Measuring shallow bore

Well you could buy gage rods that are available in 0.001mm increments and use them to feel how easy they go in (if you need a hammer, then ...). Certainly, you will have to insert them patiently with calm hands. It's done every day around the world. But a certainly cheaper way is to cast it out with an special zinc alloy (cerrobond? forgot the name) used for measuring chambers of riffles. You cast the metal in, wait to solidify, pull it out, wait an hour or so and then measure. They have the property of shrinking and then expanding back to size again. Don't know wether they work on alumin(i)um, but I think so.

Nick

Cerrosafe.

Wes

Yes, right!

Isn't it stunning how it shrinks and expands?

Nick

Sounds like some way-cool matereials science going on there.

I imagine it has a very slow crystal formation rate.

Maybe it forms one variant of crystal that make it shrink, then those crystals change to a different type that cause it to expand, or, maybe the crystals that make it shrink form relatively quickly and then the ones that make it expand form more slowly.

I wonder if the shrinking was a happy accident, or designed in to aid in removal?

Dave

Cerrobend is another alloy that expands when it cools. It differs from Cerrosafe in that it does not shrink first. This expansion property is what makes it work so well for bending tubing because it fills the tubing tightly. ERS

You need to clarify that, while metals generally shrink when cooling the transition from a liquid to a solid may exhibit an increase in volume. Some metals such as antimony and bismuth exhibit this property, maybe others I have forgotten. This characteristic of antimony is used with modern pewter alloys (Brittania metal) in that it provides a better casting definition due to the lower shrinkage rates of the alloy.

The Cerrobond sounds like it might due the trick for some of the bores, but the others have an 0.030" O ring groove, which could make removal a problem.

You can always put a bushing into the bigger bore.

Nick

NO!

Buy a set of Deltronic pins, which consists of 25 pins in .0001" increments, from .0012" under to .0012" over nominal.

Harold

I have heard that sulphur works like the Cerrosafe. You melt it and pour into place (with a suitable way to pull it out). I think the Cerrosafe is about 30-some dollars per pound or more. But I noticed that one poster mentioned its use for bending tubing, so it might be a good investment for the future, anyway. But----- if it returns to its normal size, isn't that going to be a pretty tight fit?

Pete Stanaitis

------------------ oldjag wrote:

I'm ordering the Cerrosafe and the deltronic pins. Thanks

Welcome.

You're learn to love those Deltronics. We used them routinely when honing small bores. Sure takes the guess work out of measuring.

Harold