8" Rotary Table

[Hamstn]

Don't know if I need one but I came across the plans for a rotary table here and in following Arnond"s build I decided to start one of my own. I am a real newby when it comes to machining as I have only had my mill and lathe for a few months. I decided to build the table mainly to gain experience on both machines and thought this project would challenge me, and it has to some degree. This type of stuff seems to come natural. I have made many mistakes on each part but one thing about machining you can a lot of times dig your way out, rebuild the part, or modify it at a later date to suite your needs.

I have used the plans as a reference, adapted what I had on hand, and added my own touch so to speak.

Here is the base. I started with an 8" wide by 1/2" thick piece of flat stock and cut pieces from it with the plasma cutter. I then milled the peices down so they were the same and even, and then welded everything together.

I wanted to use the T nuts and bolts I made for my vice to hold down the RT instead of the clamping kit. I also wanted to be able to mount it away from the column as far as possible if I should need it to work on a large piece. So I welded on clamping tabs to serve this purpose. I also welded the tops first so they would warp up just a bit.

I used a face mill? to mill all the parts up to now but even with the biggest fly cutter I had I would have had to take two passes to cover the top. So I chucked it up in the 4 jaw on the lathe and faced it off. My first major mistake, I grabbed the carriage feed instead of the cross feed and you see my mistake but it will be covered by the table and will not affect the operation of the RT. I might add I got to use my boring head for the first time to bore the hole for the bearing cup.

 

[Hamstn]

When I said I was using parts I had on hand when I was at the scrap dealer I saw some weights and bought a few. Here is one that i will be using for the table. Getting the outer skin off was a pita. It would eat a HHS tool up in no time.So I picked up a C2 carbide tipped tool to finish the job. Once the outer skin was off it machines fairly well.

Here is the top side of the table. Again you can see one of my mishaps when I grabbed the wrong power feed handle. Hopefully threw experience I will learn or pay closer attention. Used a cut off blade to cut the clamping groove around the bottom edge.

Here is the hub I made for the RT. I wanted to practice threading so I found a 1"-14 castle nut and threaded the shaft. Well when I thought I was getting close I backed off the tail stock and tried the nut. I was a bit tight so I went to make a few more passes. When I slid the tail stock back up and tightened it down I went to much and it slid the piece in the chuck there by throwing off my timing. Well I goofed up half the threads and never got it timed 100% but the nut went on and it will be very tight without having to use a cotter pin to hold it. Threads on the nut are not 100% either

 

[Hamstn]

I made some more progress today but I did not get any pictures and I am having trouble uploading to my host. The rest of the week will be very very busy so I doubt I will get more done unless it rains. Posted below is the hub mounted into the table and a poor picture of my lathe. I am sure someone will ask how I cut down the weight which was around 12" to start and 8" X 8" base. It's a 15x54 tray top.

 

[Deanofid]

You sure have made a good start on it, Hamstn. Good idea using the weight for making the table.
It sure looks sturdy.
The table looks quite a bit larger than the base. Will you have enough room for the table locks?

Dean

 

[lordedmond]

Danger Will Robinson


chuck key left in chuck

 

[New_Guy]

looking good what is your lathe a LeBlond? you must have a decent size mill thats good the bigger the better ;D

looking forward to updates chears

 

[Hamstn]

Dean yes there appears to be enough room in each corner of the base for a lock. The base is 8x8 but the table is 9" . I am thinking later I may run into a problem with the crank handle more then anything, but it can be turned down easy enough.

New guy the lathe is a Cincinnati.

The chuck well good eyes and oops.

 

[arnoldb]

That's a good start on it Hamstn. Your welding is a LOT better than mine Thm:

Mishaps happen - all the time ;D; It's good to see that you're not letting it get you down.

What are you using for worm and wheel ?

Regards, Arnold

 

[Hamstn]

I was able to get a bit done today but mostly it was thinking and searching the junk box to continue the project.

Earlier you saw the ****oo I made in the center of the table. Well here is the fix. I bored out the mistake and made the spindle to fit the bored hole then faced it off.

Next I mounted the spindle to the table with three screws. I didn't have a counter sink to match the back side of the screw heads so I took an old end mill and ground the 90* included angle into it and sharpened it. I also had to use a cut off saw to cut grooves in the end

Arnold asked what I was going to use for the gear and worm. Well I had a gear box I saved from a coal burning stove. It ran the auger that fed the stove. I gutted it out and am going to use the gear and worm. Only problem is it is 55:1 ratio and probably not the best choice for indexing.

Faced with the 55 tooth worm gear I tore apart an old angle grinder I had just about thrown in the trash. I was actually looking for bearings but what I took apart the right angle gear I started to do some math and an idea to use it in conjunction with the worm gear to give me finer adjustments.

Would someone with better skills then I check my math for me. The right angle gear is 11 tooth on drive gear and 36 on driven. Not sure if I did it right but I came up with 179.9999 turns of crank for one turn of table....2 degrees per turn? i plan on making two handles to turn the table. one direct to for 55:1 and one for the right angle gears.

