Ahhhhh!!!! Trying to cut thread with die

[NobbyParticipant @nobby]

Hi Again
Here is the handle i use when threading and screwcutting to a shoulder ? Note on leaving go it pops out similar to the ones on milling machines.
Nobby

[Robert DoddsParticipant @robertdodds43397]

Mike,

Can't disagree with any of the foregoing comments re cheap tools but at the risk of asking the obvious, Have you tried turning the die round to the other side?
I have found that many dies have more "chamfer" on the cutting edge on one side than on the other so one way is easier to start cutting but likewise the less chamfered side will get you closer to a shoulder when needed
Its a bit like second cut and plug taps.

Bob D

[Gone AwayParticipant @goneaway]

While the comments on split-dies and splitting solid dies may represent a preference, I don't think that is the answer per-se to the OP's problem. I commonly use solid dies for threads up to larger sizes than 8 mm with no problem at all even on relatively tough material. I feel sure it's not the type of dies that's causing the problem, probably – as others have stated – die quality.

I chamfer the work and do apply support and pressure via the tailstock .A fair pressure is required for starting the thread (but no more than is often used in drilling). I sometimes reduce the work dia a little from nominal but only for "difficult" or very soft materials. Depending on material and size, I can often run the 3-ph controller down to zero, apply pressure with the tailstock and crank up the speed until the work rotates and the die starts to cut.

I was brought up in the UK on split dies and was somewhat perturbed to find them a bit scarce when I moved to Canada. These days, either type are readily available but I've got used to solid dies and actually prefer them except if I'm concerned with thread fit or for unusual conditions. I also prefer split dies if I'm hand threading in the vice. If using split dies make sure the die-holder is a good fit – it's quite easy to break the die if the holder is a bit oversize …. been there, done that.

[I was also brought up in the UK on hand chasing lathe-cut threads. hand chasers are unobtainable here these days (if they ever were)].

Most of the dies here have a decent lead-in chamfer on one side and virtually none on the other side for threading up to a shoulder.(on a second pass of course)

Edited By Sid Herbage on 05/08/2013 01:36:09

[HopperParticipant @hopper]

Sometimes if you put a small hacksaw cut on the chamfered end of the rod, it helps the die teeth get that first bite.

[Michael Edwards 1Participant @michaeledwards1]

Well finished my tail stock die holder. My father in law came to the rescue. He brought down a cheap set of 'Workzone' taps and dies. I think they are Aldi's make. They worked a treat.

Not only that but he got me these two items from a car boot sale

moore and wright 2-6 micrometer

and a Mercer comparator

not a bad day after all

 

 

Edited By Michael Edwards 1 on 05/08/2013 12:01:50

Edited By Michael Edwards 1 on 05/08/2013 12:04:43

[Sub MandrelParticipant @submandrel]

He brought down a cheap set of 'Workzone' taps and dies. I think they are Aldi's make. They worked a treat.

LOL!

Cost may be correlated with quality, but r is considerably less than 1!

Neil

[Ian PParticipant @ianp]

Neil

I have the use of a no-name (Taiwanese/Chinese/Korean?) large set of taps and dies. I think it is M6 to M20 and has Metric coarse and fine taps and dies in all sizes. Claims to be high quality ALLOY TOOL STEEL with a Rockwell hardness of 58-61.

It looks rubbish and it not something I would have bought, BUT, I have given it some stick over several years now and some of the taps have cut maybe hundreds of threads. I made a batch of 48 stainless steel M12 wheel nuts with one of the taps with no problem recently. The only thing that I had to replace ws the M8 split die (because it split completely).

Experiences tell me that you get what you pay for but this set is an exception to that rule. Even better the set is on permanent loan to me.

Ian P

[DAVID POWELL 4Participant @davidpowell4]

I had exactly the same problem with an M8 die (HSS) although other sizes from the same source work OK. Is it permitted for contributors to say where they buy quality taps and dies from?

[CrabtreeengineerParticipant @crabtreeengineer]

Hi guys. For threading in the smaller sizes, the tailstock die holder really can't be beaten as it enables the die to be held square to the work whilst applying the required end force. 10mm is my cut off size for threading with a button die, above that I will either single point cut or use the Coventry die box. I have had good success cutting 10mm by 1.5 on EN8 using HSS button dies, but equally have had major problems with the same thread & material when using carbon steel button dies. Hence the quality of the button die is indeed critical. Only buy the size you need from a reputable dealer who specialises in taps & dies & if you are going to be cutting a lot in exotic materials then buy HSS button dies. Remember that threading is often the last operation & you may have already invested several hours into your work piece just to "Screw" it up by using a cheap carbon steel button die! I do not use a tail stock die holder under power unless you are using a turret type tailstock. With a conventional tail stock it can be difficult to keep sufficient end force on the button die & the thread just strips at the start. Hence when using a conventional tail stock I bring the die holder up to the work & lock the tail stock to the bed. With the lathe in neutral I use the chuck to manually turn the die holder on whilst keeping pressure in the button die by turning in the tailstock. Once the button die has taken a bite with a couple of threads if will pull itself on & you do not any further pressure from the tail stock. With a HSS button die one can cut a good clean 8mm thread on EN8 easily by hand using cutting oil to reduce friction. With a cheap carbon steel button die on the same material you will find it extremely difficult to turn the button die on by hand indicating that the die is not cutting cleanly even when using cutting oil & if you attempt to use lathe power you will either just turn a nice big chamfer on the end of your work, strip your thread, or cut a very under sized thread. As my old papi used to say penny wise pound foolish!

