Preferred Sizes, tools and other types of hardware

MaxPete

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Howdy!

We are having a chat about tools on the ST Owners website and I joined in (I like tools) and wrote a note about some issues which I thought might be of interest to the XS650 group as well.

Have you ever noticed that some socket sets do not come with certain size sockets.

In most engineering design work there are "preferred" sizes which most designers select. Moving off those preferred sizes is discouraged because the cost of components goes up dramatically - for virtually no added functionality. For example, most Imperial fasteners normally come in 1/4" increments of length. So, you will find 1/2", 3/4". 1", 1-1/4" and 1-1/2" long bolts easy to find. Just try to find a 1-1/8" long bolt (in ANY size) and you'll likely be stumped. The fastener manufacturers will be happy to make them for you - but they'll charge an arm and leg for them, so you would need a pretty compelling reason to select that length in a given application. The same goes for almost any standard item such as seals, bearings, I- and H-beams, roll pins, etc.

On the issue of hex sockets, in my work we normally would select a bolt with a 13, 15, 17 or 19 mm hex head whereas on the Japanese bikes I own, a commonly used sizes seem to be 12, 14, 16 and 18 mm. As a result, I have had to buy a selection of 12, 14, 16 and 18 mm hex sockets in shorty, medium and deep with 3/8" and 1/2" drives to suit my ratchets. The same goes for open and box-end wrenches (aka spanners) and many other items in the mechanical world. I guess the preferred sizes in Japan are 12, 14, 16 and 18 mm rather than 13, 15, 17 and 19 mm - but as noted above, the square drive sizes are the same everywhere in the world (thank goodne$$).

There are other differences in hardware and tools in various countries.

In Japan, they have adopted the JIS (Japan Industrial Standard) screw head design that is used on our Yamaha bikes, as well as on ANYTHING else built in Japan. The JIS is a much better design than the Phillips even though the two seem identical at first glance. If you are working on an XS650 (and who on this site isn't) you would really benefit from getting yourself a set of JIS drivers. They are not expensive or hard to find - just look on eBay for "Vessel" brand JIS screwdrivers - and be sure to include the big #3 silver-handled "Impacta" driver which is perfect for removing the usually f@cked-up clutch basket screws.

In Canada, we use Robertson screws for anything wooden like boats, decks on houses, furniture etc., for electrical panels and house wiring or for self-tapped metal construction. Conversely, this type of fastener is pretty rare outside of the country. I think in the US, they are known as "square drive" screws but they're not often used. I must say, the Robertson is also much superior to the Phillips because the fastener won't strip and can be loaded onto the screwdriver and it won't fall off which makes one-handed installations waaaay faster and easier. Robertson drivers are not expensive and are available at any hardware store in the country in a wide array of lengths and styles including 1/4" hex-drive bits for use in screw guns.
1552745416345-png.236882

Also, there are only four sizes of square sockets in the heads of Robertson fasteners and the matching drivers are always colour-coded so that you know which one to use. They go in order of size: yellow, green, red and black and so it is always easy to pick the correct one out of a crowded toolbox. In Canadian house wiring, every single ground screw inside a box is a "red" size and every single terminal screw on a device such as a receptacle or light switch will be a "green" size Robertson - which is convenient because it means that you can do this work with very few tools in your tool-belt.
img_2434-jpg.236883

When I was a service engineer for a Toronto-based company that built big injection molding machines in the 1980's, our electrical panels were assembled with Robertson screws and the personnel at our customer's US plants absolutely hated that because the service people couldn't easily find tools and replacement screws. I started packing a few boxes of common size screws and several sets of screwdrivers with me on business trips and boy, can you ever make a friend fast by giving a mechanic a new tool - especially one that is a bright colour and sort of unique. Within a few weeks, it was noticed by management that the operational "up" time of our machines soared in those plants and we figured that it was simply because the service folks liked working with their odd-ball new screwdrivers.

The square drive screw head was invented much earlier by Cummings in the US, but it was patented, commercialized and named by P.L. Robertson near Toronto around 1910. Henry Ford used them to assemble the bodies of the earliest Model T automobiles. Henry calculated that use of the Robertson screw saved two hours of labour in building each of his cars and so he wanted to actually buy the design and patents from Robertson and have an exclusive on the new type of screw. However, Robertson wouldn't sell and simply wanted to supply screws and drivers to Henry - but Ford wouldn't agree to that arrangement and so that is why the US auto industry adopted to the inferior Phillips screw subsequent to about 1912.

