Mods to a Dividing Head

[chipenter]

I have just got out of hospital and am not allowed to do any heavy work , I have had this indexing head for thirty years it came with four disks 24,30,36 and 42 divisions , as I make clocks this wasn't enough so I made an attachment for dividing a 30 to 1 worm from a burnt out motor but it has backlash , I decided to improve it needed a new worm to fit my 20dp change gears so I set the lath up before the opp to just turn handles and push buttons .

[chipenter]

I was surprised to find that the angle when the worm was clamped to the wheel was only 3 degrees , set the frame over and drilled for the spindle and milled a slot in the head , I can fit 35 ,40 ,45 and 50 change wheels I haven't done all the calks yet but I get more numbers from my 30 wheel so modified that to fit as well , so why are dividing heads usually 40 to 1 if you get more divisions from a 30 or 60 to 1 ratio ?

[vtsteam]

I thought 60 to 1 was the favored ratio.

[awemawson]

Well I suppose 60 can do all that 30 can do. We need John S to chip in here as he's done lots of work hobbing gears and worms for rotary tables

Andrew

[chipenter]

Well I know Ellis and Vertex are 40 to 1 , still punching numbers in the calculator in fits and starts .

Jeff