Decent CHEAP calipers

[Steel Horse Rider]

I am surprised that you don't have a set of telescope gauges. I have a set of Starrett telescoping gauges which allow you to use a micrometer up to 3". But, most work reloaders do don't require such accuracy.

 

[MachIVshooter]

I am surprised that you don't have a set of telescope gauges. I have a set of Starrett telescoping gauges which allow you to use a micrometer up to 3". But, most work reloaders do don't require such accuracy.

You mean these?



Got digital and dial inside calipers as well.

The nice thing about the little ID mic I posted earlier is that it gives you a live measurement without having to wiggle it out of a hole, and it's especially useful if you have a step up in diameter deeper inside a small bore. Sometimes rough machined thread crests give you a smaller ID than the actual bore ID, too, and you're left to guess by how much with a telescoping gauge. Obviously that doesn't matter so much for fitting a part inside, since it will have to clear the smallest ID, but there are many parts which step up ID inside, so to duplicate or produce them, you need to know by how much. The booster pistons and muzzle brakes I make step up ID after the threads. Granted, not very critical dimesions there since it's just removing weight (and creating a chamber in the case of the brakes), but I still need to make sure the walls are sufficiently thick, and one can't count on cross feed measurements translating to exact material removal/part dimensions, especially with the deflection of a skinny bar that is reaching through a .456" ID to create a .600" ID 1.75" deep on the part.

 

[jmorris]

Just depends on the tolerances.

This is true, if your making pipe gate hinges you don’t even machine parts you buy stock that is ID/OD compatible and just cut it.

If you need accuracy to two tenths of a thousandth, that can cost more than a thousand dollars (each) for the proper tool, they also have a very narrow range, like these inside micrometers.

 

[Swifty Morgan]

In the machining world you use a tape measure to cut the stock to length (oversize).

Calipers are what you use to get the part close to the final dimension (again on the + side).

Micrometers and other precision tools are what you use towards the end of the processes.

Exactly. It would be misleading to make people think you should use calipers to get within a thousandth. It's not what they're made for. You may get lucky most of the time, but it doesn't mean you're doing it right. I've seen a dog ride a bicycle, but people do it a lot better.

I use calipers for reloading pistol rounds because I don't give a crap about three thousandths. If I need real accuracy, I use the correct tool.