Simple Rotary Table

rdean

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Feb 2, 2014
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I started this project about a week ago after getting some inspiration from posts like "A dividing head by Wayne" , and from Mark Frazier's builds and several others here on the forum.
I have been experimenting making spur gears and gear reduction units but the post I did about a year ago on worm gears still had me thinking. You can really get a lot of reduction in a small space with a worm gear.
This is the new worm I made to see how it would turn out.
It has 90 teeth using a 1/2" by 13 tap.
s1.jpg

It turned out very well with nicely formed teeth. It is mounted in a 1.5 by 3.5 block of 6061 about 18" long. When you design as you go along I have learned not to cut the parts to size but leave them longer than you think you will need them. This usually turns out to be the case.

This is how I bored the block for the bearings with a medium press fit. I didn't press them all the way in as I didn't know just where I wanted the worm gear located until later.
s2.jpg

s3.jpg

I turned the ends down to make bearing surface and then pressed the 0.750 bar through the center of the block. I also bored the worm axle out for a #3 Morse taper.

s4.jpg

I cut the block back to length plus about 1/2 inch more for future needs.
I had a 4th axis that I made years back and it has been replaced with better version so I just used some of that material for this project. Please disregard the extra holes.

s5.jpg

s6.jpg

The tilt works well and the base fits my table slots so I will keep on building. Who knows just what it will look like.

Thanks for looking.
Ray
 
Looks great , does the gear blank get rotated by the tap as it turns? And in the last pic one tooth on the left side looks thicker than the rest or is this just the light messing with my eyes?
 
Great execution!
Thanks for sharing it.
-brino
 
I do a fair amount of small diameter welds a slow speed rotating table comes to mind and would save me from trying to run around my work to catch-up to the puddle . Very interesting thread thx for sharing
 
I did some work on mounting the worm and getting it aligned on the base. I decided that the worm gear should be as low as possible so I pressed the bearings down even with the block. This will give me more room to mount the shaft collars to the sides of the block and make them more rigid.


s7.jpg

After a lot of measuring and a little luck I got them mounted. I made the holes a little bit big so I would have some wiggle room.

s8.jpg

There is 0.015 space under the worm shaft and it lines up almost perfect.
I wanted the table to be 6" in diameter but that won't happen with the worm mounts that high.
Back to the mill to make adjustments.

s9.jpg

I have a 6" X 1" plate on order that I will turn down to thickness of 0.750 on all but the center 3". That will allow the table to clear the mounts and still have a full 1" thickness to press onto the worm gear shaft.
Here it is with a temporary handle to check the operation.

s10.jpg

Still a long way to go but things have worked out surprisingly well so far.

Thanks for looking

Ray
 
I want to make dividing plates and dividing fingers so I need something to mount them to.
I made this adapter with 12 TPI but I think the nut was 11.5 but that worked just fine as the plastic nut still screws on and stays where you put it. I don't have to worry that it will tighten up or loosen during use it is locked in place. (I may have to fix that we will see)
s11.jpg

s12.jpg

Thanks for looking

Ray
 
My only concern so far, is that there doesn't seem to be an adjustment to move the worm in and out against the worm wheel.
my very cheap grizzly 4" rotary table can adjust the pressure between the worm and the worm wheel (gear). I have rebuilt
several telescope mounts that use worm gears (very pricey ones) and they all have the means to micro adjust the contact pressure.
As the worm and gear rotate they reshape each other (again on the micro scale) and need to be adjusted, especially in the beginning.

Just the words of an old man who mutters to himself a lot.
 
Yes you are right I don't have a way to adjust the worm by just turning an adjustment or a way to unmesh the screw from the gear. I have given these items some thought and may redesign if it proves to be an issue. Right now I am adjusting the backlash by moving the worm mounting brackets in their holes.
Thanks for the input.
Ray
 
Made a little more progress still waiting on the metal for the table.

Made up three dividing plates with some of the most common hole sets. There is only room for three sets of holes per plate because that is the largest piece I had.
39 43 49 and 17 19 33 and 16 18 20 holes.

s14.jpg

Here is one mounted.

s13.jpg

That's all for today
Thanks for looking

Ray
 
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