Thanks for posting this Mike. A lot of helpful info.

 

Thanks!

 

Thank you! Very useful: much more useful than some of the chatty marathon threads found here

 

Might want to cross-reference DonW's plane notes somewhere in there.

 

Excellent Mike! Thanks for posting this. I'll fill in blanks as I can for you/us.

Edit: Ignore this information on 78 threads. Lazyman's plane was a Craftsman not a Stanley.
Are you certain on the #78 fence rod thread? My Millers Falls #85 is 1/4-20 and Lazyman asked me to turn him a rod for his 78 so I just duplicated my Millers Falls part and it fit his 78. Just wondering if Stanley may have changed pitch somewhere along the line on the 78 rod…

And, here's another weird one…. Just checked the fence locking screw on my MF 85. #10-30. Yep, that's right. .189" major diameter with 30 tpi and UN thread form. No guarantee Stanley is the same of course.

 

Another parameter to consider is the use of screws with a 55-degree thread angle, as opposed to the standard 60-degree thread angle.

When I read comments about how a screw will thread into a tapped hole and suddenly feel resistance after a few turns, it makes me wonder if there is a Whitworth screw thread on one or the other. My thread gauges are Brown and Sharp, and sometimes only a 55-degree gauge eliminates all daylight on a screw that I know for sure came off an old Stanley.

I once bought a assortment of various Whitworths from a British industrial supplier, and it solved a couple of questions I had in the past.

Just when you thought it was safe to go back in the water….

 

There's another thread where a guy has a Stanley with a tote rod that appear to have Whitworth threads PK. I know I've measured threads on a Stanley and found a 60 degree form but I don't currently possess any Stanley bench planes so I can't verify. It would be nice if anyone with gauges for both threadforms that has Stanley planes checked them all to see if they're all one or the other or if it's a mix of the two. I can only say for sure that Millers Falls uses the UN form.

 

There's another thread where a guy has a Stanley with a tote rod that appear to have Whitworth threads PK. I know I've measured threads on a Stanley and found a 60 degree form but I don't currently possess any Stanley bench planes so I can't verify. It would be nice if anyone with gauges for both threadforms that has Stanley planes checked them all to see if they're all one or the other or if it's a mix of the two. I can only say for sure that Millers Falls uses the UN form.

- HokieKen

Yup, I've got some different thread gauges, but you know I got more than a few planes, right? If I still have any English Stanleys, I'd be curious to see if there's any Whitworths hiding in them!

Oh, by the way, I found a rod for a toilet tank, the one that goes between the valve and the float, to be a perfect #12-20, hmmm I also have commercial door fasteners that are also #12-20, and even some marked #14-20, used for lock hardware and for hinges. NOT compatible with 1/4-20. My father, 60 years ago used to bring home fasteners from the machine shop where he worked, and had an abundance of this kind of stuff, but it's long gone now.

 

Good point PK. I guess checking ALL of their planes would be daunting for some folks ;-) I guess I should say, see if you can identify both threadforms or only one.

 

The plane screws you're calling #12 are 7/32. Put a micrometer on the screws and compare them to any other #12 screws and you'll see what I mean. The major diameter of a #12 screw, regardless of thread density, is 12×0.013" + .06" = 0.216" Unless your threads are very worn, they should measure closer to 0.21875". Anything bigger than 0.216 can't be a #12.

If you want to post tables, try Google Docs. You can create and share spreadshets that can be exported to other spreadsheet programs. For example: https://docs.google.com/spreadsheets/d/1c6ddTyWfRhpT4x61WQqoJLr-QtDrqoFd3HolNZXubto/edit?usp=sharing

 

Hap, I used Dropbox, but it isn't local, so I have found external references don't work - for instance, you won't download a .pdf.

Do you want to make a change; tell me specifically what to change. But please don't tell me to measure something I don't have.

 

Change the #12s to 7/32. I'm skeptical of the other numeric series sizes too, but I don't have any to measure.

 

Cap iron screw for No 5 Type 19 Stanley plane: 5/16-18.

 

Change the #12s to 7/32. I m skeptical of the other numeric series sizes too, but I don t have any to measure.

- HapHazzard

What size tap should I ask for at the hardware store, if I wanted to thread a hole for a #12-20 screw?

