Taper on watchmakers lathe tailstock?

No, there's no standard. Each manufacturer made tapers to their own standard. I would guess that some would be the same, but I'm not aware of the information being listed anywhere. The best thing to do is to find out if it belonged to the same type lathe as the one you have, or even better would be the ability to actually try the fit but that would probably be difficult today with buying things remotely.

 

Good Day,

There is not a single defined standard but there were attempts to adhere to the rules that were set by some manufacturers themselves.

G. Boley, Leinen, Boley & Leinen, Lorch Schmidt, Wolf Jahn as well as many other each have picked a taper for their own use and only varied diameter of taper as needed for particular use.

Leinen, Boley & Leinen and G. Boley used for tailstock attachments taper defined by included angle of 3 1/2 degrees of arc (3º 30') and they still do it today.

For example:

Brown & Sharp defined their tapers #1 to #15, by 1/2" to 1' or 1:24 regardless of the taper diameter.

Jacobs is using tapers 1:20 and 1:12 that I know of.

G. Boley used 1:12 for colleted dead centres, male and female, while Whitcomb uses 1:14 for the same purpose and then again G. Boley uses the same taper as Whitcomb, 1:14, for the US market.

Difference between the two can be seen in markings e.g. G. Boley 1:12 tapered centre bearing collets are marked with "2". Like "G. Boley Germany2" marks collets with taper 1:12 while "G. Boley Germany" marks collets with taper 1:14.

This is how it was done from one maker to the other, simple to understand as this way of thinking allowed the grinding machines to be set once for all tapers hence machines have seldom required taper adjustments irrespective of the actual diameter of the taper being made which could easily be changed without disturbing the taper setting.

It would be a good idea if ones among us that are able to accurately measure tapers on their lathes and their accessories, would report the tapers measured so that a table of a kind can be produced that may contribute in correlating the tapers across various manufacturers.

I suspect that they are not all that different from each other as only a narrow specter of taper angles does allow firm hold of the tooling in working metals although there is always a possibility that minute differences were intentionally introduced just in order of stopping users to buy from competition.

Perhaps some machinist among us can give us broader explanation of these matters.


Cheers

Dushan

 

Hi,

This thread has become a go-to search result resource for folks to get info on tapered dead centers for various older horological lathes. Awesome.

But, we never went on to catalog anything, so I'd like to reinvigorate "It would be a good idea if ones among us that are able to accurately measure tapers on their lathes and their accessories, would report the tapers measured so that a table of a kind can be produced that may contribute in correlating the tapers across various manufacturers."

If it's already been done, can someone please post a link? Maybe it's all listed in one of those great old lathe books?

If not, here's what I found for Leinen (a.k.a. Boley & Leinen --or B&L) sold in the USA by Henry Paulson & Co., but mostly smaller units and a narrower range of add-ons. Other great German lathes Wolf Jahn, F. Lorch and G. Boley (slightly different from Leinen - or B&L - often confused) are sadly no longer being made, though good info is available on www.lathes.co.uk and youtube/sites, like Steffan Pahlow, Niels Machines, etc. But, the modern German firm Boley GmbH at www.boley.de (no idea on the name there) still sells Leinen 8mm WW pattern lathes and components, and they also provide data on the tapers! The thing is...there are several different Leinen tapered components available today (and in the past) --and the angles do not appear to be cut from different axial sections of a single tapered cone.

Also, of many sites for folks working with machine tapers, a good one is www.magafor.com/841/uk.htm And, to help out those who want to cut their own, RDG sells an affordable 8mm WW style live male center for G. Boley lathes that fits many other makes, which is great for cutting tapers. OK, so for Leinen, B&L, and Paulson, there are (at least) four different kinds of tapered components:

1) the larger diameter (like 4mm-ish) and stubbier 3°30' components that fit into a) the Leinen (B&L) "a30e" crank tailstock, b) more recent versions of the 8mm "sleeve" tailstock runner, and c) a big-bore Leinen WW style 8mm collet. These components are like rose cutters, fine-work tips/points and the D bit countersinks/cutters/drills, as well as the drill pad, male and female dead (and now live) centers, etc. This taper value can be used to cut any "bigger" sized Leinen (B&L) component replacements folks may want. I don't have any newer/big G. Boley stuff, like the F1, but maybe those also use this same taper?

