Dividing head advice

[Howard LewisParticipant @howardlewis46836]

If you are still looking for a Rotary Table, the vertex HV6 can, as the name says, be used in Vertical or Horizontal mode. With the face of the table vertical, the centre height is 4 inches.

The mounting slots may need to be extended to take Tee bolts / studs to enable it to be fitted some milling machine tables.

The Myford R T that i saw, bore an uncanny resemblance to my Vertex. There used to be a another lookalike made by Soba.

I use a Tailstock and the Division Plates for gear cutting, rather than the vernier scale. Although for some tooth counts, not obtainable with the three Division Plates, this may be needed..

Having made stepped dowels to align the Tailstock along the Mill table, I devised a means of aligning the Tailstock vertically, whilst simultaneously aligning the R T across the Table, after it had been set approximately with a square.

(The blank is turned in the lathe, using a Myford threaded chuck on a Myford / 2MT arbor, so that it can be transferred directly to the HV6 to minimise eccentricity )

Using this set up, I have cut gears from 20T 20DP to 100T Module 1 gears (for a mini lathe ).

I found out the hard way, that the division chart for my HV6 contained an error. Some work with EXCEL showed other errors and omissions.

So DO check that your chart is accurate for the number of divisions that you wish to produce.

A useful tip was to use a peg to prevent one of the fingers from moving whilst indexing..

HTH

Howard

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[SillyOldDufferModerator @sillyoldduffer]

Posted by Howard Lewis on 27/03/2022 15:01:05:

…

The Myford R T that i saw, bore an uncanny resemblance to my Vertex. There used to be a another lookalike made by Soba.

…

.

Does anyone know who invented the HV6-style rotary table?

Many are described today as being Vertex copies, but I suspect Vertex are a Johnny-Come-Lately themselves, and the original design is much older.

A scamper round the web shows many big names made similar rotary tables in the past: Jones and Shipman, Clausing, Yuasa, Elliot, SIP, Palmgren and several others, branded and unbranded.

My bet is on an American company, because they developed vertical mills, and at early date – 19th Century. I reckon there's a long expired patent somewhere, covering a good design, which is why they are much copied.

Dave

[Pete RimmerParticipant @peterimmer30576]

Hardinge made a HV4 but it's an indexer not a rotary table. I don't know if they made a rotary/dividing version but it should be easy enough to find out with a search because Hardinge stuff is very well documented.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Howard Lewis on 27/03/2022 15:01:05:

[…]

The Myford R T that i saw, bore an uncanny resemblance to my Vertex. […]

.

.

The Myford-branded ones were made by Vertex

MichaelG.

[CalumParticipant @calumgalleitch87969]

Since we're talking about dividing heads, there is an excellent series on a George H. Thomas dividing head build currently ongoing on Youtube:

https://www.youtube.com/watch?v=q57xnGpfhA8

Very well paced and explained, I thought.

[Grindstone CowboyParticipant @grindstonecowboy]

Just to drift slightly off-topic, the funnel shape of a blunderbuss was more to make it easier to load than to scatter the shot over a wider area. Similarly with sawn-off shotguns, it's to make them easier to conceal, not spread shot.

Back to the dividing heads…

Rob

[DC31kParticipant @dc31k]

Posted by Robert Trethewey on 27/03/2022 14:30:32:

…it appears to be a Hoffmann type unit…

Hofmann-type is a good description because it is surely not a Hofman.

For interest, their brochure is here: http://www.hofmann-rt.com/HTH-ENG.pdf

In all the online pictures of Hofmann ones, the notched indexing plate is at the rear of the spindle and there is a spindle lock (Kipp-style lever) at the front.

[John CParticipant @johnc47954]

Robert T: Your dividing head bears a resemblance to my EME model. Not an exact match, but similar in many features.

John

[RobinParticipant @robin]

I see the attraction in antique dividing heads but the days of picking up a bargain on eBay are long gone. All too often they are missing useful things like foot stocks, division plates, chucks, worms etc.

