Details from my c.1770 Gabriel hollows and rounds

As some of you know, I'm the proud owner of a full set of 18th century hollows and rounds made by Christopher Gabriel c.1770. These planes could have been on the shelf next to those that found their way into the famous Benjamin Seaton tool chest, which is incredibly cool to me. All bear the same owner's mark and seem to always have been together (thanks again Patrick!)

Pardon the halo on these, a small part of my prized collection

I recently had a request over on my Instagram feed for some specific measurements from these planes from a fellow woodworker who is seeking to make his own set of molding planes. In doing so I noticed something very interesting regarding the width of the chamfers that are cut to soften the top corners and make the planes more comfortable to hold.
#2, #8, #16 pairs

The #1 set, i.e. 1/16" wide, has a chamfer which is 3/16" (or 6/32") wide. The #2 pair goes to 7/32", and this measurement stays the same all the way through the #11 pair. Starting with the #12 pair, the measurement goes up by approximately 1/32" of an inch for each pair of pairs (even and odd), i.e. #12 and #13 pairs are 8/32" (1/4"), the #14 and #15 pairs are 9/32", the #16 and #17 pairs are 10/32" (5/16"). The #18 pair is 11/32" but I do not have anything larger to know if that same formula would continue into larger, joiner sized planes.

#2 pair - 7/32"

#8 - 7/32"

#16 - 10/32"

In a world where many modern makers use the same sized chamfer for all their molding planes, regardless of size, this is an interesting detail. I found it intriguing that handmade planes exhibited this type of precise formulation.

I'd be very interested to learn if anyone else has a set of planes like this which displays this sort of sizing formula.

- Zach Dillinger