I need to clean the timing gear end thread up inside a crank. Does anyone up this end of the woods have a 5/8 whitworth form by 16 teeth/inch tap I could borrow or come and use. I have tried all avenues to obtain one but they appear to be like hens teeth.

Regards(in desperation) Ian,Worksop notts.

Location: At Work.

Good morning. Suitable taps are listed by Uni-Thread, Totnes.
Regards from the creative county
Stuart

Location: Staffordshire

Thanks for the lead Stuart. Just tried them and they tell the same tale as every othere company I've contacted. They have to have them made in batches and because the demand for a particular oddball size isn't there they won't do it. I could have one made special but the cost is prohibitive. (Around £150 )
Regards Ian.

Location: At Work.

Ian ,you might try this , I have done it,and it works. .Get and old starter dog ,and with a thin cutting wheel cut 2 longdatudinal slots up the threads. you can then use it as a thread cutter/cleaner,if you screw it in slowly.

Location: u.k. sunny sussex

If its to clean the thread only?

Find an old starter dog and put either a 1mm angle grinder disk down it, or with a haxsaw.

That should clean the thread for you. Unless it is terribly burred.

Ian,

Have you tried 'Tracy Tools Ltd' in Torquay - Tel: 01803 328603 E-Mail: info@tracytools.com

The size you want is listed in their 'Specials Catalogue'. I received new catalogues from them at the end of last year.

Jeff.

Location: Almost but not quite the far North East of England

Jeff thanks for the reply but sadly yes I have tried them. I'd like to bet I've probably tried them all and got the same answer.

Mac and Hedd, I'll give your suggestion a go nothing to lose I suppose. Cheers.

Regards Ian.

Location: At Work.

remember to use lub!

Result chaps. Chris Garner has very kindly offered to lend me his tap and is sending it in the post ASAP. How good is that
I'm really greatfull to Chris and all who have proffered help.
How good is this forum!!!!

Regards Ian.

Location: At Work.

Great news. If you hadn't had success, I was going to suggest you approach someone with a vintage tractor or traction engine. The latter will almost certainly encounter such a size amongst their smaller threads!

Posted as a suggestion to others in similar desperate need.

Location: North Cornwall heading for BA7C rally tomorrow in RP

5/8 BSW is 11TPI. 5/8 BSF is 14TPI.

5/8 16TPI is a B@stard size.

It's not quite accurate to ascribe 5/8" x 16 tpi to being a b@stard size.
What I cannot ascertain is whether the thread is a 55 degree Whitworth form or a 60 degree UNS ( American Unified Special form ). If the thread is UNS then these are specified by their tpi, a 5/8" size therefore could have several different tpis
The tap I have supplied to Ian is not marked so could be either. I ran it down a crank end and it only appeared to pick up dirt, not to cut metal.
Why Austin's chose to use this size and type is open to conjecture but interesting the A series engine crank has the same size and tpi. Was this coincidence or a carry over by an BMC designer? Again whether the form is Whit or UNS I am unable to determine. I expect the current manufacturers of both Seven and A series cranks could advise.

Location: Melton Mowbray

Chris

You should be able to measure the thread angle on your tap. Or at least confirm if it is 'whit' threadform or not. Frankly I think it is unlikely that it is anything else.

I've found oddball sizes and pitch are quite common on all vintage tack. My Fowler steam roller for example mostly has 14TPI fasteners irrespective of diameter. In that case whit form.

In the steam world there have been many theories banded about. I suspect the answer lies with production, and simply to make the cranks with the minimum of 'new' tooling (and thus at minimum expense), the production guys at Longbridge chose that pitch.

I have always believed that these threads were the outcome of a load of excess tooling left over after the end of The Great War when Austins had done much work for the Admiralty.I was told this by a certain Stanley Edge who said he had been involved.

Location: Wessex

I think we have discussed this before- the Admiralty thread standard is listed somewhere.

It is highly unlikely Austins would have used the American UTS system - and I think the UNC standard wasn't adopted until post war.

The Seven has a few of these non Whitworth TPI threads.

Tony.

Location: Malvern, Melbourne, Australia

This doesn't really help but I've just had a sort through my taps and dies because I thought I had a tap but I haven't, what I have got is a die made by Dormer and is marked 5/8" 16 WF H.S.S. WF stands for Whitworth Fine or Whitworth Form.

Location: Near M1 Jtn 28

Hi Brian, just doing a search for a 5/8" 16 TPI die and have found your wonderful site.

I have been asked by a good friend, if I can make a manifold blanking plug for his Mk2 Mini Cooper, that he is restoring. He has given the size above and I have found it to be a very odd-ball size!

I know you don't know me from Adam but I was wondering if it is at all possible to borrow your die to make the plug for him?

Obviously, I am happy to pay all costs and a deposit for the die.


Thanks for talking the time to read this.
Kind Regards,
Andy

Location: Kent

Drill Services of Horley supplied both a tap and die for me.
They will make any size or pitch that you want.
A fantastic company to deal with.

Location: Deepest darkest Kent.

Hello Andy, just read your plea in A7 Friends and I've managed to find the die.
It is a Dormer one marked 5/8" 16 WF HSS. It looks like a split die but it is not split as it came from a clear out at Dormers many years ago. If you give me your address, I'll get it in the post to you.
When you have finished with it just post it back and make a small donation to the RNLI, if that is OK.

Location: Near M1 Jtn 28

I am surprised that in all this series of posts no one has mentioned the alternative of screwcutting in a lathe.

Obviously not an option with a component in place, and a tedious business for amateur operators, but those who undertake lathework regularly can sort very quickly, although the crank does require a lathe of reasonable size.

Components made of carbon steel will respond to some extent to hardening. So if a disposable item available the method of cutting slots followed by hardening may produce a workable die or tap, although somewhat over/undersize.

I have always found with die nuts and solid dies that it is difficult to start on a damaged thread exactly "in phase". Split dies are superior.

Bob Culver

Location: Auckland