Dividing head advice

[Steve355Participant @steve355]

Posted by JasonB on 29/12/2021 10:29:53:

Steve, those items in you photo are really indexers as they will just give a small range of numbers which will divide into the 48notched plate eg 2. 3, 4, 6, 8, 12 & 24.

If you could do away with the chuck and mount the gear blank to a short arbor fitted to the taper you may just be able to get it low enough to be able to cut a 45deg bevel, nor sure if there is a way to retain the tapered arbor in the socket.

I notice you also have a Dore, why can't you use that and just angle the dividing head on the mill table? That's how I do bevels on my vertical mill.

You are right about the Burke head, I found some more pictures of it, which showed numerous indexing plates, simply with different numbers of notches around the outside. So that one isn’t much use.

I could certainly use the Dore Westbury, however having now bought and refurbished the Burke horizontal mill, if I am to buy a dividing head I would like one if possible that does fit it. It came with a number of involute cutters, and has clearly been used for that purpose in the past, and gear cutting is a natural operation for a horizontal mill.

I took another look at the grinder I want to fix, looks like it’s a 5 1/4” gear with 144 helical teeth.

Perhaps I will start with a couple of change gears for the lathe!

Steve

 

 

Edited By Steve355 on 29/12/2021 12:16:55

[JasonBModerator @jasonb]

Well you could always just use the existing gear to index 144T on the new one or just make a section to fit into the gap and save yourself the cost of a dividing head.

[Anonymous]

Posted by Steve355 on 29/12/2021 12:09:46:

…..looks like it’s a 5 1/4” gear with 144 helical teeth.

If it is a helical gear then one ideally needs a universal dividing head (where the dividing head can be driven by the table leadscrew) and a universal mill (where the table swivels). Like this:

To cut the tooth spaces on a helix:

However, if the gear is narrow, and the helix angle small, then one might be able to get away with a straight cut at the helix angle. A picture of the gear in question would be useful.

Andrew

[DiogenesIIParticipant @diogenesii]

..there're a few bits and pieces that might be of interest here, not that easy to hit results from a search, but if you pick your way through the various indices..

Vintagemachinery.org – Photo Index – Jefferson Machine..

..if nothing else, you might find some further 'names' to do further searches on, small dividing heads & indexers were also made for lathes & shapers..

[Steve355Participant @steve355]

Posted by Andrew Johnston on 29/12/2021 14:49:18:

Posted by Steve355 on 29/12/2021 12:09:46:

…..looks like it’s a 5 1/4” gear with 144 helical teeth.

If it is a helical gear then one ideally needs a universal dividing head (where the dividing head can be driven by the table leadscrew) and a universal mill (where the table swivels). Like this:

To cut the tooth spaces on a helix:

However, if the gear is narrow, and the helix angle small, then one might be able to get away with a straight cut at the helix angle. A picture of the gear in question would be useful.

Andrew

here’s a couple of pics Andrew. The small gear is clearly helical, but the large one (the one I want to remake) may just be diagonal cuts. I would say that if a universal table and head is needed, that’s well beyond the scope of me and my little mill. I’ve just had this grinding wheel for ages, it has a broken gear, and I thought it might be a decent little project to learn the process. But perhaps not… there are probably much easier ways to fix it – a welder and a file come to mind.

Steve

[BazyleParticipant @bazyle]

Don't worry, you don't need the rotating bed for that, just move the vice or whatever over at an angle. And you don't need a dividing head to make the repair piece. After silver soldering in a repair piece (remember to heat all the gear not just locally to avoid stress) you can mount the gear and with a detent in its one of its own teeth to align the cutter with an existing tooth. Then index off the teeth.

[Neil WyattModerator @neilwyatt]

Posted by Steve355 on 29/12/2021 12:09:46:

Posted by JasonB on 29/12/2021 10:29:53:

Steve, those items in you photo are really indexers as they will just give a small range of numbers which will divide into the 48notched plate eg 2. 3, 4, 6, 8, 12 & 24.

If you could do away with the chuck and mount the gear blank to a short arbor fitted to the taper you may just be able to get it low enough to be able to cut a 45deg bevel, nor sure if there is a way to retain the tapered arbor in the socket.

