Cos-Par Alfa 1 Universal Divider - Universeller Teiler

I was extremely lucky and bought a very beautiful Cos-Par Alfa 1 Universal Divider - I'd thought I'd be outbid but guessing that I was very lucky and others either didn't know what it was or couldn't lift it.

I'd initially thought that it was a direct and indirect divider with 2 dividing wheels for indirect dividing and the option to use off-the-shelf or custom made custom dividers for direct dividing.

Looking at it in more detail though I realized that I'd got something more special in my hands. It can be attached to an external drive and I think the idea is that a blank divider disk can be made and slots cut in the reverse side of it so that it can act as some sort of programming wheel to allow the indirect divider to be programmed to automatically move through a predefined sequence of steps. It's more sophisticated than any other mechanical divider I've seen though and I'm having difficulty working out how to use it in fully automated mode. I can't find anything about it online. Does anyone have any details?

Here are some photos then a video with the indirect dividing disk removed to show the mechanism in action :

Cos-Par Alfa 1 Universal Divider - Universeller Teiler Video

Edited By Will Robertson on 30/03/2023 23:15:22

Edited By Will Robertson on 30/03/2023 23:16:06

Wow! One lucky find!

I wonder if is not only for static spin-indexing and compound dividing, e.g. for cutting spur-gears, apparently using change-wheels as well as the usual "holy" division-plates.

It's not clear from the photos, but can it also be used for spiral-milling: helical gears and worm-wheels, long-lead threads, and similar work, for which the spindle is usually geared to the milling-machine's long-travel screw?

It has had careful owners too. Yes the paintwork and labels are rather aged, but the direct-indexer is still shapely, the chuck jaws seem in good condition.... Look too at the circular nuts on the operating-spindle: still square-edged, not bashed about by hammers and makeshift drifts!

'''''

I have just had a far-out thought, looking at the labels on this dividing-head. Recalling that strange "circular slide rule" that had us all foxed a couple of years ago now, might that have been some sort of highly-specialised gearing calculator?

You might have to look at it in more detail than the detail you have already used to look at it. In particular, look at universal dividing heads from other manufacturers. There is a great deal of free information on the US manufacturers at vintagemachinery.org . Both Cincinnati and Brown & Sharpe have treatises on milling, both of which show how to get the best of item.

If you peruse that, you will realise that the device, although a beautiful work of engineering, is not 'special'. It is a canonical example of a universal dividing head. Once you know the concepts of the class of machine you have, some intelligent use of Google translate will allow you to work out what the data plates are telling you.

Possibly the most relevant publication at vintagemachinery is this one:

http://vintagemachinery.org/pubs/detail.aspx?id=27825

Ah - I had not quite twigged the purpose of the gears. They are for the technique of Differential Dividing.

My own dividing head is a clone of the simpler Vertex device using only division-plates.

A nice bit of kit, too big for the mills at the museum, a bridgeport size mill would be a good match. It must have been made for the German speaking market, by the Italian manufacturer.

Lovely bit of kit; did it come with all the gears, brackets and a tailstock?

It can be used for direct indexing using the plate behind the chuck, simple indexing using the division plates and compound, and differential, indexing for divisions not available using the standard division plates. As stated above, in conjunction with a universal horizontal mill it can be used for milling helical gears:

Or on a Bridgeport for high helix gears:

Like this:

Andrew

Hi Andrew,

Thank you very much!

Those are wonderful photos of helical gear making!

Although the indexer itself seemed in very good condition (there was a little backlash but I think that can be adjusted away, addressed by locking before each cut or addressed by always cutting in the same direction) the tailstock, gears and brackets were all missing - one of the direct indexing wheels had a few teeth missing but I think they were intended to be replaceable so that custom direct indexing wheels could be made for frequently used sequences.

My guess was that I could run without the tailstock if I kept the cuts very light - or should maybe try to make a new tailstock for it?

With the gears and brackets missing would it be better to replace them with a stepper or servo motor and driver and use electronic synchronisation?

The part that fits into the notch at the top looks like it was designed to be easily removable and replaceable - is that simply so that it can be removed when using a gear train to move the indirect indexing wheel for differential dividing? What does the second notch cut into the back of the dividing wheels do?

Will

Hi Nigel,

Yes - I was lucky to find such a beautiful instrument. I work as a climbing arborist and one unusual requirement of the work is very fine control over enormous muscle power - I suspect that others may have been put off bidding for equipment like this by being unable to lift it.

I bought it in Switzerland so guessing that it must have been made near Milan then labels made in French, German and Italian for the Swiss market.

> still square-edged, not bashed about by hammers and makeshift drifts!

Yes - makeshift drifting is one of my pet hates.

> I have just had a far-out thought, looking at the labels on this dividing-head. Recalling that strange "circular slide rule" that had us all foxed a couple of years ago now, might that have been some sort of highly-specialised gearing calculator?