2) there are much thinner tiny bits (like, 2mm-ish) that fit into a center of the Leinen (B&L) WW style safety roller, and were (previously) also sold with an eccentric/offset 8mm runner for their sleeve tailstock. All bits were sold with their receivers in a set of 6 or 12, and tapered at 2°34' With this, we can make replacements, as these safety rollers are not hard to find used, but are usually missing the good stuff.

3) there are the pair of centers (m/f) that come with the Leinen (B&L) "Drive Plate," often with pig tails for ejection out via a finger. These are used with a carrier/dog, for turning between centers. These are part of the drive plate, but unlike the tiny inserts, the taper angles were not provided at boley.de.

4) the typical "regular guy" long, thin (like 2 to 3.5mm) old-fashioned m/f dead centers which fit the old small-bore tapered hole/center collets. These collets and their centers are no longer sold by Boley GMBH, so they are obsolete. My guess is these would have been copied exactly by Leinen from G. Boley a hundred or so years ago, and might be 1:12, as suggested in the post above. The Paulsons fit interchangeably in my Leinen's (and B&L's), but I am not 100% sure on Leinen being 1:12. According to the online calculator, and if I have it all right, 1:12 has a cone angle of 4°46' and I think this means the taper is losing/gaining 1mm in diameter for every 12mm of axial distance (or half that -- .5mm for every 6mm of travel, which is easier to measure on short components, like these old centers). Please correct me if I'm mistaken, as this is all new to me, I'm not an engineer, and my Leinen stuff is all mothballed in storage, so I also have no direct measurements.

As requested earlier, please jump in with anything that helps us all understand this stuff better?

All the best...

 

Fooling around, I've identified the German distributors of the Leinen (etc.) pattern equipment, which is only 30 minutes east of Esslingen am Neckar, where these things were first made sometime between WWI and WWII.

These guys do provide the taper specification for the 25mm circular diameter "drive plate" (for turning with a dog between centers --e.g. #3 above)) male and female tapers as 3°56’ So, if you want to make a pair, use the calculator website and you have the angles and dimensions to grind them out correctly. The catalog images show the approximate length; I'm guessing they are about 30mm. These don't have ejection tails, so pass them through a bit more for a light brass head hammer tap on the butt to smoothly drive them back out.

They also show the eccentric 8mm tailstock runner and mini-bits (same size as mini bits from #2 above) if you're into making those. And, FWIW, the engraving on some of their collet stems reads "Boley & Leinen, Germany." And, yes, "Prätecma lathes are high-quality lathes from German production." Certified according to DIN EN ISO 9001: 2015 So, pretty far from China...at least for now. Info is available only in German.

Machines are here https://praetecma.de/fileadmin/template/Dokumente/Praetecma-Drehbaenke_.pdf
Components are here: https://praetecma.de/fileadmin/template/Dokumente/Praetecma-Zubehoer.pdf

So, I think it's just a few folks 100% confirming the taper angle on the old obsolete (longer, thin) traditional centers as 1:12 (or something else?) NOTE: this should be the exact same taper found in the older small-bore 8mm plain sleeve tailstock runners. After this is done, I think the 4 different B&L tapers will all be katalogisiert.

 

Betzel

As has been mentioned, all watchmakers lathes I have owned and inspected, have had different tapers with some even different within the same brand.

For myself personally, a chart would be of no use since the chance of finding/measuring something that fit and functioned properly would typically require more time than it would be worth.

When I have needed a tapered arbor, I simply turned one that was a accurate fit to a specific female taper that I have. This allows me to turn one or a life time supply since it only takes a few minutes. The process that I use is as follows.

(1) The runner or spindle is mounted in a Lathe with a rotating headstock per first attached photo.

(2) The angle is set until a indicator has no movement over the length of the taper establishing the proper angle also per the first photo. While a compound slide can be used in the same manner, they are generally not as accurate or stable as a machine tool lathe Carriage.

(3) From this point the indicator and spindle are removed. Arbor stock is installed and the stock is easily machined to a perfect fit per the second photo.

