4th Axis

[Hood]

I recently bought an old air operated index head and have stripped all of the air and indexing parts from it and propose to drive it with a stepper motor so that I can use as a 4th Axis on my BOSS retrofit. Can anyone offer advice or thoughts on what reduction I should use, it will be timing belt driven so I have a large range of possible combinations to choose from and was wondering if there was an optimum.
Hood

[machintek]

Hood, I am sure I am not telling you anything new but typically a 4th axis/rotary table is driven by a worm gear. This for the ability to better hold position as well as for better resolution/accuracy. Most now have a brake on them as well.

George

[Hood]

George
This Indexer has a worm but it has a fair bit of backlash so I thought of driving with a stepper and pulley arrangement. Its a good quality Indexer, Bristol Erickson 800 but I think there was no need for a zero backlash worm as the way it indexed was it rotated until a pawl dropped into the next notch, this activated a reverse in rotation which locked the pawl into the back of the notch then a brake was operated to hold everthing in place. As I am not wanting a fixed Indexing axis I was hoping a stepper with maybe a reduction of 10:1 would give me enough holding torque and also the resolution would be reasonable.
Possibly I might be better looking to see if there is any way that I can mount the worm in a cam so that I can adjust the backlash out of it.
Thanks for the reply and the possible headaches I am going to get by actually having to think about this

Hood