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[4]

4th axis servo controlled rotary table build

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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:
 

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Comments

#4
I should be getting the rotary table in this coming week. I don't have a chuck for it yet, but I plan to get one for it some time soon.
 
#5
I did this exact job a few years ago. You will love this added capability.
 
#6
I did this exact job a few years ago. You will love this added capability.
I can't wait! One of the things I have been wanting to make is gears and having a servo controlled rotary table will get rid of the need for dividing heads.

What software did you decide on for your 4th axis work? Fusion 360 has been very slow in coming up with a good 4th axis solution. Their CAM software can really only do indexed 4th axis and not live 4th axis(it can do live, but only in a couple special cases for finishing work). I found posts on their forums from early 2016 where they said they would have a solution soon...

I saw this software called "DeskProto". I don't know anything about it, but it looks like it can do live 4th axis, and the price is much better as compared to the big players out there.
 
#7
I am watching some of their videos. It looks like their software is better suited for soft material work because the tools don't appear to be able to do any helical ramps into the work, but rather plunge moves. BUT, the software is live 4th axis capable.
 
#8
I have a shelf full of gear hobs...
I use electronic gearing with my control, Camsoft, to quickly knock out any gear.

Yep, CAM software for 4rth axis is hard to come by. Got a fairly easy work around. its a piece of cake to change the encoder counts per unit length in the control. So, lay out your project with X being the X axis and Y being the circumference of your part. Then take the resulting Gcode and change Y to A. Of course, this does not work for code sections that do have a Y move. You got to run that separate.
 
#10
It seems to be nicely built and I can't hardly tell if there is backlash present. I would have to put an indicator on it to see how much there is.
 

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#11
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.
 
#18
The two pulleys and the belt have been ordered and should come some time this week. Looks like All I will need to do is fab up a bracket. Jim Dawson suggested that I could cut two linear slots for the four screws that the servo would use for mounting. That way I can easily adjust belt tension. Sounded like a great idea to me :cool:.
 
#19
The two pulleys and the belt have been ordered and should come some time this week. Looks like All I will need to do is fab up a bracket. Jim Dawson suggested that I could cut two linear slots for the four screws that the servo would use for mounting. That way I can easily adjust belt tension. Sounded like a great idea to me :cool:.
That's what i did. i also put a large pulley on the RT to mathc the size of the handwheel. A small one on the servo gave a 5:1 gearing gave a real torque advantage
 
#20
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.
 
#21
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.
 
#22
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.
 
#26
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?
 
#27
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?
 
#28
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.
 
#29
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.
 
#30
The two pulleys and the belt are supposed to come in the mail tomorrow.
 
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