Odd Thread Size

Hi

I was Given an old record vice last year and have just got around to looking at it. After drilling out the sloted countersunk screws that hold the jaws on, I am having trouble identifying the thread. They could be a metric M8 x 1 fine thread or a 5/16 26tpi. The only other bolt on it is a 5/16 BSW.

I have tried looking up 5/16 26tpi but this seems to refer to a bicycle thread. Anyone know what size these screw are suppose to be?

If it's an old record it will be BSW 5/16" bsw is 18tpi. 26tpi can be cycle or brass, whit form and ANY dia ! 1/4"BSF is also 26tpi. Good luck. Noel.

Just to add this bolt is 7.7mm dia and with my pitch gauge is ithere 26 tpi or 1 mm.

I think i will thread a piece of bar M8 X 1 and see if it fits.

I would plump for the 5/16 x 26. When I bought the present house, there was a poor looking old vise in the garage. It turned out to be a 5" Record steel bodied model. The jaws were scrap and I had great difficulty getting the screws undone and the threads were 5/16 26 BSC. I made some new jaws and got a couple of suitable screws on ebay, cleaned up the leadscrew and the jaws are parallel to within 0.002". That makes up for my mistake in leaving my 4 1/2" Paramo behind when I sold my bungalow.

It would seem that Record used 5/16" BSC on some vices, as The Viceworks makes them specially , but make sure you pick the correct countersink angle.
https://www.viceworks.co.uk/products/vice-jaw-screws-and-bolts?variant=44213941076134

Bill

Edited By peak4 on 25/06/2023 20:00:17

What do you mean by "old"? I could imagine a true Briton chewing on broken glass before using a metric thread to this very day Or have you guys conceded that fight yet? It's a very nice system once you get to know it.

Besides nobody uses anything other than metric coarse (M8x1,25) unless they really have to.

Thank you everyone

The vice is an old record 34 steel and I did wonder about the countersinks as the holes looked a bit odd, been 60 Deg makes a lot more sense

According to the website, the 60° angle was used on 34/35/36 vices.

Bill

I have recently done up an old Record vice. The thread is 60 deg 5/16x26 TPI. I found Tap that suited , and cleaned up the damaged threads with that tap. It was available here in NZ. it was called a Bicycle 5/16-26 tpi, different to the Brass being 55 deg pitch angle.

I made the screws from long M8 capscrews. Cut the M8 thread off, trued the head diameters to the shank. Put in a small centre, and then held onto them from the head and a steady, and screw cut with a 26 tpi partial form 60 deg threading insert, until the diameter of the thread outer diameter was 8.87mm diameter.

I couterbored the existing jaws, so the normal caphead screws would fit. I plan on makeing other jaw sets for this vice, so using a ball end hex key makes them easy to install..

Neil

Chris , Maybe worth having a word with Wilkes Engineering and Machinery, also know as The Vice Works . They manufacture replacement jaws for a number of British vices , so perhaps could supply you with the correct screws. Trevor .