Dividing head for lathe - Myford vs BS0/1?

I have a Myford 254s lathe - centre height 4 3/4" , and I'm looking at buying a dividing head to cut spur gears. Could anyone give me the various pros and cons of the Myford dividing head versus the BS0/BS1 types available from the usual suppliers?

They seem to be very different designs. The Myford ones seem designed for lathe use but are expensive and seem flimsy, whereas the BS0/1 look good value, sturdy and versatile, but perhaps I don't have enough height from the cross slide table to get effective use from them.

The lathe will soon have an emco mentor milling attachment bolted to the bed (I don't have the room for a separate mill), but I'm not sure whether it has the rigidity necessary to mill the gears, and I may end up using the headstock instead.

Lots of variables here I know, but the knowing the pros/cons of Myford vs BS0/1 type would be a good start

The BS0 is way too big for a lathe, especially as you probably wouldn't have it on center line of the bed. A lathe cross slide is not very soid and relies on gravity for the most part to hold it in place plus there isn't much real estate for mounting.
Look at the GHT and Sparey designs or just plan to use the main spindle.

I have an Alan Timmins dividing head which came from Blackgates as it has the same spindle and thread as the Myford and chucks etc can be used on it.

David

Another alternative is the GH Thomas designed Versatile Dividing Head. Kits available from Hemingway and sometimes completed examples come up for sale in the usual places. A job in itself to make one yourself though.

The thing with using dividing head in the lathe is it has to be small enough to bolt onto a vertical milling slide so it can be used in most instances. And for larger gears, you won't get the blank in underneath the cutter so they have to be perched up fairly high, or the vertical slide swivelled at an angle and suitable adjustment made to achieve correct tooth depth. ISTR GH Thomas's books outline this method. And on the "normal" Myfords such as 7 Series, there is a raising block that goes under the vertical slide to accommodate the extra height needed for gear cutting.

The genuine Myford dividing heads seem to be advertised for pretty steep prices these days.

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There is a great deal of merit in that approach

Generations of watch and clock makers can’t all be wrong

MichaelG.

The Vertex BS and their clones are designed to fit milling-machines, not lathes, so it's not really a fair comparison.

I have Warco-badged, Vertex copy, and it would be a struggle to use it on the Harrison L5, bigger than the Myford, even I fit the L5's boring-table and the centre-heights match. It would not be suitable for gear-cutting anyway because it would have no vertical travel, and so be limited to certain radial tasks over a small radius range.

If division-milling in the lathe, especially operations like gear-cutting, you need the attachments designed for such work on that the lathe.

Thank you all - I can now stop scratching my head about the BS type heads. I think the Myford one is the way to go as I don't have the time (or skill, probably) to build one from a kit.

There's one up at the moment, but the Morse Taper looks heavily scored. I have an MT2 reamer, but I think it would need to go too deep to get the scores out.

Scores don't matter. It's the raised burrs around the edge of them that do. If you can ream the raised bits down flat, probably will be ok. Depends on how extensive the scoring is of course.

I have a Myford Dividing Head which can be mounted to divide the lathe spindle or on a raising block or vertical slide. I also have a George Thomas versatile dividing head which is cross slide mountable at centre hight and a Headstock (GHT Radford design) dividing head that attaches to the bull wheel. The last unit is stepper converted and is very usefull for clock wheels along with it's electronics but I also have an overhead drive which drives a spindle mounted on the vertical slide. The GHT cross slide unit is also mountable on my mill using adaptor plates and has it's own tailstock. With the micrometer adjust on the GHT and the GHT/Radford any angle can be set. I do have a BS dividing head but I have never used it.

If you are cutting clock wheels (high speed cutter) I suggest dividing the lathe spindle and using an auxilliary spindle for the cutter, if it's spur gears in steel for traction engines (low speed cutter) then you need something on the crosslide/ virtical slide or on the mill.

regards Martin

Someone used to sell the GHT version ready made. I thought it was RDG, but can't find it on their website. No idea on quality.

