Rotary table 4th axis set up
What all do people consider when choosing their motors and encoders? Is the idea to match your resolution and max feed rate at the max diameter of the rotary table with that of the rest of the mill?
I'm setting up my 1st cnc mill and immediately after getting it's current goodies running I'm adding a rotary table to it. I already have a large, brand new camco rotary table for the job. Right this second I don't remember how large since I've had it and the mill sitting while I've been busy finishing a couple masters degrees which I just finished (sitting somewhere else or yes I would go look, lol). I've been collecting up the parts the last couple weeks to go ahead with this project and now that I have the parts for the x,y, and z I'm starting to think about the rotary table.
What I'm looking for here is advice from people who have rotary tables or are very familiar with their set up. Hopefully someone can put me on the right track and tell me what I need to know to do it to full advantage. Precision and finish quality requirements on the parts I'll machine on the rotary table will be very high. The camco rotary table is set up to be able to be used in a gang set up so it has both a servo motor mount and an output shaft so I have plenty of places to mount encoders if they aren't integral to the servo motor. I am using servo motors by the way. I have a galil 2160 controller and am using 110V 5.9A 1800RPM DC servo motors with a 60V power supply, 1000 line encoders with indexes, and 5 tpi precision ground ball screws. The gears in the camco rotary table are 30 to 1. I'm going to guess my rotary table is 12" if not it's 10. What all do people consider when choosing their motors and encoders? Is the idea to match your resolution and max feed rate at the max diameter of the rotary table with that of the rest of the mill?
I know on the galil control I can set the home routine to look only for the index and not worry about a home switch. Is this how homing a rotary table is normally accomplished?
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I did a bridgeport series 1 retrofit recently and a rotary table.
The one thing you did not mention was backlash on the rotary table. Of extreme importance is a table with low backlash that is adjustable. Many have converted rotary tables to cnc only to find them unsuitable due to backlash issues.
I hear ya. I never even considered trying to throw a motor onto a manual indexing table though. I'm using a brand new camco table.
Originally Posted by Sparky_NY
What did you end up doing with the camco. By the way anyone curious camco uses a cam drive zero backlash setup so it’s nothing like a cheap hand crank conversion. I know someone sitting on half dozen or more low profile camco rotaries. Looks like 6” using an 8” faceplate. I was thinking of direct drive with a high torque ac servo. As they are with Baldor setups they’re more for indexing and use cams to locate position. I would be shortening the shaft on one end and capping off and using a servo and encoder at the other end. If you look at many applications they actually use a worm drive to turn the cam drive which defeats the purpose to me but I’m sure is what gives them ridiculous torque ratings. Perhaps a AT or XL belt at a 5:1 ratio with servo would be more ideal. My other option is a direct harmonic drive which will require more money. If your still on the board please share what you did for your setup.
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