[cwm9]

How many pounds may I safely put onto my taig? I'm building a 4th axis, but just the gear box is about 17lbs so I'm guessing somewhere around 25-30 lbs when I'm done, and I don't want to destroy the table.

[Stepper Monkey]

I have no idea what the max load is for the table, but that much weight isn't going to damage it or anything. It will increase machine wear, and will slow the machine down a LOT trying to accelerate and decelerate that much mass.

May I ask why the giant rotary table? I haven't found any job a Taig can do that can't be handled quite well by a little Sherline rotary stage. Unlike the rest of the flimsy crap Sherline turns out, those tables are robust, accurate, and indestructable.
Also seen them made from planetary gear boxes and a size 23 motor, but they only weigh a few pounds as well.

[cwm9]

I have no idea what the max load is for the table, but that much weight isn't going to damage it or anything. It will increase machine wear, and will slow the machine down a LOT trying to accelerate and decelerate that much mass.

May I ask why the giant rotary table? I haven't found any job a Taig can do that can't be handled quite well by a little Sherline rotary stage. Unlike the rest of the flimsy crap Sherline turns out, those tables are robust, accurate, and indestructable.
Also seen them made from planetary gear boxes and a size 23 motor, but they only weigh a few pounds as well.

Well, it was because I didn't want to spend $600 and I snagged this for $150. I didn't realize it would be quite this large. I was thinking I could slap on an L bracket, replace the servo with a stepper motor, and presto: cheap 4th axis. It didn't quite turn out that way.

One possibility is to remove the harmonic drive from the rest of the overly massive bearing/spindle section and replace it with a much smaller bearing+table.

It's not too important to me to have this done anytime soon, but it is turning out to be more of a project than I thought it would be.

[Stepper Monkey]

Harmonic drives have been generally overlooked by machinists for years. I was able for the longest time to quietly snap up smaller harmonics on ebay for nothing. Small ones were not in demand, large ones are more so.
A harmonic drive as large as you have is likely worth a goodly amount to the right person, sounds like you got a good deal, but maybe isn't exactly what you needed. I still have a few extras laying around, likely just the sizes you are looking for.
You may do better selling it off and picking up a smaller one, or I will happily trade you for the right size one, as I have uses for bigger ones too on some of my weird non-machining projects.
Some of mine even have steppers built right onto them and I have the proper five-phase drivers to go with them. Something to think about if the project is getting out of hand!

[cwm9]

That's a tempting offer. I have to think about it. I really the idea of using the harmonic drive, but the lack of available torque is a bit of an issue. This one already has poor torque. I'd be afraid if I went to an even smaller size I'd be even worse off. (This one is about 95mm maximum diameter more or less. My vernier calipers don't have long enough jaws to get around it.)