I notice you also have a Dore, why can't you use that and just angle the dividing head on the mill table? That's how I do bevels on my vertical mill.

You are right about the Burke head, I found some more pictures of it, which showed numerous indexing plates, simply with different numbers of notches around the outside. So that one isn’t much use.

I could certainly use the Dore Westbury, however having now bought and refurbished the Burke horizontal mill, if I am to buy a dividing head I would like one if possible that does fit it. It came with a number of involute cutters, and has clearly been used for that purpose in the past, and gear cutting is a natural operation for a horizontal mill.

I took another look at the grinder I want to fix, looks like it’s a 5 1/4” gear with 144 helical teeth.

Perhaps I will start with a couple of change gears for the lathe!

Steve

Edited By Steve355 on 29/12/2021 12:16:55

In the good old days, a skilled fitter would file a dovetail for a plug of cast iron to fit in, then hand file the teeth.

Neil

[Steve355Participant @steve355]

The thing is, the pic shows the worst area but there are several other damaged teeth, perhaps 5 or 6 damaged areas altogether. One other damaged tooth can be seen in the pic of the gear out of the casing. Hence why I was considering making a new gear originally.

The purpose was to learn how to do it rather than necessarily fix this 110 yr old grinder. But fixing it is on my list of things to do so I thought perhaps I could combine the two.

Anyway, assuming I am going to do the repair on the mill and not with a file, I would still need a chuck or arbor holding device to keep it steady and concentric. If so, I may as well get a dividing head or similar.

Steve

Edited By Steve355 on 29/12/2021 22:30:52

[Howard LewisParticipant @howardlewis46836]

144T and 5.25" dia gives 27.8 DP, so 28DP, for a 5.21" OD?

Since it is an old machine, a guess says 14.5 P A?

Relatively easy, if it were a spur gear. The inclined teeth make it more difficult, but not impossible, if the teeth are straight rather than genuine helical.

So the D H will need to be set at an angle across the table of a horizontal mill or inclined on a vertical mill.

It will be interesting to know how you proceed.

Howard

Edited By Howard Lewis on 29/12/2021 22:46:57

[Anonymous]

Posted by Howard Lewis on 29/12/2021 22:46:04:

144T and 5.25" dia gives 27.8 DP, so 28DP, for a 5.21" OD?

The equation for OD, number of teeth and DP for a spur gear does not work for a helical gear. The helix angle also needs to be taken into account. A helical gear has two DP values, normal and transverse. Normal DP is most common, ie, the DP at right angles to the helix. If I get time I'll look at the numbers in more detail later.

My gut feel is that straight cut teeth would probably work, although it would depend upon the precise application and how fast the gear runs. I'm not sure what grinder means; the gear shown looks similar to that on my defunct power hacksaw, used to give a substantial speed reduction.

Andrew

[JasonBModerator @jasonb]

Large dia wet wheel grinder maybe, my Tormek stone runs very slowly.

Tooth count on the pinion would be helpful for those wanting to crunch the numbers as that can be used to get the two helix angles.

[Steve355Participant @steve355]

It’s a simple hand crank bench chisel grinder. The type your grandad had in his garage. Quite old, made in 1910.

[JasonBModerator @jasonb]

Ah so the big one is the pinion

You can use an online calculator to work out angles and the DP. I did it for 12T & 144T but just change the tooth count to suit your machine

[RobinParticipant @robin]

Posted by Mick B1 on 28/12/2021 12:50:4

Hey, if you gotta source for blunderbusses that can compete with used divvy heads on price, please share!!

You couldn't expect a sliding safety or the spring bayonet of course

[Mick B1Participant @mickb1]

Posted by Robin on 30/12/2021 10:39:05:

Posted by Mick B1 on 28/12/2021 12:50:4

Hey, if you gotta source for blunderbusses that can compete with used divvy heads on price, please share!!

You couldn't expect a sliding safety or the spring bayonet of course

Very nice collection there. Never tried one myself – do you shoot any of them? Top and middle ones look as if they're made for a realistic dispersal pattern of shot. Fourth one down looks especially exaggerated, presumably for visual effect.

