Anyone have a 7/16 x 18 Whitworth tap I could borrow?

Question

I need to make a special toolpost clamp bolt for my Myford (I'm adapting a Chinese quick-change toolpost to fit). It's either find the right tap, or spend a very long time grinding a special Whitworth (55 degree included angle) deep internal single point tool. Yeah, I know that I can probably use a 60 degree tool and make it work, but I have no 60 degree tool that small, so would have to grind something out of solid anyway.

If someone has the right tap, I would like to borrow it to tap this one hole. If you're in the UK, I'll happen to be in Cardiff this weekend, London Monday, Cambridge Tuesday, and Ascot Wednesday morning. I could borrow it when I'm over there, and mail it back as soon as I get back to the US and can use it. I would really appreciate some help. Thanks.

Andy Dingley · Accepted Answer

7/16 x 18 is BSF, not BSW   Whit is 14 pitch.I've a couple of Whitworth plug taps here and it wouldn't matter if onemet a grinder and ended up tapered.  Still trying to find some BSFthough.

Bob Chilcoat · Answer

You're right, Andy.  It's BSF, not BSW.  The chart I was looking at had two charts on the page for Whitworth threads, and 7/16 x 18 was on the lower (BSF) chart.  Nevertheless, BSF is still a Whitworth thread form.  I'm still looking for a tap to borrow :-)

Christopher Tidy · Answer

Get it from the Tap & Die Co. while you're in England

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It's £6.00 plus tax and delivery. They dispatch fast, so you could probably have it sent to your hotel, or maybe you could pick it up from them in London.

Chris

Anyone have a 7/16 x 18 Whitworth tap I could borrow?

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