Spur gear source?




Aren't they cutting metric threads? --jsw
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On Mon, 22 Feb 2016 20:48:23 -0500, "Jim Wilkins"

I finished my apprenticeship in 1950.... I don't think that they had metric threads in those days :-)
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wrote:

Are you really that silly or are out making an effort? You don't cut threads when you reverse the lathe. Well, most people don't anyway, of course if they do they have very poor results.
Geeze, 60 years old and hasn't learned a thing.
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wrote:

Goodness, and you have a reading disability, or is it "aphasia" which is frequently a result of stroke?
In the future I will try using words of fewer syllables as I understand that those suffering from the disability have fewer problems comprehending simple words.
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Cool. I have a 11x44 myself.
Is the 15 tooth a metric threading gear ? Just a thought.
Martin
On 2/21/2016 7:43 AM, Gerry wrote:

The kicker is that the original gear was 15 tooth! I've had the lathe since new for 9 years.
I've never been able to thread with the lathe and I guess the 15 tooth gear explains why.
I always figured that I was doing something wrong and found other ways to work.
I am retired now and am trying to get things right. BTW,
my previous lathe was a Sheldon 11X56 and never had problems of any kind except wear

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On Sunday, February 21, 2016 at 8:40:25 PM UTC-6, Martin Eastburn wrote:

slight helix.

Could be, Martin, but the metric versions of my lathe use a different style thread dial, one with three gears and three mounting holes. BTW the seller , Matt at Quality Machine Tools is going to send me the proper gear this we ek. Lathe is a Precision Mathews 1340. I thank all of you for your input
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On Sunday, February 21, 2016 at 9:40:25 PM UTC-5, Martin Eastburn wrote:

I can not see how a 15 tooth gear would be for metric. Especially with a un ch lead screw.
I think the original might have had a 16 tooth gear and when the design was copied someone miscounted the number of teeth. The Chinese have no idea of what the threading dial is used for. I say that because I have a Taiwan lathe that had the wrong number of teeth on the threading dial. And I tri ed to explain to the manufacturer what was needed.
Dan
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wrote:
Greetings Gerry, The gear should ideally have helical teeth so that the threading dial will still be at 90 degrees to the leadscrew. But you may have a hard time finding one. However, the gear only has to transmit enough torque to spin the thread dial. You could get away with a disc with pins sticking out as your gear. The pins should be tapered to match the angle of the leadscrew, just so that there is line contact instead of just point contact. If a regular spur gear is used, one with straight teeth, only the corners of the leadscrew thread will make contact with the gear teeth unless the axis of the gear is tilted to the same angle as the helix on the leadscrew. Eric
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    Assuming a standard Acme thread on the leadscrew, go for a 14 degree pressure angle.
    You'll need to mount the gear at a sight angle to make the teeth parallel the thread faces.
    If you had an index head -- or something which could work like one, you could set up the lathe to do milling well enough to do the job, and turn a cutter to make the cuts.

    Sorry -- my newsreader does not do e-mail forwarding as set up. I hope that you find this here.
    You need to get a newsreader with a good killfile, and use that to get rid of most of the junk -- by name of poster, and by words in the "Subject: " header
    Good luck,         DoN.
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