CW wrote:

"Bill" wrote in message
...

To me, a beginner, it seems that marking the tenon from alternate
sides of the end of a beam using a single-bladed guage would yield
better
results than try to center a double-bladed guage by hand.


Any error is then doubled.

Not the error in the measurement of the shoulder width, and this
way the tenon would be more likely to be centered. At least, that's
the way I thought about it. How do you prefer to think about it--by
calculating the tenon width in advance and then trying to mark the
lines about the center by eye, or do you use a measuring rule?

Best,
Bill