Using a rotary table

This topic has 10 replies, 6 voices, and was last updated 6 October 2013 at 22:38 by Chris Parsons.

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2 October 2013 at 12:03 #6892
Chris Parsons
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@chrisparsons64193
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2 October 2013 at 12:03 #131306
Chris Parsons
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@chrisparsons64193
Having just bought a rotary table and looking around for a 4 jaw independent chuck to sit on it I am seeking opinions/advice about setting it up?

The table is 110mm with three slots (it is a Soba HV4) so I guess I will have to get a 80mm vice and make up a mounting plate – first thought was about checking the 'tram' of the table surface – to make sure it is parallel with the mill table surface, and shimming it up if required, or is this unlikely to be an issue?

I have read about aligning the chuck centre to the rotary table, and then the rotary table to the axis of the mill spindle but if I mount the workpiece in the four jaw and centre this to the mill spindle will this not be correct? Or have I missed something?

If the chuck is not quite centred on the rotary table surely centering the work piece in the chuck will correct this?

If I elect to bolt the work to the surface of the rotary table directly I guess I would use a DTI on the MT2 centre hole to align it?

Any observations would be gratefully received – I am also intending to get a tailstock and dividing plate set for it at some point.

Final question is adjustment (it was not quite new) There are six screws in the base, alternating cap screws and grub screws, and when I got it, it was stiff at a certain point in its rotation – which I sorted by carefully adjusting these screws, and now it is nice and smooth all the way around – I presume these are the equivalent of 'gib' screws – is there a particular technique to setting/adjusting these? There is no movement up or down but a very small amount of play around the axis of rotation which I cannot see how these screws would effect (and if I rotate it clockwise all the time to avoid backlash and lock it down before machining this would have no effect anyway?)

Thanks

Chris
2 October 2013 at 12:15 #131308
Speedy Builder5
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@speedybuilder5
If your chuck is of the screw on type, make sure it doesn't 'unscrew' whilst you are milling.
2 October 2013 at 12:23 #131309
David Clark 13
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@davidclark13
As long as the work centre is centered on the table it will mill circular to the center. What you hold the work in or on does not matter.

Yes, align the centre of the rotary table by clocking the centre hole.

Note: Rotate the test indicator round the hole.

That will align the table.

Rotating the table against the clock will not work.

regard david
2 October 2013 at 12:58 #131310
Chris Parsons
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@chrisparsons64193
Thanks very much – point taken about the screw in chuck, and I have a DTI holder that clamps around the quill so can use this (although I have seen co-axial tools to do this at around 50 quid but can't see what they would do that is different – other than having the dial visible all the time)

Chris
2 October 2013 at 13:13 #131315
Michael Gilligan
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@michaelgilligan61133
Chris,

Let me start the ball rolling …

Unless you intend to keep transferring "mounted" work between the lathe and the mill, I would recommend getting a 4-jaw that mounts [preferably from the front] with cap-screws.

You have 3 slots on your table, and a typical 4-jaw would have four holes … so you will need to make an adapter plate. It should be bigger diameter than the chuck, so that it forms a flange. [unfortunately this is all getting raher tight on an HV4]

Bore a central hole in that plate; probably the size of the hole in the chuck, and definitely bigger than MT2.

Four tapped holes for the chuck fixings, and three clearance holes for the tee-slot fixings.

……..

In use:

First … Centre the rotary table; lock any slides on the machine; and zero any readings.

Then … Position the workpiece, using the 4-jaw, or vice, or clamps as appropriate.

Now you can unlock the slides and reposition the whole assembly using the slides.

Before you start cutting: Remember to lock everything except the movement that's in use.

….

MichaelG.

Edit: Posting was delayed by lunch; so others have beaten me to it.

Edited By Michael Gilligan on 02/10/2013 13:14:40

Edit: Link to slim front-mounted chucks

Edited By Michael Gilligan on 02/10/2013 13:25:24
2 October 2013 at 13:31 #131318
jonathan heppel
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@jonathanheppel43280
The 50 quid coaxial indicators are a great deal faster (and obviate neck craning and mirrors.) They are used with the spindle running so both hands are free for the handwheels.
2 October 2013 at 16:08 #131338
John Hinkley
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@johnhinkley26699
The only problem that I've found with the axial centring devices is that, once you've fitted a rotary table, then a chuck, possibly with an adaptor plate – it doesn't leave a lot of room for the centring tool, unless you are lucky enough to have a Bridgeport or similar. Certainly, with a mini mill such as the one I have, there just isn't enough airspace beneath the quill. In this situation I have to resort to a dial gauge method.

For what it's worth, I purchased an 80mm three-jaw from Chronos ( no connection) which was conveniently front mounting with three bolts. It came with a four-bolt adaptor plate which I shall use with the four-jaw front mounting independent chuck purchased on an earlier trip.

John
2 October 2013 at 16:26 #131343
Chris Parsons
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@chrisparsons64193
Ah – interesting, don't suppose you remember exactly which one? Don't mind making a new backplate with three slots and 80mm is the size I was thinking about

My mill is an SX3 and has a bit of space when the milling head it cranked up – 450mm IIRC

Cheers

Chris
3 October 2013 at 10:20 #131427
Chris Parsons
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@chrisparsons64193
Thanks very much for the advice – the conclusion I have come to is as long as the rotary table axis is lined up with the spindle and the axis of the work is also lined up with the spindle I will be ok – the Keats angle plate looks like such a useful tool I have bitten the bullet, it's a lot cheaper than a chuck too (thanks John)

I have just done a milling course at Axminster and we used angle blocks vertically to mill the end of a block (to make another angle block!) which is the same principle I guess?

I have also found a very interesting article about machining flywheel spokes using a rotary table so I know what I will be doing this weekend <g>

(probably get as far as making the hold down clamps but one can always be optimistic)

Chris
6 October 2013 at 22:38 #131885
Chris Parsons
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@chrisparsons64193
Been having a play with this over the weekend, and think I have had some success

I can see this is going to be a very useful tool, but there is one thing I couldn't work out?

How does one align the work relative to the milling table axis? For instance if I want to round the end of a bar, and wanted to line the bar up along the X (or Y) axis, so I could zero the table and vernier and know that when I rotate 90 degrees I am lined up with the Y (or X) axis?

The rotary table has three slots but none of these are aligned with the 0 degrees marked on the table edge

Of course I can just clamp the work down, unlock and rotate the table to zero it but if the work is not aligned accurately with either axis on the milling table and I use either one of the micrometer dials to move an offset I can see this is going to introduce a significant error?

Is this just a case of running a dial gauge along the axis of the work? It is going to be hard work to get the O degrees lined up as well as the work indicated – centered on the rotational axis AND along the axis of the work?

I did think about an adapter plate that keeps the rotational axis fixed (peg in a hole in the work?) – I am using a coaxial indicator on a centre punch mark on the work and if I tap the work around to line up the milling table x/y axis this is going to put the rotational axis out and vice versa?

Or is there a technique to this that has so far eluded me!

Chris

PS Should have said I am clamping the work directly to the table – no vice or chuck

Edited By Chris Parsons on 06/10/2013 22:40:28

Edited By Chris Parsons on 06/10/2013 22:44:27

Edited By Chris Parsons on 06/10/2013 22:52:33

Edited By Chris Parsons on 06/10/2013 22:59:53
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