made myself as part of refurbishing the D/H.

    Without wishing to do Elan out of his fun, if you can work out what you need I can probably cut one for you. The two gears on the start of that video are a new/old comparison from a belt sander and are around the size you want. (Tip - start belt sanders in free air rather than in hard contact with the surface or you too may be looking for another gear)


    Michael

  2. #17
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    Aug 2008
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    Melbourne
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    You're welcome to it if you want Michael
    Just wasn't sure how many people here were equipped for helicals that small so I thought I'd pipe up
    Gear cutting specialists and general engineers www.hardmanbros.com.au
    Fine pitch gear cutting from 0.1 Module www.rigear.com.au

  3. #18
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    I'm just an amateur though - you're the guy that knows what he is doing.

    Michael

  4. #19
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    Aug 2008
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    I know what I'm doing with straight gears, still learning on helicals...I just have the fancy toys to play with lol
    Gear cutting specialists and general engineers www.hardmanbros.com.au
    Fine pitch gear cutting from 0.1 Module www.rigear.com.au

  5. #20
    Join Date
    Oct 2004
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    Southern Highlands NSW
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    Quote Originally Posted by elanjacobs View Post
    Does it have any shoulders or other features, or is it just a flat gear with a hole in the middle? I'll also need the bore size before I commit to any price because if we don't have an appropriate hobbing arbor I'd have to make one and that will add to the time needed. It's very likely that we do have one amongst the probably hundreds in the cupboard, but just in case it's a weird size...

    Not sure about hardening, but I could use 4140 which should be strong enough as is or I might be able to sneak it in with a batch of nitriding.

    EDIT: The shop rate I mentioned was if you were to walk in the door at an engineering firm, I wouldn't be asking anywhere near that as a private job
    It has shoulder each end, as seen in the photo. The overall length is 22mm, the toothed part is 14mm long.
    OD=12mm, and it's pressed onto a 6mm shaft.
    It has 11 teeth.
    The gear in the photo does not have the required helix, but is identlcal in all other ways.
    When I use gears like this one, because of the wrong helix, the speedo works for a while then the teeth get chewed out.
    ducsinspeedogear.jpg

  6. #21
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    Oct 2004
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    Southern Highlands NSW
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    Quote Originally Posted by Mk1_Oz View Post
    Could you 3d print this part?

    Could you find a suitable gear in a bike or car wreckers?
    I don't know, but I haven't seen anything convincing about affordable 3D printing of metal parts.
    Maybe there's an existing gear out there, but there are so many variables the chances of identifying the right one are tiny I think.

  7. #22
    Join Date
    Mar 2011
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    Southern Flinders Ranges
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    GaugeWorks in Adelaide will likely be able to assist you with something off the shelf.

    https://www.gaugeworks.com.au/#services

  8. #23
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    24DP is the closest normal pitch, but it's still a bit off the mark...I'd want to roll the gear with a hob to confirm it.

    Could you change both gears to straight? It would make life much easier at the expense of a bit of whine; 14.5 degree pressure angle runs pretty quiet and a smear of good grease might help damp the noise.
    Gear cutting specialists and general engineers www.hardmanbros.com.au
    Fine pitch gear cutting from 0.1 Module www.rigear.com.au

  9. #24
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    Apr 2012
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    Healesville
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    Quote Originally Posted by nadroj View Post
    C'mon nadroj.....you are holding out on us m8.... how about a few pics of the bike

  10. #25
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    Wow, it's been a rapid exchange of messages, and it sounds like I might have a couple of possible helpers after all.

    I will try to get the module, PA and helix info to progress the project!

    Nadroj

  11. #26
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    Oct 2004
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    Southern Highlands NSW
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    Quote Originally Posted by elanjacobs View Post
    24DP is the closest normal pitch, but it's still a bit off the mark...I'd want to roll the gear with a hob to confirm it.

    Could you change both gears to straight? It would make life much easier at the expense of a bit of whine; 14.5 degree pressure angle runs pretty quiet and a smear of good grease might help damp the noise.
    Can you do metric module gears? It's on an Italian bike.
    They can't be straight because the pair of mating gears aren't on parallel shafts.
    Rather, they are skewed so the speedo cable exits at an angle from the brake's backing plate.

  12. #27
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    Oct 2004
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    Southern Highlands NSW
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    Quote Originally Posted by shedhappens View Post
    C'mon nadroj.....you are holding out on us m8.... how about a few pics of the bike
    Due to the popular demand of one, here's some pics.
    Attached Images Attached Images

  13. #28
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    Apr 2019
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    Adelaide
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    589

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    Quote Originally Posted by nadroj View Post
    I don't know, but I haven't seen anything convincing about affordable 3D printing of metal parts.
    Why does it have to be metal? I would have thought a speedo drive could easily be nylon. I am sure I have seen nylon ones in cars b4.
    Last edited by Mk1_Oz; 26th May 2021 at 12:27 AM. Reason: dodo

  14. #29
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    Ok, turns out I can't do math But it's still a weird pitch...

    12mm, 11 teeth = 0.923 Mod, nearest imperial is 28DP (0.907 Mod). Again, I'd want to run it with a hob to confirm what it actually is because helicals can be a bit weird when it comes to pitch (transverse pitch vs. normal pitch, or pitch at 90 degrees to the bore vs. pitch at 90 degrees to the helix)
    Gear cutting specialists and general engineers www.hardmanbros.com.au
    Fine pitch gear cutting from 0.1 Module www.rigear.com.au

  15. #30
    Join Date
    Apr 2012
    Location
    Healesville
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    A sweet 450 desmo, thanks for the pic's.

    I think I have one of the first ducati engines somewhere, 50cc 4 stroke with exposed pull rods.
    They made them to bolt onto push bikes.

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