Sizing up Hollow & Rounds moulding planes

Molding or Moulding planes? Well, moulding is the old English term, and also what we still used here in Canada, so moulding it is, same as colour, flavour and etc :-)

If you research these very useful planes, chances are you will quickly becomes confused about their sizes and nomenclature. Why? Because there is not a singular Numbering system used to differentiate them.... Surprise! Wonder who ever came up with the, surely, long obsolete word "Standard" cause they're ain't no such thing...  

Anyhoo, here's what you should know about H&R sizes and how to tell them apart.

H&R were available in full set (18 pairs, 36 planes), half set (odd or even sets of 9 pairs) or individually.

So you would think that they would be simply numbered from No 1 (smallest) to No 18. But that would be too easy, I also have a No 21, 92 and 180 in my collection of No 16s... So what gives?

First lets look at their cutting geometry to make sense of it all.
These planes cut approximately an arc of 60 degrees.  This means you can actually cut a bigger circle than the blade width by tilting the plane sideways.

Blade width is length of radius, and cut a 60 degrees arc of the circle.

A 1-1/4 in blade can cut a circle twice its size (twice its radius) 

its full circle being 2-1/2 in Dia. and could be stamped No 9, No 16, No 180 and etc.

If you look at their construction, you can see that often the sole is tilted or shaped to facilitate this.

Round No 12. Notice the asymmetrical rounded sole. Front view.

Hollow No 16. Notice how the sole is not centered and made to be tilted.

Rear view.

Ok, so far so good, so where is all the confusion coming from?
Turns out not every manufacturers made all the available sizes (18, 36 H&R planes) and not everyone used the same numbering system.  In addition, if you were to order a set, they would use different numbering system to denote part of an even or odd or full set etc.  Oh, and then there are the different bedding angles to accommodate hardwood or softwood and did I mentioned some have skew blades?

So there you have it, a plethora of numbering systems ready to trip the unwary collector, even when armed with a list of wanted DAMHIKT :-)

As a rule of thumb, going by the size of the blade, is a more reliable means of determining "its size" than relying solely on the number stamped on them.
Only exception would be if you stick with a particular maker from a specific period. But most of us, acquired our set of H&R from a variety of plane makers over time.  It is called assembling an Harlequin set, but even then, there are pitfalls.

The last set of matched H&R I bought at LV was in fact different sizes, even if both Mathieson and both stamped No 16.

Here are some typical number systems

Number	Iron width	Circle Diameter
1	¼	½
2	3/8	¾
3	½	1
4	5/8	1 ¼
5	¾	1 ½
6	7/8	1 ¾
7	1	2
8	1 1/8	2 ¼
9	1 ¼	2 ½
10	1 3/8	2 ¾
11	1 ½	3
12	1 5/8	3 ¼
13	1 ¾	3 ½
14	1 7/8	3 ¾
15	2	4

and another

	Chapin-Stephens		Greenfield
Number	Iron Width	Circle Diameter	Iron Width	Circle Diameter
2	1/4	1/2	1/8	1/4
4	3/8	3/4	1/4	1/2
6	1/2	1	3/8	3/4
8	5/8	1 1/4	1/2	1
10	3/4	1 1/2	5/8	1 1/4
12	7/8	1 3/4	3/4	1 1/2
14	1	2	7/8	1 3/4
16	1 1/8	2 1/4	1	2
18	1 1/4	2 1/2	1 1/8	2 1/4
20	1 3/8	2 3/4	1 1/4	2 1/2
22	1 1/2	3	1 1/2	3
24	1 5/8	3 1/4	1 3/4	3 1/2
26	1 3/4	3 1/2
28	1 7/8	3 3/4
30	2	4

As an example a Hollow or Round plane Stamped No 6 could be 

7/8, 1/2, or 3/8 in wide.

One thing we can glean from these tables is the fact that most start at 1/4 in (Greenfield start at 1/8) and progress in sizes by 1/8 in up to 2 in... and yes, there are some bigger!

A half set, even or odd, will progress in size by 1/4 in and is more than adequate for most situations, hence why not everyone bought a full set. They were and remains, rather expensive to buy anyway (36 planes), so why buy sizes you are not likely to use! 

If using for architectural uses or for furniture uses, chances are, you would uses different range of  different sizes. 

Lets have a closer look at my "assortment" of eight No 16 H&R look-A-Like.

The three on the right have been culled from the pile on the left (5) 

of No 16s or equivalent. They have slightly bigger blade width.

Out of the 8 ones I pulled from my plane tills, only 5 have a blade width of 1-1/4 in wide, which makes them all No 16 (as mostly stamped) in one "other" numbering system. As per the table shown previously they would be No 9, 18 or 20

Lets first eliminate the other three.

They are

VA Emond, a Quebec plane maker, stamped 1-1/2 (inches). It is a Round, blade is 1-1/2 wide and bedded at 47.8 degrees.

J.Kellogg Amherst MS, stamped No 21. It is an Hollow, blade is 1-1/2 wide, bedded at 49.1 degrees

This next one was a surprise, it came from my latest pair I just bought, stamped No 16. But it should be a No 10 or No 20

Alex Mathieson & Son Glasgow, stamped 16. It is an Hollow, blade is 1-3/8 wide, bedded at 49.8 degrees

The remaining fives are all 1-1/4 in wide blades.
They are:

A. Mathieson & Son Glasgow, stamped 16. It is an Hollow with a skew blade 1-1/4 wide, bedded at 50.2 degrees.

 Auburn tool co Auburn NJ, stamped No 181 and 16. It is an Hollow, blade is 1-1/4 wide, bedded at 46.7 degrees.

Mason, stamped 16. It is a Round, blade is 1-1/4 wide, bedded at 54.7 degrees.

A. Mathieson & Son Glasgow, stamped 16. It is a round, blade is 1-1/4 wide, bedded at 50.5 degrees.

Unmarked, 10-1/2 in long. It is a Round, blade is 1-1/4 wide, bedded at 47.7 degrees.

Here is how I measured the bed angle, using a digital protractor.
I line the blade with the bed on the plane without its blade, so it sit flat on the stock of the digital angle finder.

This is the Mason Round

So what is it with the various bedding angles?
Well first of all, these are all pretty close to 50 degrees (49-50.5), which was probably what the maker was shooting for. Some are closer to 45 degrees (46-47)
But one, the Mason is bedded at 54.5 degrees, obviously intended for hardwoods.

Moulding planes are usually bedded at 45 degrees (like most bench planes)
but the British usually made them at York pitch (50 degrees)
As a general rule, the higher the pitch, the more of a scraping action you get and the better for uses on hardwood. It also becomes harder to push, hence why they came up with skew blades.

Here is the slight mishmash between that last set of "matched " pair of H&R

They are both stamped 16 but one has a blade 1-1/4 the other 1-3/8 wide

Close but no cigars

Easy enough to be fooled, especially if they are both stamped No 16 and both Mathieson & son. One is A. Mathieson, the other Alex Mathieson.

Same maker, different time period, different numbering system 

Confusing? You bet!
Best thing to do is to stick to the actual blade width measurements. The plane sole itself is sometimes slightly wider or worn. Uses this handy chart table I just made to keep in my wallet. Now I just need to carry a small ruler with me :-)

The actual Nos are irrelevant, what matter is the progression of blade width.

And then armed with my wife trusty P-Touch label maker, I'm going to re-labelled them according to Bob's table numbers...

Bob, trying to stuff a 1 ft ruler in his wallet :-)