Taps and dies

Hello all, and Happy New Year.....

I was playing in my workshop over Christmas where I needed to increase the thread length on some partially threaded stainless steel bolts. I wound my die down the thread and continued to cut the thread a little longer. All good for the first three or four, and then I noticed the die cutter I was using was cutting poor threads and assumed that my die cutter had become worn rather quickly i.e poor quality.

I googled cutting threads in stainless steel and then realised that perhaps it was a harder material to work with than I had assumed, and that there are some issues with cutting threads in stainless (material hardening etc)....... Anyway this made me think are my taps good or poor quality.

So my questions to you all are these..

1/ I have a set of taps from the Tap and Die co in London Can anyone verify if they consider them to be of good quality?

2/ What are the best quality of taps on the market and who are they made by?

Finally I would like to say that I liked the Pic on the Jan issue (Front cover) of the Model Engineering Workshop mag ....Brill, Silly old duffer keep up the good work.

Gary

Stainless steel can be difficult to cut, as it work-hardens. Your problem may not be because of duff taps, but the condition of the bolt you started with. If (as is likely) the bolt had a rolled thread then the surface will have been hardened in this process. To identify this, a rolled thread tends to blend into the plain section of the bolt without the characteristic cutting-edge marks from a die.

A further factor is the lubricant you were using. Stainless can be prone to tearing rather than cutting, and can even seize to a mating part if the surfaces are bone dry.

And of course, it may not be the 'quality' of the die, but the sharpness after use - particularly if it is used on a material which is too hard (including work-hardened stainless.

I am not familiar with the company you mention, but my guess is that they sell dies (and taps) from all over the world. Some good, some not so good. Of course, I might be wrong ...

Regards, Tim

I've never heard of The Tap and Die Company of London, for postal stuff & odd-ball threads I always use Tracy Tools.

.

But some significant purchasers have ...

**LINK**

http://www.tap-die.com/contents/en-uk/d6_What_Customers_Say_About_Us.html

... unlikey to be much wrong with the quality, methinks.

MichaelG.

Tapdie stuff is OK I have a few of their HQS one, Tracy tools also sell some of their dies

Michael G

Thats what I thought, it would appear that they have some impressive clients, so you would think that their quality was good.

Gary

So what is this 'HQS' voodoo that Tap-Die speak of?

Sorry, I'll check my post again and see if I said no one else has heard of them.

Nope, didn't say that :D

Gary

Most importantly, have you found yourself a new lathe yet?

Several old threads on here delving into the true meaning of life HQS

I know Jason.

I was being slightly mischievous

I thread a lot of stainless, (304 and 316). I have only really had good results with high quality dies and decent cutting oil.

I use "spiral entry" dies, to cut under power in the lathe, (these are around £25-£30 each) and Rocol RTD liquid.

Jim

Let alone HQSS...

Neil

The Tap and Die Co. of London have been a regular advertiser in the back of MEW for years. I though everyone would have heard of them?

A.B. if your dies are not made of High Speed Steel, they will wear more quickly on tough materials such as work hardened stainless steel etc. The HSS ones invariably cost quite a bit more than the carbon steel jobs. This seems to be the case regardless of manufacturer.

I was given a set of BA taps and dies from the Tap & Die company as an Xmas present 30 years ago still as good as new despite regular use. Also ME set just as good. Made in UK

Hugh

I've often seen good (& poor quality) taps &die sets at autojumbles for sale but on close inspection quite a lot of them were rusty or blunt/damaged also trays of loose taps with people raking through them.

You may also wish to measure the diameter of the non-threaded portion of the bolt. In some cases this may exceed the nominal diameter of the thread in which case the best options are to reduce the diameter before threading with a die or cut the thread using the lathe (or both). This is more generally a problem with larger size bolts (6 mm and up).

It goes without saying the use of a good cutting compound (I use Trefolex but everyone has their own favorite) is essential on stainless steel.

I have some Goliath taps which IIRC are U.K made they seem to be very good .

Any of the recognized production makes are very good ie Guhring, Dormer, OSG ect Best taps/dies I have are by Titex and Emuge Franken. I have a dolly mixture of many makes. I've only ever bought any size when I needed it.

Gary,

From your description it seems that you are possibly trying to cut a tough stainless steel part with a carbon steel die. I used to work as a sales engineer for a British manufacturer of all types of threading tools & have seen this situation many times when visiting clients to discuss their threading problems.

Taps & dies are essentially manufactured from either carbon (CSCT) or high speed steel (HSSGT). What’s the difference you may ask? Well it’s price for a start. If you look at any tap manufacturers or sellers price list including Tracy Tools & The Tap & Die Company’s you’ll notice in the small print that HSS is available for an additional charge which from memory is at least 150%. For that reason most of us will always opt for Carbon Steel, the cheapest & in most cases more than adequate for our needs.

What are the differences between taps & dies made from the two materials? Firstly the abbreviation CSCT stands for Carbon Steel Cut Thread & it refers to a tap that is to all intents & purposes produced with a single point tool or screwcut just as you would on your lathe. HSSGT is an abbreviation for High Speed Steel Ground Thread & refers to a thread that is produced by grinding using a wheel dressed to the thread form. The materials that are used are different also. Carbon Steel is easier to work & is essentially similar to silver steel & it is hardened & tempered after machining similar to how we do it in our workshops. HSSGT though is another matter; it hardens & is tempered at much higher temperatures & difficult to do in the home workshop! HSSGT taps are ground from a finished ground & fluted blank, the thread form is the last feature to be produced. CSCT dies are produced with a tap, HSSGT dies are thread form ground, just like a tap but obviously internally ground rather than external. There is still more to it though.

What your 150% premium for a HSSGT tap also buys is a tap or die produced to tighter tolerances & it is thus capable of producing internal threads to tighter tolerances. CSCT taps are also made by reputable manufacturers to a tolerance but the tolerance band is much wider. Dies are also produced to a tolerance but because a split die is slightly adjustable the physical size of the thread produced can vary. With a solid die however the die is manufactured to a different tolerance. In all cases taps & dies from reputable manufacturers will have the tolerance band stamped, engraved or etched onto the shank of the tap or the face of the die. I can no longer recall what the tolerance bands are unfortunately.

How does all that I have written apply to your problem you may well ask? Hopper has summed it up very well in that you probably need to us HSSGT, but unfortunately HSSGT may not be the solution in itself. Tapping & threading lubricants have part to play in the process & help to improve the quality of the cut thread in most cases.

The Tap & Die Company have been around for many years. As they say on the website, since 1978.

I Hope that the above is of interest to you & to others who have possibly wondered about the difference between cheap & expensive threading tools. There’s more to them than meets the eye at first glance.

Alan