I am well pleased with my cheapy BS-0 clone. Many YouTubers try to persuade me that they have perfected the beast by changing the odd bearing, clamp or thrust washer here and there, but I think they are merely stealing the applause from our Asian chums who managed to put together this wonderful machine at such an unbelievable price.

So what would you change?

[JasonBModerator @jasonb]

Posted by SillyOldDuffer on 27/03/2022 18:51:32:

Does anyone know who invented the HV6-style rotary table?

My bet is on an American company, because they developed vertical mills, and at early date – 19th Century. I reckon there's a long expired patent somewhere, covering a good design, which is why they are much copied.

You might be a bit early there Dave, looking at my 1895 Chas Strellinger & Cp catalogue reprint there are 20 pages of lathes, 12 pages of shapers and just one image of a horizontal mill. No sign of anything like a rotary table but there is something we would recognise as a dividing head.

[Nick HughesParticipant @nickhughes97026]

Posted by Robert Trethewey on 27/03/2022 14:30:32:

I recently purchased a 6in dividing head and and have stripped and rebuilt it – However the original manufacturers nameplate had the name rubbed off – please can anyone identify for me the original manufactrurers name as the name plate says Made in Spain the part number is D1494A and it appears to be a Hoffmann type unit it weighs 50Kg it has a double sided plate with hole circles ranging from 49 down to 15 holes per circle it has a DIN 55022 or DIN 55027 faceplate see attached images 24 stop positions and power feed via 25mm shaft 6mm key

My album Robert Trethewey (6in Dividing Head Rebuild)

 

 

 

 

 

 

 

Here you go:-

Edited By Nick Hughes on 28/03/2022 18:33:03

[Robert TretheweyParticipant @roberttrethewey]

Hi: Can anyone please help me identify the Dividing Head shown in my latest album 4in Dividing Head the item I'm most interested in is finding out if anyone knows where I can find new or used pin plates to go along with the number 3 plate that came with the DH when purchased. The DH is a 4in the pin plate is 123.6mm dia. and has a knurled edge with a black plate pinned on the outside circumference saying each division =1mm the plate is 5mm thick it has a 30mm inside dia. the number 3 plate has 4 sets of drilled holes 40, 37, 36 and 29 holes. The plate is attached to it's backing piece by two chamfered screws the holes are 3.3mm dia. and have a 42mm PCD

[bernard towersParticipant @bernardtowers37738]

You've got the div head can't you make them???

[AJAXParticipant @ajax]

Posted by Robert Trethewey on 14/04/2022 10:27:17:

Hi: Can anyone please help me identify the Dividing Head shown in my latest album 4in Dividing Head the item I'm most interested in is finding out if anyone knows where I can find new or used pin plates to go along with the number 3 plate that came with the DH when purchased. The DH is a 4in the pin plate is 123.6mm dia. and has a knurled edge with a black plate pinned on the outside circumference saying each division =1mm the plate is 5mm thick it has a 30mm inside dia. the number 3 plate has 4 sets of drilled holes 40, 37, 36 and 29 holes. The plate is attached to it's backing piece by two chamfered screws the holes are 3.3mm dia. and have a 42mm PCD

I've not used a dividing head, but I'm guessing the plates don't need to be particularly robust. Would a laser cut and engraved plate in 4 or 5mm cast acrylic be acceptable? I could do a run of them if they proved ok.

[John HinkleyParticipant @johnhinkley26699]

Robert,

You say in your post that the outside of the plate shows 1 division = 1mm, but the photo shows 1 division = 1 min. Either a misreading or typo.

Sorry, can't help with the identification. They are all basically the same internally – at least in the manner of their function – what you need to know is the worm/wheel ratio to aid with the choice, or design, of additional plates. Yours is unusual in that it is secured with only two screws. Most that I've seen use three. That, in itself may help to narrow down the manufacturer.

