Bore Measuring

[tornitore45]

Lohring, I suppose the 4 ball gauge must be held on axis or it gives a cosine error.
What technique you use to keep the gauge on axis or the base perpendicular to the bore axis?

 

[lohring]

That error would apply to most of the bore measuring techniques. It is very small even with a several degree misalignment. The ball gauge measures over a small range. If the cylinder holding the balls has a small clearance in the nominal bore that error will be almost non existent. The article I posted suggests a tapered ring around the cylinder. Look at the picture. That completely solves the problem.

Lohring Miller

 

[tornitore45]

Did not associate the tapered cylinder with its function.

 

[fencer]

I have a vernier caliper with rounded jaws on the outside edge allowing the measuring of bores.These have limitations as you can't detect a taper in the bore.I made a set of differet size size tapered parallels with round edges on the staight side ,used in different formats measuring with a mike gives an accurate reading .I will still make one of the guages shown.
Frank