“Following a need to change the range of divs., on my pulley mounted disc type indexing plate I was contemplating a peripheral arrangement, a sort of drum extension fitted on the pulley, but I required 3 rows of holes and it was apparent that there would only be room for two, and as I did not have any large diam., metal to hand the back burner beckoned this project. Then while downing another cup of tea the solution (pun?) appeared, three inches from the problem! It was the band of metal at the rear of the 4J chuck. Ok so I had the Where, now the How. I elected to have 50,60 and 72 div., and obtained some gear wheels with teeth to suit. I turned some clamp able mountings out of acetal, the height to suite the gear/chuck height req'd with a small spigot to fit each gear and a captive retaining bolt. Each gear has a short spigot to match the 4J registry. A centre drill is mounted in a head stock chuck, this is lined up with the captive bolt with this using the x slide, lock the x slide. The hex key was mounted in the tailstock chuck, select a size that sits between the teeth and does not bottom. Make sure the gear teeth are clean. Disconnect the drilling lever. For each series of holes the gear is kept in register by the stepped adaptor and double sided sticky tape - forget this at your peril. One important check, rotate the chuck by hand to ensure there is no wobble in the stacked assy.. (One of my gears was sawn from stock not turned, it looked like my wife's sliced bread!!)
I elected to start with the middle row of holes (X60).
Setting up procedure. Touch chuck to drill and back off 1/2" from drill. Slacken gear/chuck nut, slacken ram clamp, move tailstock assy., up to the carriage and lock. Hand feed the hex key/chuck into the gear teeth, this will align the gear radially and the hex key vertically at the same time, clamp both.
Switch on. Wind the carriage left and drill the 1st., hole to req'd depth, set the carriage stop. Back off, slacken off nut, right carriage to index next gear tooth, tighten nut, carriage left - drill second hole, back off, slacken off - - 58 to go. Ready for that next cup of tea?
The same procedure for the other gears, just remember the correct thickness packing for the corresponding gear to locate the ring of holes on the chuck.”
“The sliding lever assy., is more or less self explanatory. The asymmetric mounting footprint was to cater for other items to be fitted to the head stock. The bracket assy., was made from 1/8" steel angle, like wise the flying clamp part, both of these components were crimped in a vice to key the inner faces. The slotted lever is from 1/4" alloy, and the slot long enough to slide across the three rows of holes. This clamping method was found strong enough to support the weight of the lathe! Move your clamping hole 1/4" to the left (ref., my pics) and extend the lever by the same amount, you can see in the pics that one of my mounting bolts is under the lever, OOPS!
The only downside so far - I can't index using chucks or collets. YET------. Now where is that cup of tea?”