Indispensable Gragg Chair Tool – 1/8″ Mortising Chisel

Making a Gragg chair requires chopping 17 mortises for their respective tenon partners.  No big deal.  Except these mortises are only 1/8″ wide.  For that task you obviously have to possess a 1/8″ mortising chisel.  You could get by with something 5/32″, but probably not 3/16″  The stock is just not beefy enough to try that.

I have three chisels in my arsenal for this process.  The first is one that came for a box of tools I got at a flea market, it is a 1/8″ long chisel with a turned bulb handle.  A second is from a no account 1/4″ Stanley chisel that I ground down to 1/8″ wide, and the third an my “go to” chisel is one I made from a derelict plow plane iron.  All three are delightfully short in their overall length, a definite advantage when working inside the quirky confines of of the Gragg chair.

The mortises in question are for the rungs and fitting the seat slat tenons into the underside of the crest rail.

I’m not sure if the 1/8″ mortise chisel is THE most important tool in the project, but I do know that Gragg himself did not use the mortise-and-tenon method for attaching the rungs – he just drilled full-size holes and punched the rungs through – and every Gragg chair I have seen is broken at this point.  This is definitely one case where an acolyte can improve on the methods of the master.  I once asked some engineers to analyze my approach with Gragg’s, and they told me the 1/8″ M-n-T construction was ultimately 4x to 5x less likely to fracture than the original.