Thread: Rotary Tables

I concur bob!

So, let me get this straight, you have 2 bearings. One at the top plate and then the sharft continues past the worm gear and there is another bearing housed in the base?

Or, just the one bearing housed in the top plate?

Cheers,

Simon

Yes and no Simon, the bearings are both (top and bottom - either side of the worm wheel - and another two each end of the worm) built into the reduction box case. You can almost see the top one in the second photo of Post #30. You can see the mounting flange and my skimming cut to ensure that this casting is dead flat and parallel to the bottom. The top and bottom plates are bolted to the case (4 bolts - not 6 as I mentioned in my previous post). So I did not add any bearings myself. The whole reduction box case is filled with gear oil by the way.

Joe

Originally Posted by jhovel

What if I give you the circuit and the PIC program and you help design that highly critical amendment?

Joe

Well, I would, but it just so happens I finished off all those helical milled parts I needed yesterday....

Being serious for a moment though (this probably is a question for a new thread), how does one set up to mill some kind of spiral around a part? I was looking at an alloy radiator neck on a car radiator the other day, and trying to figure out how to do it accurately (as opposed to hitting table feed and cranking away on the rotary table!). The best solution I could think of at the time was some kind of electronically controlled rotary table with a feed from the Z axis...... Hence the smartass comment.

I suspect these days they would be done on a 4 axis CNC machine.
You could do it on a lathe with the lead screw or on a mill with a gear train driven rotary table or dividing head. The latter would be the traditional way but takes a lot of drive tooling. Few workshops would have been equipped to do that dort of thing.
With a CNC machine, its as easy a CAD drawing and some 10001001011011100
Joe

Originally Posted by Jekyll and Hyde

Well, I would, but it just so happens I finished off all those helical milled parts I needed yesterday....

Being serious for a moment though (this probably is a question for a new thread), how does one set up to mill some kind of spiral around a part? I was looking at an alloy radiator neck on a car radiator the other day, and trying to figure out how to do it accurately (as opposed to hitting table feed and cranking away on the rotary table!). The best solution I could think of at the time was some kind of electronically controlled rotary table with a feed from the Z axis...... Hence the smartass comment.

I've got a 10" RT with input shaft for power feed (F-N-R). If I had to I'm sure I could gear it to the X axis table movement to machine spirals. Fortunately I do not foresee any possible time when I may have to actually do it......

Agree that 6" is too small. 10" is starting to get bloody heavy, it's about the limit of what I can comfortably lift, sans chuck etc. Generally I slide it off a cart onto the table.

PDW

Originally Posted by jhovel

I suspect these days they would be done on a 4 axis CNC machine.
You could do it on a lathe with the lead screw or on a mill with a gear train driven rotary table or dividing head. The latter would be the traditional way but takes a lot of drive tooling. Few workshops would have been equipped to do that dort of thing.
With a CNC machine, its as easy a CAD drawing and some 10001001011011100
Joe

Hi Joe

no need for a 4 axis machine you can do it with three as long as the part isnt too long I will post a pic's of some testing i did in wood when i get home if i can find them

cheers
Harty

This was a test to make a new square thread nut for my shaper which is broken
the part is held vertically and the tool runs around the outside
Attachment 195044
this is the nut still held vertically but obviously runs around the inside
Attachment 195045
Perfect fit
Attachment 195046
it even fits the thread on the shaper


cheers
Harty

Originally Posted by jhovel

I suspect these days they would be done on a 4 axis CNC machine.
You could do it on a lathe with the lead screw or on a mill with a gear train driven rotary table or dividing head. The latter would be the traditional way but takes a lot of drive tooling. Few workshops would have been equipped to do that dort of thing.
With a CNC machine, its as easy a CAD drawing and some 10001001011011100
Joe

Hmmm... about what I thought (the drive train idea). I'd considered that thought, and assumed that must have been the way it would have been done way back when. I could see the logistics getting awkward fast, hence the electronic rotary table idea.

Agreed that the CNC would be the easiest solution, but it does sort of take some of the fun out of it for me anyway. I like trying to work out how something was done before CNC came along!

Although, a CNC gantry for the plasma cutter would be useful, I seem to be too uncoordinated to cut shapes out neatly - always end up with the torch on an angle going around a corner, or traveling at inconsistent speeds...

Anyway, end derail here, back to topic!

On the subject of which, it is possible to cut ones own worm gears with nothing more than a lathe or a mill... I made a 90 tooth one out of a lump of aluminium at one stage as a test for making a rotary table. Seemed to come out all right, but then I was given a 10" Vertex for Christmas, so development stopped! Which, as PDW says, is bloody heavy. I now have an 8 inch 4 jaw chuck on adaptor plate sitting atop it, no way I'll ever move it assembled. Have to mount the chuck on the table after putting the table on the mill at this stage, in the magical far far away land of the new workshop there will be lifting gear for this job!

I have just taken stock of the material I have at hand. Is 25mm sufficient thickness for the table part of a rotary table? Assuming when it's clamped down it will be resting on the base and any chance of flex or movement would be removed yes? Assume at this stage that the material is mild steel, however there is every chance it may be harder as it's definitely not made out of merchant plate bar. It's more a slab of steel, 38mm thick, 400mm wide by about 800 long. It has been milled down to 25mm in parts and has holes bored in strategic places.

If I wish to make an 8 inch table I can do this with a 25mm top. Or, I can make a 6 inch with a 38mm top? This is due to previous machining.

If I 'm going to the trouble, I would prefer to make an 8 inch but not if it will be of insufficient strength.

Thanks,

Simon

Oh, heres a pic of the steel I have in mind to use. The bit on the RHS is what I will use as it has no holes. The full thickness part is about 180mm wide.

How I go about machining a piece off of it that I need is another issue. Not sure what it weighs, but would have to be too heavy for my mill.

Simon

When I need to cut something this big recently, I found someone with a large metal bandsaw and they cut it for me in a few minutes for $10.
Would have taken me days and worn out more then $10 worth of cutting tools...
Joe

Originally Posted by jhovel

When I need to cut something this big recently, I found someone with a large metal bandsaw and they cut it for me in a few minutes for $10.
Would have taken me days and worn out more then $10 worth of cutting tools...
Joe

Yea, I'm thinking the same.

Originally Posted by simonl

Oh, heres a pic of the steel I have in mind to use. The bit on the RHS is what I will use as it has no holes. The full thickness part is about 180mm wide.

How I go about machining a piece off of it that I need is another issue. Not sure what it weighs, but would have to be too heavy for my mill.

Simon

Find someone with an oxy cutting torch. 5 minute job, tops.

Don't neglect to grind back the HAZ before machining it.

25mm is probably not thick enough for T slots but fine for a grid of tapped holes. That's what I did for a big tilting angle plate and I'd do the same again.

PDW

Originally Posted by PDW

Find someone with an oxy cutting torch. 5 minute job, tops.

Don't neglect to grind back the HAZ before machining it.

25mm is probably not thick enough for T slots but fine for a grid of tapped holes. That's what I did for a big tilting angle plate and I'd do the same again.

PDW

I have re-visited my ideas. I can make the top out of 45mm (approx) thick steel, the sides out of 19mm and the top and base out of 25mm steel.

That should do it, surely?

I just need to nut out what type of bearings to use. Tapered roller bearings, maybe a set of Timken axle bearings for the table? A simple thrust bearing for the worm should present little problem. Just need to find that ellusive worm and gear......

Simon