"Pittsburghing" a thread..?

[SLW]

Has anyone ever heard of this? I had some parts with threads that the pitch diameter was oversize, and the no go thread gage flew right in there. (The part has a drill hole in it which gets tapped). The guy who runs the same machine on day shift mentioned he was able to save one of them by "pittsburghing" the thread.. He didn't really explain it that well, but he said something about a ball bearing.. and it apparently works, the no go gage won't go further than the first thread after doing it. I am just curious if anyone has heard of this, and how exactly it works. I realize this isn't much to go off of and it isn't a very good explanation, but if anyone has heard of "pittsburghing" threads and knows what it is, I would like to know.

 

[Hertz]

Basically tapping the top of the thread pushing the threads in preventing the no go from starting but still allowing the go. This is an unorthodox way of "fixing" a thread since it does not actually fix anything. It just "damages" the top of the thread slightly to stop the no go from going in. The rest of the thread is still no good.
Never heard of it being called "Pittsburghing" though.

 

[TeachMePlease]

Yeah, your guy didn't "fix" shit.... He polished a turd in a clever enough way that your customer likely won't catch on.

It's up to you to decide whether or not you'll pass a dishonest part that doesn't actually meet specs to your customer.

 

[Scottl]

Mickey Mouse bullshit cobbler's trick!

 

[SLW]

Haha okay thanks guys. That's what he said to me, it only messes up the first thread so it appears as if it is still in tolerance. And I think with these parts, there is actually a threaded insert that gets loc-tited in the threads. He said they ain't gonna know the difference, so f**k 'em.

 

[Hertz]

Haha okay thanks guys. That's what he said to me, it only messes up the first thread so it appears as if it is still in tolerance. And I think with these parts, there is actually a threaded insert that gets loc-tited in the threads. He said they ain't gonna know the difference, so f**k 'em.

Not really a good attitude to have towards a customer but to each their own. Lets just hope the customer is not a member of PM

 

[bw_4000]

I wouldn't put my location either if I made bullshit like this LOL

 

[Gordon B. Clarke]

Give the guy a warning and keep an eye on him. Not only could you loose customers if they found out you were pulling a stunt like that (and it always gets discovered at some point in time) but you could be sued BIG TIME if your crap failed and caused damage or personal injury.

I'll add another piece of advice. Leave PM and log back on with a completely different AKA.

 

[EDM JOE]

Better yet, keep the same name so we don't accidentally send work your way.

 

[bloomautomatic]

I've heard that term before. I was told it was when you peen a hole over to fix a sloppy fit on a dowel pin. Or using the center punch on the pin to raise up the OD a bit. But yeah, it doesn't "fix" anything.

Vince

 

[in2glamisgirl]

One way fix slightly oversize internal threads is to re-tap with a cold form tap of the next higher H number. External threads can also be re-rolled to bring up the pitch dia. This type of fix will sometimes bring threads back into tolerance. The best chance of success is when the minor dia. (internal thread) and major dia. (external) near is nominal.

 

[scadvice]

I caught a guy doing something similar on both sides of a reamed hole the was oversize slightly... though I didn't know he was from Pittsburgh.

One way fix slightly oversize internal threads is to re-tap with a cold form tap of the next higher H number. External threads can also be re-rolled to bring up the pitch dia. This type of fix will sometimes bring threads back into tolerance. The best chance of success is when the minor dia. (internal thread) and major dia. (external) near is nominal. in2...

Have not heard that one. I wonder how the thread profile looks after?

Here is one I did years back. Complex parts with 6-32 and 8 - 32 tapped holes in them (6 in each part) came back from the anodizer with crystals in them and then would not then pass GONOGO gage. They, (all 150 parts) did pass when they went out for anodize. They were first alodine then the tapped holes plugged along with some bores. The problem was the crystals would not wash or clean out of the tapped holes, however the bores were OK. When you tried to re-tap them, the cutting taps would jam and it would then break trying to get it back out. This problem was solved using a forming tap to crush the crystals and them rinsing them out. (BTW -The customer approved the removal process.)

