Correction for a longer contact point

[Skedaddle Shooter]

I have a Mitutoyo 513 504. It had a short contact point on it when purchased. I have a longer contact point I’ve installed so I can index in the throat area of a pre drilled chamber. The original contact point was ~ .65” the new one is ~1.65”. The new one is 154% longer than the original.
This is where my carpenter math gets a little weak. With the new CP being 150% longer would the total indicated runout on a tenths indicator be 1 tenth (the original calibration) plus 1.5 tenths (the correction factor for the longer contact point) equaling 2.5 tenths per graduation?
Thanks for the help, all my measuring tools for the last 50 years just have 1\16 of an inch on them
Joe

 

[xr650rRider]

The default tip is 18.7 mm or .7362" to the pivot point but the same amount would be added to the longer tip, so ratio would be the same. 1.65/.65 * .0001 = .000254 so you have the same result. Stated accuracy of that indicator is .0002", so accuracy would be .00051" per division.

https://www.mitutoyo.com/products/s...l-test-indicators/pocket-dial-test-indicator/

 

[Skedaddle Shooter]

The default tip is 18.7 mm or .7362" to the pivot point but the same amount would be added to the longer tip, so ratio would be the same. 1.65/.65 * .0001 = .000254 so you have the same result. Stated accuracy of that indicator is .0002", so accuracy would be .00051" per division.

Thanks, I’m just getting started, so learning as I go, but isn’t the accuracy of the indicator .0001?

 

[Dusty Stevens]

Thanks, I’m just getting started, so learning as I go, but isn’t the accuracy of the indicator .0001?

It is with the factory length tip

 

[Dusty Stevens]

This is why folks use the interapid with longer contact points. Its all about the movement you can see not about what it measures, on the interapid you can see it

 

[xr650rRider]

Thanks, I’m just getting started, so learning as I go, but isn’t the accuracy of the indicator .0001?

If you click on the link I provided above and scroll down to the list of indicators, then scroll down to the 513-504, Mitutoyo lists graduation = .0001", accuracy = ±.0002" that is with factory supplied contact point.

 

[Skedaddle Shooter]

If you click on the link I provided above and scroll down to the list of indicators, then scroll down to the 513-504, Mitutoyo lists graduation = .0001", accuracy = ±.0002" that is with factory supplied contact point.

Thanks

 

[Henryrifle]

@Dusty Stevens: Can the contact point on the Interapid be positioned like the Mitutoyo can? I am curious how you read the Intrepid if it is vertical and the dial is pointing at the tailstock.

I think this is the one that is recommended for this kind of work:

Interapid Test Indicator 312B-15V, Vertical, 0.060" Range, 1-1/2" Dia., 0.0005" Graduation

Hank

 

[WSnyder]

Can the contact point on the Interapid be positioned like the Mitutoyo can?

Yes, pretty much on any test indicator the point can be positioned where you want it.

 

[B Nettesheim]

Try setting it up on a surface plate and use a feeler gauge to check the actual readings

 

[Skedaddle Shooter]

Try setting it up on a surface plate and use a feeler gauge to check the actual readings

Thanks, I’ll try that.