The arbor is either fitted to whatever or the opposite end is machined for whatever specific use is required. The arbor is held for further machining by installing in the runner that is in turn mounted in the lathe spindle.

Jerry Kieffer

 

Jerry,

That's a great technique for folks with a DTI and the tools to closely copy existing tapers. Thanks for sharing it, and your photos. I don't have a DTI or a Sherline, but wish I did - they're getting more advanced every day! Somehow, I thought carriages only ran perpendicular to the spindle? If so, are you using a tailstock (or runner) offset to cut your tapers?

---------

I guess the rest of of us can use whatever we have with a compound using the method above. For smaller holes this may be a challenge, but (though I don't know how small the DTI ball is) an older or cheap one could be ground down to sneak into smaller areas, like the colleted dead centers that originally started this thread. Not recommending DTI destruction to anyone, just saying it might work. I had forgotten many lathes do use different tapers --even within the same brand. So, I guess the idea of the "taperbase" is impractical.

I feel lucky mine's a Leinen (WW-83), the last of the popular German makers to start production. They are still being made, and to the same (or better) quality and precise dimensions as the old days. But, like Levin, Derbyshire, Bergeon, Myford, etc. OEM equipment is just too expensive to buy new, and as a recovering OCD sufferer, I can't go Chinese.

Like a lot of you with older stuff, I scrounge around for accessories at reasonable prices online and fix them up, which means I have 5 different (but constant!) tapers, now counting the wax chucks. And, I have a newer G. Boley (not an F1, just hammertone green) with a complete set of collets marked "2" (likely 1:12 for the small centers as Dushan outlined, above, but I need to confirm) and these two lathes are not 100% interchangeable, but highly compatible, especially with the dead centers. So, for all you B&L users out there maybe the 3 of 5 data points help? With the online taper tool, a mic and a vernier, you can make precision inserts by hand, but why not measure per the above method first? I'd be curious if any of the Leinen stuff you find is inconsistent.

All the best,

 

Betzel

You are correct in that a lathe carriage runs parallel with the lathe bed. The headstock is rotated so that one taper surface is parallel to the lathe bed per the attached sketch. The indicator is used to determine if that surface is parallel to the lathe bed. No deflection of the needle indicates that surface is parallel to the bed when setup per per the sketch. Indicator balls come in sizes that are far smaller than required for this application. No tailstock is used for this procedure per the sketch, Replaced Arbor stock can then be machined with proper taper per second photo post #6.

For general machining on a daily basis including Micro machining, I no longer use a Watchmakers lathe because of their limited capabilities as well as any other Lathe with the same issues including limited accessory availability.

Quality Vintage equipment was judged on its construction appearance and construction materials. In todays world, the highest quality equipment is judged on its accuracy, capabilities and its efficiency and nothing else. Another words what it can actually do in a timely fashion. What it is made from, how its made and what it looks like is of no concern.

In regard to your Sherline comment, The Early Sherline equipment was less than desired like most other small machines of their time. However todays current production machines along with a couple other more expensive brands, are capable of doing what is possible on small machine tools within their envelope.

The Lathe in post #6 will out perform all of my watchmakers lathes in regard to accuracy, capability, and efficiency especially efficiency.

The following is a very basic example.

At the Milwaukee National convention a couple of years ago or so, I was asked to do Lathe and mill demonstrations both watch and clock or whatever was requested.

An attendee along with other observers timed the Machining of a small basic Wrist crown on the lathe (in post #6) shown in the attached photo. It took 4 minutes 13 seconds as shown in the photo minus threading. While a crown was available, this matching crown was machined for an attendee where an extended post allowed picking up an existing broken stem. The post was also machined slightly larger in diameter to compensate for case wear. While this would have been possible on my watchmakers lathes, it and many other basic machining practices have not been practical.

My personal philosophy at this point, is that if any one machine can not do as I wish, when I wish and how I wish to a high standard, it is immediately removed from the shop and replaced with one that can. It took many years, but I learned that if your not happy, its often best to sell everything and replace it with something that actually works. By the time you find out that life is short, its often to late.

jerry Kieffer

 

Jerry,

A rotating headstock? A crown in 4:13? Wow.

