ME taps and dies

I have quite a few different types of ME taps and dies from a well known supplier and I'm not happy with them, I've had them for two years so have tried all hole sizes but never get a good thread. The threads always are sloppy and the dies have a start front and back so not good when a stub of a few millimetres are to be threaded. I could grind the dies down on one side but the smaller dies will be rather thin after and I'm not happy to do this with a hand grinder.

My question is would metric fine be a good alternative to ME taps and dies. My ME dies are split and have tried every way for a good thread, but when I tap metric course I always get a good results.

The ME taps and dies came from a supplier that have indorsements from well known company's so they are no rubbish.

Bob

Some of the finer ME threads can be a problem Bob, even with a tailstock guide. I've taken to screw-cutting a 'starter' thread when I'm doing 40tpi and then finishing with the die. I just do this just by turning the lathe by hand to about half depth (not very much in fact). Also for short threads, allow a little extra length and turn this off after threading.

All my ME dies have a tapered face and a plain face. I've had them a long time but I think they were from Tracy Tools...

Also, you mention that your dies are split. Check that your die holder has pointed grub screws - one of mine had stub screws and wasn't capable of fitting the die adjusting gap - took me a while to realise it though I'm afraid..

Regards,

IanT

Thanks Ian,

I have a tailstock die holder that slides, but will check that it has a pointed grub screw later but I think it is flat. Why have my dies have starts on both sides,it don't make sense.

Bob

Edited By BOB BLACKSHAW on 17/02/2020 10:47:44

Edited By BOB BLACKSHAW on 17/02/2020 10:49:30

I had trouble starting a 1/4" 40TPI die recently and on the next workpiece did a preliminary screwcutting to nominal full depth (it's 16 thou for 40 TPI, of course). Like IanT I did this by hand (using a handle in the tail of the spindle).

If using the die alone it will help to turn the work to slightly less than nominal.

GHT has good advice for those regularly using ME dies: basically, installing them pre-adjusted into dedicated holders.

I agree with Ian, the 40TPI threads are problematic, at least for my old eyes and fingers. So now I rarely use 40TPI, only 32TPI ME threads.
Where I live metric taps/dies are readily available (both coarse and fine) so I usually use metric threads. If I buy fittings from the UK I have to use ME threads so I have a few Carbon Steel taps/dies from Tracy Tools, they have worked very well in brass/gunmetal.

Thor

No! For external threads I normally turn to the nominal diameter. Although to be fair for most of my external threads I screwcut or use a Coventry diehead rather than split dies.

Andrew

I used 40 tpi on my stainless flash steam pump ball valves and used to screw cut them and finish with a Tracy tools carbon die.

Most were ok but had to watch for sometimes a small bit of metal would seem to weld to the die thread a bit like ally can build up on a turning tool.

That same build up of metal on a tap would sometimes happen as well so check your taps and dies threads are crisp and clean.

Use plenty of threading lube

Dormer recommend reducing outside diameter by 1/10 of the pitch before threading .

I have always followed this recommendation and it works fine for me.

Jan

Hi Bob, Some years back I purchase a seat of ME taps and dies in carbon steel and was disappointed with the fit in particular, several were very sloppy others were OK. In the end I spoke to the company Tracy Tools were excellent in their response particularly so when there was a considerable time from my original purchase and my decision to "do a swop" with cash adjustment for HSS, these are much better regarding fit and they cut better IMO than the CS ones.

Regards John

Bob, the company you purchased your taps and dies from, would it be the Tap and Die company, if it is I have had a few dies from them that have a lead on both sides. I have also purchased a set of ME dies at a show many years ago that were twisted, it transpires they were originally solid dies but some enterprising soul decided it would be a good idea to make them into split dies so they slit them and ground a chamfer on them for the adjusting screw and all was well, until they removed them from the vice, and they twisted, not a lot but enough to stop them cutting a thread, no matter what I done with them all they would do is just chew up the material. Learnt my lesson, buy cheap, buy twice!

Well I'm certainly going over towards metric more for this sort of thing, all the "Series 24" engines that I have built and made drawings available for some have metric fine rather than ME, some also have the constant pitch Metric threads such as M10x1 or M18x1. I've just got a couple of ARCs metric fine dies as a late Xmas gift so may give them a go and report back

Like Andrew I always leave the stock full size and if you are suffering from slack threads I would certainly not want to be reducing the OD.

have had a few ME dies from RDG that did give a slack fit so just don't buy from them now.

I do have a few where I have hollowed out the back to make it easier to thread to a shoulder but will undercut the end of the thread if there is enough material in the part or drill clearance a short depth in the mating part if not to ensure the items screw together all the way.

I have migrated to Metric and they have a good range of pitches all my large collection of ME have been disposed of now.

Off the shelf mm fasteners are easier to find as well.

Metric vs ME?

Depends where you are coming from and what you want or need to do...

Nearly all of my new machinery, jig, tool-builds etc use metric fasteners - and I've standardised on M6/M8 for my clamping devices (regardless of T-slot size). Metric fasteners are generally cheaper and easier to get hold of.

However, for my model work, I've stuck with BA and ME sizes - because I already have the tools and a good inventory of fittings collected over the years. I've no good reason to want to migrate now and my models were all built using them.

I also own old British & American machine tools - so they need non-metric fasteners for any repair or maintenance.

There is also one other reason to use older, imperial threads. There is a great deal of good quality, imperial sized tooling still available at reasonable cost if you need it - versus a lot of sometimes questionable metric 'new' tooling.

I've just purchased a full set of 3/8ths taps, plus matching die for a job - and they are good quality British HSS tools that will last me out. Why? Well I needed L/H threads - and couldn't find metric near equivalents that I wanted to afford....

So generally, yes going metric makes sense - but there are also good reasons not to...at least for me.

Regards,

IanT

My first experience with ME 40 threads was to strip the thread. Serves me right for asking it to drag the Tailsock along the lathe bed! The thread is only 0.016" deep!

40 tpi provides a means of adjustment like a micrometer. twenty five divisions on knob or handwhel provide 0.001" increments.

Using a sliding Tap, or Die holder, a loose fit on an arbor in the Tailstock lubricated with Rocol RTD seems to give no problems.

With a lead in chamfer, it is not possible to thread right upto a shoulder. Having cut as far as possible,, I turn the die around to cut the last couple of threads, by hand.

Howard

Thanks for the replies,

Mine are the same where Baz got his from, I shall get some metric fine and try those, but the unions are usually ME, so mix and match. All of what I've made so far have a mix of threads so if any one in the future gets what I've made will have a problem if taken apart.

Bob

I wonder how many ME taps and dies are sold? Not many I'd guess, and most of them in the UK.

Is the quality problem down to low production runs of cheaply made items selling very slowly, perhaps taking years for a bad batch to reach a customer?

When ME was invented, there were plenty of small jobbing British engineering firms who might be happy to make them. Not how manufacturing works today. Much more choice buying Taps & Dies in standard thread sizes, with cost and quality benefits from being mass produced. As a general rule in engineering, best to swim with the tide and avoid buying specials unless essential.

Dave

With union nuts I usually make my own but have brought some 1/4 ME , I've just had a quick look on the internet for M6 unions but the ones I've seen are M10 for brake pipes, so what unions are used for a model steam loco ?

Bob

If you want metric nuts or steam fittings the european suppliers do them such as these otherwise UK tends to be ME in the smaller sizes and BSP in larger.