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

[Splat]

Well gents, instead of minus tolerance I mistakenly bought a set of plus tolerance 0.061-0.250" gage pins. I did get a helluva deal on them and will mic them tomorrow to see how good they are. For bores/holes measuring the consensus is to go with minus sets. If I return them to the seller I'd have to pay to ship them back at a charge of $50. I really don't know what I should do here as I've never used gage pins before and what to expect from them. What say you?

Also, while mulling over what to do I happened upon a great writeup on Go/No-Go gages by AA Jansson/Trescal. I hope this is OK to attach it here and might help others flummoxed by the thinking behind the Go/No-go nomenclature. Thanks.

 

[RJSakowski]

I got that same set and by the same method. I kept mine. By measure, most, if not all the pins were .0002" oversized and my plan is to get the undersize pin set. The will get me to close to within .0005", e.g. .1248", .1252", .1258", etc.

 

[Splat]

I got that same set and by the same method. I kept mine. By measure, most, if not all the pins were .0002" oversized and my plan is to get the undersize pin set. The will get me to close to within .0005", e.g. .1248", .1252", .1258", etc.

You were probably as mad as I was. Wanted to kick myself. That's a good idea so I'll just keep them. I can get a few minus pins for what I'm working on now instead of another whole set. Thanks.

 

[Splat]

Just finished mic'ing the whole plus set. I've had them on my kitchen table for past 3 days and they didnt feel cold. Most of the pins were dead on their nominal size. A few were 0.0001" over. Pretty happy with that. Now I'm wondering if its minus brother set would be as on-nominal as these.

 

[woodchucker]

I have plus. They are fine for my needs.

 

[extropic]

Just finished mic'ing the whole plus set. I've had them on my kitchen table for past 6 days and they didnt feel cold. Most of the pins were dead on their nominal size. A few were 0.0001" over. Pretty happy with that. Now I'm wondering if its minus brother set would be as on-nominal as these.

Reading that causes me to question whether your measuring tool (micrometer?) was properly calibrated and/or read.

I don't see a link to the set you purchased. I'd appreciate it if you'd post one.

What sizes and tolerances of gage pins you'll want depends on the tolerances you're working to. That factor isn't mentioned here so . . . TBD.
You certainly should keep the set you bought. If it was a "helluva deal" and you return them, IIUC, you'll be out twice as much money and have zero pins to show for that money.

 

[Splat]

The pins are in spec as plus tolerances for ZZ up to 0.825" are -0.0" +0.0002". Yes, my mic was/is calibrated. I'm keeping them.

 

[Rex Walters]

I’d keep ‘em for sure, but I’d also get a set of minus pins!

FWIW, plus pins are still useful for more than just gaging bores. I use mine (albeit minus pins) all the time for tasks like:

• Setting cutter heights (rolling under a cutter until light contact, then punching the number into my DRO)
• Positioning a stop on the lathe accurately
• Locating work or tooling a fixed distance from a feature or pressed in dowel pin
• One thou increments to 0.500”, plus a single 1.000” pin, plus a pair of 123 blocks let me position things accurately almost to the travel limits on my machines. I am seriously thinking of making a .5-1-1.5 block (probably a matched pair, though it’s less necessary) once my surface grinder is operational. They will help avoid the need to use two pins for a final offset between 0.501” and 0.999” (it’s easier to stack a pin on a flat surface than hold two pins orthogonal to one another). I’ll probably make a matched pair of 246 blocks while I’m at it, for the extremely infrequent case (for me) when a pair of 123 blocks doesn’t suffice.

I use mine for such tasks constantly. Having pins in one thou increments has saved me from (error prone) measuring countless times.

About the only errors I make with them is from accidentally grabbing a pin from the wrong row or putting one back in the wrong hole, but that can be mitigated by ALWAYS checking the value printed in the pin itself (or mic’ing the ones too tiny for a label).

Pins and adjustable parallels are about my favorite tools in the shop. So handy!

 

[woodchucker]

I’d keep ‘em for sure, but I’d also get a set of minus pins!

FWIW, plus pins are still useful for more than just gaging bores. I use mine (albeit minus pins) all the time for tasks like:

• Setting cutter heights (rolling under a cutter until light contact, then punching the number into my DRO)
• Positioning a stop on the lathe accurately
• Locating work or tooling a fixed distance from a feature or pressed in dowel pin
• One thou increments to 0.500”, plus a single 1.000” pin, plus a pair of 123 blocks let me position things accurately almost to the travel limits on my machines. I am seriously thinking of making a .5-1-1.5 block (probably a matched pair, though it’s less necessary) once my surface grinder is operational. They will help avoid the need to use two pins for a final offset between 0.501” and 0.999” (it’s easier to stack a pin on a flat surface than hold two pins orthogonal to one another). I’ll probably make a matched pair of 246 blocks while I’m at it, for the extremely infrequent case (for me) when a pair of 123 blocks doesn’t suffice.

I use mine for such tasks constantly. Having pins in one thou increments has saved me from (error prone) measuring countless times.

About the only errors I make with them is from accidentally grabbing a pin from the wrong row or putting one back in the wrong hole, but that can be mitigated by ALWAYS checking the value printed in the pin itself (or mic’ing the ones too tiny for a label).

Pins and adjustable parallels are about my favorite tools in the shop. So handy!

for most of us hobbiests, one set of pins is all that is needed. enuf said.
either will work for most.

 

[Rex Walters]

for most of us hobbiests, one set of pins is all that is needed.

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!