 

What size tap should I ask for at the hardware store, if I wanted to thread a hole for a #12-20 screw?
- poopiekat

Last I checked the only place to reliably find/buy Stanley special thread taps was Victor Machinery Exchange:
https://www.victornet.com/subdepartments/Special-Pitch-Taps-up-to-1/2-inch/1260.html

Page for #12-20 > https://www.victornet.com/detail/TAST-12-20.html

If you need #12-20 threading dies - Greenfield and Well Brothers sold 'Little Giant' adjustable dies with replaceable inserts that are easy to find on fleabay, and 1/4-20 can be closed down enough to make perfect #12-20 threads on right diameter rod.

They come in several different die OD sizes, so be sure to buy die same size as die handle, if not buying a set.

YMMV

 

Whew, I just measured my No 55 (older, '17 patent on skate). There are a number of 1/4-28 threads. wow, an actual modern standard…

 

Regarding 7/32 or #12 size screws on bench planes, from what I've read over the years in various places, #12 seems to be the generally accepted size. But as HapHazzard has found, there are always exceptions to the rule! If we look on page 21 of Stanley Planes and Screw Sizes Part I we find Table 2 where the author measured all of the screws from his 4-1/2 plane manufactured around 1950. We see some variation in size of the major diameter even from the same plane. And in the paragraph previous, we see reference to measurements taken on Stanley planes by two other guys that fall within tolerance for #12 screws but vary from one to another by a significant amount.

And though I've read Bates' paper several times before, I never noticed that he notes that, at least on the plane he measured, the threads on the tote and knob rods appeared to be rolled rather than chased or cut. This could contribute to the major diameter being larger on some of these rods. When rolling threads, the material is basically being deformed to the thread shape rather than material being removed to create the threadform. So it wouldn't surprise me for some rolled threads to show out of spec with reference to the measured major diameter. But, that wouldn't necessarily prevent the thread from fitting the tapped threads either. And I'm sure, at least in early production, if it fit, it was good regardless of actual dimensions. Since it wasn't intended to be replaceable by off-the-shelf parts, there was no need to conform to a spec as long as the male fit the female.

As I said before, I'm a Millers Falls guy and that's what all of my bench planes are. So my measurements aren't necessarily valid for this thread. I have found that MF did use the same threads as Stanley and that the parts are interchangeable but when we get down to details like thread form and measured major diameter I doubt I have much to add.

But, this thread and the other discussing the 12-20 / 7/32 thread have piqued my curiousity. So I'd be interested in knowing the following from anyone willing and able to measure it for the tote/knob rods AND for the frog screws since in the referenced paper they appear to be two different forming methods:

1. Measured major diameter of male threads.
2. Measured minor diameter of female threads.
3. Threadform angle (for anyone that has 55 and 60 degree fishtail gauges or if you have a 60 degree, does it fit well or does it appear to be off a bit)
4. This is probably a stretch but if you have the ability to measure pitch diameter directly (three-wire or screw thread micrometer) it would be interesting to know if the pitch diameter conforms to spec even when the major diameter does not.

Like I said, this is just out of curiosity for me but it would be nice to get some data for a variety of planes/types Stanley made over the years. It would be good to document here on the interwebs for posterity as well.

 

Mike - I'll try to remember to measure the knicker screws on my 45 and 46 tonight. I had to make one for my 46 and I'm fairly sure it was a #5-40 but I'll verify before you put it in the OP. Not sure about the 45 but I can measure it.

 

Thanks Kenny.
I have measured a bunch of tote/knob rods, and got 0.205 to 0.217. And I have a mix of both rolled and cut. Maybe evenly split (?). When I get a chance I will check some of my long nut (pre 1892) early planes and see what they are.

And thanks for the data Hap.

 

Okay Kenny… here goes:

Plane A, Stanley #5 1/2 Type 11

Frog Screw OD .2205, ID .1875, 20 TPI
Cap Screw OD .2755, ID .2475 24 TPI
Knob Screw OD .1855, ID .1830 20 TPI
Tote screw OD .2105, ID .1855 20 TPI
Toe Screw OD .2112, ID .1860 20 TPI

Plane B Stanley #4 Type 19

Frog Screw OD .2165, ID .1815 24TPI
Cap Screw OD .2385, ID .2175 28 TPI
Tote Screw OD .1875, ID .1855 24 TPI
Knob Screw OD .1865, ID .1850 24 TPI

All are 60 Degrees

Inside diameters gauged by drill blank inserted in holes and miked. I don't have proper hole gauges.
I chose two divergent plane types for comparison. Hope this helps!!

