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Are all the old Thread pitches still needed? Thread per inch, and some odd metrics.

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
OT:
QT: Those will be dull times in a thousand years,

I wonder what the unionized Robots will go on strike for.
Likely they will want an opposite sex appreciation chip.

We will all become a no gender it, and they will become men a ladies.

Ops, Don't say manual because that might suggest made for Men

(X) Just kidding ..end of this or it will ruin the thrd subject.

Oh, the (X)..if you see that in a shophre I work, it means "Something wrong with this" or "Something in question"

The other simple code is a number with a circle means "number of" so not be confused with any other numbers.
Back to topic.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
QT peteM: [The 22 tpi is one I'd be inclined to keep. A lot of the legacy Brit stuff has 5/16-22 threads.]
this chart is for 60* threads, is the British 5/16-22 a 60*? I did take 22 out but can put it back in.

QT ViedoMan: [FWIW, microphone stand adapters and other a/v devices use 27 tpi, and garden hose fittings use 11 1/2.]
Thanks, 27 and 11 1/2 are still in.

There are about 12 common metrics, from .2 to 1.5mm for m1.8x.2 to m18x1.5. I haven't decided if to include them or make a separate chart. I may have to go to the legal-size paper/ or go to a print shop special size.

Also, I have to check that I went to the greater size on each thread, so being minus the tolerance. Mostly I like to go about -.001 from max when I wire check.

This is why I posted this thread, To get some good advice. Thanks.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
OT

I could see getting your Farrah Fawcett poster laminated, but a thread chart??

Me: Takes me back to my first apartment. I had the full size Farrah in blue sparkly spandex with the ten speed. Wasn't laminated tho. Mores the shame.

Gen Alpha: Farrah who? Again, the shame.
 

Mechanola

Stainless
Joined
Mar 21, 2011
Location
Äsch
Since I understood the initial fractions such as a half, a quarter, an eighth I got the hang of it down to something like [SUP]307[/SUP]/[SUB]400[/SUB]". You can secure an unmistakable measure by an odd number numerator in the fraction. It’s a mixture of the decimal and the direct fractional system. I think people moved away from it after WWII towards the pure decimal inch measurement report like 0.375". I recognise ⅜" immediately by that.
 

swarfless

Cast Iron
Joined
Aug 31, 2005
Location
South Australia
Hey Buck, I thought it was fair your dropping one of yours (27 tpi 1/8" NPT) and one of ours (19 tpi 1/4" BSP also ISO) but now you're leaving us out in the cold?
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Qt awarf: Hey Buck, I thought it was fair your dropping one of yours (27 tpi 1/8" NPT) and one of ours (19 tpi 1/4" BSP

27 is still in, but I did tale out 19. I make a not of that and see what I can do.
I May have to go to the legal size chart 8 1/2 x 13"
 

Greg Menke

Diamond
Joined
Feb 22, 2004
Location
Baltimore, MD, USA
I would keep my old chart but consider dropping 17, 19,21,23,25,27,29, and 30 along with 2 1/8, 2 1/4, 2 3/4, and the like. likely keep some of the even halves like 3 1/2, 4 1/2, 5 1/2, 6 1/2, and the like.

I don't think anyone uses those drops nowadays.

I could use a 17tpi setting on my lathe right now... its a lot closer to the metric thread I'm cutting than 18tpi which is my next closest. I'm hoping the 18tpi is not so awful that I have to make a changegear or buy a probably horrible ebay die and hope that it will cut.
 

DMF_TomB

Diamond
Joined
Dec 13, 2008
Location
Rochester, NY, USA
I am revising my thread chart and wonder if I should drop some now uncommon threads.
For example, the old Hendy Norton thread plate had 2, 2 1/8, 2 1/2, ..and some lathe plates go to 224 TPI.

I am thinking that I might just use the threads given on a high-quality modern lathe, and dump many of the oddball threads...

Here is an example of an old tread plate, on page 16:
http://pounceatron.dreamhosters.com/docs/hendey/1920-Hendey-manual.pdf

Seems like a modern lathe might have 44 standard threads 2 to 72, and 39 metrics .2 to 14
that is still a lot of threads.

.
I have used 127 tpi for steel screw, making a tap and a "split brass nut" that is tightened to grip screw tight.
the threads are so fine they dont look like threads more like a medium coarse turning
.
the front of sharp V cutter (not top) is forced into metal it basically is knurling or cold
forming the metal to create threads, pushing metal around tends to increase dia. I used a anti seez
thread compound as "threading oil)
.
this 127 tpi thread was for a optical instrument, rather than a differential thread screw i had a
single thread screw, the split nut needed periodic adjustment if it opened too far the screw
wouldnt engage the nut threads
.
really old lathes just cause it said it was at 40 tpi if measured over 10" you might have 399 or 401
threads. when thread pitch not same on screw and nut the more screw is screwed into nut the tighter
the threads feel.... just saying I could see somebody trying a "odd" screw pitch so it matched better
that is new screw into old nut
or new nut for old screw
..... just saying even 24 tpi and 25 tpi is close enough to maybe not notice, short of counting threads
per 1 or 2 or 3" distance
.
for making replacement parts for old machines the old machines might be full of odd threads like 1/2-12 not 1/2-13
sometimes they deliberately used odd threads for the replacement part so they had to be bought by the
original tool maker. Starrett used to use odd threads on their precision levels not sure if they still do
i seem to remember 12-24 thread being used
 








 
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