I think Lorch or Clement did that back in the day, but they were rare. Now I get the degree marks - you don't need a cross-slide! "By the time you find out that life is short, it's often too late." So true...

Ideal for the trade practitioner. With DRO and CNC options they really have come a long way. For those of us who may be retired, or hobbyists with less money and/or more (? heh) time on our hands, and folks that irrationally just love old cool stuff (and do not require the efficiency) impractical adventures can be rewarding, but frustrating. I'm happy with what I have, but if I ever see any of those social security checks, I'm getting a Sherline!

Great conversations. Thanks again!

 

I have machined tapers, as Jerry has shown, on my watchmakers lathe. Using an existing insert as template together with an indicator is a safer and quicker method than setting the cross-slide to a theoretical angle.

I don't make money from it, so I can indulge in the good old industrial workmanship and looks - I know, Sherline is good quality (own some chucks and motors made by them), but just can't get used to their plasticky 1970s look ...

Anyway, Wolf, Jahn & Co. and Lorch, Schmidt & Co. tailstock tapers seem to be interchangeable. I have a whole collection of them and don't really know by which manufacturer individual items are - these parts were never stamped. Both manufacturers were Frankfurt based, but I have not been able to find out in what way they may have been related or co-operating, given the fact that many parts are interchangeable. The archives of both companies were lost, after they went into insolvency in the 1960s.

For the reason that tailstock inserts were not stamped, I would buy second-hands only, when I am sure what lathe they came from. So there is not much point in a catalogue. You have the tailstock (runner) and you have to find inserts from the same manufacturer.

BTW, revolving headstock for the D-bed lathes of the above two companies, particularly those of Lorch, are not so rare at all. They were used together with a vertical slide and a milling spindle for one-off wheel-cutting.

 

I can certainly understand.

As such, I have managed to have the best of both worlds. My small tool collection contains my Watchmakers lathes as well as other tools. They are prominently displayed on display shelves and glass display cases for all to admire.

However, on my bench, the only thing I would like to admire is the parts that come off of the machines.


Jerry Kieffer

 

Agreeing with using modern "production" tools to run a real service business, I'm not in the business. I'm retired, and I like to refurbish and restore old, cool stuff for the love of antique precision machinery as art/craft not just to admire, but to use them as well. What follows on measuring tapers may only be helpful if you're like me.

So, I just bought another old Geneva pattern lathe, with the 80x7mm diameter double-ended (M/F) tailstock runner, which is unmarked but appears identical to the Wolf Jahn. I think someone nicked it from the factory and finished it at home The Lorch was a better unit, IMHO, but the core parts for both Geneva pattern lathes do seem to share manufacturing origins and significant interchangeability, as also mentioned above. They look a lot alike, but the Lorch seems to have longer, and more slender thumbscrews, among other features. There are variations across time in both.

Anyway, it was rusty, but not abused. So I brought it back from the dead. After lapping the cones, it does not leak sewing machine oil. Now, I want to find an indexing arm. with that weirdo (maybe longer and fatter than those dead male and female small-sized collet centers) tapered pin on the bottom of the arm where it locates into the drawbar side of the headstock, keeping me marginally on-topic. Who knows which used one on the internet will fit? Its usually trial and error as no seller knows which lathe these came from --they are all pretty much "lost and found," one-off items. The taper has to fit YOUR headstock taper, and the pin needs to locate in YOUR headstock pulley. Ugh.

So, when the taper is small (3-4mm or even less) and you want to buy used parts online, it helps to ask the seller for measurements. But how do you measure the female taper on your lathe to know if a second-hand part will fit? I thought about melting lead fishing weights, or making a blank out of aluminum foil and hammering it in to make an impression, but the thought of not getting anything back out of the hole scared me. And, though the advice on using a test indicator works on a female center collet, this tapered hole is inconveniently located.

Then, I remembered the cone angle computing website from the dead center tapers discussion on this thread, Taper and angle calculation Using flat-faced 3mm and 4mm drill rod to measure the depths from the top (using a razor blade to etch into a permanent marker stripe on the steel). With this, I (fairly) accurately computed the rest of the taper from the two values and distance between them in just a few minutes. It's repeatable! Real engineers will have a chuckle, but for the rest of us, it was a special taper-measuring moment.

