Hey Max, getting paid $.10 an hour for recreation ain't a bad deal.
I think I know the pair of dividers you're talking about.  Nice and
heavy critter.  I have one I found in the bottom of an old tool chest
I picked up many years ago.  Love them.  Dividers are subtly addictive
tools.  Not to gloat too much, I actually have a 24 inch pair of
blacksmith made dividers.  And once I get my shop organized I'll look
around for the drawings and rubbings I made of the wooden dividers
James Marshall made and used in making the saw mill where gold was
discovered.

> If I could return to the question that spawned all of this, how much
> better does a stair (dado) saw work than ye olde backsaw (tenon saw,
> Geoff)? I used to think that I needed one, but I've been cutting a
> fair amount of stopped dados (not grooves) with a backsaw without
> incident.

Judging from the number of shop made antique stair (or dado) saws
around, they have an advantage over the back saw -- you know, the
motherhood of necessity and all that. I have one that very rarely
gets used (by Disston).  One advantage is that, mine at least, is
adjustable for depth of cut.  When it bottoms out, you're done.
One less thing to think about, and the less you have to think, the
fewer mistakes you make.  There's also better control since both
hands can be used.

Depending on the number and length of the dados to be made, the
stair saw might lose some of its advantage.  If you are making
dados for a staircase, though, duplicating the depth of cut
makes the stair saw a real champ.

Mike in Sacto