1967 Dream RebuildJIS vs MetricEnlighten me, what is the difference? I'm replacing with all button head Cap screws as these JIS heads suck. Also, most of the side case screws are the JIS (looks a lot like Phillips to me), the thread pitch is a standard M6X1.0. What gives, I thought JIS was a different pitch. Also, there are some M5s on side cases and starter. All I could find was 0.8 pitch, these appear finer.
"When the going gets weird, the weird go pro." H.S. Thompson..... JISI understand that JIS are the same as ISO except for 3, 4, 5 and 12 mm. If I have my information correct the JIS pitches are as follows:
3mm is .6 pitch vs .5 pitch for ISO 4mm is .75 pitch vs .7 pitch for ISO 5mm is .9 pitch vs .8 pitch for ISO 12mm is 1.5 pitch vs 1.25 pitch for ISO The heads look like Phillips, but JIS heads are different and reportedly designed that way to help eliminate "cam out" where the screwdriver tip fits the head - if you use the right JIS screw drivers on them. If you try to use a regular phillips screw driver on a JIS head you will cam it out more often than not. If you get a good JIS screwdriver, you will find the JIS screws are designed pretty well. JIS =GAYAlas a "solution." Harbor Freight, that bastion of Chinese throw away tools had a tap and die set for the now obsolete "old" JIS standard. So, I was able to re-thread an M5 from a 0.8 to a 0.9.
I can hear it now from my fellow wretched wrenches, "But Doc, you can't re-thread from fine to coarse!" And to that Id say...you're right! But, for a few precious turns of the wrench they hold nicely. So, the nightmare is becoming a bit more dreamy. That's all for now.... JB
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