 

What size tap should I ask for at the hardware store, if I wanted to thread a hole for a #12-20 screw?*

- poopiekat

If you want to cut #12-20 threads, use a #12-20 tap. You can find them all over, but they're not a stock item anywhere as far as I know, so you can order them from Victor (https://www.victornet.com/detail/TAST-12-20.html), zorotools (https://www.zoro.com/drill-america-12-20-hss-plug-hand-tap-dwtst12-20p/i/G1839987/) or Home Depot (https://www.homedepot.com/p/Drill-America-12-20-High-Speed-Steel-Plug-Hand-Tap-1-Piece-DWTST12-20P/305700301). Victor is cheapest, but Home Depot has the fastest delivery and it's free. This is a plug tap, so you have to be really careful getting it started, and it won't work for threading blind holes, so you might want to order three and grind one as a taper tap and one as a bottoming tap.

 

The tote and knob rods on my No 5 Type 19 are rolled, which makes it hard to tell the exact screw size because the peaks don't always come up all the way. The rods are 3/16 and, as far as I can tell, the major diameter is supposed to be 7/16, based on the female threads of the brass nuts and the knob and tote receivers. A #12-20 tap fits very loosely in the holes, but it rattles around so much that it's just not possible to believe they were threaded with this tap.

The other reason I keep insisting that these threads have nothing to do with a #12 screw size is this: imagine you're an engineer at Stanley Works, two years after the end of the Civil War, and you want to build these planes. Supplies are scarce, so are standards, but you're a hardware company, so when it comes to screws, the easiest thing to do is to roll (or cut) your own. Are you going to use readily available fractional stock for everything, or are you going to use this arcane formula using integers 0-12, where the major diameter of the screw equals that number times 0.013" plus .06" for everything less than ¼"?

Bear in mind that Sellers had only proposed his system, which was based on a simplified Whitworth thread, three years earlier, and I'm not even sure when the numbered series was added to that standard. It was not part of the Whitworth standard, so it must have been added to Sellers at some point, probably around the turn of the century, but it was an evolving standard, and it would take some time for manufacturers to adopt it, and Stanley had been making these planes for about 30 years by then.

Manufacturers have always been reluctant to adopt new standards. Remember how enthusiastically they all jumped on the metric bandwagon back in the 1970s? And, to this day, when you get a 1" coarse bolt, it will have a 14 tpi thread instead of the 12 tpi density called for by the standard.

One more thing to remember is that Stanley was originally a hinge company. Their claim to fame was that they included screws with their hinges, giving customers everything they needed in one small package and cornering the hinge market in a few years. They were not in the business of helping competing harware companies sell their screws, so why would they want to use screws on their planes that you could replace with screws from another hardware company? That's just not who they were.

But, history and speculation aside, the best argument is to take your mics and gauges out, measure the screws, compare them to known standards, and believe your eyes. Don't try to force everything into the nearest modern standard.

 

If you need #12-20 threading dies - Greenfield and Well Brothers sold Little Giant adjustable dies with replaceable inserts that are easy to find on fleabay, and 1/4-20 can be closed down enough to make perfect #12-20 threads on right diameter rod.

They come in several different die OD sizes, so be sure to buy die same size as die handle, if not buying a set.

YMMV

- CaptainKlutz

Victor has a #12-20 adjustable die too. https://www.victornet.com/detail/RD-12-20-B.html It fits in a standard 1" round diestock.

If you adjust it, you can cut 20 threads/inch on 7/32" stock, but rolling 7/32" threads on 3/16" stock, which is apparently what Stanley did, is a little trickier. What you need to do is force the die onto the round stock from the "wrong" side so the rake of the teeth pushes metal out of the way instead of cutting into it. To make it easier to start you need to taper the rod. You can either anneal the rod and harden it later or use a work-hardening stainless alloy.

 

.

 

Agreed Hap. I've no confidence that we'll find a standard that these threads conform to precisely. Regardless of whether it was intended to be a #12 or 7/32 (or neither one) it is a special thread by today's standards. The 7/32 threads in the Whitworth system would have a pitch of 24 or 28 (coarse and fine) and #12 UNC/UNF would have the same pitches.

Interestingly, I did find this chart from the American Screw Company showing that 12-20 was a standard thread for some companies in 1916.

And I agree, I don't know why we have to have wire size type standards for screw threads < 1/4". 1/64" isn't that much larger than .013 so I don't know why we didn't increment using X/64 diameters rather than resorting to the numbering system. But, we got what we got I guess…

Regarding the loose tap in the threaded holes, we must remember that the recommended drill size for internal threads assumes a 75% thread. However that isn't always necessary depending on the application and materials used. So it's possible that Stanley drilled the brass nuts and the cast iron bases with different size drills to get different effective thread depths. So an over-sized tap drill doesn't necessarily mean that the threadform itself isn't consistent.