Re-tapping a Whitworth Thread
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- This topic has 5 replies, 3 voices, and was last updated 6 years ago by Dave Ring.
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7 May 2018 at 5:51 pm #541027
Hi.
Does anybody know if it would be possible to re-tap a 3/16″ 24TPI thread to metric?
I have a rebate plane and a plough plane that need some adjustment screws (thumbscrews) and I just can’t find what I need. However, I can get what I want straight away in Metric for a couple of pounds.
Thanks guys
Paul7 May 2018 at 7:12 pm #541047Before you do that, check to make sure it’s not #10-24 you need.
3/16 is .1875” and #10 is .19”, so very close. With a loose fit thread, they are easy to confuse.
10-24 is still a universal size for electronic racks and such( and lamp parts in the USA.)Looking on eBay.uk and searching “10-24 thumbscrew” there are several offerings for that size. Even if you bought in quantity, it might be cheaper than buying the tap and drill.
But if you want to go metric, 3/16” converts to 4.7625 mm so to get fresh threads you need to drill larger than that.
Looking at the tap charts, an M6 x 1 tap requires a 5mm drill.
That would give you clean threads in metric
- This reply was modified 6 years ago by Larry Geib.
- This reply was modified 6 years ago by Larry Geib.
- This reply was modified 6 years ago by Larry Geib.
8 May 2018 at 8:36 pm #541474Paul hasn’t actually told us what plane he has or even that it is a Stanley.
For all we know these are antique wooden planes.
But on the off chance it is a known metallic brand, here is a good link for sizing.
There are also two link for PDFs on Stanley thread sizes on that page.
8 May 2018 at 9:28 pm #541506Hi, thanks for the info so far, really appreciate it.
The planes in question are a Record 044C plough and a Record 778 rebate.
I’m no expert on this stuff but I was told on a forum that the screws were 3/16” 24 TPI.
On both planes, it is the fence/ rod adjustment screws I’m after.
Thanks again.
Paul -
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