For this Lathe's index taper, the cone angle, α, was 4.01° with a taper of 7.004%. There's a margin of error for sure, but I can use it before I buy to see if replacement parts from sellers might be close enough to fit, and lap it in if needed. Especially if you don't have a test indicator, you can use this to buy or make dead centers that should fit your oddball female-tapered center collets. Worked for me...

HTH.

 

G'Day!

To accurately measure the included angle of a taper of a female centre one should use calibrated steel ball gauges. One should pick two ball gauges of different and known diameters, that will fit the taper. Place one inside of the female centre and set the zero point (tip of the gauge ball) on a dial indicator, place the second ball gauge in and then measure the distance from the zero point to the tip of second gauge ball. The rest is just application of trigonometry to calculate the actual included angle of the taper.

Of course, everything must be immaculately clean.

Cheers, Dushan

 

Ball gauges for the win!

I did not even know those existed --and they're cheap enough to make (reduce one side of, and then radius both ends of some old bar stock?)

-old Wolf Jahn tapered center dimensions below-

A used 8mm Wolf, Jahn & Co (the only markings on it) male dead center and collet arrived in the post today. It was frozen in both time and space. I believe it's from an old Geneva set, but who knows. The center was fit perfectly to the collet, with the taper precisely ending just at the collet face when fit up tightly. It took a few (very hard) punch blows to the back side of the center from the rear to drive it out (with some oil and swearing) but there were no impact marks on the center from the punch; good stuff! For a used item, the useful part had a lot of meat left on it and it's super hard appearing ground, leading me to think it's all original. It may have been trued, but not a lot of obvious wear, so maybe a good reference. Lorch might be identical, but then again maybe not. Maybe later WJ's are different as well - who knows? Anyway, the total overall length of the tapered male dead center (e.g. the center part alone, tip to toe, not the collet) = 21.63mm. It's visibly fat, short, and very slight as these tapers go, compared to most of the others used or NOS OEM's I've seen (German and American). This one was:

D=4.4831 (this end-of-taper dimension breaks right into the parallel "working width" running out to the tip)
d=4.1402 (taper limit, just before the base)
L=9.450 (just the taper)

So, using that calculator: cone angle (α) = 2.08° or 2°05' and Taper = 3.629% Not even close to fitting the indexing arm hole for the headstock! D and d dimensions were taken with a traditional hard-faced "outside" (screw-type) micrometer and converted from .xxx inches to .yyyy millimeters. The L (length) was done with a digital slider using the rub-spot against a felt tip marker. Same for the overall length. FWIW, I bought a full set of similarly-vintaged WJ collets a few years back and it came in a cool wood box with 3 steps (1,3,5) a screw-in wax chuck (steel), 4 brass parts for that as well as 4 tapered blank centers, so you could make whatever you wanted with them. I have not seen any of those blanks since!

 

G'Day Betzel!

Taper on Lorch, Schmidt & Co. 6 and 8 mm lathes, a.k.a. D-bed, is always 1:25, regardless of the the taper diameter. Measured, tested, and a number of male centres made as replacement of the missing and damaged ones. Thus, the Wolf, Jahn & Co. taper should be exactly the same since the centres are interchangeable with Lorch, Schmidt & Co., I am not sure about Star lathes.

Also, it should perhaps be mentioned that Favorite brand lathes used standard Metric tapers 4 mm and 6 mm. The same Metric taper standard was used by German watchmaker's lathe manufacturer Andrä & Zwingenberger KG, as well as Russian watchmaker's lathe manufacturers.

Cheers, Dushan

 

I didn't think of the steel-ball method for this, but it is indeed used for other measurements like this. However, I would just put the dial test-indicator onto the cross-slide and run it up and down inside the taper - provided your cross-slide axis is parallel to the lathe axis the amount of travel read on the micrometer screw and the the difference on the dial give you the number to calculate the taper.

I have a wild mixture of LS&Co. and WJ&Co. stuff that came from both, D-bed 6 mm/8 mm and WW-lathes. They are all interchangeable without a problem and I can use any insert on any tailstock. They must have been ground in a jig, but somehow centre-less - no idea how.

