# Change Gear Chart For 9 Tpi Lead Screw?



## PAturner (Nov 26, 2016)

Hi all,

I've been investigating and it turns out my lead screw is 9 TPI, so I'm unable to use a south bend change gear chart. Anyone have any idea where a chart can be found for a 9 TPI leadscrew?



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## CluelessNewB (Nov 26, 2016)

Can't help you specifically but there is a calculator on this web site that may help:
http://littlemachineshop.com/reference/change_gears.php

and here: 
http://bilar.co.uk/cgi-bin/change-gear-calculator.pl


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## 4GSR (Nov 26, 2016)

I must ask, what brand of lathe do you have that would have a 9 pitch threaded leadscrew on it?  Ken


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## Tersti (Nov 27, 2016)

I can make you a chart if you tell me what gears you have, I initially made a tool for this to make metric approximations on an imperial lathe but it seemed likely that someone might need a chart for a lathe with an unusual leadscrew so that functionality is already written into the program. All I need to do is plug some gears and a leadscrew in. Would you also like a chart for metric approximations? It's a bit fiddly getting everything lined up at the start of each pass if you don't have any tools to make that easier but it's fine for low volumes of work.


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## PAturner (Nov 27, 2016)

Tersti, that would be great, thanks for the offer! I'll be able to tell you the gears later today. 
And 4gsr, I have no idea what brand the lathe is, I haven't been able to ID it.


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## Wreck™Wreck (Nov 27, 2016)

.11111111111111 is an unusual thread lead, who would make such a machine?


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## Tersti (Nov 27, 2016)

Wreck™Wreck said:


> .11111111111111 is an unusual thread lead, who would make such a machine?


I'll be fascinated to see if the changewheel set has some really odd gears in it. It's a minimisation problem and the designers may have had a changewheel set in mind which would minimise the number of changewheels required, which may or may not still be with the lathe. I imagine that if it's the same set as you'd get with an ML7 (all multiples of five) it would be very hard to cut common threads.


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## 4GSR (Nov 27, 2016)

If you have a scale marked in 1/8th gradulations like a Starrett 4R scale, hold it up to the thread and see if the marks align up with the thread.  If it does, it is a 8 pitch thread.  I'm with Wreck, who would design a lathe with a 9 pitch lead screw?


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## Wreck™Wreck (Nov 27, 2016)

4gsr said:


> If you have a scale marked in 1/8th gradulations like a Starrett 4R scale, hold it up to the thread and see if the marks align up with the thread.  If it does, it is a 8 pitch thread.  I'm with Wreck, who would design a lathe with a 9 pitch lead screw?


Do not confuse PITCH and LEAD, they are not the same thing.


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## 4GSR (Nov 27, 2016)

Wreck™Wreck said:


> Do not confuse PITCH and LEAD, they are not the same thing.


Agree, but we have the habit of using them interchangeably together.  Let's don't confuse people here over this right now.  Wait until someone starts a thread on multiple start threads.  I know you had one a while back on some stuff you did.  Let's not get off subject here.  If you want to resurrect the thread, that's fine but not here.  Ken


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## Wreck™Wreck (Nov 27, 2016)

I have been told to stop talking about completely machining related subjects, nice work.


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## francist (Nov 29, 2016)

Still looking for a definitive statement, but according to some chatter on one of the other popular discussion groups way back a few years, some of the older Seneca Falls "Star" lathes used a 9 TPI  lead screw. Had something to do with a 4/3 reduction gear setup in the headstock if remember correctly. 

If so, might be a worthwhile lead (ha ha) to track down and maybe get a positive ID on the machine.

-frank


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## higgite (Nov 29, 2016)

Deleted. I was wrong. Had a senior moment.

Tom


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## NortonDommi (Dec 6, 2016)

Hi,
       Give me a day and I'll post a link to LatheGears. Wonderful program I have been using for years.
Author has given permission to disseminate freely. Very easy to use. Values to enter are leadscrew pitch/TPI, available change gears and gearbox ratios if you have a gearbox. Does Imperial and/or metrickery.  Most useful computer program I have ever come across.
  I have found my lathe can turn threads not listed.


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## NortonDommi (Dec 7, 2016)

Well it didn't take a day but this is not latest version. I have had major crash and lost years of acumullated stuff but here is LatheGears.
  Please send the author a big thank you. This little program has pulled me out of the poo many, many times, I hope it helps.
  Barry.


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## Billh50 (Dec 7, 2016)

Not seeing any attachment.


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## NortonDommi (Dec 12, 2016)

Sorry, I'll try again.


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## NortonDommi (Dec 13, 2016)

Last try.

Zip file : LGV1.2.zip


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