Strange bore dial indicator

[jdm23]

I have never used one of these. How do I calibrate to a known 18mm, 21mm or whatever starting size i fit the threaded tip, plus 1 or 2mm shims into the handle? For example when the 18mm tip is fitted with no shims, there is slightly less than 20mm uncompresed to the feeler tip, so how I do know or set things?

The dial indicator in itself is also strange. Why a 0-10mm range when the feeler handle has range of 1mm only? It appears to be original to the set, of course Borletti was making 5mm range instruments.

Also, is has a dampening function, provided by a flat coiled spring inside, so that the needle moves very slowly, like one division per second, in either direction. It's kind of painful to just watch it move.

 

[Chipper5783]

That is a very common style of dial bore gauge. The way I use mine is I'll use an inside micrometer on the bore, then I set the gauge (pin, spacers, dial) to read zero - then I use the gauge to quickly and accurately check for out of round, for taper, measuring deep in the bore. It is a very quick way to make accurate measurements, but you have to set it against a known reference. The dial should move quickly- like any normal dial movement. Something is gummed up on that one of yours - perhaps in the handle portion?

 

[L98fiero]

That is a very common style of dial bore gauge. The way I use mine is I'll use an inside micrometer on the bore, then I set the gauge (pin, spacers, dial) to read zero - then I use the gauge to quickly and accurately check for out of round, for taper, measuring deep in the bore. It is a very quick way to make accurate measurements, but you have to set it against a known reference. The dial should move quickly- like any normal dial movement. Something is gummed up on that one of yours - perhaps in the handle portion?

Best way to set it is with a ring gauge, next best is between a clamped gauge block stack and last, in an outside micrometer

 

[craniac]

Best way to set it is with a ring gauge, next best is between a clamped gauge block stack and last, in an outside micrometer

could you elaborate more on the clamped gauge block stack? Having trouble visualizing that.

Tim

 

[L98fiero]

This is like the one I have though mine is the longer type that will hold a six inch stack. I don't have the wear blocks but what works pretty well is a piece of 3/8" square high speed steel at the top and bottom of the stack
Just found this picture that shows the complete set as it should be and it's the long clamp like mine