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  1. J

    How to make a plastic gear!

    Phenolic, is that the stuff that smells like horse pee when it gets hot? This was more like a hard pitch. I don't think it would be very good for fine pitch gears, but ABS would be. BTW, I am not claiming that this is a 'mature process' but certainly the ABS gear surprised me how well it...
  2. J

    How to make a plastic gear!

    At the end of the day they are still plastic gears and not all plastics lend themselves to this method. The best plastic I have found has been ABS (what Lego is made from), 'engineering' plastics such as the white stuff that looks like nylon is not so good as it has too much 'spring' and the...
  3. J

    How to make a plastic gear!

    No Chuck I didn't measure the overall diameter but it has the right number of teeth and the plastic teeth mesh fully with the steel gear. John
  4. J

    How to make a plastic gear!

    Fairly slow I think. That blue one I did at about 200 rpm.
  5. J

    How to make a plastic gear!

    The plastic is not cut or removed, it is displaced to form the teeth. The bit below the PCD is forced upwards to form the tips of the teeth. This is a heat forming process, with soft plastic just the friction is enough to form the teeth with some plastics friction is not enough so you need...
  6. J

    How to make a plastic gear!

    The number of teeth is set by the diameter of the blank which should be the PCD of the required gear, plus a little bit for squish allowance. If you want to use heat to soften the plastic you must make metal plates to fit each side of the blank leaving only the bit you want softened exposed...
  7. J

    How to make a plastic gear!

    I discovered (some time ago) a simple way to make plastic gears. DSCN0196 by aardvark_akubra, on Flickr A plastic blank is mounted on the lathe spindle and a steel gear of the required gear 'family' is mounted on a spindle on the tool post. The size of the steel gear is not important...
  8. J

    sherline machines

    I have a Sherline lathe, it is one of the very early ones from when they were made in Australia. The bed and cross slide etc are all brass. It is a very nice little machine and would be better if I replaced a few parts on it.
  9. J

    Gear cutting on a lathe

    This is how I cut some gears on a lathe.. The cutting rig.. geared slotter by aardvark_akubra, on Flickr ..and the indexing arrangement.. IMGP8706 by aardvark_akubra, on Flickr These pictures show the machine set up to cut a slot across the end of a shaft but it is the same set up I...
  10. J

    SteaMECH in NZ

    I have a name, address and phone number now. I will call him tomorrow and see where we are at.
  11. J

    SteaMECH in NZ

    I might be close enough to the action to ask some questions, maybe, I will let you know if I find anything. I would not be at all suprised if the guy has given it up and Paypal are still taking the money and holding it in an account,. John
  12. J

    Maybe, the problem with vacuum, flame eater, atmospheric engines?

    Thanks, I have a feeling they produce too little power because so much of the gas is cold before the port closes.
  13. J

    Maybe, the problem with vacuum, flame eater, atmospheric engines?

    Hi Frazer, as I see it what is needed idealy is highly conductive cylinder walls, piston crown and cylinder head, for the power stroke but insulated for the induction stroke! :-\
  14. J

    Maybe, the problem with vacuum, flame eater, atmospheric engines?

    Maybe, the problem with vacuum, flame eater, atmospheric engines? Atmospheric engines under various names and configuration are popular home shop projects and many seem to be a real challenge to get to run. One of the popular types is the 'flame licker' where a port opens and hot gases are...
  15. J

    Power feed for my mill, revised.

    Worm and peg wheel by aardvark_akubra, on Flickr My first attempt at a power feed for my mill worked OK but the aluminium worm wheel had a very short life, perhaps due to my not being able to make a highly polished surface on the worm I was using, so I tried another approach, this time it is...
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