I've got a cylinder bore dial gauge by Central Tools) that reads out to .0005". The gauge comes with a range of extensions to accomodate a range of 2 1/8" to 7" bores.

The problem is that I don't know what the exact size of the extension with the gauge is (nor are they given with the documentation or written anywhere obvious)....so I can't take exact measurements....only relative measurements (ie: cylinder wall taper, out-of-roundness). I'm guessing that I'm limited to relative measurements, and that's why I had to get a set of telescoping gauges to use with outside micrometers to take exact measurements.

Question: Is there any way to use the cylinder bore gauge to take exact measurements?

 

You use a micrometer to set a reference on the bore gauge and go from there.

 

Thanks Steve. I thought about that, but b/c the plunger moves...it makes it hard to make an accurate measurement.

Oh wait...I got it! I'll just tape the plunger! OK. Thanks.

 

IMO, that's why you use a dial bore guage (for out of round, balooned and tapered conditions). I'd rather take measurements with your snap guages. More accurate.

 

What does it matter if the plunger moves?
You set the mic to the desired starting point. we'll say that its 81.00mm
and set the bore gauge into the mic, then 0 the dial indicator. simple.

 

I never considered that b/c I didn't have a 3" to 4" micrometer. I could just buy a cheapy caliper tho. Thanks.

 

sorry to bring this topic from the dead.

The problem I'm running into is that how do I know that the gage is dead perpendicular to the cylinder? My readings are never consistent.

 

anybody?

 

egsdg

 

when you say there never consistent, the gauge will move back and forth you have to look at where the needle goes to meaning you can't just stick it in there and lift it and get a reading. I don't know how else to explain it. How are yu setting the pre-load? What kind of guage is it?

 

I pivot it up and down until I find the apex, I guess you could call it. The needle will hit that point (where it's the smallest reading) and then come back up. Maybe I'll draw it out graphically on a piece of paper if I did a crappy job of explaining it.

BTW, the gauge I was using when I first asked the question was a cylinder bore taper gauge....I just didn't know it at the time, two years ago.

 

the proper way to measure cylinder sizes is to use a snap guage and good micrometers. you insert the snap guage and let it expand and tighten the stop adjuster just a little bit so that it allows the guage to compress under pressure but stops it from expanding freely. then you, instead of pulling the gauge straight out, push the handle of the gauge towards the outside of the cylinder bore and then remove the gauge. use this same process when measuring the snap guage with the micrometer. you want the rock the snap gauge inside the calipers so that it measures corner to corner on the snap gauge. This should help you guys measure your cylinder bores.