Sled type bore gages

[rslaback]

Local auction house near me has a Central 6460 bore gage on it that I am considering. In looking it up some it is referred to as a sled type which I am not familiar with. All the bore gages I have ever used are a more standard design. Somebody help me understand how the sled on this thing doesn't get in the way.

https://images.toolsid.com/central-tools/items/pdf/6460-instructions.pdf

 

[Packard V8]

Those are mostly used for indicating taper in worn cylinders. They're pretty useless for measuring actual bore diameter to fit pistons.

jack vines

 

[RPH]

Agree, taper and out of roundness. Both data bits are useful for engine building.

 

[rslaback]

Based on the cut out of the base it looks like maybe the actual indicator can be moved up and down. I can see how that would work, then giving you a 3 point stance on the cylinder bore and even holding the indicator in a perpendicularity relationship with the centerline of the cylinder while also being in the middle of the circle. I've never really liked how the standard two point bore gage just gets wiggled a bit while you look for the smallest number.

 

[Packard V8]

FWIW, these are very old tech. I've got one which I've had for more than fifty years and seldom use it.

jack vines