Gage Pins: Keep or Return.... and Go/No-Go help

[woodchucker]

Agreed!

This was the intent of the smiley - I was poking fun at myself. Pretty sure I NEED four sets (plus/minus in metric/imperial)!

More than enuf:

If your primary use case is simply to check holes while progressively boring them larger, it is at least slightly preferable to have pins that are on or slightly under your target (it’s easier to lap a hole a tenth or three larger than it is to put a smidge back in).

True (non-hobbyist) QA use (making interchangeable parts for others) needs both go and no-go pins of course (minus and plus). I’ve had exactly one occasion when I kinda wished I also had a set of plus (imperial) pins, and even then I was willing to ignore calibration and shop temperature.

But to your point, one set of even plus pins should suffice for most of our hobbyist needs — especially for locating/positioning. That was the point of my post!

But then we are not measuring 10ths so usually.001 is close enough.

 

[Rex Walters]

usually.001 is close enough.

Yes. I’m obviously not making myself clear. 99.987% of the time I don’t care about tenths. YMMV.

The exceptions are almost always when I’m gaging tight or interference fits for shafts in a bore. Even with shafts in a bore, I’m usually going for slip fits so tenths don’t matter (clearance is clearance, Clarence) When it does, though, minus pins work better for me.

When locating/positioning, closest thou is pretty much always good enough for my work.

I do want my metrology equipment more precise than the tolerances I work to, though. I want to at least KNOW whether I’m holding a minus tolerance or plus tolerance pin, for example.

 

[woodchucker]

Yes. I’m obviously not making myself clear. 99.987% of the time I don’t care about tenths. YMMV.

The exceptions are almost always when I’m gaging tight or interference fits for shafts in a bore. Even with shafts in a bore, I’m usually going for slip fits so tenths don’t matter (clearance is clearance, Clarence) When it does, though, minus pins work better for me.

When locating/positioning, closest thou is pretty much always good enough for my work.

I do want my metrology equipment more precise than the tolerances I work to, though. I want to at least KNOW whether I’m holding a minus tolerance or plus tolerance pin, for example.

You were. I don't know where my post came from...

 

[Rex Walters]

I happened upon a great writeup on Go/No-Go gages by AA Jansson/Trescal.

Finally remembered to take a look at this doc you posted. Really great - thanks for posting!

 

[metalmaster1]

in theory you could buy plus pin and minus pin sets and they could measure the same. I worked as a QC inspector for almost 30 years. if you wanted accurate pins you used Deltronic class X pins

 

[Rex Walters]

Deltronic class X pins

Hey, Christmas is coming. I’ll mention it to my wife!

(Suspect she’d just point me at equally expensive stuff that comes in nice boxes)

 

[Splat]

in theory you could buy plus pin and minus pin sets and they could measure the same. I worked as a QC inspector for almost 30 years. if you wanted accurate pins you used Deltronic class X pins

Yeah I figured that and why I dont plan on getting minuses in that range now. Oh, and my Santa can't afford Deltronics. Ha

 

[pontiac428]

The plus pins are fine for all of the many uses of gauging, like measuring gaps between parallel planes, finding the angle of intersecting planes, etc. For gauging round holes (boring, honing, reaming...) the minus pins are the thing to have, because you will feel those tenths. But if you're mindful of the value you're approaching and what side your gauge falls on, you'll be glad to have them for all purposes.