Dual Dimensioned Drawings

I suppose you want me to burn my house down too.

Thank god electricity is all metric.

Dan

Only if you're using micrometers for C-clamps.

Yes, I noticed that all my wires are metric. I can tell because I can measure them with a metric micrometer.

When I worked as a QA Inspector in a sheet metal shop, one of our customers was a German owned company. Some of the drawings received from them had both metric and U.S. dimensions on the same drawing.

I think that a lot of Europeans, and Japanese, with whom I've worked a lot more, think that we don't understand what metric is, and that we don't have the tools to measure it.

A Japanese engineer I used to work with used to struggle with a piece of paper and a calculator when he talked to me, converting metric dimensions into inch -- with fractions rather than decimal inches. Maybe he thought I was a house carpenter.

After re-reading my post and your reply I think that I should be more specific. For instance,they would call out the length and width in metric, then spec the hole distances in U.S., the hole diameters in U.S with a metric thread. It was not to bad for me but the CNC programmers and the machinist always complained.

Oh, jeez. That is a problem.

Did you ever find out why they did that?

Not for sure. But I always suspected that the original drawings came from Germany all metric and they were redrawn here at the local plant. Why this would happen I do not know.

Actually, that's a bit of a mess, too....

--SEE:

Ah, it was a joke. If I can measure it with a metric micrometer...oh, never mind. d8-)

The dimension in brackets is a reference, as the guy you quoted reasoned.

I agree, the ambiguity is unfortunate, but it seems to me treating the bracketed dimensions as a reference is the reasonable interpretation.

By the way, Y14.5 doesn't support the use of "REF", parentheses only. Nor "TYP". I can live the parens, but prefer "TYP" to "4X" in some cases.

Agreed, I don't care if the machinist chews the part out with his teeth as long as it matches the print. But if I had an easy out in mind, as in the example below, I don't want the shop to miss it on account of some non-obvious dimension conversion.

Then I don't think we have much to disagree about.

I beg to differ...

I'm the reverse. I think in mm and have to do some mental arithmetic to convert from inches. I have 25.4 set into the memory of the mant calculators I use.

Another odd thing is standard collet sizes. I have a spindle that has 1/4",

6mm and 8mm collets, with sleeves taking it to 1/8". I can only just distinguish the 1/4" collet from the 6mm one.

Personally I prefer mm as I find 1 base 10 system much easier to work with, but then again I live in a metric country.

days typically having been designed by Frankenstein or relative if you catch my drift.

We're "metric" for certain values of "metric". Calling a 7/16 bolt "11.11mm" on the drawing it "metric" but it doesn't really do anything for clarity.

How so? Nobody really gives a crap if the screws used to hold their iphone together are inch, metric, Whitworth, or Klingon as long as they hold the iphone together.

Well if that sort of thing is such a big issue for you, never buy a '72 Volvo. I had '72 Volvo that had SAE, Metric, and Whitworth on it (at least the only wrench that would fit one particular nut was Whitworth--I didn't check the thread). Seems that the Swedes were at that time even more "backward" than we ignorant colonials.

days typically having been designed by Frankenstein or relative if you catch my drift.

Right. You may recall that the US automobile industry spent a couple of years diddling with what they called "soft metrics." They were inch values converted to metric, and they produced results like your example.

Here's a fairly current drafting manual on the subject:

"2.2 Soft Metric ? Soft metric conversion drawings maintain the original inch design but are converted to express the units of measurement in the SI metric language, including dimensioning and tolerancing in millimeters (mm). Soft conversion drawings are used when expensive tooling and production equipment cannot be immediately replaced or when the transition period to metric is limited. Soft metric may also include using metric fasteners."

It's been decades since it happened in the car business, but my recollection is that they used inch fasteners, expressed in metric conversions, at the time.

But in that industry, as well as many others, they've long since converted to "hard" metrics.

And - since they thread into plastic, any of the above will work fine!

It happens that Richard formulated :

Or even Coarse lol

these days typically having been designed by Frankenstein or relative if you catch my drift.

>

There have been some messes out there. Chrysler supposedly was all-metric by the late '70s, and my '89 Caravan was, but I didn't try to turn every nut and bolt.

Here are GM's metric standards for suppliers as of 1999. They include soft metrics:

There probably are a few bits of inch/Imperial stuff out there. It may be that a few suppliers are still covered by the soft-metric standards.