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so you can also use them as a thread chaser.
Why do thread plugs have the notch in the go plug? (I can make some obvious guesses but I'd like to hear from you)
I think it's just to help get crud out of the thread before the gage goes thru so the gage lasts longer. Also, why you don't need one on the no-go end. It doesn't, or shouldn't, get threaded into anything.
Gordon - I've had operators come get me because of machine alarm, and they can't even hand jog it. Go over to the machine, quick look, "Hey, you have so many chips piled behind the table that the machine can't physically move any more".
I'm glad you work with good machinists, but "who wouldn't clean the thread first?"
Lots of operators. Lol. But hey, at least they are gauging the parts.
Plus clean is a relative term. The 1st shop I worked ran a lot of cast iron housings. There was a deburr/gage bench. The deburring was done with abrasive tools. So of course there was abrasive particles and cast iron dust everywhere. They blew off the parts, but it would never be what you and I would consider clean. Compared to where I work now I would say "oh my goodness, what a dungeon".
But at the time I worked it seemed fairly clean. I worked my way thru community college classes for machining at a large grey iron foundry, so that shop seemed clean comparitvly at the time.
And even with blowing out the holes at that 1st shop, the thread gages still had to be replaced every couple months. The amount of use they got combined with the environment wore them down pretty quick.
I think most lost cost production environments are going to be fairly similar to that.
That notch is a cheap easy way to "blunt start" or "block" remove the imperfect thread to the first full profile of the thread on the manufacture of a thread gage. True, it catches crud when entering the thread gage into the thread. And true, it's used for determining if a thread is cut deep enough, length wise to to qualify to the dimension given on the engineering drawing or work instructions for that given part.
Ken
It could be used for that purpose but why then the entire length of the Go thread? Has anyone ever seen a similar notch on a Go thread ring?
Is this something you know for a fact or, like me with "avoiding compression in a blind hole", taking a guess?
If threads needed "cleaning" to be inspected what about those that weren't inspected? The Go thread gauge is after all at the bottom of the tolerance and should go in easily. If not then your external thread (screw, bolt etc.) will have a bigger problem.
I'm trying to imagine the reply from a customer who rejects the parts and is asked, "Did you try with a notched thread plug gauge?"
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hole is normally blown out 3 times. holes will look clean. notch is for small particles no average human can see that might give a false ok. that is the no go might not go in cause .001" of a burr or metal dust not seen
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if that little notch helps no go to go in proving threads are too big and out of specs then it is worth having the thread notch.
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when you machine many metals you get a fuzz on surface that many will use nylon abrasive on OD parts to remove the fuzz and then wipe with a rag and it appears as black dust. obviously on internal features it is not as easy to clean. like when boring a hole to +/-.0001" tolerances that fuzz can easily give a false reading. is there a technical term for fuzz ??
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nobody saying to force the thread gage in the hole. if it turns hard obviously use a tap first to clean out the hole. some of us actually worry about .001" or less of stuff that is not easily seen. notch is for rust too not easily seen
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