Rotary table inspiration....

Thought it was about time my new (well, new to me!) rotary table got some use...

I have a 4 inch table that, unusually it seems, has three not four T slots - which does make things a bit awkward when trying to clamp things down.

So I thought about making a face plate with some threaded holes that I can attach to the existing table (with countersunk screws) - but am thinking about the best layout of the holes, initial thinking was two rows at 90 degrees to each other aligned with the axis but now I am wondering whether two parallel rows at 90 degrees centred on the axis might be better? The idea being I could centre a bar along the axis and use the holes either side to clamp it down for instance?

Another thought is the size of the face plate - if I decide to fit a chuck I guess I would make a four inch plate and buy a three inch chuck to give me a flange to bolt it down, but could make the 'threaded hole' plate bigger? (would make it difficult to reach the locking clamps if it was too big)

Howard Hall has an excellent article on his website about making a centre plate with a set of spigots which I will make to fit the three slots but will still have the clamping down problem.

The RT also has a 2MT hole so Howards adaptor will help me with centering workpieces on the axis - by making a adaptor to turn the 2MT hole into a parallel one which he also suggests in the article.

Any ideas/observations would be gratefully received!

Chris

Edited By Chris Parsons on 04/12/2013 09:27:04

I have a quite useful jig plate here, not on a RT but still used a lot.

It has the tapped holes set in 4 quadrants. NE and SW are in a grid pattern equal from either imaginary cross line.

NW and SE are set radially in rings.

It's about 10" and the holes are on 3/4" or 20mm centres approx. No idea what it came off but it was part of a machine at some point.

Edited By John Stevenson on 04/12/2013 09:32:58

Chris,

You have a 4 inch table ...

Will your Adapter Plate also need to be 4" diameter?

... It may be worth considering a modest overhang, and perhaps a different shape.

MichaelG.

Thanks for the comments

John, your jig plate sounds interesting - think I can visualise it, grid and radial holes sound like an excellent idea, and perhaps not too hard to make, although 10 inches would be a bit big perhaps

Michael - no, it could be bigger but I need to be able to reach the locking clamps - although I could make longer levers, and I guess it doesn't have to be round

One issue I have had is sometimes the clamps tighten themselves up when cranking around and I sometimes remove them (depending on how annoying it gets)  and if there was an overhang it would prevent me doing this - if the jig was rectangular though I could make it 4 inches by (whatever) and leave them accessible (there are two, 180 degrees apart)

Need to have a ponder methinks!

I have just found and ordered a 100mm chuck with 3 front mounting holes from RDG which should hopefully fit nicely - someone suggested this a while ago which is a good idea

Regards

Chris

Edited By Chris Parsons on 04/12/2013 11:11:02

Chris

I have a 4"/100mm table marketed under the Vertex label with 3 slots. Some time ago I bought a 100m 3 jaw chuck from RDG and mounted this on the table. The only problem I have had is that the T nuts I made needed rounding/radiusing to clear the locking lugs on the table. As the table has an MT2 taper I can set the chuck, central to the table rotational axis, quickly by using a 2MT test bar and gently gripping this with the chuck before tightening the securing screws. While this may not satisfy the purists it is certainly a good starting point for final centring of the chuck.

Martin

Edited By Martin W on 04/12/2013 11:33:59

Chris,

The reason I hinted at making the plate with some overhang [aside from the obvious increase in Real Estate], is that it gives the option to use hooked bolts to clamp-down long bars.

Also worthing mentioning: If you make the plate reasonably thick, you can drill & tap the edges, which gives extra options.

...

Thinking about it further; I would make two adapter plates [each 5-6" across]

1. Hexagonal, with tapped holes on a radial array
2. Square [but with the corners chopped off], with a rectangular array of holes.

That done ...

Sod's Law dictates that you will probably want to clamp-down some Pentagons.

MichaelG.

.

Yes folks; I know that [2] is an Octogon, of sorts ...but I don't mean a regular one, and I can't remember the technically correct name.

Edited By Michael Gilligan on 04/12/2013 12:11:08

octagon-with-unequal-sides-thingy

Octagonoid?

Neil

Eight nuts Neil - and its spelt "Octagonad"

Perhaps think about a 4 jaw self centering chuck - just gives a little more support when milling.

.

I suppose it depends whose definition you use

Wikipedia is certainly more specific.

and yes, I know I spelled it wrong, but it was too late to edit.

MichaelG.

I thought they had eight tentacles, Rik!

Neil

Chris,

Back to your question ...

I would also suggest making a third plate ... any shape & size that's convenient, and undrilled [except for its fixings to the table].

This is the one that you drill & tap to suit the really awkward jobs.

When it finally resembles a Swiss Cheese, just throw it away and make another.

MichaelG.

What a great idea,saves messing about making a precise fitting plug .. John

Your mounting plate can be larger than your rotary table. Just depends on how rigid it is.

I have a 6" rotary table on which I bolted a much larger plate. The plate locates on the centre spigot and is restrained by 4 countersunk cap screws and tee nuts. I then tapped some holes and used my mill clamps to hold the job.

Edited By Paul Janes on 05/12/2013 11:08:07