Buying Used Thread Gages

Such a deal... but how would you check a used thread gage to see if it was good?
For that matter, how do you know the new thread gage you purchased is
good? ;>)
Jon Banquer San Diego, CA
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They're the same as vises.......look for the words " Made in China". Do I have to tell you everything....doofus.
You're welcome Barn
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On Sun, 10 May 2009 13:43:26 -0700 (PDT), jon_banquer
What type of thread gage?
Plug, ring, snap, ID or OD single element indicating, ID or OD functional indicating, tri-roll, thread overlay, etc., etc., etc.....

Do you really not know the answer?
How would you check a pitch micrometer?
There is usually a product such as a set gage or master involved.

You don't unless you can check it yourself. Being given a certification means next to nothing unless you purchase your gage from a reputable gage manufacturer and there are a bunch of bad ones out there.
Thread ring and plug gages check very little, they check functionality to mating part (sort of) but they can't tell you if a thread is good.
In some industries, some products using thread ring or plug gages may be acceptable but in reality they only give an indication if thread is good or not. For some industries and products they are near useless especially for critical applications.
Tom
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wrote:

ANSI and NIST for starters.

All any feature has to do is meet the print.

Machinery's handbook has been publishing the standards for decades, if not at least a millennia.
And if you cant handle simple math;
http://www.osbornproducts.com/software.htm
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On Sun, 10 May 2009 16:39:55 -0700, "Scott"

A big tip off is when you open a box of brand new gages, unpack them and look only to find chatter all along the gage surfaces (threads).

Never would have thought of that.....LOL.

Machinery Handbook tells you how to inspect a thread and what methods are acceptable in all situations, for all products, parts, industries, employers & customers?

Finding a thread spec wasn't the point. I was talking thread inspection, acceptable inspection methods which is an entirely different matter than reading a thread spec or finding the size chart and tolerance information on a print or in a book.
Tom
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On Sun, 10 May 2009 20:25:05 -0700, "Scott"

Used to be.....maybe till about the mid 80's IIRC.
How did you check threads, internal and/or external?
There are still people today that check an internal or external thread with a pair of calipers, micrometer and a bolt, nut or mating part and that's it. As Mr. Wuhl on HBO says, "I shit you not!"
If someone is using caliper to check minor diameter on internal thread and OD micrometer to check major diameter on external along with go ring or plug gage it's the same frickn' thing, neither method tells you if you have a good thread...."I shit you not!".
Tom
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wrote:

Pee Dee, but mike 'em first.
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On Mon, 11 May 2009 06:23:19 -0700, "Scott"

Can you please be more specific on exactly how you inspected threads?
It seems you said you checked the pitch diameter and major diameter only.
Tom
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What color is your cape, Superman?
What class thread?
What surface finish callout?
Ground, cut, formed or rolled?
What concentricity?
Get a grip.
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On Mon, 11 May 2009 19:32:05 -0700, "Scott"

I don't know why you are becoming aggressive. I am only trying to understand what you wrote because your responses so far are not clear to me.

Doesn't matter running class 1, 2 or 3 thread, all have the same dimensions to be checked.

UNJF

Are you a machinist? I ask because by your responses and questions so far like this one here, make me wonder if you actually have any first hand experience making or inspecting threads.
Direct answer to this question:
Doesn't matter how a thread is made, Thread Form, Dimensions, Tolerances don't change due to method of manufacture. For instance if the thread form calls for a .012" Rounded Root Radius, doesn't matter how the thread was made or what type of machine was used, the threaded part needs to have a rounded root radius within tolerance.
In my case having threaded millions of parts, frequency of inspection during a run may vary due to method of manufacture. For instance I will check Root Radius much more frequently on Cut Threads vs. Rolled Threads.

Yes, that is one thing to check but most people don't.

Answer a direct question with a direct answer. If you weren't evasive and/or unclear in your responses we would be done by now.
Tom
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He's not saying the method of manufacture is not important. He's saying they *all* need to be properly inspected, regardless of method of manufacture.
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wrote:

Sure, again, that is obvious.
And depending upon the use, spinning a class 2 nut onto it may be all the "inspection" needed.
For instance, when was the last time you used a fishtail to grind a high-speed steel threading tool?
I have a 55 degree fishtail for Whitworth threads that is older than I am, and I have actually used it twice.
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On Tue, 12 May 2009 08:46:45 -0700, "Scott"

A class 2A thread callout on the print means "spinning a class 2 nut onto it may be all the inspection needed" "depending upon the use".
*****
OK, NOW I understand why you said "Threads are the simplest of our trade." That is all I was trying to get to, now I understand how you can make that statement.
******

I used to make my own single point threading tools. I would braze carbide tip to HSS square shank, grind the included angle on pedestal grinder check on comparator, if good with diamond file tool on comparator put the radius on. Big deal, still has nothing absolutely nothing to do with how a threaded part is inspected which is the subject you keep trying to change.

Who cares? It has nothing to do with inspecting threads.
Tom
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Now you're simply being pedantic and obtuse.
There is no magic to inspecting a thread or any other feature of any other common part.
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Wow.
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Come on guys.
How do you check the gage?
Measure it.
How do you measure it?
How far down the ridiculously simple do you want to go?
All the math is in Machinery's Handbook and has been for a century.
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On Tue, 12 May 2009 07:29:59 -0700, "Scott"

You took the lead.

Then why are you having such difficulty clearly stating how YOU inspect threads?

The question wasn't what you "would" use, the question is how do/did YOU check threads.

Which has absolutely NOTHING to do with what I wrote. Try to focus, the issue is and has been inspecting a thread NOT making one.
I wrote: "Doesn't matter how a thread is made, Thread Form, Dimensions, Tolerances don't change due to method of manufacture. For instance if the thread form calls for a .012" Rounded Root Radius, doesn't matter how the thread was made or what type of machine was used, the threaded part needs to have a rounded root radius within tolerance."
Tom
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Bullshit.
I am not the one with the difficulty.
Obviously, it depends upon the surface finish and tolerance call outs. Most often I use three wires and a magnifier on an OD thread, or I use ThreadTech to make a gage. Never had one rejected, and as I said before and again, it aint rocket surgery.
Why are you making such a big deal out of nothing?
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On Tue, 12 May 2009 12:33:08 -0700, "Scott"

YOUR very first post in this thread;
"And if you cant handle simple math;"
Or your
"What color is your cape, Superman?
Came first, I responded in kind.

You most often check thread pitch diameter with wires on external threads or you made a homemade go functional gage and use it. And that's fine, in some places it's more than enough.
Asking how you check a thread wasn't a trick question.

I said OK, I now understand why you can say "Threads are the simplest of our trade." That is all I was trying to find out and you finally made it clear. By your description of how you normally check threads I can now understand your statement that "Threads are the simplest of our trade."
If all anybody ever had to do was use thread wires on external threads and sometimes use a go gage for ID or OD threads and not having to inspect any of the other thread dimensions then yes, threading truly is simple, easy even, lucky you.
Tom
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The more I think about it, it seems to me there should be some soft of optical gauging system that one could use to check thread gages with.
Jon Banquer San Diego, CA
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