More recently, the auto industry has adopted the Torx head which shares many of the benefits of the Robertson, but is much more costly to make.

Sorry to get so far off-topic from XS650's, but I do like tools and hardware.

Pete
 
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MaxPete, I have never used a Robertson screw. A quick search on Ebay-UK shows them to be readily available and not expensive. What I find to be a pain is the lack of 10mm x 1.25mm pitch bolts in the UK. Very expensive compared to the standard M10 here. The Japanese seem to use the finer threads. I recently had to cut four 12mm finer pitch studs on the lathe because I could not get hold of then easily and cheaply.

Why didn't pipe threads become metric?
 
I prefer a nice, firm C-cup...oh...wait...that's not the sort of "size" we were talking about, eh?

JIS is a huge improvement over Phillips, but I tend to use socket head wherever I can. Torx would be a close second and is my go-to for wood working.
 
I prefer a nice, firm C-cup

JIS is a huge improvement over Phillips,
Exactly ! Yesterday while choosing a screw driver very carefully for a small tight screw that was clearly ready to fail. I found a driver from a Honda tool kit fit the best !
Question , Are the original tool kits for Japanese motorcycles fitted with JIS drivers? I kinda think so.
-RT
 
MaxPete, I have never used a Robertson screw. A quick search on Ebay-UK shows them to be readily available and not expensive. What I find to be a pain is the lack of 10mm x 1.25mm pitch bolts in the UK. Very expensive compared to the standard M10 here. The Japanese seem to use the finer threads. I recently had to cut four 12mm finer pitch studs on the lathe because I could not get hold of then easily and cheaply.

Why didn't pipe threads become metric?

Hi Paul!
You have raised a couple interesting points:
  • the finer pitch fasteners, while a bit slower to install and a tiny bit more expensive to make, are stronger than coarse pitch threads and I suspect that is why the thorough quality-oriented Japanese use them (and yes, they are slightly harder to find here too).
  • tapered pipe thread - or NPT which actually stands for National Pipe Tapered threads were developed in the mid-19th century for use where a fluid-tight seal was needed. They do work well in applications where fluid pressures are low such as in residential plumbing - but there are several key disadvantages:
    • the thread is cut relatively deep and so the strength of the pipe itself is compromised which limits the safe pressure at which it can function;
    • NPT threads can be over-tightened which makes them leak and can result in the pipe shearing-off;
    • in general, they are best left alone after the initial installation: re-use of an NPT threaded joint is often not successful, particularly if it has been over-tightened so they are sort of a one-shot item.
The NPT thread form is shown below and it tapers at the rate of 1" per 16" of length (regardless of nominal fitting diameter). So, a fictitious 1" diameter NPT fitting that was 16" long would be 1" larger in diameter at the big end than at the small end. Obviously, one would never find a 16" long tapered fitting.

NPT_Dimensions.svg.png


When NPT threads were introduced, fluid system operating pressures were quite low. Even early aircraft hydraulic systems used only a few hundred psi pressure (the one that sticks in my mind is the Douglas DC-3 Dakota which, I think, ran at only 700 psi). Modern systems run MUCH higher pressures like at least 2000 psi in factory machinery and some mobile equipment and as much as 5-10,000 psi in some of the latest aircraft and fuel cell hydrogen supply systems. There is no way that an NPT threaded joint would be safe at those pressure levels. Even modern home plumbing systems generally use some sort of o-ring or other elastomeric sealing system rather than a tapered thread, even though they still operate at less than 100 psi.

So - to answer your original question, NPT and its British counterpart - the British Standard Pipe Thread, is really an outmoded format and so making a metric version of it would not serve much purpose.

Cheers,

Pete
 
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Exactly ! Yesterday while choosing a screw driver very carefully for a small tight screw that was clearly ready to fail. I found a driver from a Honda tool kit fit the best !
Question , Are the original tool kits for Japanese motorcycles fitted with JIS drivers? I kinda think so.
-RT

Yup - anything made in Japan that looks like a Phillips - isn't. It will be a JIS - and that is just one reason why keeping your old bike tool kits is worth doing, IMO.

...and yes DE - I do like the larger cup sizes myself.....;)

Pete
 
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I never knew the square drive had a name. Interesting info about it. We had a recent discussion on here about JIS and came to the conclusion that it might be something close to a myth, if you remember. I don't think robertson would be better than phillips necessarily. I think the square has its own set of problems equal to phillips. I wouldn't dismiss something in such global usage so quickly.
 
