In message , John Weeks
writes
I've been trying to construct and indexing disk for my lathe. It has
24 hole indexing built in, but I want 48 and 96 as well. I'm trying to
come up with the best way to lay out the holes and dril them on the
drill press. My first thought was to use a pin guide, something like
cutting box joints on a table saw, to avoid having to position the
drill bit by eye.


Hi John, not exactly sure of the design of your indexing disk, ( A
picture would help - but not here)

Have you considered a different approach
24 is half of 48
48 is half of 96

Rather than drill 96 holes, is there a way you can apply an offset to
the indexing pin ?

I.e.

----------o
-----------------o
-----------------------o


On my chuck I have a number of holes which I can locate the indexing
pin into.

The indexing arm is fixed to the lathe.

But supposing the arm is square section . Make a sliding attachment that
has 3 pins in it.

Each pin offset from the index arm mount by say half inch the closest
pin to the chuck being half inch long the middle one being 3/4 inch and
the closest to the head stock being 1 inch. The reason for the length
variations is to ensure the next pin is clear of obstructions on the
chuck

If you have a round arm you could make a simple 4 way offset indexing
guide which rotates on the arm and is located by a pin in through the
shaft. Made from a square section with hole in middle to fit arm, you
then fit a pin in each face at a suitable offset.

There may be a minor issue with the curvature of the indexing ring , but
I am sure you can overcome it
--
John