Small Rotary Table

[cfellows]

One of the biggest problems with any rotary table is attaching the work. It's often time consuming and the clamps wind up right in the path of the milling cutter.

I had an extra 3" 3-jaw chuck laying around so I decided to make a small rotary table with a dedicated 3 jaw chuck so mounting round work would be easy and repeatable. I used a 72 tooth worm gear and worm I had on hand and used a piece of 4" channel iron for the body. I also mounted the chuck in an adjustable fixture so I could accurately center the chuck by turning the 4 equally spaced set screws around the perimeter. This type of fixture has worked out extremely well on my mini lathe, so I thought I'd repeat it on the rotary table.

It also fits nicely in my 4" milling vice. I do still need to do some additional work on the crank mechanism. I want to make up a collar with 20 division to increase the number of indexing positions I have.

Chuck

 

[Metal Butcher]

That's great idea Chuck. I could defiantly use one of those.

The gears are always the problem for me. :'(

-MB

 

[milotrain]

Very nice. Is there a bearing somewhere in there or is the chuck shaft pressed into a bushing? I've been thinking about building a rotary table for a while but this is the simplest and cleanest design I've seen yet!

 

[Maryak]

Chuck,

:bow: :bow: :bow: :bow:

Why not fit an index plate and use the back of the handle for the detente.

Best Regards
Bob

 

[cfellows]

Very nice. Is there a bearing somewhere in there or is the chuck shaft pressed into a bushing? I've been thinking about building a rotary table for a while but this is the simplest and cleanest design I've seen yet!

Yes, I made a 7/8" long brass bushing with a 1.75" diameter flange on top that is pressed into a 7/8" hole I bored in the top of the channel iron. The adjusting fixture was turned from a solid piece of steel.

Chuck

 

[cfellows]

That's great idea Chuck. I could defiantly use one of those.

The gears are always the problem for me. :'(

-MB

Thx, MB. I also have a gear problem... too many. I love gears and over the years I have acquired quite a collection. Unfortunately, I seldom have the right size on hand for a specific project, unless I design the project myself!

Chuck

 

[arnoldb]

Nice one Chuck Thm: - Will come in very handy!

Kind regards, Arnold

 

[cl350rr]

great! another tool project to ad to the list. really a simple and rugged design. have you thought about adding another bearing to the other end of the worm shaft?

Randel

 

[cfellows]

great! another tool project to ad to the list. really a simple and rugged design. have you thought about adding another bearing to the other end of the worm shaft?

Randel

Thanks, John, I actually have small ball bearing races on both ends of the worm shaft. I'm posting some additional pictures and information here in a minute.

Chuck

 

[ironman]

That is pretty cool Chuck. Randel beat me to the question about the other end of the worm.
Did you mill all surfaces of the channel or just clean it up? More questions but will wait for up to date photos and details.
Good job.
ironman (Ray)

 

[cfellows]

Here are some additional pictures and comments for people that are interesting making their own.

The base is made from a piece of 4" wide channel iron, 3 7/8" long so it will fit in my milling vice jaws. I had to do a little face milling on one side and on the edges of the bottoms to square things up and make it sit flat. You may notice a small concavity in the top, but that doesn't hurt anything since there is a separate, flat bearing surface for the chuck assembly to ride on. The flanged bearing was turned about .002" oversize and pressed into the channel iron hole.

Here is the worm assembly. The worm shaft is 1/4" and it fits into flanged ball bearing races on either end of the carrier. The bearings have an OD of 3/8" (the flanges are larger) and the ID is a light press fit over the worm shaft. The hole through the center of the carrier is bored 1/16" off center so that rotating the the carrier would provide adjustment for the worm proximity to the worm wheel. The 3/8" hole was bored completely through the carrier to fit the ball bearing OD rather than trying to bore a smaller hole then enlarging the ends to fit the ball bearings. The OD of the 12L14 steel carrier is 5/8" and the flange is 1".

The 72 tooth, 24 pitch worm wheel was one (of 5) that I had on hand. I made a 1.25" diameter hub to press into the center of the wormwheel. The hub has a .625" diameter hole and is held onto the chuck assembly shaft with a 1/4" set screw. I originaly tried silver soldering the hub to the gear, but it got too hot and melted in a couple of places. So I salvaged the hub by turning the ruined gear off in my lathe and press fitting it to another gear (so now I'm down to 3 spares).

Here is the chuck assembly. The disk was cut from 1/2" thick hot rolled steel. I first rough cut an octagon from the steel plate, bored a 1/4" hole in the center, then tuned it into a disk by pressing it against my lathe chuck with a live center. Next I mounted and centered the disk in my 4 jaw chuck and cut a 5/16" deep recess for the chuck to sit in. The recess is about .030" larger than the chuck diameter to provide lateral adjustment room. The shaft started out as a 3/4" piece of cold rolled steel. I bored the center hole in the disk about .003" smaller than the shaft, then heated the disk as hot as I could get it with my map gas torch. Luckily, the 3/4" shaft slid into the heated disk easily and straight. After everything cooled, I re-mounted the disk in my 4 jaw chuck making sure it was trued and centered. Then I turned the shaft down to .625" for a nice sliding fit in the brass bushing in the base. This procedure assured that the shaft was concentric and true to disk fixture.

At this point I was able to assemble the rotary table and use it to evenly drill the 3, 1/4" holes for mounting the chuck. These holes, by the way are on a 2.6" circle which is very close to the 66mm circle specified for the minilathe chucks. The 1/4" size is sufficiently larger than the mounting studs to allow adjustment. I then drilled and tapped the 4, 10-24 set screw holes around the periphery of the disk to provide for lateral adjustment of the chuck.

Chuck

 

[krv3000]

HI thats brill

 

[ironman]

No more questions Chuck. You said it all in your documentation. Thm:

ironman (Ray)

 

[AlanHaisley]

It is so cool when you can use a tool in its own fabrication! :bow:

At this point I was able to assemble the rotary table and use it to evenly drill the 3, 1/4" holes for mounting the chuck. These holes, by the way are on a 2.6" circle which is very close to the 66mm circle specified for the minilathe chucks. The 1/4" size is sufficiently larger than the mounting studs to allow adjustment. I then drilled and tapped the 4, 10-24 set screw holes around the periphery of the disk to provide for lateral adjustment of the chuck.

Alan