Regards R

[Steve WithnellParticipant @stevewithnell34426]

I have thought about taking a very light skim off the bottom of the die holder just to make sure it's true. Although I do have a tailstock dieholder, I have had problems getting a "clean" start to a thread. M6 and above, I've settled into the habit of taking a first cut with a single point tool, then using a die to clean up. Maybe I should spend some time making sure the Indians made everything square in the first place.

Steve

[Rick Kirkland 1Participant @rickkirkland1]

Aldi tools. German engineering. Jolly good!

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Cheap dies often are poorly finished within the thread and lead-in chamfer .

Most commonly :

Burrs left on the thread form anywhere within die .

Ends of thread form at lead in end swaged over so that at the primary point of contact there is no cutting action .

A little work dressing a new die often produces surprising results .

Dies which require large end load to start cutting are defective anyway – renovate or scrap .

Dies which were once ok but now underperforming can be renovated sometimes by dressing the ‘ holes ‘ with a round slip stone .

The correct od for die cutting steel is not the nominal diameter . Much better results will usually be obtained in steel and other difficult metals and with poor dies if od is reduced by about two times 10% of the tooth form height .

The correct lead in for die cutting is not a blunt taper but a short length a much slower taper and / or a short length of parallel reduced section .

Must be said though that important threads above very small sizes are far better screwcut and then – if you want – just finished with a die .

MikeW

[speelwerkParticipant @speelwerk]

Can someone explain to me why you have 3 stage taps and dies only come in one stage. Niko.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by speelwerk on 01/01/2014 11:56:31:

Can someone explain to me why you have 3 stage taps and dies only come in one stage. Niko.

.

The split dies are infinitely adjustable [over their very limited range]

Solid ones are best only used for cleaning-up existing threads.

MichaelG.

[speelwerkParticipant @speelwerk]

Posted by Michael Gilligan on 01/01/2014 12:11:40:

Posted by speelwerk on 01/01/2014 11:56:31:

Can someone explain to me why you have 3 stage taps and dies only come in one stage. Niko.

.

The split dies are infinitely adjustable [over their very limited range]

Solid ones are best only used for cleaning-up existing threads.

MichaelG.

That is fine for the smaller diameters but if you go to M10 or more, the force to turn your die becomes very large, so if you can make the thread in stages it makes it easier. Niko.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

In early days when taps and dies were carbon steel the taps were very weak in the core section and if thread cut full depth in one go there was always likeihood of breakage . Hence set of three taps each cutting a little bit at a time .

Even Carbon steel dies though are very strong and breakage is much less likely therefore full depth cut usually acceptable .

As time went on materials and cutting edge technology improved and taps got stronger . In many cases now threads can be cut full depth in one go and this is common practice in machine tapping .

Really for many threads where you don’t need full threads to the absolute bottom of a hole and where you are not working on difficult materials the traditional second cut tap will do the whole job .

Still worth using all three though for difficult and sticky materials in home workshops .

Anyone buying new might like to try sets of three progressive cutting taps rather than the traditional taper – second – plug . The cutting action and durability is far superior .

MikeW

Edited By MICHAEL WILLIAMS on 01/01/2014 12:28:30

Edited By MICHAEL WILLIAMS on 01/01/2014 12:30:14

Edited By MICHAEL WILLIAMS on 01/01/2014 12:31:36

[Michael GilliganParticipant @michaelgilligan61133]

Posted by speelwerk on 01/01/2014 12:22:35:

Posted by Michael Gilligan on 01/01/2014 12:11:40:

Posted by speelwerk on 01/01/2014 11:56:31:

Can someone explain to me why you have 3 stage taps and dies only come in one stage. Niko.

.

The split dies are infinitely adjustable [over their very limited range]

Solid ones are best only used for cleaning-up existing threads.

MichaelG.

That is fine for the smaller diameters but if you go to M10 or more, the force to turn your die becomes very large, so if you can make the thread in stages it makes it easier. Niko.

.

Sorry Niko, I only answered the specific question

But: If you go back a few decades you will find that Adjustable Dies were available; either as a "plate" with sliding blocks in, or sets.

Try a Google image search for "little giant adjustable dies"

… Not sure if anything similar is made these days.

MichaelG.

.

Edit: Thinking about it … I'm pretty sure that Pipe-Fitters still use adjustable threading tools.

… Something like this

Edited By Michael Gilligan on 01/01/2014 12:49:36

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