On 2012-02-23, wrote:
On 22 Feb 2012 05:47:38 GMT, "DoN. Nichols"
wrote:

On 2012-02-22, wrote:
On 20 Feb 2012 05:11:58 GMT, "DoN. Nichols"
wrote:

[...]

d) The manual says this should be a M8 screw. This was clearly wrong,
the screw is 5/16-18.

You know that 5/16 is *very* close to 8mm?

[...]

The critical point is that this set screw would not go into * the hole
it came out of in the first place*. It was not particularly difficult
to unscrew either.

It was a perfect fit into a 5/16-18 screw gauge.

Which suggests that the threaded hole in the hub was metric,
while the screw was not.

But how many threads did the gauge engage. Mine (a
"Screw-Chckr" plate) is not much over two threads when you get that
coarse -- not enough to tell the difference between 5/16-18 and M8.x1.5.

I can find no evidence that M8 with 1.5 mm pitch exists - all the
references I have seen mention only 1mm and 1.25 mm pitch in this
size. What are the odds that a set screw of this nature would be of so
uncommon configuration?

A result of a search for M8x1.5 on Google (one of many returns,
BTW).

http://www.globalindustrial.com/p/tools/industrial-tools/Dies1-Round/m8x1-5-hss-tmx-round-adjustable-die-metric-left-hand-1-inch-od?utm_source=google_pr;utm_medium=cpc;utm_campaig n=Dies-Round-google_pr;infoParam.campaignId=T9F

And I see hints that it was used in some automotive
applications.

This one is sort of confusing:

http://www.ngpracing.com/store/index.php?dispatch=products.view&product_id=5035

Because it has a "code" of "M8-1.25-32CR", but down in the description I
find:

Thread size / Pitch = M8mm x 1.5

Note that the Japanese have their own interpretation of metric
threads, which do not always match the ISO threads, so they may have
used it as well.

And the saws come from either China or Taiwan, and they tend to
use sizes which are very close to fractional inch sizes, so they may use
the M8x1.5 *because* it is so close to 5/16-18. And that screw may have
vibrated out in transportation, and the importers screwed in the nearest
inch size, because it *looked* like it fit.

Pull the hub, and re-tap *fully* for the 5/16-18 and you should
be fine.

Enjoy,
DoN.

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