Roubo Panel Gauge – Design

RPG_finished

Let’s get the punch line out of the way.  Here is the finished panel gauge and the source of inspiration.  Now we return you to your regularly scheduled “how to build it” segment. Thanks for watching.

Between big projects I like to have a few quick wins.  Some would (rightly) call this stalling the next big thing, but it also lets me feel the satisfaction of completion more often.  I decided that my tool cabinet could benefit from a few upgrades and I started with my old panel gauge.

old_panel_gauge

My old panel gauge is no slouch, but it offers several opportunities for improvement.

This gauge is based in a classic and common style with a wedge-locked rectangular beam and a body with concave and convex curves.  It works and takes little time to construct.  The pencil is press fit into it’s home and the wedge locks the beam just enough to call itself locked. I was pretty happy with this little gauge until I read Roubo’s description of a good trammel gauge.

RPG_design1

Inspiration flows from every page of “To Make as Perfectly as Possible“.

Roubo described how wedge locked beams were the norm, but were fussy in use (my paraphrase).  He described his gauge as a big improvement with it’s screw lock and trapezoidal beam.  This made a lot of sense to me and after reading this I noticed that when setting my panel gauge I typically had to knock the wedge and beam in and out of place a few times to get the setting right.  Having no vision for anything better, I was satisfied with that.  Roubo changed my expectation of a well functioning gauge and I added it to my build list.

RPG_design3 RPG_design2

No, I don’t typically doodle in marker, but I figured it would show up better in pictures.  I have no interest in CAD at home.

I started the project by playing with designs for the body.  I couldn’t copy Roubo, because he actually drew a set of trammels.  I turned to “By Hand and Eye” for guidance on design.  I used their “module” approach to design and it was really fun.  Since this gauge is to be handheld, I made my handspan the module.  This set the length of the body.  The rest of the dimensions were felt out using a compass, dividers, and eraser.

RPG_build1

With the body designed, I went to my scrap pile to see what I could scratch up.  It looks like my new gauge will also be walnut and cherry.  If you think that is all I use, you are forgetting about cypress.

Bob Jones

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