Plug guages

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Dobetown

Bearcat
Joined
Jun 7, 2009
Messages
72
Somewhere I saw an article on a set of plug guages for checking revolver cylinder throats and now I can't find it. Can anyone help? Thanks
 

Chuckbuster

Single-Sixer
Joined
May 28, 2009
Messages
492
Mike Venturino had an article very recently about them in HANDLOADER.

You can get a set that goes from .250"-.500" in .001" steps. They are made in either Plus or Minus tolerance, an "economy" set will be +/- .0002" from marked size. Normally with a plug gage + is the smaller dimension and considered "GO". - is of course the larger and "NO GO". This is for when you are checking a hole in a part and have a size with a tolerance such as .4290" +.003/-.001. For checking cylinders etc. it really does not matter which you have since we just want to know what the holes measure within a thou or so. You can also save some $$ by not bothering with buying a set with "certification". The certification only is an issue in a MFG. situation where you are doing Quality Documentation.

"GRIZZLY" is one source, since I work for a Tool Supply house and sell this stuff all day every day I won't advertise any further. PM me if you like
Kevin
 

Bullet Puller

Bearcat
Joined
Jul 16, 2009
Messages
36
You might also check ENCO Supply. (USE-ENCO.COM) They have boxed sets as described in Mike Venturino's column. I think that is where "Duke" bought his. I have the .010"-.250" set. I need to get the .250"-.500" set.

Larry
 

Hashknife Hartley

Single-Sixer
Joined
Jul 16, 2003
Messages
359
I got the set that Mike Venturino talked about from Enco and they're well worth the cost. Besides checking cylinder throats, I found them very useful for checking alignment when trying to drill or ream a straight hole in something that already has a hole like a cylinder, as you can get a pretty good alignment with a plug gauge that fits the existing hole. No slightly off center or canted holes.
HH
 

woodman0663

Bearcat
Joined
Nov 24, 2009
Messages
2
Just to set the record straight on plug gage size tolerances. Yes, plug gages do come in plus and minus tolerances, this is actually a series. The plus series plug gages can be on size up to .0002 inches over size, and the minus series can be on size and down to .0002 under size. For example a .250 plus plug gage can be .250 to .2502, and a .250 minus plug gage can be .250 to .2498. Usually the minus plug gage is the "GO" gage and the plus plug gage is the "NO GO" gage.
 

Chuckbuster

Single-Sixer
Joined
May 28, 2009
Messages
492
You have the Go and No Go reversed.
Plus is the small dimension on a Go/No Go gage and considered the GO.
Minus is the large end and is the No Go.

If your hole size on a part is allowed to be .251-.260 your Go/No Go assembly would be a .251+ pin and a .260- That way when you check your part if the .251+ fits you know the hole is large enough but if the .260- fits you know it is potentially oversize even if only a couple of tenths.

I did not describe the +/- very well in my first post. A gage can be anywhere from "On Size" up to the + or - tolerance amount. We have been talking .0002" which is the tolerance on "CLASS ZZ" gages. Different tolerance Classes are made from ZZ up through XXX.

ZZ is sufficient for what we are doing here.
 

woodman0663

Bearcat
Joined
Nov 24, 2009
Messages
2
Good point Chuckbuster. I was thinking of a closer tolerance hole when I said about the minus being the 'GO' and the plus being the "NOGO'. For example, a hole of .250 with a tolerance of plus or minus .0002. The .250 minus could possibly be used for the 'GO' and the .250 plus could be used for the 'NOGO'. In cases like this, you definitly need to measure the plug gages to know the actual size as best that can be determined. If the .250 minus measured .2498 or .2499 and the .250 plus measured .2501 or .2502, then these would be acceptable 'GO', 'NOGO' gages. At times, I revert back to my days as a precision Jig Grinder. In the old days of manual precision grinding (pre CNC grinding), a good jig grinder could hold a hole size tolerance well within a total of .0001 of actual hole size, and a location tolerance within .00005 (not a typo).
 

Chuckbuster

Single-Sixer
Joined
May 28, 2009
Messages
492
With a +/- .0002" tolerance I would not use or reccomend a class ZZ gage, need at least a Z (+/- .0001) and a Y or even X would be better.

Go is still the +, No GO the Minus
 

1ruger

Single-Sixer
Joined
Nov 19, 2009
Messages
151
Hashknife Hartley":3w1n8533 said:
I got the set that Mike Venturino talked about from Enco and they're well worth the cost.

Which set is this?
Can you send me a link or a part number?
Thank you in advance.
 

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