 

[Deanofid]

Hi Hamstn;
Your table is coming along!
I understand the need to use what you have, but truly, 55:1 is going to be miserable to work with. You really need something that divides into 360 in whole numbers, at least.
Not sure how you mean to use the bevel gears with the whole thing, unless you are talking about compounding them to the worm. Then I think your figure is correct.

Try to find something else for your worm gear to make your new rotary table more enjoyable to use.
If it ends up a chore to work with, it won't be much fun.

Dean

 

[Hamstn]

I hear you Dean. I looked up some gears and figured for the cost I might as well just by a commercial RT. I would really like to do is learn and cut my own gear but I have no way to index them. If I placed my cards right I may be able to use the RT to make one once it is done and then replace the original or stumble across a different donor.

The way I was looking to use the right angle gears is mount the driven gear on the same shaft as the worm. When I want to mill a radius or move the table fast I use the handle that is connected to the main shaft. When I need to index or make fine adjustments I will turn another handle that is attached to the drive gear of the right angle set. If I can mount it this way and my math is correct I will have the best of both worlds and an easy way to index down to 1/2* or less. (1/4 turn of right angle gear)

Matter of fact i was just thinking about how I was going to mark the table and cranks with degree marks without some way to index. If I can get the gears to work I then will be able to use my RT to do so. Also need to work on how to make is a vertical table, as it stands now the table is 9" so i may have to turn it down so it does not extend past the base.

 

[arnoldb]

Hi Hamstn

Do you perhaps have change gears for your lathe ? - these can be used to make a simple indexing jig.

Regards, Arnold

 

[kcmillin]

Just a thought, if you cannot change the gear ratio to better suit the 360 degree system. You can make your own unit of measurement. For example: you can take the 55:1 ratio and say that each revolution of the handwheel could be 8 degrees then instead of having 360 degrees you would have an even 440 degrees. Then from here you could divide evenly into this, without having to worry about the standard degree system.



Kel

 

[Hamstn]

I don't have any change gears but I do have a big idler that connects the spindle to the feed gear box. I have thought about using it in some way to index but have not taken the time yet to see what it would take. I saw a setup where someone posted some pics of them doing it that way. If I can find a gear or something I could also built a hub and mount it in or onto the spindle shaft, like maybe a ring gear from a flywheel.

Thanks Kel. Never really thought about approaching it that way. Why is it so hard to think outside the box? LOL

 

[djc]

Would someone with better skills then I check my math for me. The right angle gear is 11 tooth on drive gear and 36 on driven. Not sure if I did it right but I came up with 179.9999 turns of crank for one turn of table....2 degrees per turn?

Your maths is spot-on. You have been very fortunate to have found a set of bevel gears containing a factor of 11, which correlates with the same factor of 11 in the 55 tooth worm wheel.

If you put the handle on the 11 tooth gear, and the 36 tooth gear on the worm, you get 11/(36 x 55)=1/(36x5)=1/180, hence 2 degrees per turn. Many 'standard' tables are 90:1 ratio (4 degrees per turn) so if you want to use dividing plates with it, standard 90:1 plates will be perfect, just double all 'turns-and-holes' in the tables. The only problem with the bevel gear set-up is that it will have a lot of backlash - not a problem as long as you always rotate in the same direction, lock the table down before cutting and don't climb mill when circular milling.


(Edited for civility. Let's not be calling anyone names.)

 

[Deanofid]

Ham, if you want to try cutting your own gear for a more usable tooth count, I have a small 72 tooth composite gear I'd gladly loan you. It's not metal, but made of tough enough stuff to be used as an indexer. You could turn up a simple mount to attach it to whatever machine you want to use for indexing.

If you're interested in giving it a try, just say the word.

Dean

 

[RichD]

Ham,
Marv Klotz has a great web sitehttp://www.myvirtualnetwork.com/mklotz/ with a couple programs specifically for what you may be after for calculations. One (divhead) lets you input different ratios, and the other (divplates) figures out the dividing plates you need for that ratio.

I have a jury-rigged dividing head with an oddball ratio of 25:1 and it's great for marking lathe dials (25,50,100,125,250) and such, but at 14.4° per revolution there was no really good way to mark the input collar. I compromised by multiplying 14.4 x 100 for 144 divisions on the dial. Each division is .1° with a .01° veneer (veneer is also a Marv Klotz program).

Mine is kind of a pain to use to be honest. Since you're building such a nice table from scratch, I think you'll be happier later with a more direct system. But like someone said, whatever works!

Rich

 

[Hamstn]

Thanks for the generous offer Dean, I will keep it in mind if I can't come up with something around here.

Rich I will have a look at the programs and see if I can make use of them in one way or another.

I have not had time to do any work on it, it is low on the priority list right now. I did however order some bearings for the shaft that the worm will mount on. Been very busy with farming 16-17 hours a day.