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Simple Rotary Table

rdean

Active User
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#1
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
 

Alittlerusty

Active Member
Active Member
#2
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?
 

rdean

Active User
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#6
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
 

rdean

Active User
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#7
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
 

ch2co

Grumpy Old Man
H-M Supporter-Premium
#8
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.
 

rdean

Active User
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#9
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
 

rdean

Active User
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#10
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
 

ch2co

Grumpy Old Man
H-M Supporter-Premium
#11
Gorgeous. What metal did you use? What's the diameter? How did work out your hole spacing?

CHuck the grumpy old guy.
 

rdean

Active User
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#12
I used an aluminum plate 3.5 X 0.250 X 12" long I had left over from another project. I was able to get all three out of this one piece.
The small holes were made with a center drill and then an end mill for the cutouts all done on my CNC mill. I would hate to think how I would have done it accurately on a manual mill.

Thanks

Ray
 

jbolt

Active User
H-M Supporter-Premium
#14
Looks great Ray. Very cool project.

Is the threaded "worm" gear steel? Having made several equatorial telescope mounts and tracking drives for Dobson telescopes I have found that brass/steel, brass/aluminum. brass/brass, brass/HDPE and Steel HDPE work well for worm drives. Steel on aluminum needs good lubrication to keep from galling.
 

rdean

Active User
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#15
Well that remains to be seen as the worm wheel is aluminum with a steel worm.
I will keep an eye on it for excessive wear.
If it proves to be a problem I can make one from brass or steel and replace the aluminum one.
Thanks for the heads up.

Ray
 

rdean

Active User
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#16
Aluminum has arrived!
I had ordered two plates 6 X 1 so if I messed up the first one I would have another chance to make it right but I didn't need it. The plate turned out right the first time and now I have a garbage bag full of aluminum chips.
The top section of the plate is 6" X 5/8" thick. I originally wanted it to be 3/4" thick but that didn't leave much room above the worm brackets but by making it thinner I was able to press the plate further on to the spindle. So all is well.

s17.jpg

s18.jpg

s19.jpg


I changed the finger lock so it would hold position without tipping the outer finger. I found a brass nut for the fingers to replace the plastic one. I also shined up some of the pieces.
Here it is so far.
s20.jpg

Thanks for looking

Ray
 

jbolt

Active User
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#17
Well that remains to be seen as the worm wheel is aluminum with a steel worm.
I will keep an eye on it for excessive wear.
If it proves to be a problem I can make one from brass or steel and replace the aluminum one.
Thanks for the heads up.

Ray
No problem, been there done that.

Also in precision applications the where the worm gear is turning or supporting a load there is usually some type of thrust bearing(s) or AC bearings because the worm wheel is applying an axial force to the worm gear. If you are just indexing and locking the table then it is not as much of an issue.
 

rdean

Active User
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#19
The small parts take the most time and sometimes you need to even start over.
Here are the parts for the lock I made.

s21.jpg

This shows them mounted. I do not like that black knob it has to go, later.

s22.jpg

Here are the parts for the worm shaft brake and a pin to lock the table horizontal or vertical position.
I will just use a protractor to set the table at any other angle when needed.

s24.jpg

Table lock pin for horizontal position. The hole for vertical is on the other side.

s23.jpg

More tomorrow.

Thanks for looking

Ray
 

rdean

Active User
H-M Supporter-Premium
#20
This picture shows how the table brake is assembled. It pushes against the table spindle land above the worm wheel.
s25.jpg

This is how I cut the divisions using the bed of my lathe. I messed up on the first try so I cut them off and had another go.
360 marks of different lengths was quite a job but I only made a couple of minor oops.

s26.jpg

After a little bit of sanding than a coat of paint. (wife's finger nail polish)
s27.jpg

This is the result.

s28.jpg

They are not all perfect but they turned out better than I had hoped.
I don't think I will try to number them now as that never turns out very well for me and I am not sure it is needed.
The long lines are 90 degrees apart and the next shorter ones are every 5 degrees. It should be easy enough to figure out.

Thanks for the likes everyone and thanks for looking.
Ray
 

rdean

Active User
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#22
Thanks brino
After examining the dial closer it is some of the 5 degree marks that are off by about 1/2 degree. All the 1 degree lines and the 90 degree lines look fine. It must have been that I had the brake a little too tight when I did the 5 degree lines.

Ray
 

2volts

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#23
You have done a top job Ray. Well done.
I like Projects that start out with "what if I..."
pete
 

rdean

Active User
H-M Supporter-Premium
#24
I did a little more cleaning up all over and assembeled.
s29.jpg

s30.jpg

Marking holes for my 4" 4 jaw chuck mounting plate.

s31.jpg

Here it is all done for now.

s32.jpg

I may add some T slots later but most of my work will be either in the 4 jaw or through the morse taper.
It weighs just over 11 pounds and very sturdy.

When I started I was going to make a simple rotary table but as it progressed the project just kept on growing.
I have surprised myself how it turned out.

I want to thank everyone for suggestions and encouragement along the way.
Thanks for looking

Ray
 

rdean

Active User
H-M Supporter-Premium
#25
I told my friend Chris that I was going to make a box to store the rotary table and the pieces that went with it and he said it will probably be some exotic thing with mitered corners.
"No" I told him just a simple wood box for storage.
Well like so many of my projects it got a little out of hand and one thing led to another.

rt1.jpg

rt2.jpg

rt3.jpg

rt4.jpg

The table sits in a recess in the bottom and I had to cut out some of the side for the table to fit.
It has felt feet on the underside so it won't get scratched.
Maybe over the top?

Thanks for looking

Ray
 

brino

Active User
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#26
It resembles a treasure chest.......but that's fitting, considering the contents.
Well done all around.

-brino
 

FOMOGO

Active User
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#30
Very impressive project all around Ray. I would be delighted with an outcome like that, one big att'a boy, on a job well done. Cheers, Mike