Rotary Table Centering

[Nick_GParticipant @nick_g]

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Hi guy's.

What's the best way (sure there are a few) to center a rotary table under a mill spindle.?

Cheers, Nick

[Nick_GParticipant @nick_g]

[John BromleyParticipant @johnbromley78794]

For rough and ready location I stick a 2mt centre up the mills spout, then lower it into the centre bore of the table, lock the down feed and then tighten down the RT. Gets me close enough for most stuff.

John

[FatgadgiParticipant @fatgadgi]

Hi Nick

The most accurate way in my experience is to use a DTI, such as the Verdict type held in the spindle chuck and clock off the central bore.

Both my tables have parallel holes and some types have morse tapers but they are concentric and accurate.

I made an adjustable holder for the DTI for using in the chuck, but often the standard accessories can be used.

Cheers – Will

[David Clark 13Participant @davidclark13]

Use a dial test indicator. Turn the dti from the head spindle. Turning the rotary table will not clock it true as the hole in the table will remain true. The dti must rotate.

[Douglas JohnstonParticipant @douglasjohnston98463]

If you have a DRO and an edge finder it is very easy to centre anything below the mill chuck. The DRO manual will give instructions for doing this.

Doug

[Les Jones 1Participant @lesjones1]

Hi Nick,
An alternative would be to mount a short piece of ground bar in the spindle collet and mount the DTI an the rotary table in contact with the bar. Rotate the rotary table to align it. This would ensure that the axis of rotation of the table was aligned with the spindle. As I have DROs I would probably use an electrical edge finder in the spindle. I would first centre it roughly by eye. Then move say the X axis until the edge finder made contact with one side of the hole in the centre of the rotary table. Zero the DRO then move the table till the edge finder made contact with the other side of the hole. Then either use the centre function on the DRO or move the table back to half the reading. (and re zero the DRO if this is going to be your zero reference.) Repeat for the Y axis.

Les.

[IanTParticipant @iant]

Marv (MKLotz) has a few good thoughts on this subject here:

**LINK**

He also mentions the "zero-it" which I seem to recall was originally a commercial product but which I'm also sure I have a DIY design of somewhere in my digital archives (which of course I can't find at the moment). It is the ideal solution although (like so many other useful things) I've not got around to making one so far….

Regards,

IanT

PS Marv has a lot of very good/useful ideas btw – he's a very inventive guy – so well worth searching and reading his posts…

[Nick_GParticipant @nick_g]

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Thanks folks.

I have a DRO on the mill. It's as I thought, but I just wondered if there was 'Some trick of the trade'

Thanks, Nick

[VicParticipant @vic]

Similar to post #2 but use a large ball bearing between the quill and the hole in the RT, and yes I've got one, about 30mm dia!

[JasonBModerator @jasonb]

Most of the time I use the electronic edge finder and the DRO , touch front then back then press half half, touch left then right then press half.

If I can be bothered to wind the head up I may use the co-axial indicator

[ChrisHParticipant @chrish]

Hi – check out 'Tom's Techniques' website (http://tomstechniques.com). Under the section on Milling in the 'Instructional Videos' dropdown he has a short video of how to 'Center a Rotary table in Under a Minute Without an Indicator' – it doesn't get much simpler and quicker than that!

Chris

[Anonymous]

I used to use "Osborne's Maneuver", as detailed by Guy Lautard. You touch one side of the rotary table, and then move exactly half the diameter of the table. Then repeat on the perpendicular axis. Then repeat both axes. Three passes gives a neglible error. I now use a co-axial indicator on the centre hole:

I also set the rotary table to zero and align the T-slots to the axes of the mill; makes it a lot easier when cutting to specific angles. Of course all the methods assume that the rotary table, any centre hole, and the axis of rotation are concentric.

Andrew

[Nick_GParticipant @nick_g]

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Again thanks.

It has now arrived. What the hell do Vertex add to their packing / transit grease.? My vice was the same smell. I am sure Bolton sewage works smells sweeter.

Nick

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