4th axis servo controlled rotary table build

Hi everyone,

I am getting ready to build a 4th axis for my CNC mill. I should be getting the rotary table in the mail in about a week. I will be posting pictures as I go along :).

The rotary table is one from eBay. It is of the 8" variety. I believe the brand is CME.

The servo and drive is from Leadshine and is 400w.

Here are a couple pictures of the servo and drive:

20180109_202924.jpg

20180109_202942.jpg

servo.jpg
 
Did you plan out your ratio? I would do that first. You want a ratio that gives you more whole numbers than not. Whole numbers will increase your division accuracy.

I did :). The servo encoder gives 10000 pulses per rev and the ratio on the rotary table is 90:1. So, 10,000(90)/360 = 2500 pulses/deg.
 
Suggestion. Make the three jaw chuck "adjust true" type. Being able to dial your part to have zero run out is critical on many parts. This is not a real difficult task to add to any chuck.

That sounds like a good idea. I was thinking about how I am going to get a 6" chuck bolted to this thing and I realized that just making an adapter will not give me any adjustability. It will get me close, but the arrangement of the T-slots will not really work for trueing up the chuck. Being able to match centerlines between the chuck and the rotary table would be very convenient. If it was a case of only being a few thousanths off, then I would probably not sweat it, but I feel that I could be .010-.030 off, and that would be too much. Also, having a chuck that runs on a lathe that is not dead true is not that big of a deal if the bar can be turned first and left in the chuck for all the work. I won't have that option on the mill. The chuck will have to be accurate enough to get me there on it's own.
 
You might be able to ''wear'' it in after you get the motor hung on it. That's what I did with mine. Just ran it as I over tightened the worm until I was able to get zero backlash.

Have you pulled the worm cam assembley out yet and looked at the thrust bearings?
 
You might be able to ''wear'' it in after you get the motor hung on it. That's what I did with mine. Just ran it as I over tightened the worm until I was able to get zero backlash.

Have you pulled the worm cam assembley out yet and looked at the thrust bearings?

I have not pulled the assembly out yet. Is it as simple as just rotating the cam down and getting my rubber mallet and giving it a couple good bops to knock the assembly out of there?
 
There should be a set screw that runs in a slot in the cam ''can''. Remove that screw, disengage the worm the the gear, and pull the assembly out from the handle end. There may also be an end plate or something that prevents axial movement. That will have to be removed if it exists.
 
There should be a set screw that runs in a slot in the cam ''can''. Remove that screw, disengage the worm the the gear, and pull the assembly out from the handle end. There may also be an end plate or something that prevents axial movement. That will have to be removed if it exists.

I may be going back over there today. If I do, I will try to get the worm assembly out and post some pictures.
 
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