2-1/2 - 12 UNF Thread ring gage?

[orakle44]

Is there such a thing as a 2-1/2"-12 UNF thread ring gage? I've done a bunch of searching online and have found nothing. Any info is appreciated.

 

[Booze Daily]

2-1/2 - 12 UN 2A
2 1/2-12 UN Thread Gage Ring Plug Gauge 2A 2B GO&NOGO |

 

[orakle44]

Thanks so much for this! I'm usually pretty resourceful using the ol' interwebs, but this one got me.

 

[Gordon B. Clarke]

Is there such a thing as a 2-1/2"-12 UNF thread ring gage? I've done a bunch of searching online and have found nothing. Any info is appreciated.

You did write "any info" so:

OD max 2.4981
OD min 2.4867

PD max 2.4440
PD min 2.4378

As Booze pointed out the "problem" was in the "F". 2½ UNF doesn't exist.

 

[Piper3T]

I've bought from guages tools before and would not recommend for long-term use. While the gages are cheap, they are not adjustable for re-calibration. But if you have a simple need for it and don't want to make your own, it should work.

Just FYI, in my experience, a lot of "uncommon" threads get classified as UNS (Special). I work for a company that likes to optimize every last bit of wall thickness and will change a pitch to do so, so I've got a lot of UNS gages.

 

[Jgryz450]

We make our own.... Not that hard. You have the specs in the above post. Just be sure to glob sum never sieze on it so you dont ruin the starter threads when your (bringing in your parts threads)

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[Jgryz450]

I've made that thread on many occasions... It is a (fine) thread. I think 8 is the coarse..

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[Jgryz450]

Yes you are right! Sorry about that. I should have looked at the chart first... [emoji6]

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[Jgryz450]

What (experto) is that? I kinda thought you could make any thread you want..... Any size you want.... As long as it has a mating part.,.?

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[Jgryz450]

No problem,just annoying when you are told there is no such thread by an expert???

Wow, never threadmilled a 4.,.. That's a crazy thread! So im guessing the shafts we make might not exactly be by the book? Never knew it cause the handmade gauges were there before I started.

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[Gordon B. Clarke]

No problem,just annoying when you are told there is no such thread by an expert???

The thread exists. It's just not UNF. That does not exist but 2½-12 UN does.

 

[Gordon B. Clarke]

What (experto) is that? I kinda thought you could make any thread you want..... Any size you want.... As long as it has a mating part.,.?,.... No?... (In theory I mean)

You can and you don't even need a mating part. The catch is that you can't always call it anything you want.

International Thread Standards

 

[Gordon B. Clarke]

No, you are by the book,2.5"UNC AND UNF are standard threads.

2½-4 UNC is but according to ASME B1.1 there is no 2½ UNF.

2½ with 4, 6, 8, 10 and 12 TPI all exist as standard but, except for 2½-4, they are all UN.

What "book" are you referring to?

According to ASME B1.1 and all charts I can find there are no UNF threads above 1½". The (ONLY?) problem is that UNF is a specific denomination for a thread combination of a specific diameter and pitch.

If any don't believe me ask (another) thread specialist.

 

[Jgryz450]

Right... I was just trying to help... He originally asked about a gauge. I wanted him to know he could make one instead of buying one for a 1 PC job. For example..... Im sry... I'll stop trying to help... Jeez

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[Gordon B. Clarke]

Right... I was just trying to help... He originally asked about a gauge. I wanted him to know he could make one instead of buying one for a 1 PC job. For example..... Im sry... I'll stop trying to help... Jeez

I'm not sure who you're apologizing to or why.

Let's get down to basics. A 2½-12 UN thread ring gauge would be used to inspect an external thread.

The easiest and by far cheapest method would simply be to measure the pitch diameter with 3 wires.

Wire Diameters
Max 0.08420
Min 0.04210
Best 0.04811
Alternate 0.04811

Constants
Best 0.07218
Alternate 0.07218



Measurement Over Wires
Max 2.5162
Min 2.5100