Need some ideas on Rotary Indexing

[Canuck]

I managed to get my hands on a few Emco lathe accessories (3-jaw chuck, face plate and some cutting tools) and would like to build myself a rotary indexing table. I've managed to turn an adapter plate to mount the chuck and face plate to the cross slide of my SB 9A lathe - more of an exercise in turning the dovetail that I can use to mount the assembly to something else... What I would like to ask the experts out there is for a way to lay out and drill/machine a series of radial holes (48 or 60) around the outside of the adapter plate so that I can "index" the chuck with a spring-loaded locking pin. I do not have access to a rotary table - only a drill press and lathe. If this works out I want to build a larger version that I can mount on the backside of my lathe chucks. Thanks

 

[DMS]

If you have some change gears you could try using them as a reference to drill your holes. Here is a picture of a nicer implementation as an example

http://www.homemodelenginemachinist.com/f25/fixture-making-small-gears-5406/

The bigger the gear (diameter wise), the more accurately the you will be able to drill your index plate. Another option would be to turn up the blank disk, and have a friend with a rotary table drill the holes for you.

 

[Syaminab]

DMS has given me an Idea, if the drill press is big enough to get over the lathe, you could use the gears on the back of the lathe so you wont have to build DMS great example.
another way is to draw the holes over masking tape in straight line, of course equally spacing, the tape should measure exact perimeter, then tape it. Ise a v block to center under drill. Not very precise but if the circle is big enough it will help.

 

[Canuck]

Thanks for the quick responses gentlemen. I think that I might be able to build something using the gear idea...