Good luck,

John

[HopperParticipant @hopper]

A couple of overall pics showing the entire assembled divding head from different angles might help ID it.

[John HinkleyParticipant @johnhinkley26699]

Robert,

Just done a search for images and, lo and behold, Warco have come up with a set with two hole fixing. Product number 8146. Might be worth getting in touch with them and get some dimensions?

John

[Michael GilliganParticipant @michaelgilligan61133]

From the photos in your album, it looks very nicely made Robert

But I regret that I too don’t recognise it

MichaelG.

[Peter Cook 6Participant @petercook6]

For one off or occasional use it is possible to 3D print index plates.

[Howard LewisParticipant @howardlewis46836]

Some time ago, there was an article about making Division Plates.

It suggested using scrap CDs or DVDs. The method was make the first "new" division plate, and then use it to produce a replica. and so on until an acceptable level of accuracy had been achieved. With each iteration the error would be reduced by a factor which was the ratio of the Dividing Head / Rotary Table being used to set the intervals.

With a 90:1 ratio, the third plate to be produced should be fairly accurate with errors being reduced by a factor of 8100.

Howard

[DC31kParticipant @dc31k]

Posted by Robert Trethewey on 14/04/2022 10:27:17:

…the pin plate is 123.6mm dia. and has a knurled edge with a black plate pinned on the outside…

If you were a manufacturer offering this facility on your dividing head, would you duplicate this feature across all plates in the set? How much would that cost you? Is it not highly likely that the other plates do not have this feature and will just have a plain edge?

In addition to the other ideas, there are numerous webpages (e.g. https://www.cgtk.co.uk/metalwork/calculators/divider) where you can print out a piece of paper with the necessary divisions on it. Print it out at A4, photocopy it to A3 (approx. 300mm diameter) and attach it concentrically to your plate blank. Line up the marks with a pointer. Assume some error in your lining up – say 1/2mm. Work out the angular error 1/2mm at 150mm radius gives (1/300 of a radian or about 12 minutes of arc).

[John HinkleyParticipant @johnhinkley26699]

I've had another look at your album and I see that there are 360 divisions around the periphery of the plate. That would make the worm ratio 90:1, so that 90 turns of the handwheel results in one full revolution of the table.

John

[SillyOldDufferModerator @sillyoldduffer]

Posted by John Hinkley on 14/04/2022 17:28:46:

… That would make the worm ratio 90:1, so that 90 turns of the handwheel results in one full revolution of the table.

 

I started with that, and thought the dividing plates for Robert's machine would have the same number of holes as an HV6. But they don't!

HV6 plates have:

A: 15, 16, 17, 18, 19, 20 holes
B: 21, 23, 27, 29, 31, 33 holes
C: 37, 39, 41, 43, 47, 49 holes

Which match the corrected table supplied by Howard Lewis.

Whereas Robert's No 3 plate has 29, 36, 37 and 40 holes

Presumably, HV6 plates will work on Robert's Dividing Head providing his machine really is 90:1 and the plates are the same size. I'll measure mine and report back later.

Yer tis.

Or, forget the pin-clock attachment thingy and drive the head with an Arduino and stepper motor.

Dave

 

 

Edited By SillyOldDuffer on 14/04/2022 18:14:02

[Michael GilliganParticipant @michaelgilligan61133]

You may like to play with this calculator, Robert :

**LINK**

https://www.cgtk.co.uk/metalwork/calculators/dividing

I’ve just tried your worm ratio & available holes, and it seems to work nicely.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Hinkley on 14/04/2022 14:28:49:

Robert,

Just done a search for images and, lo and behold, Warco have come up with a set with two hole fixing. Product number 8146. Might be worth getting in touch with them and get some dimensions?

John

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Good find, John

‘though I was astonished to read this on Warco’s page :

”Please note the number of fixing holes shown in the photo may vary.”

MichaelG.

[Author]

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