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Old 05-27-2011, 01:14 AM
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Default change gears - working out TPI

The chart on my lathe for the change gears shows the configurations necessary to cut 1 through 20 TPI.

Is there a formula that will enable me to calculate what would be required to cut finer threads? My lead screw is 2 TPI.
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Last edited by Mayhem; 05-27-2011 at 01:15 AM. Reason: incomplete post
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Old 05-27-2011, 03:00 AM
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You will have to look through this link.
http://www.gizmology.net/changegears.htm


About the middle of the page in this link.
http://www.varmintal.com/alath.htm#Cutting_Odd_Threads
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Last edited by GWIZ; 05-27-2011 at 04:20 AM.
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Old 05-27-2011, 04:56 AM
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Quote:
Originally Posted by GWIZ View Post
You will have to look through this link.
http://www.gizmology.net/changegears.htm


About the middle of the page in this link.
http://www.varmintal.com/alath.htm#Cutting_Odd_Threads
Wow, that was really neat. Did you write that up?
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Old 05-27-2011, 06:04 AM
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Thanks GWIZ, the first link is very useful but the second confused me, as it is a web ring (or am I missing something)
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Old 05-27-2011, 06:26 AM
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Unless you plan to cut the gears yourself, figure about $300-$400 per custom made part (that price was quoted to me last week for one gear, 30 tooth, about half an inch thick and 2" diameter).
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Old 05-27-2011, 06:31 AM
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Quote:
Originally Posted by precisionworks View Post
Unless you plan to cut the gears yourself, figure about $300-$400 per custom made part (that price was quoted to me last week for one gear, 30 tooth, about half an inch thick and 2" diameter).
Barry, How come you wouldn't just cut one yourself?
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If I defend myself I am attacked.

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My attack thoughts are attacking my invulnerability.

I'd like to think of something smart, but I don't want to hurt myself.

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Another Johnson model J Project
Lathe? Maybe..... 1958 SBL 13"
Yeti Esseti Aka running welder on 3phase.

https://www.shopfloortalk.com/forums...860#post766860
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Old 05-27-2011, 12:07 PM
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4 a gear to last any length of time requires at least 1144 stress proof or 4140 h t. The cost of material is low but the labor required would be at least 2 to 3 hours. 1 of the members of the p m forum will make them for as little as 60 dollars each if 3 or more identical are ordered at 1 time.

If that were not enough, accurate gear hobbing requires a super spacer, although I could borrow 1 from work.
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Old 05-27-2011, 07:28 PM
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Quote:
Originally Posted by Mayhem View Post
...the second confused me, as it is a web ring (or am I missing something)
Ignore this - I just tried again and it went to the correct page
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Old 05-30-2011, 12:54 AM
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Quote:
Originally Posted by allessence View Post
Wow, that was really neat. Did you write that up?
No not me, but I did write a gear program years ago that worked with GW-basic.
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