What does "REF" mean?

[jlfernan]

I'm having a senior moment. Working on the forward structure on my 9A. On a few brackets, it gives you a measurement for a hole but has "REF" next to it. Does this mean to drill the hole here or mark it for a general location and use whatever it attaches to as a drill guide? And what's up with 72.6 degrees. Sometimes I can't tie my laces and thay expect this kind of precision? Just kidding.

[plehrke]

On a dimension the REF means that it is called out somewhere else on the drawing. Proper dimensioning only calls out a dimension once (to eliminate having different numbers) but once in a while it is helpfull to have a number repeated on a different view. The REF indicates that it is not the official number.

The decimal degree is a bi-product of Van going to CAD drawings. Typically a decimal will imply a tolerance. For example 72 degrees would be +/-3 degrees where 72.5 degrees would be +/- 0.3 degrees.

[jlfernan]

Thanks. I think I understand now. Also, you DO realize what time it is? We should still be in bed and instead we're typing on a computer! Gotta love this site and the people!

[Low n Slow]

Originally Posted by plehrke

On a dimension the REF means that it is called out somewhere else on the drawing. Proper dimensioning only calls out a dimension once (to eliminate having different numbers) but once in a while it is helpfull to have a number repeated on a different view. The REF indicates that it is not the official number...

Philip is correct, but I would also add that double dimensioning isn't the only reason for a REF dim. You may come across a drawing that has one or more REF dims that aren't called out twice.

They're just added (extra) info to help describe how to fab or assemble a part, but as Philip says, they're 'not official' and they have no tolerance.

Btw, besides using the word REF, a dim in parentheses (2.063) is also a reference dim.

Tom
22 years on the drafting board / 13 on CAD.