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Boxford change gears for screwcutting.

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Terryd24/04/2020 12:15:53
1936 forum posts
179 photos

Hi all,

It's several years since i posted here but I'm now active again after retirement and isolating due to CV19.

Some years ago I downloaded a small program, suppose it would now be called and 'app', which calculated gear trains for changewheels on lathes. You input leadscrew pitch and your list of changewheels and it would calculate sevearal alternative possible trains.

It's most useful feature is that it could calculate very close approximations to cut imperial threads on a metric lathe without a leadscew gearbox and visa versa, without using expensive conversion gears. I accessed it from Tony's website and the link is still there but the original download site is no longer. I have searched and the 'app' appears to have disappeared altogether.

It was called NthreadP, and was a free download. My copy was lost in a hard drive failure some time ago and I'm hoping to find someone perhaps who has a copy of this very useful program. I would like to make it available again via my blog so I would be extremely grateful if somone could send a copy, perhaps via Dropbox or similar.

Best regards and keep safe,


David Davies 824/04/2020 12:39:30
147 forum posts
9 photos

Hello Terry

Harold Hall has a page on his website which may help you, it gives all the possible changewheel selections for a given pitch based on a 5t step in wheel teeth. This may have been derived from NthreadP but only Harold could answer that.



Ronald Morrison24/04/2020 12:45:42
70 forum posts
4 photos

I've used this website to calculate different gear combinations to make specific threads.

Threading calculator

Terryd24/04/2020 15:23:34
1936 forum posts
179 photos

Hi Dave and Ronald,

those are useful resources wghich I have addad to favourites, however I particularly want a copy of NthreadP because it had the facility to input the gears owned and the leadscrew pitch/tpi and made hth calculations based on one's won situation. I note that Howard's list ins particularly for the Myford lathe and needs more calculation if one has a different lathe and leadscrew - mine is a metric Boxford. NthreadP allows one to enter and save all pertinant information and add further information such as newly aquired gear wheels. It really is a brilliant little program, I hoe that it's not lost.

Thanks for your help,


William Chitham24/04/2020 15:40:50
125 forum posts
52 photos

Hi Terry, as a fellow metric Boxford user I absolutely agree with you, it is an excellent little program. I do have a copy, I have sent you a message with a link, contact me if it doesn't work

Best, William.

Peter Hall24/04/2020 16:00:24
114 forum posts
1 photos

NthreadsP is still available on the lathes uk website.

For anyone who doesn't know, it's an absolute Godsend. Saved me the cost of a metric changewheel set.



Edited By Peter Hall on 24/04/2020 16:00:51

Andrew Johnston24/04/2020 18:46:52
6266 forum posts
677 photos
Posted by Terryd on 24/04/2020 12:15:53:

It's several years since i posted here but I'm now active again.......

Blimey, that's a blast from the past. Welcome back and great to see you.


Terryd24/04/2020 19:14:43
1936 forum posts
179 photos

Hi Peter,

Thanks for that, I can't get there with Firefox but I tried the link in Microsoft edge and I can confirm that it is still downloadable and anyone with a small lathe, Myford, Boxford, Harrison etc should have a copy if they are to do any screwcutting.


Roderick Jenkins24/04/2020 20:33:32
2123 forum posts
582 photos

Hi Terry,

Glad you got it sorted. Good to see you back - it's been a while...

Stay well,


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