Calculating lead for a helical gear - Page 2
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  1. #21
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    That's pretty slick but I no longer have the original gear to measure. I used one of those gear gauges to measure it - the little plates with the tooth profile for each size. It was clearly the best fit although the OD was slightly too large, which I understand is the case with helical gears.

    To test it, a friend used a 3D printer to make an opposite helix gear although I am certain he didn't provide for the lead. Still, in as much as we could tell from the plastic gear, the angles were the same. It's clear I have a lot to learn so if it doesn't come out right I'll just do it again until I get it right.

    jp

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    I thought I'd update this thread...
    Using the information I found as a result of this thread, I made a test gear from aluminum.

    img_3806.jpg

    I sent it to the gentleman who owns the 1917 White who tried it. He told me that, when fully inserted it fit perfectly but that there was some slight drag inserting it. He returned the gear so I could see where it's rubbing. You'll notice a little burr at the pitch line of one of the teeth...

    img_3807.jpg

    So...I'm wondering what I did wrong. I'm guessing the depth is slightly too shallow. When I measured the original gear, the depth was .265. When I finished this one and measured it, even though I aimed at .265, it actually measured .255. I tried it in any case because I'm always skeptical of my measuring skills...

    This was my third attempt...the first two ended with various failures, including having one of the gears fall off the dividing head in the middle of a cut, but I do have another test gear with only half the teeth cut but about .010 deeper and I'm thinking of sending that one to see if it works before going on with cutting the steel gears.

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  4. #23
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    Good Going Joe. One way to get it done - you are ahead of me - I can write at length about making them, but never made one.

  5. #24
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    Thanks John, it's certainly an interesting project. I had a long conversation with Hendeyman today about this and we agreed the error was likely that I simply didn't cut the teeth deep enough. After the fact I read the chapter in MH on making them - I should have read it more carefully first. The minimum total depth of the tooth is .269 and the teeth on that gear are about .255 which is very close to the "working depth". I think that explains why it did engage but dragged...

    I've a few more tweaks to make to the setup but I'm prepared to try cutting the finished gear now...

    dividing-head-1.jpg

    dividing-head-2.jpg

    I made a B&S 10 to 9 adapter for the spindle so I could use one of my collets. You were certainly right, it's thin but fortunately it doesn't have to be the full length of the taper. That worked better than it had a right to!

  6. #25
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    I finally decided it was time to try and make the gear...

    img_3823.jpg

    I'm actually making two of these...the second one is a spare but it will allow me to adjust the measurements just a little. the teeth here are about .009 deeper than the minimum depth figured from the formula in Machinery's Handbook. On the second gear I'm aiming for .005. My thinking here is that a little additional backlash won't effect it's operation. Actually, this gear is extremely understressed - it only runs a generator and a water pump.

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  8. #26
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    Nice mill, where did you get it....lol?

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    Quote Originally Posted by 99Panhard View Post
    I'm actually making two of these...the second one is a spare but it will allow me to adjust the measurements just a little. the teeth here are about .009 deeper than the minimum depth figured from the formula in Machinery's Handbook.
    You really want to measure the tooth thickness, not the depth. Depth doesn't really matter, since the tips fit air and no one holds cutting tool size on dimensions that don't matter.

    Various ways to do this : one is gear tooth verniers (google those and you'll see how they work) or in your case, since you have one that is almost the right size, you can do a span measurement over two teeth with flange mics or even use calipers if the jaws fit, or measure over balls.

    Anyway, you want to reduce the tooth thickness by the backlash you want, plus however much your interference was. By adjusting the tooth thickness you should get exactly what you want in one try.

  11. #28
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    Quote Originally Posted by Custommachining View Post
    Nice mill, where did you get it....lol?
    You MUST recognize it!

    For everyone else...I bought the mill from Custommacining and he was kind enough to deliver it - which would have been beyond my capacity.

  12. #29
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    I finished the parts today...these are water pump shafts for a 1917 White "4-cylinder - 16 valve" motor. White only built about 140 of them and there are only 4 currently known - though I'd say there is a reasonable chance there are a few more out there. It's one shaft for the motor and the second one is a spare...though it's hard to imagine how you could wear out a 1-1/4" wide gear driving a water pump and a generator.

    white-water-pump-shafts.jpg

    Thanks for the help guys!

  13. #30
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    You done yourself proud Joe.

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    Thank you John. I've come a long way from the shop you saw years ago.
    I've put off finishing the pistons you made the patterns for because I didn't feel I had the skills to do the job correctly but I'm getting close now...in fact, the pistons, rods and main bearings are the only significant parts left to do but those require the greatest degree of precision and it's only in the last year or two that I've had the feeling I was up to it.

  15. #32
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    Quote Originally Posted by 99Panhard View Post
    I've put off finishing the pistons ....
    Did you notice the piston grinder for sale on here ? Only $500 !

  16. #33
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    NO, I didn't. thanks. I'll look right now.

    jp

    I looked...chances are I'd buy it in a heartbeat but it's in North Carolina and I'm in Rhode Island - I don't even have a trailer hitch on my Blazer and that's a long trip. Thanks for the tip though. The reference to some of them being modified to grind cams is valuable since I've been thinking of making a cam shaft. In the early days, camshafts were made with the cams separate. They were keyed to the shaft and sometimes pinned in place although putting spacers between the cams was a better method. I don't "need" to do that but it's something I'd like to try one of these days.
    Last edited by 99Panhard; 01-31-2021 at 01:45 PM.

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    Quote Originally Posted by 99Panhard View Post
    I finished the parts today...these are water pump shafts for a 1917 White "4-cylinder - 16 valve" motor. White only built about 140 of them and there are only 4 currently known - though I'd say there is a reasonable chance there are a few more out there.
    Joe,
    Nice work with the gear, I hope to hear it fits OK.

    Any chance of photos of the engine and/or car? The White engine sounds interesting! What car is it fitted too?

    Thanks, Peter

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    I've never seen the car myself. It's in Florida and I'm in Rhode Island, at the other end of the East Coast, about 1,200 miles away. But, if you go to the AACA (Antique Automobile Club of America) forum and search for "1917 White" there is a long thread about it with lots of pictures, including the engine. The owner of the car, Ed Minnie, is one of the top end mechanics for pre-WWII cars and a widely acknowledged expert on Pierce Arrow.

    It's an unusual engine...a 4-cylinbder "T" head with a detachable head and 16 valves. It was apparently their top-of-the-line" automobile in 1917. They stopped making cars shortly thereafter to concentrate on trucks...and this car is built quite a lot like a truck, at least from the point of being wildly overbuilt.

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