The Numbering System of H&R’s

The numbering system starts from 1 through to 18, this gives a us 36 moulding planes. Thanks to the 60° of a circle cut by these planes, the width of the iron is the radius of the circle the plane cuts.
There are two forms of numbering systems – Even and Odd.
Robert Demers a tool historian and blogger suggests that the even and odd numbering system has nothing to do with the profiles radius, but rather to denote that it’s part of a full set, an even set or an odd set.
Al Sellens in his book Woodworking Planes says; “The size numbering refers to iron width but the numbering schemes appear to have been established to confound the scholar and to confuse the collector.”
Hollows and rounds before 1750 were unmarked as to their size or number. There is an 18th century JENION plane in Larry’s Williams collection that is marked. It is however unknown whether the mark was placed at a later date or it’s an original, Larry believes it seems to be an original.
A standard in the numbering system developed at the start of the 19th century.
The numbering and sizing varied between manufacturers. For example, (and
I hope you’re ready to be confused as all buggery). There are plane numbers that end at 15 with an iron’s width of 2”, then there are planes that begin with no.2 and end at 30 that increase by 2. For example: 2,4,6,8,10 etc. But each plane’s iron width differs from manufacturer to manufacturer even though they may be the same number. For example, one manufacturer will stamp a No.12 representing its iron’s width to be ¾”, but another manufacturer will say our No.12 is 7/8” and a third manufacturer will say our No.12 represents 1 5/8”. Larry Williams gives a good clarification of this numbering system and I quote;
“The major British makers seem to have followed this emerging standard relatively closely. Under this system, numbers correspond to the number of 16ths of an inch in cutting width; except on those planes wider than ¾” the increment of change switches to 1/8”. For example, a number 11 would be 11/16” wide; number 12 would be ¾” wide, and a number 13 would be 7/8” wide rather than the expected 13/16ths. This change, I believe, was an attempt to offer planes which allowed for visual weight of the profiles cut. Visually, there’s little difference between a 1 ½” diameter cylinder and a 1 5/8” diameter circle.
The width of hollows and rounds directly relates to the radius of the arc they cut. Most planes cut 1/6th of a circle, or 60º of arc. This means the cutting width of these planes is equal to the radius of the arc — a number 8 plane will have a ½” cutting width and cut an arc with a radius of ½”. It is convenient to judge the size of a circle by the width of the sole of the plane. My observation is that this too has some exceptions. Larger hollows and rounds tend to cut less than 60º and often cut a radius larger than the sole of the plane would indicate. For instance, a #18 from an unused set of GRIFFITHS, Norwich (c.1860) planes we have cuts a cylinder with a 2” radius rather than the expected 1 ½”. This matches the #18 profile of a little used set of MOSELEY (c. 1810).”

A No.8 Moseley has a radius of ¾” whereas the Mathieson of the same number that follows the British standard would be ½”.
He continues to say; “Another exception is that number 1 planes were listed as being 1/8” bare or less than 1/8” but larger than 1/16”.
Many American plane making firms closely followed the British system. Some didn’t and used a variety of systems. Greenfield avoided the increment change found in the British system. Sargent offered only planes that represented the even numbers of the British system but numbered them sequentially. Those American makers who didn’t follow the British system appear to have had their own different systems and no alternative American system is apparent.”
Larry Williams chose to follow this later British system except to stay with planes cutting 60° of arc. This ensured that the plane’s width will be the radius of the arc cut.

The list below is the numbering system that Larry follows. These sizes incrementally increase by 1/16” except for the No.13, 14 and 15 which increase by 1/8”.

NumberWidthRadius
11/161/16
21/81/8
33/163/16
41/41/4
55/165/16
63/83/8
77/167/16
81/21/2
99/169/16
105/85/8
1111/1611/16
123/43/4
137/87/8
1411
151 1/81 1/8
161 1/41 1/4
171 3/81 3/8
181 1/21 1/2

Here is a list of numbering systems from other plane manufacturers including but not limited to Chapin Stephens, Moseley and Greenfield.

Plane NumberRadius of Profile
11/8
21/4
33/8
41/2
55/8
63/4
77/8
81
91 1/8
101 1/4
111 3/8
121 1/2
131 3/4
142
152 1/4
162 1/2
172 3/4
183
Plane NumberRadius
11/4
23/8
31/2
45/8
53/4
67/8
71
81 1/8
91 1/4
101 3/8
111 1/2
121 5/8
131 3/4
141 7/8
152
NumberIron Width
21/4
43/8
61/2
85/8
103/4
127/8
141
161 1/8
181 1/4
201 3/8
221 1/2
241 5/8
261 3/4
281 7/8
302
NumberIron Width
21/8
41/4
63/8
81/2
105/8
123/4
147/8
161
181 1/4
201 3/8
221 1/2
241 3/4

As we have seen not all followed a particular standard and since plane manufac-turing is no longer practiced on a large scale as it once was, we as small-scale manufacturers for the lack of a better word, can set new precedence to follow one standard.
Did you know that each plane manufacturer in the 1800’s produced about 70,000 planes a year?

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