Trade description

I ordered a 12.3 mm twist drill on eBay and got send a 31/64" (12.3038mm) instead. Bit miffed but as it was ordered for drilling wood it's not an issue. If it wasn't a cheap bit though it would have got sent back. Watch out guys!

Good grief Vic - 0.0038 mm oversize that's less than a fleas eyelash surely. What are you making that needs that sort of accuracy and, indeed, is your drill/chuck that true !

Did you check it though, Vic - with a steel rule AND a magnifying glass........

Well, I was gonna say summat, but on second thoughts I don't think I'll bother... :D

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I take it the the '' at the end denotes a tongue in cheek initial post.

Nick

I've had a few drills with inch decimal sizes when should be metric, near enough tho'. Bought a masonry drill yesterday marked 1/4" and 6mm, that's not close enough. Well for drilling in the shed wall it is.

If it was a cheapie of e-bay it will probably drill 1/2" anyway but look on the bright side you won't need to use your reamer to take that last 1/64" off

Edited By JasonB on 06/09/2017 17:09:50

Seems like you can,t trust anyone these days.

None of you got your calculators out,then?

31/64"'s actually only 0,003125mm oversize.

It is, in fact within the size range expected. 12.3mm would be between 12.15mm and 12.34mm.

Now, if you had ordered a 12.30mm item, it would be a different matter.... If there is no tolerance stated, you get what you actually ask for to the nearestrounding digit. That is why the average of 1 and 2 is 2, not 1.5!

NDIY

Read what Vic wrote "I ordered a 12.3mm............"

Yes, but didn't say anything. Did you read the recent dictat that said us mere mortals aren't allowed to comment on errors under pain of excommunication, or at least a slap on the wrist from a moderator?

Andrew

Trade description: 12.3mm would certainly be a trade description but whether it is "false to a material degree" so as to make its application an offence is another matter.

It was intended tongue in cheek, although having said that I'm going to have to look up what it's "metric" size is before I using it. For my purpose the size is fine, I just wish it was marked 12.3 ...

Oops. 12.25 - 12.34mm, not 12.15 is the range for 12.3mm. If he wanted 12.30 the precision would have been 12.295 - 12.304. All measurements within that range would be a genuine 12.30mm.

Some people might expect 1 inch to mean 1.0000000", but it doesn't. And wouldn't in a court of law. Any measurement must have a tolerance to mean much at all. Whatever units the drill might be marked in is irrelevant, as I see it. Fit for pupose is the yard stick. I don't really care if I wanted a one inch drill and it read 25.4mm on the shank - it is still one inch (and to better tolerance than I specified).

That said, 31/64 could be 12.5mm at its maximum of 31.4/64", so that drill, unless it has a lesser specified tolerance, is not a proper and true equivalent.

Edited By not done it yet on 06/09/2017 23:15:30

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I think even these puppies have a tolerance.

And different latitudes and designations of tolerance at that don't they.

So if I were to purchase a H7 tolerance reamer marked 12.30mm what +/- could it actually be.?

But if you are such a perfectionist should you not be buying drill bits specially designed for wood as they have a different geometry I think.

Nick

Edited By Nick_G on 07/09/2017 00:17:02

I think it's the tolerance of this forum that's suspect... his original post had a big smiley on it but so many serious replies!

Oh come on Neil - everyone knows that model engineering is a serious business - some folk even get PAID for their involvement!

I picked up, semi-seriously, on the title of the post. I imagine Vic might well have been able to return the drill to the eBay seller but, on the facts, doubt if he would have got much joy from the authorities if he had chosen to complain.

Incidentally, I would be interested to know the application which required a 12.3mm hole in wood.

Agreed, humour seems to be lost on some folks. Wait, best put another smiley ...