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"cox 049 gasoline"

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Post  Oldenginerod on Wed Mar 13, 2019 3:02 am

As I have done here before, I was musing over screw thread sizes as I often do, usually ending up in confusion, being far more acquainted with metric and fractional sizes than the sub-1/4" U.S. sizings.   Crazy Eyes

I came across this article and found it a really good read, making me realize that my ignorance on the matter is not just because I'm an Aussie.  Thumbs Up   It's an American article.

http://themetricmaven.com/?p=29
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Post  edw on Wed Mar 13, 2019 4:43 am

Makes sense to me. We already use the metric system. Don't believe me? How many pennies in a dollar? Dimes? Quarters? That's metric in its' basic form, and we use it every day.
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Post  Oldenginerod on Wed Mar 13, 2019 7:44 am

edw wrote:Makes sense to me. We already use the metric system. Don't believe me? How many pennies in a dollar? Dimes? Quarters? That's metric in its' basic form, and we use it every day.
I wouldn't call decimal currency metric, just because it uses decimals.  There's an awfull lot more to it than just currency.  Actually, you also use decimals when describing incomplete inches.  Rather than stating fractions of an inch, you use decimals.  We've always stated fine measurements in "thou" (thousanths of an Inch) and that is still widely used.  If we go back to the imperial system originally used, we talk in fractions.  Gauge was never really used here to my knowledge, except in fencing wire and shotguns.  Why is that?  Who knows?

Decimal Currency was introduced in Australia in 1966, well before going metric.  I guess you get to understand what you grow up with, but my confusion/frustration comes about from the fact that screw measurements in the USA use two completely different measuring systems, changing from Gauge to fractional at 1/4".  That's the subject of the article I attached.  Just seems that I'm not the only one confused by this oddity.  

There's every chance that we do have equivalent screw threads to your U.S. ones here, most likely stated as UNC or UNF, but I'm yet to find a comparison chart to point me in the right direction.  We typically used Whitworth for many years, but as the TPI measurement is the same as UNC (apart from 1/2" for some odd reason, which is one thread coarser), we go with UNC now.  Some of my older Commonwealth built engines/machinery also use B.A. screws.  Now that gets confusing.
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Post  Robbasdog on Wed Mar 13, 2019 7:53 am

Spare a thought for the keen souls intent on restoring old British motorcycles --- one bike can have up to SEVEN different thread-forms on it, according to an article I read. BSW, BSF, UNF, UNC, SAE, BA and CYCLE thread. Madness. I'll stick to Ducati, thanks!

Cheers, Rob
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Post  OVERLORD on Wed Mar 13, 2019 9:05 am

I would give a great welcome to 049 crankshafts made with an M3 thread. The diameter is practically the same as 1/8" but the pitch is finer which makes the bolt fit stronger. And propeller bolts would be available worldwide.

Only advantages!!
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Post  aspeed on Wed Mar 13, 2019 6:44 pm

OVERLORD wrote:I would give a great welcome to 049 crankshafts made with an M3 thread. The diameter is practically the same as 1/8" but the pitch is finer which makes the bolt fit stronger. And propeller bolts would be available worldwide.

Only advantages!!
If you want metric bolts, you could chuck the crank in a lathe and retap it to the next size up like maybe m 3.5. The tap drill size is 3mm which is only slightly smaller than the
#5:40 (1/8" stove bolt) tapped hole now. The crank may be hardened, but a torch on the end could cure that. Just let it get a bit past the blue colour to anneal it a bit. I think the integrity of the knurl might still be ok.
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