Here's a small 4" far east rotary table that isn't too bad for backlash but could use a bit of work. The goal is to add a stepper motor drive to it.
Here's the table broken down.
And an idea of what to do with the worm holder.
But a bronze or ZA12 casting would still require some sort of oiler so instead I may start with a 2" diameter piece of hot rolled steel and turn new holder which has the longer area for the stepper motor mount and has a relief for a thrust bearing and oilite bronze bushings. Adobe 3D PDF here.
After some further pondering I've come up with a simpler solution to at least get the table powered with minimal effort. I used a Princess Auto Flexible Spider coupler. First I mounted it on a 1/4" arbor and turned the outside down to 1" from about 1.09" so I could fit it into a 1" collet. Next, boring it out to 10mm so it would be a sliding fit over the shaft of the Worm Gear on the rotary table.
Next I took a simpler approach to mounting the stepper motor so that I wouldn't have to create the new worm holder. This one slides onto the 29mm OD of the worm holder and is held against the flange with slightly longer socket cap screws. 3D PDF here.
The two pieces could be fabricated from a square piece of 15mm thick aluminium and a section of 2" aluminium bar but since that stuff is expensive and I have the foundry, I'll cast the them, turn them down and do it that way. If I screw up the turning, I can melt it down and try again.
There are two pieces because the one end has a hole that is 29mm diameter and the other end has a hole that registers with the stepper motor flange and is 38.1mm. I can't make the inside 38.1mm and therefore cast the flange with it because then the 4 mounting screws are obstructed. Assembling the plate to the round part and boring the holes at the same time will maintain concentricity and keep the stepper motor shaft in line with the Rotary table Axis.