# Anyone heard of 1 1/16-14 thread?

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Im making an adapter for that Buffalo #18 drill press (two speeds forwards, two speeds backwards and a bunch of pully combinations

The spindle nose appears to be threaded 1 1/16 x 14

Machineries handbook didnt even mention that thread. I need to know the minor diameter so I can single point the inside of the adapter.

Gunner

"She's (my daughter) already dating a sex offender. Better that than a republican fundie neocon fascist." FF, (alt.machines.cnc)

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Hey Gunner,

My MH (25th Edition) shows a chart (page 1638) labeled:

"American Standard Unified Inch Screw Thread Form Data"

One column in the chart is called:

"Depth of Sharp V-Thread" and notes that for any sharp V-thread it will be .86603 X Pitch

and in the column it shows that for a 14 TPI thread, the depth is .06186.

There are also columns for UN threads, Int and Ext.

I did find a reference in another book for a 1" x 14 TPI, but all references to the 1&1/16" was for 18 TPI Extra Fine.

H>Im making an adapter for that Buffalo #18 drill press (two speeds

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Oddball thread indeed. There's a couple tables in Machinery Handbook to help out. On pages 1713 and 1714 of the 26th if you have it.

For a theoretical thread with perfect 60 degree pointed top and bottom: H = 0.866 * pitch pitch for 14 TPI = 0.07143 (1/14) My California math gives H = 0.0618

The flat in the bottom of the thread has a max of 0.25 H.

So 0.75 H = 0.046

In conclusion, I'd reduce that major diameter by 50 thousands radius or 100 diameter. You could go a little smaller.

Karl

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1 1/16 x 14 tpi sounds like a custom thread.

i would first find a bolt with the same tpi and check it or use the three wire method to measure the exact thread height.

or if you got an extra piece of tube to try out than try this lil formula:

Maj dia - 1/tpi = min dia

ie 1.0625 - 1/14 = min dia

1.0625 - 0.071 = 0.991 dia

Try it and let me know how it works

Raza

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From my threads file:- Thread Dia/ Dia/ Pitch/ Pitch/ Core Core Depth/ Depth/ Name Inch mm TPI mm Dia/" Dia/mm Inch mm

3/4 Whitworth 1.0625 26.988 14.0 1.814 0.9735 24.727 0.0445 1.130 Pipe Thread

That is the only 1 1/16"x14 thread I can find. It might may to check the thread form :-(. If it's rounded it's Whitworth.

Regards Mark Rand RTFM

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You might want to check :

Half way down the page they have the calculations and constants needed to determine the minor diameter. Plus they have a online tap drill calculator if you want a rough guestamate. Just a quick mental calculation .9843" hole looks good.

Best Regards Tom.

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Hey, thanks!

Ill try to single point it first though. On the other hand..Ive not had a lot of luck doing ID threads recently...sigh. I may have to take the part to a clients shop and program the thread and run it on a CNC.

Gunner

"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosphy of sniveling brats." -- P.J. O'Rourke

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Well duh, I guess I could have been a bit more responsive to your question. .

Here's what DoN's program sez for 14 pitch threads:

Sharp V Truncated single depth .0618 .0541 double depth .1237 .1082

29.5 deg feed .0710 .0622

The minor dia will be the major dia less the double depth. I use the "truncated" numbers with a sharp V bit.

These numbers are for exact geometry so you may want to fudge some clearance and tolerance allowances.

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Is guestimation (erring on the side of caution) and test-fitting (with the part still in the lathe if the drill-press spindle comes off, or still in the chuck if you're confident it can be replaced sufficiently accurately) not an option? Only any good for a one-off, but it avoids most of the tedious maths and provided you take small cuts is pretty much guaranteed to work (eventually).

Tim

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And -- if it is Whitworth, the included angle is 55 degrees, not the more common 60 degrees. This will throw off the calculations that some others have posted, which presume a 60 degree thread form.

Good Luck, DoN.

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And -- my program only is designed to calculate 60 degree threads, and another article has suggested that it is actually a Whitworth thread, which will be a 55 degree angle instead.

Good Luck, DoN.

P.S. Don, thanks for mentioning my program.

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Let's see, it is Buffalo Drill Press... Maybe it is a 27 X 1.75 mm thread.

Pete

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