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Question on thread call out

GMBM

Aluminum
Joined
Dec 20, 2006
Location
NY
What thread does this print call for
The PF 3/4 tap is cut as #12BSPP
The PT 1/4 tap is cut as #4BSPP

The 1/4 tap hole is for a grease fitting so it should have a taper

Looking at this print how would you cut these threads

Thank You
Greg
 

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If the callout is for BSPP the mating fitting would have a flange that seals against the face of the part by means of a copper gasket. BSPP stands for British Standard Parallel pipe.
 
Larry The threads in the parts are cut to BSPP I checked with a tap

But I didnt think there was enough info on that print for someone to know what thread is called for

We need a BSPT in the 1/4 tap

Looking at that print what thread would you cut
 
Its not what they want

Its a question about what was sent

The print is of a part that was sent

We are having problems with the 1/4 taped hole and wanted to verify that it is the correct thread

But it just does not seem to me that there is enough information shown on that print to know what thread should be there
 
Well, if, as you say, there is not enough information on the print, then it would seem that you can:

1. Guess. And take the consequences if your guess is wrong.

or

2. Ask for clarification.

I guess there is a third choice, don't do the job.



Its not what they want

Its a question about what was sent

The print is of a part that was sent

We are having problems with the 1/4 taped hole and wanted to verify that it is the correct thread

But it just does not seem to me that there is enough information shown on that print to know what thread should be there
 
Its not what they want

Its a question about what was sent

The print is of a part that was sent

We are having problems with the 1/4 taped hole and wanted to verify that it is the correct thread

But it just does not seem to me that there is enough information shown on that print to know what thread should be there

I'm not 100% convinced that you know what was sent.

There is no such thing as #12 or #4 BSPP. I'm guessing that you are trying some kind of fitting in there to see what fits.

But the drawing also makes no sense, as PT and PF are not proper thread callouts. PT could be assumed to mean NPT, but PF I have no idea. They could mean NPTF or NPSF. Or they could both mean something else altogether.

What thread does this print call for
The PF 3/4 tap is cut as #12BSPP
The PT 1/4 tap is cut as #4BSPP

The 1/4 tap hole is for a grease fitting so it should have a taper

If the hole is in fact BSP, for a BSP grease nipple, there should not be a taper. The taper is in the male thread.
 
Gregor

we are trying to find out what is being sent this is one part of a larger assembly of witch we get a few hundred a year and we have always had trouble keeping the grease fittings in

In the past we just installed a 1/4 pipe grease fitting (knowing that it was a BSP thread) and it would keep in place

So if I understand the call out of PT or PF would not tell what thread should be there that is what I thought

Looking at that print you would not be able to tell what thread is to be cut?

Thank You
Greg
 
Gregor

we are trying to find out what is being sent this is one part of a larger assembly of witch we get a few hundred a year and we have always had trouble keeping the grease fittings in

In the past we just installed a 1/4 pipe grease fitting (knowing that it was a BSP thread) and it would keep in place

So if I understand the call out of PT or PF would not tell what thread should be there that is what I thought

Looking at that print you would not be able to tell what thread is to be cut?

Thank You
Greg

From the print, no. Those callouts make no sense to me. It's of course possible that they are abbreviations that I am unfamiliar with, but unless someone else says otherwise I suspect they are just wrong.

The difference between 1/4NPT and 1/4BSP is pretty small - 1/4NPT is 18 threads per inch, 1/4BSP is 19 threads per inch. The pitch diameter of 1/4BSP is slightly smaller than the pitch diameter of 1/4NPT at it's gauge length, so a 1/4BSP fitting will screw into a 1/4NPT hole and be a loose at the start but tighten up due to the pitch error and the taper. Likewise, a 1/4NPT fitting can be forced into a 1/4BSP hole. The two do get mixed up quite frequently "in the field".
 








 
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