They are very good as you can adjust the dies over quite a range. To cut a standard size thread, set them slightly oversize on a standard bolt then cut the thread and try a nut on it, if it is too tight, make an adjustment and take a second cut.

The actual cutters are called Coventry Die Heads and come in matched and numbered pairs, make sure they are both of a pair and the right way up.

I have a very big one of these and just two mismatched die heads – ho hum (but it only cost me 560p at a boot sale).

Neil

Coventry die heads shown here :- **LINK**

(In the middle of the page)

Norman

Edited By NJH on 14/05/2017 22:09:03

And if you have a bolt with a damaged thread at the beginning you can slide the dies past it and work backwards.

John

Must be challenging to manufacture – made in one piece as a pair then separated perhaps?

At last count I had eight Coventry dieheads of assorted sizes. I use the smaller ones mainly on the repetition lathe. Rather than clutter up this thread I'll post a picture of a less common diehead to see who knows what it is for.

What puzzles me about the original tap & die set is that the diestocks, dies and box seem nicely made. But the taps seem to be black? Which indicates to me cheap carbon steel.

It would be useful to know what thread sizes are covered.

Andrew

Tom Senior 1939 catalogue calls them "Angle Pattern Stocks & Dies" but this name doesn't really address their two part construction.

They are shown alongside the more usual "Moorite" split circular dies.

It seems to me that the two part construction if well done would be superior in use to the split circular.

Edited By ega on 15/05/2017 11:22:36