Must of us know, even though the Ford drawings show otherwise, the notches in the castle nuts on early cars were square from the factory. Does anyone have any idea when they changed to the rounded slot in the castle nuts? I'm pulling down a very original '17 chassis now, and every castle nut on it has the rounded slots.
Larry, Your suppose to be working on the 1913 roadster chassis!
Get 'im Kim !!!!
From what I have found in research, '13 had a mix of square and round notches, '14 was pretty much all round from there on. Don't quote me! Opinions often vary
Gail Rodda 's book on page #7 ( Castle nuts square in the bottom of the cotter key slot are still used on 1913 cars .) ( Castle nuts round in the bottom of the cotter key slot begin to appear in 1914. They are mixed on 1914 cars.
All this conflicts with Ford's records. I researched this pretty heavily on a trip to the Archives a few years ago. There are NO drawings (and I looked up all of them) showing ANY square slotted castle nuts, nor ANY information in the releases regarding any changes from square to round or vice versa. ALL drawings of ALL castle nuts, many of which date to 1907, show ROUND BOTTOM nuts. The lone exception is the driveshaft pinion gear nut. So I don't know where the information about a gradual change from something non-existent (according to Ford) to something that (according to Ford) was used from the very beginning came from. No doubt there are lots of square slotted nuts surviving on early cars, it's just not shown in any drawings or mentioned in any Releases.
Last time I looked, the Modal A (28-31 version) judging standards claimed that the rounded slots were pre-1930, square after that.
Hmmmm. . . .
I checked my archives and looked at my ancient copy of the Ford Standard Parts book. The page E-130.05 titled Hexagon Castle and Slotted Nuts UNF-2B - Thread shows the rounded slots only. No optional construction or extra notes in the section appendix allowing the squared off slots.
This page is dated April 1974 although other pages like the ones for body nails go back to the fifties.
There was not even any consideration within all of industry on the idea of a slotted nut 'standard' until the 1908 summer convention of the "Master Machinist Association"
It was a topic that a day was spent trying to get commonality and the point counterpoint debates included such things as 'experience shows that forged so called slotted nuts will always yield a high degree of scrap as the forging process is too severe on the smaller sizes"...to..."simply filing a single groove into a standard nut then makes the thread engagement too little for the new ALAM thread engagement standards so the nut must be thicker in case of a service change required the use of a slotted nut substituted for a standard nut"...to..."Why don't we call them "Castle nuts" for convenience sake and quit mixing different names for the same thing"...to.."I make a motion that the association provide their own standard, based upon all of the concerns raised as I have on good authority that nut makers are prepared to build special machinery provided they on do so only once!" (The motion was accepted BTW)
I have yet to find a copy of the 1909 proceedings anywhere even with my electronic stack pass...presuming the approved motion was acted on, either a 1909 status report was given, or a 1909 dated draft standard proposed to the committee. They probably could not have acted on it needing to take the standard back to their respective companies for internal approval...so my guess and only a guess is that anything before (say) late 1910 or so...the slotted nuts were individual shop made with no rhyme or reason as to specification other than 'in-house' and since milling machines were actually new and not so common at that point in time...
I'll leave it to the brain trust here to decide that 'shaving/shaping' works better with a square nose or a rounded one...and...if you have early cars with square bottom slotted nuts, and full height for full thread...then they are probably repops even though a century old themselves now