A cheeky/optimistic request – 7/8 20 tpi die?

This topic has 19 replies, 8 voices, and was last updated 14 September 2017 at 10:12 by Symon.

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13 September 2017 at 15:36 #316833
Symon
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@symon78657
This is a bit cheeky considering none of you know me yet…but…I need a 7/8" 20tpi die (BSB?) to repair the thread on a shaft of my mill restoration. Tracy Tools have the taps and dies but I can't really afford to buy them for just one quick job.

Would any of you guys have one I could borrow? Obviously I'd cover the postage costs (both ways) and love you forever

Sorry about the sheer nerve…but I'm a wee bit desperate.
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13 September 2017 at 15:36 #25496
Symon
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@symon78657
13 September 2017 at 16:25 #316843
Chris Evans 6
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@chrisevans6
I will look in my workshop tomorrow, I do have a selection of odd ball stuff. Will PM if I find one.
13 September 2017 at 16:28 #316844
Symon
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@symon78657
That's greatly appreciated, Chris
13 September 2017 at 16:39 #316847
not done it yet
Participant
@notdoneityet
Do you really need a die or would a thread chaser be sufficient? A location might help, too. There might be someone local.
13 September 2017 at 16:45 #316848
John Rudd
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@johnrudd16576
Posted by not done it yet on 13/09/2017 16:39:15:

Do you really need a die or would a thread chaser be sufficient? A location might help, too. There might be someone local.

His intro thread gives his location as Newcastle/Durham……oop north then….
13 September 2017 at 16:47 #316849
Symon
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@symon78657
Ordinarily a thread chaser would probably do. But there's a part on the thread where an old pin is and that's stuck tight. So it'll need cut through. Also it's on the machine already which means no more bashing to get the pin out.

I'm in the North East between Durham and Newcastle.
13 September 2017 at 17:04 #316851
Symon
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@symon78657
OP should be read BSC (British Standard Cycle).
13 September 2017 at 18:33 #316866
David Standing 1
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@davidstanding1
Posted by Symon on 13/09/2017 17:04:23:

OP should be read BSC (British Standard Cycle).

Are you sure? I work on old cycles with BSC threads a lot, and 7/8" should be 24 tpi.

7/8 x 20 is however a UNEF size.

Edited By David Standing 1 on 13/09/2017 18:36:47
13 September 2017 at 18:46 #316867
Clive Brown 1
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@clivebrown1
Tracey Tools refer to 7/8" x 20 as cycle thread, presumably where the OP is coming from.

if the pin area is the only problem, I wonder whether a small triangular file could be used to dress out the remains of the pin. The thread angle seems likely to be 60 deg.
13 September 2017 at 18:55 #316870
Symon
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@symon78657
Yeh, TT calls it BSC: **LINK**

The threads measure 20tpi on my cheapo gauge, which I don't really trust…but it is.

The threads are just rounded a bit, not crossed, and I'll likely flatten the pin area to accept a grub screw instead of the original pin.
13 September 2017 at 19:00 #316872
Symon
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@symon78657
Would it not be weird to have a unf/unef thread on a late 50s UK machine which uses Whitworth for the most part?
13 September 2017 at 19:02 #316874
David Standing 1
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@davidstanding1
Posted by Clive Brown 1 on 13/09/2017 18:46:37:

Tracey Tools refer to 7/8" x 20 as cycle thread, presumably where the OP is coming from.

if the pin area is the only problem, I wonder whether a small triangular file could be used to dress out the remains of the pin. The thread angle seems likely to be 60 deg.

Yes, that's odd – Tracy Tools show two BSC pitches, 20 tpi and 26 tpi. All the cycles I have worked on are 26 tpi, 20 tpi is a new one on me!
13 September 2017 at 19:03 #316875
David Standing 1
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@davidstanding1
Posted by Symon on 13/09/2017 19:00:06:

Would it not be weird to have a unf/unef thread on a late 50s UK machine which uses Whitworth for the most part?

If it is a British machine, yes!
13 September 2017 at 19:26 #316881
Symon
Participant
@symon78657
Exactly. This thing has some weird threads, though. The pipework uses 26 tpi BSC which I had a friend tap an oil part as like now…I really didn't want to buy a use once part . BSP was well in use at the time of manufacture, and it even uses BSP in places! Ha!
13 September 2017 at 19:27 #316882
John Stevenson 1
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@johnstevenson1
Posted by David Standing 1 on 13/09/2017 19:03:26:

Posted by Symon on 13/09/2017 19:00:06:

Would it not be weird to have a unf/unef thread on a late 50s UK machine which uses Whitworth for the most part?

If it is a British machine, yes!

.

Once you get above a certain size you get an alternative of 20 from the normal 26. Pedal threads have always been 9/16" x 20 RH and LH

Chances are that I do have one, I have a full set up to 1" in RH and LH threads but I can't check as I'm off work for a while.

Can you use a thread file or at worst a small triangular file
13 September 2017 at 19:27 #316883
Symon
Participant
@symon78657
Still, it's looking beautiful, so can't be mad with it.
13 September 2017 at 19:29 #316884
Symon
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@symon78657
No thread file atm. But I could always borrow one. Would rather clean it up with a die.
14 September 2017 at 09:40 #316947
JohnF
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@johnf59703
Symon see your messages
14 September 2017 at 10:12 #316951
Symon
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@symon78657
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