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DTI identification

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Steve King 520/06/2019 19:35:34
47 forum posts
76 photos

Hi all

I have the DTI but it doesn't say if its metric or imperial nor does it say what each increment is. Its very heavy and feels smooth so I'm hoping it's a good quality one.

Can anyone help.

Thanks

Steve

20190620_191923.jpg

JasonB20/06/2019 19:40:37
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Moderator
15518 forum posts
1594 photos
1 articles

Why not mount it on your lathe or mill and move a handwheel by a known amount and see if the dial reads that amount in metric or imperial

Michael Gilligan20/06/2019 19:52:30
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13253 forum posts
578 photos

Catalogue of the more modern ones, is available:

Search for Rambold precision dial gauges and accessories

... I don't know Rambold, but they look promising.

MichaelG.

XD 35120/06/2019 19:56:10
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1268 forum posts
87 photos

I will have a guess and say a tenths indicator with a total travel of .020 inch but the only way to be certain is to do what Jason said and compare it with the movement of a graduated dial like a lathe cross slide or you could set it up in an indicator stand on a flat surface so the nib is vertical and touching said flat surface and slip a feeler gauge between the nib and the flat surface .

Have a look on the long island indicator website as they may have some info on that make of indicator .

Andrew Johnston20/06/2019 20:07:02
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4698 forum posts
532 photos

I'd be inclined to say metric +/- 10mm with each small division being 0.01mm. However, look at how much the nib is sticking out; which will equate to the total travel, that'll tell you if it's +/- 0.01" or +/- 10mm.

Is it an indicator or a test indicator? The former have a shaft that moves in the vertical direction, the latter normally have a moveable lever that can move in any position it is set.

Andrew

old mart20/06/2019 22:00:38
185 forum posts
15 photos

Metric ones are commonly yellow.

Steve King 521/06/2019 08:11:07
47 forum posts
76 photos

Think its metric as it does not line up when mounted to my lathe as suggested by JasonB.

If any one wants to swop it for a imperial equivalent drop me a message.

Thanks

Steve

JasonB21/06/2019 08:25:37
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Moderator
15518 forum posts
1594 photos
1 articles

There should not be much thinking about it.

If your lathe is imperial put on 0.050" feed and if the dial goes round 5 times it is imperial. If the dial goes round once plus 27 divisions it is metric as 50thou equals 1.27mm

If it is more sensative and does not have that range of movement try 0.005" feed

Steve King 521/06/2019 08:37:32
47 forum posts
76 photos

Thanks JasonB

Its metric 0.050 equal the one full rotation plus 27 divisions.

Thanks for helping out the novice its much appreciated .

Thanks

Steve

John Haine21/06/2019 10:14:41
2543 forum posts
132 photos

99% of the time one uses a DTI as an indicator, e.g. of runout or misalignment of a vice with a mill axis, and the measurement uints are irrelevant as you only want to get zero movement.

Steve King 521/06/2019 10:34:38
47 forum posts
76 photos

I plan on using the DTI like this

20190621_094819.jpg

20190621_094926.jpg

20190621_095049.jpg

Nicholas Farr21/06/2019 10:36:16
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1875 forum posts
915 photos

Hi, it is quite possible that it was for use in a quality control as a comparator. Either it may have been to match parts in pairs or set amounts, or to check on production runs, either way the operator would not need to know any measurement as such, but would set the test machine to a master and compare the tolerances for production runs, hence the zero being in the middle of the stroke.

Just my thought the reason that it doesn't indicate mm or inches and the fact the little 10-0-10 dial would suggest it being used horizontally..

Regards Nick.

John Haine21/06/2019 11:43:04
2543 forum posts
132 photos

I think DTIs are intended for use as comparators, not accurate or indeed precise measurement. Their calibration is ultimately dependent on a rack-and-pinion, not a precision thread or transducer. They do have high resolution, for example indicating 0.01 mm/division, but one division will not necessarily be 0.01 mm if you see what I mean. Though it would probably do the job in the application you show, for best accuracy you would be better using for example a DRO.

In the language of this a DTI has high resolution but is not very accurate or precise.

Steve King 521/06/2019 12:03:25
47 forum posts
76 photos

I'd love a DRO but even the cheapest Chinese one are hundreds and I only have tens hahaha. Maybe one day.

Thanks

Steve

old mart21/06/2019 16:47:55
185 forum posts
15 photos

If I'm not mistaken, that lathe you have is a S & B model A.

Steve King 521/06/2019 16:52:48
47 forum posts
76 photos

That's correct a mk2 I believe

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