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Author Topic: Co-axial indicator?  (Read 5420 times)

Allthumbz

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Co-axial indicator?
« on: November 13, 2010, 06:10:25 PM »
How is a co-axial indicator used on a lathe?

Thanks.

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Offline Powder Keg

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Re: Co-axial indicator?
« Reply #1 on: November 13, 2010, 06:37:36 PM »
They are mainly used on a mill to swipe in a bore or OD. The only thing I can think of on a lathe would be to check the tail stock alignment? But I've never done it.
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Offline sbwhart

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Re: Co-axial indicator?
« Reply #2 on: November 14, 2010, 02:36:46 AM »
The one I've got came supplied with a pointed stylus that you can locate in a centre pop, I guess you can hold the indicator in your tail stop locate the stylus in a centre popped bit of work held in the four jaw, then move the jaws so that the indicator show that the pop is running true, so you can machine a hole accurate positioned on the pop.

Stew
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Offline kwackers

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Re: Co-axial indicator?
« Reply #3 on: November 15, 2010, 09:15:39 AM »
I'd assume you centre a piece of bar in the chuck (or take a skim off to get it perfect), fit the co-ax indicator in the tailstock and adjust for minimum wobble?
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Offline BillTodd

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Re: Co-axial indicator?
« Reply #4 on: November 15, 2010, 10:14:02 AM »
Quote from: kwackers on November 15, 2010, 09:15:39 AM
I'd assume you centre a piece of bar in the chuck (or take a skim off to get it perfect), fit the co-ax indicator in the tailstock and adjust for minimum wobble?

Actually, the rotating part of the coax has to be in the chuck with its probe rotating around the tail stock ram (or a round reference (centre) in the tail stock). It could also be used to zero-in a drill or ream mounted on the tool post.

One thing I've over looked in my MkI design was a spring to allow it to operate horizontally (ATM it relies on gravity).

Bill
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Offline kwackers

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Re: Co-axial indicator?
« Reply #5 on: November 15, 2010, 10:17:43 AM »
Quote from: BillTodd on November 15, 2010, 10:14:02 AM
Actually, the rotating part of the coax has to be in the chuck with its probe rotating around the tail stock ram (or a round reference (centre) in the tail stock). It could also be used to zero-in a drill or ream mounted on the tool post.

One thing I've over looked in my MkI design was a spring to allow it to operate horizontally (ATM it relies on gravity).

Bill
Ah yes...

I did consider the spring thing on your design, I figured it might be possible to have another bearing on the far side with a spring loaded grub screw, would that work?
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Offline BillTodd

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Re: Co-axial indicator?
« Reply #6 on: November 15, 2010, 10:44:57 AM »
Quote
I did consider the spring thing on your design, I figured it might be possible to have another bearing on the far side with a spring loaded grub screw, would that work?

Ah Yes, good idea :) And, it would pre-load the axial bearing solving any off-centre wobble (as suggested by Richard)
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Bill
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