Tapers

Probably a daft question, but what are the B Series tapers, please ?

I was looking for an MT1 JT6 drill chuck arbour, but kept getting offered the B series ones. I´m familiar with Jacobs JT ones and even B&S ones, but B16 meant nothing. Machinerys Handbook didn´t seem to mention them.

Cheers

Peter

Hi Peter,

B tapers on chucks are what I find where I live, more info on various tapers here.

Thor

Edited By Thor on 25/07/2021 12:06:17

B16 is one of a series of European Tapers used on chucks if you search MT3 B16 in Google you should see lots of possible suppliers, I have used Amazon in the past.

Steve

Thank you. I found a supplier eventually for an MT1 JT6 and have ordered it. (I did find two others with absurd delivery charges of 15 quid, even though it was to a Brighton address and not here in Croatia. The one I got was 8 quid including delivery )

I wonder where the B series was necessary when the Jacobs ones have been around for years and are quite satisfactory.

I would be surprised if there is such a thing as a MT1 to JT6 shank available. In my experience MT1 usually only comes with either JT0 or JT1 for fitting the smaller Jacobs chucks. I have a genuine Jacobs manufactured MT1 to Jacobs JT1 arbor on which the box states - Models 1, 1A, 2A-1A, 7-1A, 30-1A, 250-1A, and 25S. Another genuine Jacobs manufactured arbor (MT2) for JT2 states - Models 2, 2A, 6-2A, 7, 8 1/2N (that is eight and a half), 11N, 30, and 32.

I have a Rohm keyless 1/32" to 1/2" with a JT6 back taper and also a Jacobs Model 34 mounted on a MT2 to JT6, and a MT3 - JT6 fitted with a 1/16" to 5/8" Rohm keyless.

The only example I have of the JT0 taper is a Model 0 chuck (0 - 5/32" )

From this I would reckon that a JT6 is best suited to a MT2 or MT3 arbor, it would seem a MT1 with a JT6 is considered as 'overloading'? Subsequently you have proved me wrong Peter! Looks like someone considers an MT1 to JT6 is within the bounds of possible, but I doubt Jacobs would agree!!

Martin

Edited to get rid of grinning buffoon emoji - and again to update with last sentence.

Edited By Oily Rag on 25/07/2021 13:33:55

Edited By Oily Rag on 25/07/2021 13:38:07

One is on its way. I agree that it is a bit OTT, but I want it for the tailstock of my Hobbymat for a 16mm drill chuck. I have needed just a touch more than the 13mm capacity of my normal chuck occasionally and I have a spare keyless 16mm one that takes a JT6.

Earlier tapers are proprietary and some of them downright peculiar, perhaps to protect licence fees. The B series are international, with no commercial restrictions.

Before standardisation, the plethora of different threads, gauges, tapers, measures, and other variations was a complete muddle. Collisions between proprietary or old and new standards still cause a fair amount of trouble. Jacobs tapers survive because a lot of them have been made and now there are no fees because the patent is expired.

I'm not aware Jacobs or B-series tapers perform any differently. It's just that they don't fit together!

Dave

… and like many ‘rationalisations’ perhaps it fed the European gravy train

B-Taper (DIN ISO 239)

MichaelG.

The Wikipedia link by Thor is well worth studying. There seems to be very little sense in just how tapers are derived. Morse tapers are all different angles and the B type are truncated Morse tapers.

Having a 16mm chuck on a MT1 taper will require very careul use with larger drills, a MT3 shank is a better match for the torque required.

My point entirely - I would have thought it would have been better to modify a 16mm drill to 'Blacksmith's Drill' specification by reducing the shank to suit the largest capacity of the chuck currently available. Even then I would want to ensure the MT taper was not bruised and the tailstock barrel female taper was in top condition (i.e not ribbed by a previously spinning taper ) - worth a pre-emptive clean up with a MT reamer?

Posted by Michael Gilligan on 25/07/2021 14:50:36

… and like many ‘rationalisations’ perhaps it fed the European gravy train

Undoubtedly Michael! it seems completely superfluous to enact yet another tooling taper to join the many already proven over the years. If they wanted a 'European Taper' why not just resurrect the Jarno (assuming it was a Swedish / Finnish invention! )

Martin

Yes but I might find it difficult to insert a 3MT into a Hobbymat tailstock !

In any case, I have no intention of using it to its maximum 16mm capacity, for obvious reasons, but I do sometimes need to use a 17/32" drill that is just outside the capacity of a 13mm chuck. Yes, I do have a set of 1MT reamers, should it be necessary.

The arbour that I have ordered is coming from Rotagrip. Perusing their website, I see Ian has still got quite a bit of Arrand tackle, for anyone wanting any.

