Thread: gear cutting set up

my first serious project on my newly aquired tom senior major milling machine is to cut some gears for my dglmh hercus lathe. Metric to imperial 39 tooth gear, i plan to use some old hercus gears that i dont use any more , it will save me reboring the hole and making key slot. remove old teeth and turn to new gear diameter . 39 tooth should be 2.777 inches i think.
i have 2 options for indexing
1 Tom senior indexing head with tail stock or
2 rotary table which can be orientated vertical or horizontal with 3 jaw chuck

which set up would you suggest and any comments why or why not
heres some pics of what i mean

horiz1.jpghoriz2.jpg

I would use the index head and tailstock.

You wont have little bits of swarf covering the face of the chuck and making there way in to the scroll if doing it with the 1st picture set up.

You should be able to give your self plenty of clearance for cutter travel with the index head and tail stock compared to the rotary.

Can you use the rotary with the tail stock by packing, if so you would have the ability to use either, the tail stock will provide more rigidity for your mandrel.

If you want place a small container ( Chinese for example ) under the gear to collect the swarf,if using coolant allow the coolant to fill the container and it will carry the swarf.

The size you mention is for a 48tooth 18DP gear, if you want 39 teeth then machine your blank to 2.277"

Thanks pipeclay yes your right on the diameter i looked at the wrong calculation now i better get to work and make a mandrel to hold the blanks and some sort of dog plate to hold the mandrel to Tom senior indexing head a pity the tail stock doesnt match the rotary table with out shimming but i guess im lucky to have an alternative.
John

I'd agree, as that way you give yourself maximum support. The other thing about cutting on a R/T set horizontally is the extra work you have to do. From memory, a TS major only feeds in one direction, and it's not Z.
I'm in Adelaide too and have broaches to do keyway slots if you need them.

Michael

Thanks Michael i may have to take you up on that offer one day but for now i have about 18 surplus hercus gears with holes and key ways already done from a past history c model lathe i had before upgrade. There is a mixture of steel and cast gears i wonder what your thoughts are on using the cast ones , too much wear on the gear cutter?
john

As you are only doing a few any wear will probably be negligible. Just remember to drop your cutter speed down (about 50% of that for steel)

Michael

I can get down as low as 50 rpm that looks about in the ball park from the chart i am using table 8.1 and 8.2 Machinist Tables for Lathes and Mills from American Machine Tools Company
John

You would probably find you would have more wear from steel than cast, 50 rpm will be fine for both materials, cut full depth , slow feed and coolant if you can.

thanks for that pipe clay another job its got coolant pump on it not sure it even works but it did when last it was used apparently. Just been out making a mandrel 180 mm long .. might have to shorten it yet
john

If you plan to cut a few gears you might want to consider making the arbor fit your index head / rotary table rather than using a chuck.

pipe clay your making more work for me i love it yes from my you tube research it appears that the arbor to indexer dog needs no back lash so i found a video some where that shows how to do it ( cant find it now but i got the idea)