Help with bore gauge measurement

[Stapes]

I'm measuring an M10 block I just bought and just wanted to confirm that my understanding of the reading on the gauge dial is good. What confuses me on the dial is the relationship between the 0.0005" and the 0-0.25".

I'm measuring Cylinder 1 here and the bore gauge is set to 3.5141" which is the first re-bore Cat. B.

I think the gauge is telling me that the the cylinder is 0.0005 past the 3.5141, basically 3.5146"

I just can't figure out the 0.25". There are 50 lines on that dial so I think one of the two seems incorrect, but I doubt Fowler fucked this up.
0.0005" x 50=0.025" and 0.005" x 50=.25" Help is much appreciated because I could be sending the block to the machine shop with very incorrect measurements

I've emailed Fowler and since its probably a stupid question they pretty much went silent

[LJ851]

The .25" is the range of stroke the gauge is capable of.

The gauge needle should rotate clockwise so i read that as .0005 over your set measurement.

Each line on the gauge is .0005, every two lines is .001 which add up to the 5,10, 15 numbers on the gauge.

[Stapes]

The .25" is the range of stroke the gauge is capable of.

The gauge needle should rotate clockwise so i read that as .0005 over your set measurement.

Each line on the gauge is .0005, every two lines is .001 which add up to the 5,10, 15 numbers on the gauge.

Thank you for your reply. I only have a few comments. I think the reading is not over but under my set as it hasn't reach the zero, meaning that the cylinder bore has .0005 wear over the 3.5141 spec.

Also, I think the reasoning on my OP is incorrect. There are 100 lines on the dial and not 50, so a full rotation of the needle would equal .05 in. So when you say that the .25" is the range of the stroke then it means that the gauge can measure up to 5 turns of the dial?

I'm a newbie on all these gadgets.

Thanks

[LJ851]

Thank you for your reply. I only have a few comments. I think the reading is not over but under my set as it hasn't reach the zero, meaning that the cylinder bore has .0005 wear over the 3.5141 spec.

Also, I think the reasoning on my OP is incorrect. There are 100 lines on the dial and not 50, so a full rotation of the needle would equal .05 in. So when you say that the .25" is the range of the stroke then it means that the gauge can measure up to 5 turns of the dial?

I'm a newbie on all these gadgets.

Thanks

You are measuring the inside diameter of the hole and when you start measuring, the bore gauge is at an angle in the bore. With the gauge at an angle, the measurement shown on the gauge is larger than the bore and as you tilt the gauge to become square with the bore the measurement will get smaller and smaller until it goes over center and starts to angle the other way in the bore.

So if the number in the picture is the peak of the measurement, the hole is larger than than the set number because it hasn't reached zero yet.


Yes, the gauge will turn about 5 revolutions to reach it's .25 stroke potential.

[Stapes]

You are measuring the inside diameter of the hole and when you start measuring, the bore gauge is at an angle in the bore. With the gauge at an angle, the measurement shown on the gauge is larger than the bore and as you tilt the gauge to become square with the bore the measurement will get smaller and smaller until it goes over center and starts to angle the other way in the bore.

So if the number in the picture is the peak of the measurement, the hole is larger than than the set number because it hasn't reached zero yet.


Yes, the gauge will turn about 5 revolutions to reach it's .25 stroke potential.

Lorin - I appreciate you taking the time to walk me through this.

Thanks.