Yes - it looks like differential dividing - which until Andrew's explanation above was a technique that I'd only known very vaguely about (I'm from the CNC generation...).

Will

Thank you very much.

That's a very valuable reference and one that I'll definitely use in the future - for my CNC generation there were a lot of techniques like differential dividing that weren't taught.

It's very valuable for me as well to know the general technique of when I cannot find the manual for a specific piece of equipment searching for a manual for a piece of equipment which is based on the same principle.

Will -

It should be used with a tailstock even if you need make one, or make some sort of adaptor for a tailstock borrowed from the lathe; at least on work needing a long overhang such as features on long shafts, and gear-cutting needing maximum rigidity and long run-outs. One sold by e.g. Warco for the Vertex clone dividing-head might work - if necessary with a raising-block.

'

Stepper-motor? Why try to complicate it? Try to keep as original as possible - especially having complimented it on its looks!

It was made in Italy for a German-speaking customer so the gears are almost certainly of mm Mod pitches though I would not like to say what pressure-angle. So it would be worth looking at what stock wheels are available, from e.g. HPC. The bracket could be designed and made from studying manuals for similar dividing-heads. It does depend a lot on how much very advanced helical milling you intend to do!

.

Those two slots in the plate puzzle me - I'd guess they are part of the controls that engage and disengage particular functions.

....

Climbing arborist.... I know an ascender from a descender and have used them enough times, but I do envy your evident head for exposed heights!

I sent the person who'd sold me the divider the information that people on here had found - he used it to have a search around his workshop and found this:

Buy some Lottery Tickets, whilst you are on a winning streak !!

MichaelG.

Wow! Almost a home run; looks like ten gears (?) whereas a standard set is eleven gears. Banjo and gear studs are an excellent find. I had to make new studs for my my dividing head.

Andrew

When you see a set of gears, eg on ebay, the inclusion of 86 is the tell-tale that they are dividing head not lathe wheels.
You will find charts for differential indexing on the internet but check the calculations as there are a couple of mistakes in the B&S ones. Also see Machinery Handbook of course, if you can read the tiny print.
you have been lucky to get what looks like the full set of 11 gears to allow indexing up to 500. For anyone who is 'making do' check the tables, work out the ratio the gears are providing, and use any other gears from your lathe to make the ratio - there is nothing magical about the actual gears used in the tables except that it was some clever mathematician that worked it out way back with only a Babbage computer to dream of helping.

The extra slot in the plate is odd but might be for linking, 'compounding' , two plates back to back for 'compound indexing' which is rarely used or referred to now but uses two sets of holes simultaneously. It should get more press as it can be used with a non-universal dividing head with minor adaptations.

That looks to be a very good quality dividing head with some similarities at least to the Brown & Sharpe universals.

Fwiw, I'd be checking that dividing heads worm and wheel ratio first. It "should" be 40-1 since most dividing head manufacturer's seemed to chose that ratio. But with an unknown head such as that one, there's really no way to be certain without verifying it yourself. To do so, all that's required is to count how many turns of the crank are needed to rotate the spindle by one complete revolution. If it really is 40-1? Any tables for any other 40-1 ratio universal dividing head can be used with yours. You'd also have to know the exact pitch on your mills X axis feed screw to do the gearing calculations for any helical milling. Secondly I would measure your heads exact center line distance from it's base. With that information then it should be easy enough to just buy a used or new dividing head foot stock instead of trying to build something that could easily cost far more in time and materials as Nigel has mentioned. The Vertex foot stocks are fairly decent or good enough, not hugely expensive, and one of there various sized foot stocks might well work with yours. On average, a great deal of work that's being machined with a plain, semi universal or true universal dividing head will use some type of mandrel to mount and rotate the work. Machining with the work or mandrel held between centers is also common. So to get the full use out of a head like that, then having a decent, rigid and adjustable foot stock really isn't optional.

While my Vertex universal was supplied with a 3 jaw chuck, in my opinion a chuck of that type on any dividing head is just about worthless due to the inherent run out all of them will have unless there of the set true type. Proper and highly accurate gear cutting really does require much better accuracy than most 3 jaws will have. So I think I'd be wanting a good brand name independent 4 jaw or re-machine that 3 jaw to a set true design instead if it has a back plate. I'd also positively identify what that heads internal spindle taper is. Hopefully it's something common such as a Morse Taper. But many were produced in at least Jarno and B & S tapers as well. Common off the shelf machinable Morse Tapers with stub ends and threaded for a draw bar are also quite handy for mounting short parts if your again lucky enough to have that taper with yours. So checking the condition and for any damage in your heads spindle taper is also important. There's too many and even professional level machinist's who are a bit too nonchalant about using damaged, dirty or rusty taper tooling inserted into what should be very high precision spindle tapers who really ought to know better.