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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

4th axis pretty much finished up. I still have to run it in and put it under some machining stress to see if the setup will actually hold. The next project will be making a mounting plate for the 4th axis so I can actually mount it at mid-point on the Y-axis travel.

Here are some things I learned doing this project:

1) It's probably best to use a 4 jaw chuck when boring holes in things that require a set amount of tension or backlash like pulleys and gears. when I rotate the shaft of the 4th axis, I can push down on the belt and notice that a few spots have more tension. Fortunately it is not enough to cause extra drag in those spots, but If I was off anymore, I probably would have been taking a one way trip to destination screwed.

2) incorporating some kind of tightening mechanism would have been a big help. Pulling on the servo to get the belt tight while trying to hold an Allen wrench in the hex socket hole and drive my electric impact gun from the other side is not fun.

Overall, I am happy with the results.

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What a cool project, nice work!. I can see a 3-D printed belt cover in your future or perhaps a Kydex formed that could screw onto the edge of your base plate.
Very cool indeed, thank for sharing.
Paco
 
What a cool project, nice work!. I can see a 3-D printed belt cover in your future or perhaps a Kydex formed that could screw onto the edge of your base plate.
Very cool indeed, thank for sharing.
Paco
You know, I always keep forgetting that 3D printers are another option :). I was looking at that belt yesterday and thinking "Ya know, I should really put some kind of guard on that thing so oil and chips don't get lodged in the cogs". I was thinking about machining some kind of aluminum guard or something like that, but It would be a pretty good waste of a bar of aluminum just to cover up the works. On the other hand, possibly 3D printing a plastic guard or even just making a sheet aluminum guard that is held together with rivets may be another option. Also, I could make a foam core molded fiberglass guard as well...Hmmm, perhaps that would be the ticket since I don't have a 3D printer. I can just hack and sand a piece of Styrofoam with the came shape of the aluminum bracket and just do a layup on the foam directly. After it dries, I can remove the foam.
 
Here is a part I will likely test with the 4th axis once I get a chuck mounted on it. It's 2" OD and 3" length.

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The 6" chuck came in. Tomorrow I plan to machine out the adapter base for the 4th axis so it can be bolted down to the center T-slot on the mill table. Also, I need to machine out four special T-slots for the 4th axis face so the chuck can be adjusted to be as concentric as possible.

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I finally finished up all of the T-nuts. The last part will be the back plate. It is partially machined out. Once it is mounted up to the face of the 4th axis, I should have up to .075" adjustability.

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