1/6" x 28tpi tap & die.

Perhaps someone knows a supplier for tap & die 1/6" x 28 tpi. I have tried to find one with no luck. Niko.

Do you mean 1/4" x 28 as that would be UNF?

No, I am looking for 1/6" x 28, if it exists.

I don't know of anything around that dia 0.167" with such a coarse pitch

An 8-30 gauge american screw is close on diameter at 0.164" but even the rare UNS special pitch is only 30tpi

I can;t think of any standard that uses 1/6"

What is it for? Could it be a pipe thread where the 1/6" refers to teh bore as 28tpi may be about right for that and also right for 1/16" if there is a typo

Edited By JasonB on 12/08/2017 21:04:53

It must be some kind of Swiss size from 1870. It is used much in musical boxes from that period. Many times the thread on the screw is gone and I have to thread cut new ones which takes too much time or use an oversize which is not ideal. Niko.

Niko,

This table includes the Thury threads:

http://pages.cs.wisc.edu/~bolo/workshop/thread.html

... but still nothing to match your spec.

It looks very much like a special.

MichaelG.

.

P.S. ... is it a full form thread ?

Just wondering if it could be a truncated form of the Thury #1

Thanks for the help, however it is a full form thread. Niko.

Swiss? 1870? I would not have thought they were using Imperial measurements a great deal - although sock machines and other similar inventions did tend to comply to the UK/US sizes. Or maybe the movements were Swiss and the container made somewhere else?

1870 pre-dates compulsory metrication, metric was optional from 1868 and compulsory from1877, so the thread could well have been specified in the old Swiss system. Almost certainly an in-house or local thread used by a single manufacturer or group of firms from the same area.

The old Swiss base unit for smaller measures was the pied (fuss) re-defined as 0.30 metres for the transition to metric but subject to local variations. Next down is the pouce at 1/12 th of a pied followed by the linie at 1/144 th of a pied or 1/12 th of a pouce.

Pied and pouce are essentially same as Imperial foot and inch so 1/6 inch diameter is likely to have been 2 linie in the old system. Which is sensible.

The 28 tip pitch doesn't appear to be related to the Thury system, which wasn't defined until 1877 or thereabouts. Thury devised the system as a standardisation of "useful" mathematically related threads close to those commonly used in the watchmaking industry. 28 tip is close to the pitch of a no 1 but the diameter is nearly mid-way between 2 and 3. Sounds too much of an outlier for one of the close to threads previously used.

Clive.

I wonder if Tracy Tools or The Tap and Die Company that advertise in the back of MEW would make special orders such as these?

You could make a tap and die to suit from silver steel. The picture shows a home made tap.

To make it I turned a length of silver steel (aka drill rod) down to the required diameter and lathe cut a thread in the usual way. Then I milled the relieving slots and squared the driving end. After the usual heat treatment the tap works surprisingly well considering how crude it is.

Once you've got a hardened tap it wouldn't be difficult to make a silver steel die with it.

Obviously home-made won't last as well as the real thing but they do work. If you mend lots of music boxes it would be worth making a batch.

Dave

Niko

Are those the screws that hold the comb onto the bedplate that you are trying to replace ?

I too have had trouble finding an exact match and have resorted to making slightly larger ones. I have looked for these sizes for around twenty years with no luck.

I wondered if you make your own gears for the governors as well ? I have also been looking for 0.32 & 0.38 Module gear cutters with no luck either.

Phil

P.S. If you run short of musical boxes to restore, I know where there are plenty of them !! (In my loft)

Yes Phil, those are the comb screws, you would like to keep it as original as possible but they can have had a hard live giving you no other option then to make slightly larger sized ones. The 0.32 & 0.38 mm module is another of those problems, you can try this one **LINK** . I use a 19th century rounding-up machine and cutters to make it mesh the other gear in the governor. It goes a little over 0.40 mm modern module but the Swiss must also have had rounding-up machines for large size wheels, but sofar never found one. I think your loft will look similar to mine. Niko.

Edited By speelwerk on 13/08/2017 11:26:01

Edited By speelwerk on 13/08/2017 11:27:22

I/16" x 28 TPI would be neared to the pitch of a wood screw.
Wood screw sizes. #0 !/16 x 32 TPI.   #1  5/64"  x  28 TPI.   #2  3/32"  x  26 TPI.

Ian S C

Edited By Ian S C on 13/08/2017 13:06:53

Have you tried Wiseman Threading Tools, **LINK**

They offer a "specials" service.

The tap was possibly made in their workshop and then a screw plate made from it and not to difficult to harden if gauge plate or an old file annealed drilled and tapped and rehardened.

Frank

Why not a 1.5M same meat, different gravy, but easier to source..

.

I think because the required diameter is 1/6" ... which is about 4.23mm

MichaelG.

Hi. Michael. 1.5mm divided by 25.4 = 0.059'' If you want to argue over 0.003'' on a screw thread be my guest, but for practical engineers its a practical answer.

.

Mick,

I don't want to argue with anyone about anything.

... but I simply don't understand your suggestion.

The screws on Niko's box are one sixth of an inch diameter.

MichaelG.