Boley stuff is different, of course. I think in some catalogue I read that the included angle was something like 2° x', similar to the 2° 40' I calculated for the LS&Co. taper, but not the same.

I have never come across blank tailstock inserts, but made some myself using the above method, adjusting the angle of the top-slide until the indicator reading was zero. It still may need a couple of trials, as the taper really has to be spot on.

The taper on the indexing levers is another matter. There is no reason that it should be the same as the tailstock inserts.

It is, indeed, an interesting question, where all these different 'standards' once came from, as they don't seem to fit into any known metric or Imperial system. I did some research on this, but never came up with any answers, as all the company records have been lost.

P.S. While I was typing this, Dushan sent his post. The LS&Co taper is probably a 1:20 taper too, as I measured a difference of 4.5 mm - 4.1 mm over a distance of 10,7 mm with a simple vernier caliper.

 

G'Day to you as well, Dushan. Incredibly handy to know -- so thanks so much for posting. Thanks for the info on the other makes and metric tapers as well.

I think you're probably right about the Wolf Jahn, as it's just too close. Probably rust, small (but critical) measurement/calibration error, and coffee working together skewed it off just a little ;-) Using the calculator for a taper where d=1mm and D=2mm and L is 25mm (so, 1:25, if I am doing it right) yields a 4% taper, with a cone angle α of 2.29° or 2°17' . Spot on is way better than close!

Wefalck, I didn't expect the center taper to fit the index arm, but thought the angle would at least be the same just to keep things simple? ;-) Uh... No. And there is one place where the Lorch / W-J interop seems to break down, at least sometimes.

And, at Boley headstock bearings Tony shows a photo of a grinding jig and geometry for cutting the two (tapered) headstock cones in one operation for the G. Boley "cone" lathes, though I don't know how they spun the stock (likely they ground them as bearings only, pressed them in, then lapped them? Who knows?) Archie Perkins shows a regrind technique like that in his lathe book, but how did they grind all those dead centers? Dunno. Harden 'em, grind the cylinder stock, grind the taper, grind the rounded butts, then grind the tips? This was before big green machines with oil and computers. Since I don't have those things either, good thing I'm not paying myself. I'm turning mine, hardening the tips and stoning 'em!

The catalog seems to be coming along pretty well, even if it's all just for the sake of curiosity. I have many G. Boley 2's (including centers and splits/wires) but one oddball split/wire collet marked with a "3" I wonder what that marking was all about? It works just fine, just further down the rat hole...

 

Normally, the number indicates the diameter in 1/10 millimetres ...

It seems that these lathe manufacturers did not make the collets themselves, but had them done by a specialised company called Julius Ortlieb & Cie. that still exists today in southern Germany, though in a different town. Sometimes you find collets marked JO (Intertwined), which indicates that it was replacement collet supplied by them directly. I have a 1930s catalogue by them that lists the collets for almost every continental European lathe manufacturer of the time.

 

Yep, thanks. Cool about Julius Ortlieb. Another "who knew?"

I was not being clear enough. The stem (not the head) of this (I think it was a #34 or so) G. Boley collet is marked "G BOLEY GERMANY3"

Looking at Dushan's third post in this thread, it made me wonder what the 3 designation meant. Maybe it's something with Julius Ortlieb?

Rat hole material for sure, as curiosity killed the cat...

 

What about the dimensions of the collets, are these WW-standards ? If they were bigger the '3' could denote the size of the lathe, as Boley designated them size 2, 3, and 4.

 

Really? Wow.

My (almost full) set of G. Boley 2's are all oiled up and in storage, so I can't measure. I had never heard of different G. Boley sizes, and have never personally seen any marked with a 4, just the really old stuff (usually in horrid shape), the rarer and more modern-looking 2's and one lonely oddball marked with a 3. Who knew?

