Tap And Dies

[Vich]

Here is a little query that is probably painfully obvious to those in the know but puzzles a tinkerer like me.

 

Got myself a little Anchor Tap and Dies set and although I have used the taps for re threading holes I have not had cause to put a thread on a bit of wire or create a screw if you like.  Can anyone educate me in simple terms on the use of the plate and in particular what the arrowed doubled holes are for.

 

 

 

Are they the actual cutting holes and the single hole opposite the one to check the thread in, I can't see how the double hole is utilised.

 

Cheers,

 

Vic

[Geo]

Are they the actual cutting holes and the single hole opposite the one to check the thread in, I can't see how the double hole is utilised.

Cheers,

Vic

You're absolutely correct Vic, the split forms the cutting edge.

[Vich]

Thanks George,

I can now sleep at night, [emoji6]

Cheers,

Vic

[teegee]

Is this one of those Indian made sets? Are those any good? I've used cheaply made (Indian or Chinese) three-flute small taps before, and they were horrible.

The Indian ones I've seen for sale are too cheap to be decent, I suspect..

[Geo]

They are better than nothing, but not by much, I know because I have a set.

[Vich]

I agree with George,

 

I think mine just cost in the region of £14.95, Red rooster sell the same set boxed up for a bit more (£18.95). 

 

I got them as I needed one size to do one job and that was only resizing a stripped out hole on.  It worked ok but I was extremely careful and they now reside in the back of my tool box awaiting the next emergency. 

 

As I just tinker I am not likely to use them often, if you are expecting to be using them often, I would probably buy a better set - those do however come at a premium but like everything else you have to balance things out - you can buy a decent Omega for the same price as a Bergeon set !.

 

Cheers,

 

Vic

[seang]

Hi Vich,

 

the other thing the hole is useful for is inserting the blade of a jewellers saw through when you shear of the wire you are trying to thread :-)

 

The most successful technique I've found is to hold the wire in a collet in the watchmakers lathe (put a good chamfer on the end), hold the die plate at 90 degrees to the wire using a tailstock tube to support it.

 

Lubricate the wire with a light oil or cutting fluid

 

turn the headstock by hand whilst putting pressure on the tailstock and die plate,

 

only turn the headstock spindle a quarter turn, back off a half turn, repeat

 

Once you have cut about two whole turns, back the die plate off the wire altogether, clean out the die

 

thread back on and carry on cutting.

 

 

I started out with brass wire (trying to make a banking pin for a cheap pocket watch) and snapped the wire off in the die more times than I care to admit, with these cheap die plates it trial and error and practice, practise, practise. The main problems I found with the finished result were the thread form was poor and as the die plate has a chamfered lead-in on both sides and so forming a thread up to a shoulder is not possible. I expected the plate to have a chamfer on one side and be flat on the other side, but all the ones I have (you end up buying another whole set when you snap the tap off trying to clean out the die) are chamfered both sides :-)

 

good luck

 

Sean

[Geo]

That's a good tip about the saw blade Sean, but it's never a good idea to run a tap through any die.

[seang]

I know GEO, I know :) but it was the only way I had at the time to get the mangled bits of brass out of the plate. After much practise I learned to saw through the wire 3/4s of the way, then use a screwdriver to unscrew the sheared wire.

[anilv]

Hi Seang,

can you remove some metal off one side to remove the chamferred cutting portion?

Anil

[Geo]

can you remove some metal off one side to remove the chamferred cutting portion?

Anil

It should be possible, but you would require access to a surface grinder to do it accurately.

[seang]

Good thinking Anil & Geo, much quicker than my idea of making my own taps and dies :-)

 

I wonder if a small end mill would give a good enough surface on the plate?

[Geo]

I wonder if a small end mill would give a good enough surface on the plate?

The plate will be too hard to cut with an endmill unless you draw the temper out and re-temper the plate afterwards. I really think the only practical option is to have it surface ground. Another good thing about surface grinding, the plate will be held perfectly flat on a magnetic chuck. You will have to de-magnetise the die plate afterwards.

[seang]

I didn't think of that, Geo! You've saved me a blunt end mill. Thanks for the advice