dividing head question

Following on from my rotary table question earlier in the week, i have a question about dividing heads. The table on my tom senior universal can swivel (obviously) and the lead screw on the x-axis has a keyway on one end to allow a universal dividing head to be geared to it to cut spirals or helical cuts on gears etc. Has anyone here ever done any of that type of work ? I hope to buy a universal dividing head soon, not that i have any particular work in mind for it, but it is another string to my bow. Does anyone know the maths involved in working out the gearing from the table to the head ?

Yes done it years ago, you need a table of leads [ correct spelling but said leeds, not ledz ]

That link I gave to the book on milling also has good info in it and the table of leeeeds

Edited By John Stevenson on 28/06/2013 22:47:27

I've never actually needed to cut spirals or a helical gear, but I did set up my universal mill and dividing head with a gear train some years ago, just to see if it all worked as advertised. Which it did. The calculations are pretty straightforward, and are covered in Machinery's Handbook.

Regards,

Andrew

my machinerys handbook is so old its carved in tablets of stone, but i'll have a look and see if i can find the info i want. Thanks john and andrew.

The standard ratios are in machinery handbook. Also in the manuals for univesal heads such as Elliott or Brown and Sharp.
However they assume the standard set of 11 gears. It is very rare to find these gears with the head as so few people associate gears with dividing heads they must get lumped in wih the lathe during workshop clearance. However you can use other gears and play with a spreadsheet.

I agree with Grahams "What needs to happen" approach for working out screw cutting either with the rotary table / mill approach or on a lathe. I just keep a note of the number of teeth on all the gears I have, the ratio's available on the gearbox on the end of the leadscrew and the pitch of the lead screw.

Les.

I made some helical gears as part of my apprenticeship back in 1989.

Not difficult but if you want to cut this type of gear you will need to rotate the machine table too. This is to stop the rear of the cutter 'back cutting'. Backlash will be a problem, so remove the cutter from the work when reversing the table to the start of the cut.

Other than that I can't remember a lot. I made some nice candlestick lamps too this way which had a nice twist up them.

Andy.

Funnily enough whist sorting out the workshop due to the parting out of old machines and influx of new the rope round my waist slipped and I was able to reach into a corner not been entered since about 1539 and I came up with a full set of brand new gears for a Cincinatti dividing head.

New but shop soiled.

Quick overnight soak in the Brick and Patio cleaner and good as new.

Only problem is, not got a dividing head that doesn't have a stepper motor drive

Sounds like an archeological dig in your workshop might prove fruitful

Impressed by the cleanup of those gears though - just straight patio/brick cleaner you say?

Chris

John,

Are you sure they are Cincinatti and not K&T from teh look of the splines? If the latter I would be very interested.

Baz,

To be honest not sure, they came from a college that had Cincinatti gear hence the guess.

Certainly no K&T machines.

I do have the full set with splinded sleeves etc and could measure one up if you are interested.

These are just one of the many articles I need to par down.

Also found a brand new set of leadscrews and nuts for a Myford VMB, these have got to be as rare as rocking horse snot ?

John. Will pm you

Chris,

read this thread.

http://www.model-engineer.co.uk/forums/postings.asp?th=83882

Edited By John Stevenson on 29/06/2013 13:00:02