Cheers

Peter

I cannot see what the difference would be except for expense of arbor and chuck if using a 16mm plain shank or a blacksmiths drill. It is the MT1 taper that is at risk.

 Reducing the rake angle of the larger drills and predrilling a pilot would help. I managed to break the MT2 taper twice the other day with a stepped shank 26mm drill in a 16mm chuck in steel. Changing to a slightly smaller drill about 24mm with integral MT was the solution. It just meant a little more to bore.

Edited By old mart on 25/07/2021 21:01:22

Question: What year is your Mach. Handbook? Mine is definitely an older version, so may not include more recent european standardisations.

In simplicity, tapers are easy to compare as long as the taper is quoted in the same units - taper per unit length.. Imperial tapers quoted as inches per foot will not be the same as the european standard, but inches taper per inch will be the same numerical value as feet per foot, or mm per mm (or even m per m!). As these comparisons will show, the B16 taper is the same as the MT2 taper.

Edited By not done it yet on 26/07/2021 09:29:32

My 20th Edition of Machinery's Handbook (1978) doesn't cover them either. (Only ISO threads are mentioned)

Looking up B-series, it seems the tapers are identical to the MT series, but much shorter. They are German in origin. Presumably German engineers needed a short version of MT, standardised it, and the sawn-off MT form has been found useful elsewhere. No idea what for!

Dave

The substitution of a shortened Morse Taper for the traditional Jacobs Taper is a simple rationalisation [the word that I used earlier] … It recognises the ubiquity of the Morse series, and adopts the same set of angles for the chuck fitments.

The tricky part of machining tapers is setting the grinders to get the angles right [and incidentally. the Pope is a Catholic]. so the ‘rationalisation’ was to reduce the range of angles in use. …

Adopting Morse must have grieved the Metric fundamentalists

MichaelG.

Edited By Michael Gilligan on 26/07/2021 10:18:45

This may be the reason I found the MT2 taper in the Emco 5 spindle would not accept a full MT2 arbor, the small end had to have the diameter reduced over a short length.

Emgee

To hi-jack Peter's thread, I apologise, but as this is a question about tapers I thought for future reference it maybe the best repository for this question, in the hope that someone will be able to answer:-

I have an Aciera F3 milling machine and have as part of the accessories the Aciera 75mm centre height dividing head and tailstock (tailstock part no 342 ). The tailstock centre (half centre type ) is an unusual taper and roughly measures Big end = <10mm (0.390" ), Small end = 7.2mm (0.284" ) with a length of 39.18mm (1.542" ). these measurements are taken over the engagement length within the tailstock barrel, the full size at the big end actually measures 10.2mm (0.402" ) giving an overall taper length of approx. 42.6mm (1.677" ). Looking at Thor's link this does not match any of the 'normal' tapers - the closest appears to be a #3 B&S or a #3 Jarno (which I erroneously, in an earlier post on this thread, accredited to being of a Northern European origin rather than, oddly, B&S themselves! ).

I can find no mention in any of my Aciera literature as to the taper used in the tailstock barrel, nor is there any mention of alternative centres that were offered for sale. I ask as I need a bull nose centre for a job and was therefore looking to either buy and modify or to make a 'special' to suit my needs.

It would be nice to have the opinions of the forum as to what this taper is liable to be. I'm guessing it may be an extended version of a #3 Jarno.

Martin

Well, after the overwhelming response to that question it looks like there are very few Aciera owners out there!

However, after some thought I looked closer at the taper angle of the Aciera tailstock centre and have concluded that it is probably a nice round 2 degree half angle which puts it close to a B&S taper of 2 degree 24', whilst all the other long tapers (i.e not Jacobs or B series) are in the range of 1.4 - 1.5 degree half angles.

Guess I'll knock up a 2 degree taper shaft, blue it and try it.

Martin

You do wonder why different manufacturers deem, or deemed, it necessary to employ different tapers.

I have drill chucks with Jacobs, Jarno, and Morse tapers in the body, Cannot remember if there are any with B series tapers, would not be surprising if there were one or two!

It would be more understandable if there was am aftermarket to be captured, but drill chuck arbors tend to be "fit and forget" items rather than high volume turnover parts, like car brake pads.

Maybe it is a desire to be exclusive. Elsewhere we have Morse, B & S, R8, and International tapers, and the collets with Morse, 5C, ER and Autolock, to name some. Each with its own specific advantage, in grip, or ease of breaking that grip.

Some have been produced by a specific manufacturer, for a particular purpose, at that time, whether need or exclusivity, just like screw threads, or gears!..

Howard

.

… The stuff of dreams

MichaelG.