Centreing a rotery table

[I.M. OUTAHEREParticipant @i-m-outahere]

Hi Michael.

Thats a good idea and adding a plate with a slightly larger diameter could make the rotary table more versatile .

I am now thinking of making a backplate but more in the line of it being a sub- table that will have radial slotsfor for small tee nuts and tapped holes for clamps so i can mount odd shaped pieces to it and it will also allow both 3 and 4 jaw chucks or a small angle plate to be fitted.

Looks like i will have to spend yet another weekend in the workshop !

Bugger !

Ian

[Raymond GriffinParticipant @raymondgriffin40985]

Dear all

I have found the comments contained in this thread both interesting and useful. In the past I also had great difficulty in getting the centre of a rotary table in line with with the spindle of my mill. For me the solution relies on alignment of a laser centre edge finder held in the chuck with a centre in the rotary table. I submitted an article showing my approach to this problem to MEW. It could be useful to someone when it appears.

Ray

[Sub MandrelParticipant @submandrel]

I use a wobbler in the mill chuck and a dummy centre with a turned point on either end. One way up it fits the hole in the table, the other way it fits my faceplate, or it can be held in a chuck..

For more critical work I hold a bar in a collet in the mill and the other end of the bar ina 3-jaw fitted to the rotary table before I tighten it up.

My DTI spends 99.9% of its life in its box.

Neil

[doubletopParticipant @doubletop]

After being enlighten by this thread, I remembered to ask my dad, when I called him the other day, about the large ball bearing with the equipment of he'd given me. He corrected me and told me it wasn't a ball bearing but an accurate reference ball for measuring, its exactly 1.75" Without prompting he then described using it to set up the round table, just about as posted in the thread.

Now I've got to work out what else I could use it for and I'll be a bit more careful with it rather than leave it skulking around in the workshop.

Pete

 

Edited By Doubletop on 10/09/2012 10:36:09

[Michael GilliganParticipant @michaelgilligan61133]

Pete,

Check through the stuff your Dad gave you, in case you have one of these gathering dust [but hopefully not rust].

A very useful little device, but easily mistaken for junk if you don't know its purpose.

MichaelG.

Edited By Michael Gilligan on 10/09/2012 12:07:32

[CabengParticipant @cabeng]

Here are some further alignment suggestions, with photographs uploaded to a new album.

First photo:

My Vertex 6" RT is fitted with an adaptor with a Myford spindle nose, which itself has been centred on the RT so that the spindle nose is accurately located relative to the RT's centre or rotation.

The RT is placed on the mill table, but not bolted down. With an accurate bar held in both chucks, the RT can then bolted to the mill table, centreing accuracy being dependant on the accuracy of the chucks, of course. WIth collet chucks, the accuracy should be very good.

Second photo:

Same idea, but this time to align a mandrel with the vertical spindle – grip the mandrel in the spindle collet chuck, then bolt the angle plate to the mill table. The component (in this case the regulator bush for my boiler) can then be drilled and tapped.

Third photo:

On the right is a 3MT blank end arbor with two diameters machined on it, 19 and 20mm, to fit the largest sizes of ER32 collets. The Omnimill vertial spindle is bored 3MT, so this fits directly in the vertical head. Why two diameters? Because the Great Law Giver Murphy has decreed that whenever alignment is required, one of those collets will already be in use elsewhere!

The various tapered mandrels are used position pre-drilled holes under the vertical spindle – mandrel in a collet chuck in the vertical spindle, poke the tapered bit into the hole in the workpiece, then clamp the work to the mill table.

The two methods work well in combination – use the 2-chuck method to centre the RT, remove the chuck from the RT, substitute the faceplate, then use a tapered mandrel to align the hole and its surrounding metalwork on the faceplate – clamp the work to the faceplate, and everything's set up for milling around the hole.

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