# Dial type lathe tool center gauge



## DICKEYBIRD (Jul 22, 2013)

Here's a shop-made gauge for accurately setting lathe tools on center made from scrap aluminum, ½ drill rod & an ebay dial indicator.  It helps to quickly & easily set the tool on center within a thou (or less) on any lathe.  I used a short travel, small dial indicator so it would be compact enough to clear the ways on my 8 swing lathes.  

Its calibrated with a .250 dowel pin that slides in & out of a close fitting reamed hole in the center of the shaft. The indicator dial is set & locked so that the needle sits on zero with the dial tip extended exactly .125 It works great and is very consistent. The only variable is making sure its set at 90 degrees to the carriage but thats pretty easy using an accurate square. I thought about adding a level but I think the square is more accurate.


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## Sshire (Jul 22, 2013)

That is brilliant! Going down to the shop now to make it.  Thanks.


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## canadianhorsepower (Jul 22, 2013)

looks good but I cant figure out the purpose of the drill rodscratch.gif
can you please explain t

thanks


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## kvom (Jul 22, 2013)

canadianhorsepower said:


> looks good but I cant figure out the purpose of the drill rodscratch.gif
> can you please explain t
> 
> thanks



It's used to set the DTI.  It then slides out of the way to allow the tool tip to be under the DTI plunger.


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## chucketn (Jul 22, 2013)

Maybe I'm thick-headed, Dickybird, but I still don't see how it works. Do you zero the DI on the rod? Then the tool bit, if zeroed, is still .125 high, right?
What am I missing?

Chuck


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## canadianhorsepower (Jul 22, 2013)

chucketn said:


> Maybe I'm thick-headed, Dickybird, but I still don't see how it works. Do you zero the DI on the rod? Then the tool bit, if zeroed, is still .125 high, right?
> What am I missing?
> 
> Chuck


 
My understanding is that it is set at.125 with the pin in 
and when remove the dial would show zero:hDe:


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## DICKEYBIRD (Jul 22, 2013)

chucketn said:


> Do you zero the DI on the rod? Then the tool bit, if zeroed, is still .125 high, right?


Correct Chuck.  I rotated the dial to read 25 at that point , locked it and removed the dowel.  The dial tip then drops 5 rotations of the needle (.025" per revolution), touches a properly adjusted tool tip & the dial reads exactly zero.  Much easier to do than explain in writing.

I just thought of another use of the thing, dunno why it didn't occur to me sooner.  Once the tool is adjusted on center, I can back it off a hundred thou or so, rotate the gauge 90 degrees away from the tool & re-square it, jog back in (I'm using it on a Mach3 controlled CNC lathe) until the clock reads zero again and I can compute the tool tip offset to go into Mach's tool offsets table.  Easy-peasy!;D


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## Forestgnome (Jul 23, 2013)

Nice tool, but it would take me longer to use that than using the steel rule trick.


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## Sshire (Jul 23, 2013)

I made one last evening. Works great. As far as the time that it takes, I set the height on 10 tools in about 20 minutes. I guess if  one were not using a QCTP with a holder for each tool, time might be an issue. But, no one is paying me by the hour to make engines, so time isn't an issue. Finally, it's not like you need to do this every day. Once the tools are set in the QCTP holders, they generally don't move about. 
If I ever move to a lantern toolpost and Armstrong tool holders, I'd probably use the 6" scale technique.


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## DICKEYBIRD (Jul 23, 2013)

Sshire said:


> I made one last evening. Works great.


Cool!  Glad it works for you Stan.Thm:

Did you have a small D.I. on hand or did you use a "normal" sized one?


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## Swifty (Jul 23, 2013)

Great idea. One of these days, when I get a quick change toolpost, I will make one the same.

Paul.


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## Sshire (Jul 23, 2013)

Had a regular size, not a small one. I also have a few HF digitals and am going to try one tonight. Just because I need a break from the engine detailing.


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## DICKEYBIRD (Aug 2, 2013)

DICKEYBIRD said:


> Correct Chuck.  I rotated the dial to read 25 at that point , locked it and removed the dowel.  The dial tip then drops 5 rotations of the needle (.025" per revolution), touches a properly adjusted tool tip & the dial reads exactly zero.


Beep....WRONG! 

Sorry, it's actually 2 1/2 revolutions of the needle since the D.I. is .050" per revolution.  Dohh!


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