 

[tazmo16]

pittsburging my ass sounds like making chicken salad out of chicken shit maybe you two should be employed at billy bobs machine and junk yard

 

[Krutch]

Hope the threaded hole isn't for a military weapon system or have a weight hanging from it. I've seen that done before and didn't like it then. If costumer finds out you could lose his business.
Worked at a place where the owner got a call from his main customer about a reamed hole needing to be a bit larger than the print callout. He told customer he had already machined half of them and got a rework order to open the hole in the revised size. So boss comes out to shop floor excited as all get out and has a job torn off a machine which had just been documented with good parts after spending several hours dialing it in. To run a pile of parts at the original ream size in case the customer rep showed up. I consider that less than honest. Worked less than a year there and saw too much how NOT to run a shop.
Like a tube for recoil for some machine gun gets ID threaded on both ends and the thread gage to check was shop made plus modified to OK parts which may not be to specs. If the gage only had about 2 threads left to check with. All the lathe operator was to do was get the gage in the hole, didn't matter if the gage wanted to fall out as long as it would thread in. One could see where threads had been machined off the gage until the gage screwed in but not whether or not the threads were in spec. I hated working for that outfit.

 

[sable]

Well I have heard of a "Pittsburgh Lock" , it's a sheet metal seam ,so perhaps this is what a sheet metal worker does to get a thread to guage .

 

[scadvice]

Hope the threaded hole isn't for a military weapon system or have a weight hanging from it. I've seen that done before and didn't like it then. If costumer finds out you could lose his business.
Worked at a place where the owner got a call from his main customer about a reamed hole needing to be a bit larger than the print callout. He told customer he had already machined half of them and got a rework order to open the hole in the revised size. So boss comes out to shop floor excited as all get out and has a job torn off a machine which had just been documented with good parts after spending several hours dialing it in. To run a pile of parts at the original ream size in case the customer rep showed up. I consider that less than honest. Worked less than a year there and saw too much how NOT to run a shop.
Like a tube for recoil for some machine gun gets ID threaded on both ends and the thread gage to check was shop made plus modified to OK parts which may not be to specs. If the gage only had about 2 threads left to check with. All the lathe operator was to do was get the gage in the hole, didn't matter if the gage wanted to fall out as long as it would thread in. One could see where threads had been machined off the gage until the gage screwed in but not whether or not the threads were in spec. I hated working for that outfit.

Yep, doing defense work that way can get you put in jail also.

 

[extropic]

Yep, doing defense work that way can get you put in jail also.

We can only hope.

 

[MachEng]

Once when I was working as a Manufacturing Engineer we had some parts from a supplier with oversize threads. No Go would go in easily. I dispositioned them to be returned to the vendor.
We sent them back and they came back the next day (reworked) and the no go wouldn't go. Since I had been a machinist I called the quality manager and asked him if he thought I was an idiot.
"what you think I never heard of peening the first thread with a ball bearing" Needless to say he got them all back. Needless to say he is no longer a supplier.

 

[Gordon B. Clarke]

One way fix slightly oversize internal threads is to re-tap with a cold form tap of the next higher H number. External threads can also be re-rolled to bring up the pitch dia. This type of fix will sometimes bring threads back into tolerance. The best chance of success is when the minor dia. (internal thread) and major dia. (external) near is nominal.

Stop with the shitty advice. You'll only start giving idiots ideas. There's only one reliable way to fix an oversize thread and that's to use a thread insert.

I'm starting to understand why some of you use AKAs.

 

[Gordon B. Clarke]

Has anyone ever heard of this? I had some parts with threads that the pitch diameter was oversize, and the no go thread gage flew right in there. (The part has a drill hole in it which gets tapped). The guy who runs the same machine on day shift mentioned he was able to save one of them by "pittsburghing" the thread.. He didn't really explain it that well, but he said something about a ball bearing.. and it apparently works, the no go gage won't go further than the first thread after doing it. I am just curious if anyone has heard of this, and how exactly it works. I realize this isn't much to go off of and it isn't a very good explanation, but if anyone has heard of "pittsburghing" threads and knows what it is, I would like to know.

Unless you're really stupid I'm hoping you've learned something from the replies.