# Thread Cutting Change Gears



## Nigel Taylor (14 Dec 2021)

Just made an online calculator for the simple 4 change gears and leadscrew pitch calculation for cutting threads







Hopefully this is useful to a few people. Let me know if you would rather it was an excel workbook.


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## Inspector (14 Dec 2021)

Thank you. I bookmarked it in my calculator folder. 

Pete


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## AES (14 Dec 2021)

Excellent, thanks for doing this Nigel, v helpful for many. I have no preferences re excel or online, and haven't bookmarked it because I already have one that was published in "MEW" some years back. That one "fits" my lathe (a Chinese Mini) exactly. But as said, thanks


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## Nigel Taylor (15 Dec 2021)

I have updated the excel calculations with a much more enhanced version whereby you can enter thread pitch you want to cut, leadscrew pitch and then 3 gear options for each of the positions. This then looks at all combinations and highlights the closest match in green. This also finds options for TPI threads with a metric leadscrew and vice versa.


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## Inspector (15 Dec 2021)

The dolt in me can't find the spreadsheet. Any possibility you can link it?
Thanks
Pete


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## Nigel Taylor (15 Dec 2021)

Inspector said:


> The dolt in me can't find the spreadsheet. Any possibility you can link it?
> Thanks
> Pete



Hi Pete,

link to workshop calculations (<- here)

Click "Free - Purchase" button and once you have filled in your name and email you then get a "Confirmation Page" and a link to the excel sheet.






Being an excel sheet it's not easy just to link to it and this way it gets scanned for malicious content.

Thanks, Nigel


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## Inspector (15 Dec 2021)

Sorry Nigel. When I filled the email etc, I got the confirmation email but it loops me back to the page and wants the email again. Nowhere that I can see to download. I am using Safari if that has anything to do with it.

Pete


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## woodfarmer (16 Dec 2021)

I have been playing around with my old imperial Holbrook.... and what you have printed confirms what I have found.

If you make Layshaft gear 1 the same as the spindle gear and layshaft gear 2 fifty (or a 100) and the leadscrew gear 127 you will have a fair range of metric threads off the gearbox. the layshaft gear has to be multiple of 50 and acts as a multiplyer. On the holbrook there is an additional transfer gear between the second layshaft and the leadscrew. It does not matter how many teeth as it is just used to fill the gap between them.


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