A year or so ago I found a very nice type 11 #7 plane at a local antique mall for a reasonable price.
Unfortunately the sole of the plane had a bit if a warp and twist. It worked well enough for roughing stock to dimension but try as I might I could not get this plane to shoot a straight edge.
I have trued the soles of smaller planes before; a tedious task of lapping the sole against a flat surface covered with sandpaper or a sheet of glass covered with abrasive grit. I was not looking forward to spending hours, possibly days, lapping the sole of a 22″ plane.
Last night I came up with two possible solutions.
The first was to contact a local shoemaker to see if I could borrow his night crew to do the work while I sleep.
That didn’t work out so I went with plan B.
I decided to try truing the sole in a manner similar to leveling the frets on a stringed instrument. I lowered the blade and clamped the plane upside down in my bench vice and stoned the sole with diamond stones. I frequently checked progress with a straight edge. I was able to feel the drag of high spots on the sole just as I feel the high spots on frets.
The work went surprisingly fast.
I would not say the sole is perfectly flat but after about an hour of work I was able to make see-through shavings a yard long and leave the board I was planing very straight and flat!
I figured I wasn’t the first! I did use some feeler gauges to make sure my eye was seeing things correctly. The thinnest I had was .003 it wouldn’t fit between the straight edge and sole.
Doug… thirty odd years ago, before the advent of the Flat Sole Society, I simply did what you did. I had an early diamond stone from Woodcraft. It worked well too. Periodic checking with a straightedge and I had a plane or two that worked just fine. I did have a set of feeler gauges from when cars needed them but never thought to use it.
I wonder if the Dominy’s had diamond stones or feeler gauges?
Gary