I never knew the square drive had a name. Interesting info about it. We had a recent discussion on here about JIS and came to the conclusion that it might be something close to a myth, if you remember. I don't think robertson would be better than phillips necessarily. I think the square has its own set of problems equal to phillips. I wouldn't dismiss something in such global usage so quickly.

Hmmmm....well, I'm afraid I don't recall any sort of conclusion that the JIS is a myth. I'd say that its superiority is pretty widely acknowledged by anyone who has used both of them, and in any event, it IS the geometric form of the screw heads on Yamahas, Hondas, Suzukis, Kawasakis and Toyotas etc. and using the wrong tool is simply always a mistake and likely to lead to tears.

As for the Robertson versus Phillips issue, believe me, I've used both countless times and the Robertson wins, without question or exception, every time. The only thing about the Phillips that is superior is that it is more widely available - just as sh!tty wine is more widely available than good wine.

Having said all of that, I agree with DownEaster that the Allen hex socket head is better than either the JIS or the Robertson and so I'd use that if at all possible. The difficulty I have with those is that finding the correct size Allen head screw (actually, it is finding the correct thread) is sometimes a challenge. When I do find the right ones, I'll usually buy a bunch of them.

Anyhow - to each his own!

Pete
 
In my experience with older Jap bikes, the nut/bolt head sizes I encounter mostly are 10, 12, 13, 14, 17, and 19mm. I've rarely encountered an 11mm, and pretty much never found any 15, 16, or 18mm ones. Yamaha seems big on the 12mm size. Actually, it's the J.I.S. bolt head size for an M8 bolt. Normal M8 bolts have a 13mm head.
 
In my experience with older Jap bikes, the nut/bolt head sizes I encounter mostly are 10, 12, 13, 14, 17, and 19mm. I've rarely encountered an 11mm, and pretty much never found any 15, 16, or 18mm ones. Yamaha seems big on the 12mm size. Actually, it's the J.I.S. bolt head size for an M8 bolt. Normal M8 bolts have a 13mm head.

Hmmmm....maybe I boobed on the preferred sizes 5T. It HAS been quite some time since I was able to get into the garage and mess with my toys!

Cheers,

Pete
 
Draggin' up old memories here, Pete.

The ol' shop daze, everybody had full sets of box, combo, socket. All well used.

Except the 15mm and 18mm.
Those always had the new/shiny look.

Some guys even tossed those out. Just got in the way, and couldn't be used as substitutes on other stuff.

The 11mm got used often for 7/16".

Fast forward, now I'm finding 15s and 18s all over my trucks.

Still thinking that's a conspiracy, punishing those fellows who threw them out...
 
I'm finding the odd 15 as well, especially on automotive applications.

What grinds my gears is sets that don't include common sizes. Like the really nice set of metric gear wrenches (May even be Gearwrench branded, I'd have to go look) that didn't include a 17mm. WTF? An 18 (never used one that I can recall) but no 17? What marketing genius came up with that one?
 
Little off point... (but that's me I guess :rolleyes:)....Worked at B. F. Goodrich Aerospace back in the 90's doin' heavy checks on Boeing's. Company decided to open an Airbus A320 check line... you know, the French/European airliner. When they announced it, I started the rumor that Airbus' were put together with metric hardware... and the company was NOT gonna pay us to buy metric wrenches and sockets. Within an hr. the whole hanger was in an uproar.... everyone threatening to walk off..... it was hilarious.
Ain't I a stinker.....;)
 
I use a 15mm when I can't find my 14mm. It works reasonable well but probably will not take much more than 14ftlb. My car has 18mm on the front suspension.
 
Draggin' up old memories here, Pete.

The ol' shop daze, everybody had full sets of box, combo, socket. All well used.

Except the 15mm and 18mm.
Those always had the new/shiny look.

Some guys even tossed those out. Just got in the way, and couldn't be used as substitutes on other stuff.

The 11mm got used often for 7/16".

Fast forward, now I'm finding 15s and 18s all over my trucks.

Still thinking that's a conspiracy, punishing those fellows who threw them out...
I have a garage full of bicycles, (31 last count) from tandems to mini clowns, and quite a few have 15mm rear axle nuts, and 14's on the front, but 18mm? Instead of going on the forum, tonight, I went wild and bought sae and metric slim line wrenches. You got to be careful, though. Some of these slim lines are not what they claim. You really have to check the reviews and look at all the pictures. I like the Craftsman from eBay with 11 1/2 inch handles, but only come in standard size 5 pc sets.
 
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