It was and they were very good.

regards Martin

I can't see why a BS0 dividing head (4" centre height) fitted on the cross slide of a Myford 254S and a Mentor milling column bolted to the back of the lathe bed, which has flat ways with a vertically restrained cross slide, wouldn't work very well for milling gears. The Myford dividing head would need some sort of mounting since it is designed for fixing to a vertical slide.

Rod

It is not that it couldn't work but the thing weighs 40lb. I don't recommend buying a 7.5 ton truck for nipping down to the corner shop.

It probably would have helped if I'd said what size gears I want to cut. The first job will be some 16DP sacrificial gears in tufnol - up to 100 tooth, but I'd like to have the option of cutting them in steel or cast iron in the future. I realise that's going to push my setup to the limit, and will need a lot of fine passes.

The Myford Rotary Table, looks to be a rebadged Vertex HV6 . In which case it will have a 4 inch centre height, and will require a raising block to raise it to the centre height of the 254.,Nominally 3/4" by the sound of it.

But, is the 4 3/4" the centre height over the Bed or the Cross Slide?

Presumably, you are thinking in terms of mounting a gear cutter on an arbor, either in a chuck, or on a Morse taper, so that the Cross Slide sets Depth of Cut, and the Saddle is moved along the bed to provide the feed, while the Dividing Head / Rotary Table takes care of the dividing?

Mounting the DH or RT on the Saddle may bring the centre height above that of the Lathe, unless the raising block can be attached to the Cross Slide by some means, whilst resting on the lathe bed.

Howard

Edited By Howard Lewis on 05/03/2021 17:14:28

Yes it's 4 3/4" above the bed. I think the centre height to cross slide is 83mm, which rules out an HV4/6 if the cutter is in the headstock, though I think the old type Myford dividing head attached to a vertical slide would be able to manage it, using the methods outlined by GH Thomas.

Also, if the Mentor milling column can handle the size of gears I want to cut, then it looks like I have a lot more choice. It's arriving next week, so I guess I need to install it and make a few test cuts before deciding.

Apart from high speed cutting of clock wheels,I never did see any point in using a lathe spindle as the dividing element and cutting with another attachment, A lathe spindle is designed to be used for driving work and cutters so why waste the spindle,far better to have a separate index device,I have a Myford dividing head,and found it useful,the only snag as I see it is that the main workholding device is the chuck which being threaded could under intermittent cuts become loose. though this can be overcome by using the 2MT spindle socket,and make up a mandrel to suit the socket and secure the gear to be cut,support the outer end of the mandrel with the centre. There are a lot of illustrations in tearly technical books of workpieces secured via the M/Taper. the mandrel should be secured in the taper by a stud and nut, and idealy the gear held firm by a nut and a keyway in the gear locating in a key way in the mandrel. The book "a practical treatice on milling "by Brown and Sharpe who were one of the most famous machine tool makers in years gone by is a good read I got mine via ABE books for a few pounds those published in the 1930s are very good though it shows industrial use not model work,though there is a good chapter on gear cutting.

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... perhaps because the lathe spindle is far more robust than most attachments, and it can also accommodate large workpieces.

The [relatively small diameter] cutter can be on a light bearing with small ‘swing’

MichaelG.

As you say cutting clock wheels is a very good reason to divide the headstock indeed any second operation where it is useful to be able to do the machining at the same setting and hence concentricity. Cutting spines, drilling on a pitch circle for lantern pinions, cutting squares on the ends of shafts, planing straight knurlings, engraving chapter rings and micrometer dials and stamping numbers the list goes on. Possibly the only reason for a dividing head on the crosslide/vertical slide is cutting spur gears which are better done on the vertical mill in any case.

regrds Martin

16DP x 100 teeth is over 7 inches outside diameter. Pretty ambitious in a small lathe. I would think you will need a substantial raising block under the Myford vertical slide even using the GHT angled slide method.