Why?

Recently bought a set of dies with die stock. Something of a surprise when they arrived and I discovered the size and form. Not seen similar previously and don't understand why they should be made so. Range is 1/8th to 1/2. Any thoughts, please?

rgds

Bill

Are they for pipe threading ?

Phil

Lower one is obviously fixed size, effectively what is now called a die nut, and should produce a rightsize thread of correct form.

Not seen one exactly like the upper one before but I have seen similar carriers for opposed rectangular half thread dies with adjustment screws to set them to the correct size for the thread in question. Was told that these would be set up by appropriately skilled personnel and handed out to semi skilled workers who could not be expected to set an ordinary adjustable die correctly. Presumably field maintenance guys and the like.

Clive

Thank you for the replies - Phil, that sounds reasonable; what I find particularly odd is the extra size versus 'normal' dies stocks. Clive - the lower one is the obverse of the upper and each is similarly formed.

I suppose the real question is, what process would require this specialised form and the extra heft (twice as much) to produce the thread? Odd!

rgds

Bill

The top one looks like a pipe vice. I have one with the split dies.

.

Now I’m really bewildered, Bill

Are you saying that each die is ‘composite’ :

Solid on one face and adjustable on t'other ?

... That really would be unusual.

... Probably worthy of a patent.

MichaelG.

Nice one Derek. Classic single size, two piece die, pipe threading die stock with guide. Top one in Bills picture uses same style of dies in a normal type of diestock via an adapter block.

You can either use one adapter block with a set of two piece dies or, as I mentioned previously, have an adapter for each size pre-set to cut an accurate thread. I'd always understood that the adapters were primarily made so dies could be kept pre-set to size rather than simply to allow two piece dies to be used in an ordinary, round diestock.

The other common form of stock for two piece dies has a long rectangular cut out carrying a stack of double sided dies with a clamping screw. You slide the appropriate pair of dies apard and adjust to the correct spacing to cut a thread. I have two such sets. Generally more PIA than useful but very handy if the end threads on abolt, pipe or unobtanium shaft have beed damaged as the dies can be opened up far enough to pass over the damaged end then nipped down on the good threads to recut the bad ones without pitch offset error. One of mine has a taper edged disk to massage threads back into shape using this technique.

Clive

As pic

Hi Bill, the style has been around before I ever started working, often referred as American Pattern and made by various manufacturers and is the type I first used when I started working. A couple of scans below from a 1964 Buck & Hickman catalogue.

As you can see, many types of thread available. I have one die block and three sets of replaceable dies, but the block will only take the 5/16th ones.

MichaelG, I think Bill is taking about the die block itself, not the actual die's, as in his photo (view of the die side & view of the guide side.)

Regards Nick.

P.S. Bill, maybe these were made how they are so as not to infringe any copyrights, as they are adjustable as split die's are, just a guess on my part.

Edited By Nicholas Farr on 18/02/2020 16:20:48

loads'a of that type on French car boots......

Thank you to everyone for their replies

Michael - as you will have gathered, the 'double-sided' form is correct.

From the info given, I had a look through the 1974 edition of Serjeants' tool catalogue and they have a similar set labelled as 'American pattern'. I still wonder why the stock is so much heftier than an equivalent 'normal' stock and die set.

Thank you all again

rgds

Bill

.

I understand now, thanks

MichaelG.

Perhaps they were originally a larger standard and the hard steel part reduced in size as a war saving but needing to be compatible with existing die-stocks so a filler was made. Then it just kept going.