Unknown thread

I need to duplicate a screw from an old (circa 1910) British machine, but I can't identify the thread from my references. Does anybody recognise it? 36
TPI with a diameter across the thread of 0.135".
Cliff Coggin.
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Most likely , what we on the left side of the pond, would call a 6-36. Very uncommon even here.
Chuck P.
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wrote:

Thanks for that Chuck. Just how uncommon a size is it? If it isn't too much trouble would you be able to easily get hold of such a screw for me? I need a piece about 3/8" long to which I can attach the necessary large head.
Cliff.
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I will check my stock to see what I have and get back to you.
Chuck P.
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In article

Sorry, I have none in stock and have no idea where to find any.
Chuck P.
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wrote:

Thanks for looking.
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Cliff Coggin wrote:

Cliff, Is it feasible to drill out and retap the hole larger and with a standard thread? Or does this contravene any restoration rules you are following perhaps.
Bob
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wrote:

Bob. I wouldn't want in principle to change the hole and thread because I am restoring this machine to near original condition. (It is a time recorder or clocking in machine which is costing a lot of money to have the nickel plating on many of the parts replaced for example.) In practice I doubt it is possible because the screw goes into the end of a thin-walled tube so there is very little metal to spare.
Cliff.
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Cliff Coggin wrote:

Ah! a possible clock thread? Often these have metric roots. Maybe your thread is 3.5mm x 0.7mm pitch??
Lowenherz is 3.5 x 0.6 or 4.0 x .7 ( 53.8 degree thread angle)so it is not that series although both these combinations have found there way into the iso metric coarse series but 60 degrees of course.
M3.5 X 0.6 is the standard for electrical fittings - light switch boxes etc
However it seems that metric thread users are more likely to mix diameter and pitches according to application than imperial thread users so you might have a special chosen to be compatible with standard tubing. It is just possible that Tracy tools might just have a die - might be worth a call 01803 328603.
Good Luck
Bob
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wrote:

I had checked for metric threads and found that 3.5 x 0.7 mm is close but not a prefect match, so if push comes to shove I can force such a screw in. However I have had an offer to turn a 6/36 screw so I'll go with that initially.
The age and British origin of this machine was always going to make metric threads unlikely, though you are right that clocks often use an odd mix of threads, some of them even being non-standard. All the other threads on this time recorder were BSF, and I count myself lucky that when I sheared a stud, because I hadn't realised it had a left hand thread, I was able to buy a L/H 3/16" BSF die from Tracy Tools and make a new stud.
Cliff.
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wrote:

Is a 6x32 any use? I have a few.
Archie
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wrote:>>>>>>>>>>> 36

Thanks but it does need to be 36 TPI.
Cliff.
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Get an 8 x 36 standard from Tracy tools 3.00 for a die. Open the split out with a slitting disk and tighten it up, if it cracks it will still do a one or two off.
If that don't suit then learn to screwcut, which is probably quicker than waiting 8 days for replies.
John S.
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wrote:

Get an 8 x 36 standard from Tracy tools 3.00 for a die. Open the split out with a slitting disk and tighten it up, if it cracks it will still do a one or two off.
If that don't suit then learn to screwcut, which is probably quicker than waiting 8 days for replies.
John S. --------------------------------------------------------------- Thanks for the idea. I shall do that, though longer term I do intend to learn screw cutting if I can find all the change wheels that came with my ML7.
Cliff.
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On Wed, 17 Jun 2009 14:16:27 +0100, "Cliff Coggin"

For 36 TPi on the ML7 you will need 33/45/20/55/60 tooth gears. Screwcutting isn't all that hard really, and once you've done it you'll wonder what all the fuss was about.
Peter
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Cliff, here is a link to a list of tables.Most of them handy.No313 is the thread data although I`ve not looked to see if yours is there. http://mdmetric.com/home3.htm Mark
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On Sun, 14 Jun 2009 16:29:58 +0100, "Cliff Coggin"

As Chuck indicates, the _only_ threads I can find with 36tpi in the lists I've got are the ASME threads. Might be a case of making rather than buying... 6-36 would be 0.138" OD
Mark Rand RTFM
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wrote:

Thanks all. I really didn't want to learn screwcutting for the sake of one screw, but needs must etc.
Cliff.
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you'll never regret it .. it's like riding a bike once set in your mind ..
forget trying to learn it off the web ..
somehow people on the web ..or books, make it look a lot more complicated than it actually is .
Have an experienced guy come round and show you ..it's the best way . Don't start off with your compound slide set to 29.5 degrees ..this will only confuse you further ..at a time when you don't need this on your mind .work up to that .and also work up to tool design ..
couple of hours and you've grasped it ..honest.
all the best.markj
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Cliff Coggin wrote:

It's not that close, but would a 4BA do the job?
--
Charles Lamont

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