In my G. Boley "2" set, in the nice yellow /black logo wood box (which is all I have for my traditional cone bearing setup, e.g. a long-bed with feet, and in hammertone green, maybe from the 1960's right as the F1 was coming out?) I had only one with the "3" designation on the stem and wondered what that meant. Till now, I thought that the number was for the set's taper ratio (back on topic with the 2 being 1:12 for dead centers in collets, etc. per post #3 at the beginning of this thread). I never noticed much difference besides the trumpet flare part being slightly larger, more closely resembling my Leinens, in that there was no "step" or "notch" cut between the body and trumpet flare: just one smooth cut into the flare. Maybe they are different sizes. Huh.

FWIW, the G. Boley "2" collets (and IIRC the lone "3") fit fine in all my Leinen equipment, but the Leinens (marked LEINEN MADE in GERMANY, in the big font -- likely mid-century as the guy I got them from had his name and the year 1943 scribed into his home-made box) will not fit into the G. Boley hammertone headstock. Strange, but true.

 

Cheers, Dushan. I'm making up some larger diameter tapered bits, but don't have an original to pattern them after. Looks like you may have a few? When you have a minute, would you be willing to post back with the small-end diameter and rough length dimensions for those larger-sized tapered centers/drills/mills? Thanks in advance if you can help!

 

For those interested in the taper sections/sizes for the Wolf Jahn set of (maybe a dozen) fine working tips and other tools such as the d-bit drills and 4 flute end-mills (and presumably for the Lorch lathes as well), I just got some old points and a tailstock tapered hole inside a short 7mm runner. It's the one with a brown bakelite trumpet flare on the outer end and an ejector pin with a smaller trumpet tip that fits inside it. Amazingly, though beat to death, this post may still be on topic

This is all from a 1900's-ish WJ Geneva pattern lathe, but I think it may apply to the WW styles as well: the OEM dead center that fits in my OEM W-J 8mm center threaded collet fits identically and equally well into the tapered hole in the tailstock . So, the tips and centers are all interchangeable, and at both ends. These measured from about 4.2mm at the smaller end (with a nice radius at that end) to about 4.5mm where the taper stops and the various tooling contours begin. These bits slide into the tapered hole about 8-9mm or so to seat perfectly. Copy the taper from a good center or these measurements to make anything you want, sticking with 25:1. These bits were all different lengths around 22mm +/-.

I'm used to using the Leinen bits (or Boley & Leinen), which are wider at the base and do not fit into the older, standard small center collet in sets and lathes most folks have, but require a larger hole, meaning a separate center collet with a bigger hole like the one provided the lever/handle screw-feed type tailstock which came out later. I think, but do not know, G. Boley does this larger bit size thing as well for their newer units, but have only seen F1 photos which (to me) look kinda similar to the Leinen/B&L tooling.

But, there's more...

I also got a safety roller 8mm collet with 4 OEM and 1 shop-made centers. These are the toothpick-sized ones that fit into the safety roller for super-fine work. And, there is a taper adapter in the standard bit-set that lets you use all of these tiny centers as extensions! Even better, the ejector rod that goes into the tailstock runner passes right through the hole in that adapter to eject the toothpick sized bits. If you push it farther, it will eject the larger diameter adapter. A lot of these for sale are stuck/rusted in, so at first I did not know they came out, or were missing something, etc. So, if you have a safety roller for one of these, but no center bits, use the 25:1 taper, starting around 1mm going up to 1.5mm, then make your tips with working ends projecting about 4-5mm out after that, or however you want them. Mine were about 17mm overall length.

HTH someone somewhere.

 

I just realised that I have the correct tool to measure the taper on an insert - a clockmakers sector. By opening the arms to 10mm at a distance of 200mm from the centre of the hinge (for example) I can accurately measure 1 in 20. This can easily detect the difference between 1 in 20 from 1 in 25. It has also made me realise that an apparently good fit may not be accurate. Many that I thought to be the same are not. Also, when cutting a taper, an existing insert is simply too short to be used for setting the taper. Much more accurate is by reference to a dti over a distance of at least say 40mm once you have measured the taper. By these means a set of gauges could be made. (an acceptable substitute to a sector could be made from a woodworkers folding rule with a flush pivot )
Dave.

 

While not exactly a tailstock taper, the G.Boley drillstock taper (for insertion in a solid collet) which tapers from about 4.5mm to 4.1mm over 15mm measures 1 in 22.5 using a sector.
Dave.