Test Dial Indicator

[Darren]

I would like to find a DTI that has the measuring button on the rear, usually a larger button than the normal types ... no luck so far ..

Does anyone know if they have a special name?

[websterz]

I have always heard them called "button-back".

[websterz]

I have always heard them called "button-back".

http://cgi.ebay.com/Starrett-196-back-plunger-Dial-Indicator-OB_W0QQitemZ350303654809QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item518fb99399

[Darren]

That's the type, I've not been able to find one in the UK .... 

[websterz]

That's the type, I've not been able to find one in the UK .... 

Here's one.

http://cgi.ebay.co.uk/Mitutoyo-Series-1-dial-test-indicator-2226_W0QQitemZ200427731702QQcmdZViewItemQQptZLH_DefaultDomain_3?hash=item2eaa6c7af6

[Darren]

Blimey, I thought that was a normal type when I scanned it quickly .... thanks, you're a star 

[websterz]

Glad to help.

[Darren]

Thanks to a little help from here I managed to get hold of one of these "button back" dial gauges

First job was to make a holder for it to use with the milling machine for tramming the head. A simple 20mm SS bar with a grub screw arrangement to hold the arm.





In the past I have used a normal type dti that we are all familiar with. Although this works well enough reading the dial as you spin it around is a real chore when it faces away from you.
With this gauge you can always read the dial with little trouble at all.

Here you can see the tram was about 8 thou out. The gauge reads in tenths so every ten divisions is one thou.
I got the tram down to two tenths in all directions which is rather pedantic but it I wanted to see if it could be done 
Rather pointless I know, cos if you lean on the machine it move a whole thou anyway so we can only guess what it's doing when cutting.

I would guess normally tramming to a thou would be close enough.

[websterz]

Looks like that stem will accept different points, like a regular dial indicator. That could come in extremely handy! Looks like a right smart bit of kit. 

[Darren]

Yes the tip unscrews, as does the fixing arm.

It also has thread to take a tip to use like a regular plunge dti, though it's a different thread to the one on the back. You can see where it fits in the second picture.

[raynerd]

Darren, nice idea! I like the tramming jig/equipment that John and Stew made: http://madmodder.net/index.php?topic=822.0 but I don`t think I`d accurately be able to make everything square enough for a true reading! This bit of kit is excellent and I could do with another DTI.
Where did you buy from in the end?

Chris

[Darren]

Hi Chris,

This gauge came up on the bay. 

I too like Johns idea, but although making it accurately seems reasonable enough I just can't get it out of my head that loosing the squareness would be all to easy making it useless. A little knock or a warp and it would need re-machining.

Maybe I worry to much and the concept is fine, but this way I don't have to worry about such issues.

[Stilldrillin]

Hi Chris,

This gauge came up on the bay. 

I too like Johns idea, but although making it accurately seems reasonable enough I just can't get it out of my head that loosing the squareness would be all to easy making it useless. A little knock or a warp and it would need re-machining.

Maybe I worry to much and the concept is fine, but this way I don't have to worry about such issues.

Darren,

They were my thoughts at the time........

A finger clock has always worked fine for me. 

David D