I guess it'd be hard to find a use for that many divvy heads…

[Steve355Participant @steve355]

That’s the first time I’ve had a thread hijacked by an actual highwayman

[RobinParticipant @robin]

Posted by Steve355 on 30/12/2021 11:53:54:

That’s the first time I’ve had a thread hijacked by an actual highwayman

Oops! Back on topic… The Vevor BS-0 spindle is bored through at 0.735" which is 12 bore but they haven't cut the chamber

[DiogenesIIParticipant @diogenesii]

Just for the interest, there's a D/H on Ebay at the moment that is the right kind of thing – it's currently bolted to a sub-plate, but was originally supplied for a centre-slot machine…

Ebay – Indexing head…

[Clock polisherParticipant @clockpolisher]

Good evening,

For work on longcase clock parts I took the very easy way out of buying a 3 inch diameter tilting rotary table and chuck backplate from WARCO. The backplate has an M14x1 stub thread. £80 or thereabouts brand new.

I tried to get a new 3 jaw chuck but failed miserably, imports just aren't accurate enough. Ended up with a three jaw from a Unimat 3 which screws straight onto the plate. £60 second hand from EBAY.

I can set any whole number angles using the scale on the table, for any uneven angle I go back to geometry and mark the required intervals out on a piece of paper which I then fit behind the chuck mounting plate. Using an external datum point I wind the table round to that point and Bob's a relative.

regards,

David

[Tony Pratt 1Participant @tonypratt1]

Posted by DiogenesII on 30/12/2021 18:52:04:

Just for the interest, there's a D/H on Ebay at the moment that is the right kind of thing – it's currently bolted to a sub-plate, but was originally supplied for a centre-slot machine…

Ebay – Indexing head…

I think the seller is dreaming at £275 but we will see.

Tony

[JasonBModerator @jasonb]

If the steps on the hop up it is stood on are anything to go by then it's a 6" maybe even 8" chuck so no way it will fit on the small mill and no tilt for the bevel gears either.

[Steve355Participant @steve355]

Posted by JasonB on 30/12/2021 19:42:52:

If the steps on the hop up it is stood on are anything to go by then it's a 6" maybe even 8" chuck so no way it will fit on the small mill and no tilt for the bevel gears either.

Yes, I had the same thought about that one.

Most vintage DHs on eBay seem to be professional tools for large mills, with a minimum centre height of 5.5”.

I keep coming back to the same choices… the Hemingway ones, which don’t tilt, may not be rigid enough and tend not to come with chucks. Or the Vevor 4”, which on paper is too big to use with the supplied tailstock on the Burke #4 …. But presuming the centre hole is MT2, a suitable arbor could be made.

looking at the rotary table, it seems the tilting ones don’t divide, and the dividing ones don’t tilt. So that’s out i think.

And watching Keith Rucker cut bevel gears, he didn’t use a tailstock (how would you) but I’m not sure if my bevel gear would work or not, it would be close. But if it failed I could fall back on the Dore Westbury, which has acres of headroom.

[JasonBModerator @jasonb]

It's not impossible to mount Hor/vert rotary tables at an angle, I've certainly done it a few times and also have a small indexer that I can put in my mill vice at any angle.

tailstock is generally not used for bevels but most do have some height/angle adjustment which is useful when working with long tapered parts like fluted columns

Edited By JasonB on 30/12/2021 20:30:47

[IanTParticipant @iant]

Posted by David George 1 on 28/12/2021 17:42:29:

Hi Steve this is my dividing head.

It has two positions taller for larger diameters on its side for more clearance under spindle. I bought it from the last Doncaster show for about £40.00 but I had to make two more plates for the gears I needed to cut.

David

Pretty sure this is a Timmins Dividing Head David – nice size for a Myford type machine, comes with a Myford chuck 'nose' and MT2 taper.

As David notes, it can be used on it's side (on a Myford or similar) or upright (on a Mill table). There's a matching tailstock casting too should you need one. Still available from Blackgates I believe (with the MT2 taper already machined). Doesn't "tilt" as such but you could probably work out a way to 'angle' it if required.

Big advantage is that they don't seem to go for the same kind of price as the other popular D/H alternatives but can still do just about everything the others can do too.

Regards,

IanT

[Robert TretheweyParticipant @roberttrethewey]

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)

[Author]

Posts