OLD BLUEPRINT DIMENSION QUESTION.

[CEMENTHE4D]

We have a job that details a square taper as...
______________________

.50 PF LARGE END
OF SQUARE .75
PER FOOT TAPER
(TOTAL)
______________________

The "PF" is throwing me off. I'm assuming Press Fit?

Never seen it detailed like that before.

TIA ~CH

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[mactec54]

We have a job that details a square taper as...
______________________

.50 PF LARGE END
OF SQUARE .75
PER FOOT TAPER
(TOTAL)
______________________

The "PF" is throwing me off. I'm assuming Press Fit?

Never seen it detailed like that before.

TIA ~CH

The PF is per foot taper without seeing the drawing it does not make much sense the way that this is written

[CEMENTHE4D]

The PF is per foot taper without seeing the drawing it does not make much sense the way that this is written

It's written exactly the way I typed it out. only thing missing is the Arrow pointing to the square on the end of a shaft.

[mactec54]

It's written exactly the way I typed it out. only thing missing is the Arrow pointing to the square on the end of a shaft.

Is there a thread involved

[CEMENTHE4D]

Is there a thread involved

.375-16 UNC 2A on Square end and a 1.5-4 acme on the shaft.

[mactec54]

.375-16 UNC 2A on Square end and a 1.5-4 acme on the shaft.

It makes a little more sense the PF is not per foot it is a reference to a Thread JIS PF series thread so it is basally saying a Parallel Pipe thread, but your threads don't match up to that so still unknown as to what they mean, unless the thread was changed at some time, what is this drawings origin

[CEMENTHE4D]

snippet

[z369]

I could be wrong but in my mind I'm thinking the .50 PF designates Press Fit. There is already a taper per foot callout (.75), hence the reason for such a tight tolerance at the small end of the square and finish callout as well. If I had to guess I would say that square gets press fit into a mating part and yet another part screws on the end to hold it in place.

[mactec54]

I could be wrong but in my mind I'm thinking the .50 PF designates Press Fit. There is already a taper per foot callout (.75), hence the reason for such a tight tolerance at the small end of the square and finish callout as well. If I had to guess I would say that square gets press fit into a mating part and yet another part screws on the end to hold it in place.

It's a Taper so would not be a press fit designed like it is, that also has a large tolerance +/- .010" .50= 2 decimal places=+/- .010"

Looking at the drawing snip I would say the drawing was changed at some time and this is a mistake as it does not reference anything

PF designates a JIS parallel pipe thread

[peteeng]

Hi - This wiki says PF is press fit. Peter

https://en.wikipedia.org/wiki/Engine...ns_and_symbols

[mactec54]

Hi - This wiki says PF is press fit. Peter

https://en.wikipedia.org/wiki/Engine...ns_and_symbols

It is not going to be a Press Fit with a +/- .010" tolerance

Note how it is used P.S. = Press Fit not just straight PS = Parallel thread for Jis standard, so it has more than one meaning depending on how it is written and what it is referring too

I wonder if the Machinery Hand Book has how it should be used