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JOEL Joel's Blog

Back Bevels, The Norris High Pitch Setting Device - The Thing That Never Was

10/02/2019

Back Bevels, The Norris High Pitch Setting Device  - The Thing That Never Was 1

This blog entry is about the Norris High Pitch Setting Device, a rare plane collectible that is so rare it doesn't seem to exist.

But first some background information



One of the basic rules of geometry that affect hand-planing is that the higher the effective cutting angle of a plane angle, the better the plane is able to turn and break a chip. This reduces tear-out, but requires more force to push the plane through the wood. Most wooden plane were made at anywhere from 45-60 degree bed angles, depending on whether the plane was intended for hard or soft wood or for moldings. Stanley bench planes are all set at 45 degrees; premium steel plane maker Thomas Norris made his planes at either 45 or 47 1/2 degrees. It would seem logical, however, to use the lowest possible angle for regular planing (to make the plane easier to push) but raising the angle a bit occasionally for difficult woods (to prevent tearing out the wood) .

One strategy is using separate planes. Modern manufacturers have a different solution: Both Lie-Nielsen and Lee Valley manufacture large bevel-up planes in which you can change the bevel angle of the blade and raise or lower the effective angle of the plane. You can do this with a block plane or a miter plane too.

In a bevel up plane the effective angle is the angle of the bed plus the angle of the blade bevel
In a bevel up plane the effective angle is the angle of the bed plus the angle of the blade bevel


The problem with bevel-up planes is that you can easily change the angle of the bevel, but if you use a secondary bevel, over time the effective planing angle will go higher and higher when you don't want to. With bevel-down planes, a secondary bevel doesn't matter as long as it isn't so low you start rubbing the wood behind the cut.

In a bevel-down plane the effective angle is the angle of the bed  or frog
In a bevel-down plane the effective angle is the angle of the bed or frog


Overall, most generic planing was historically done with bevel-down bench planes. There are two ways I know of of changing the effective angle of a regular bench plane.

The first is put a shim behind the top of the blade. This method doesn't really work with thin Stanley blades, but it does work on heavy stiff irons. It also reduces the bearing surface of the iron on the frog of the plane, which isn't good. But it's less expensive than buying a new plane.

Another way of changing the effective angle is by putting a back bevel on the iron itself. The back bevel doesn't need to be very big, just wider than a shaving. There are a couple of issues with this method. If the back bevel angle is too steep, it will rub on the work. On a 45 degree plane bed it needs to be less than that. Adding the back bevel freehand isn't a big deal, but you have to chase a wire edge much like you would do on a carving tool. There are also additional issues of resharpening or removing the back bevel entirely. Finally, a back bevel on the blade opens the space in front of the iron, increasing the mouth and thereby defeats the purpose of having a back bevel in the first place. You can mitigate that result by using a thicker iron just for the back bevel, or by putting a shim on the frog of the tool to move the entire blade forward. There are a few other ways of doing this, which I will go into later on.

With a back beveled iron the effective angle is the angle of the bed plus the angle of the back bevel
With a back beveled iron the effective angle is the angle of the bed plus the angle of the back bevel


Complicated, eh?

Norris to the rescue!



The 1914 Norris catalog features an engraving of a new honing guide for putting a uniform back bevel on a plane iron. According to the catalog, the "Norris High Pitch Setting Device" allowed you to get very satisfactory results on hard or curly grained material (instructions included with each device). As near as I can tell, the device would get bolted onto your iron and run the flat side on your stone, creating a uniform back bevel. The guide would also serve as a reference when chasing the burr and flipping the iron back and forth. See the rendering below the text for my conception of how this device was supposed to be used.

But did it work?

The picture in the catalog is actually the only reference to the device I know of - even after asking many prominent tool collectors. Nobody can recall ever seeing one. I have a vague memory of possibly seeing a picture of one, but I probably am imagining it. At best I can say the Norris device is hellishly rare and probably was never made in any more than a few test pieces. It is also possible it was never actually sold. According to the catalog, an entry patent was applied for it but I could find no record of the application, much less an actual patent. It disappeared from later catalogs.

For comparison on rarity, I own a Norris 114, a plane that never made it into their catalogs - at best was only marginally produced. It took some asking around about it, but I know of the existence of at least two others. I also have a prototype Norris smooth plane from the late 19th century. It's just a prototype, but at least two others survive. So when I say this device is rare and possibly non-existent, I am comparing it to known prototypes of which we would expect very very few to exist. Here we've got NONE.

Is it a good idea?



Probably not.

In the modern world if you want to have a higher effective pitch and you have a Lie-Nielsen bench plane, you can purchase from a higher angle frog from Lie-Nielsen.

You can also use any of the ideas mentioned above and freehand the back bevel. If you don't feel comfortable with freehanding the back bevel, you can use any of the modern honing guides by flipping the iron upside down. Modern honing guides have wheels so you won't wear down the guide in use, as you would with the Norris guide. With David Charlesworth "Ruler Trick" (that puts a tiny back bevel on your iron), using a thicker ruler allows you to create a backbevel of enough angle to create a performance difference.

But back in 1914, two things happened that might have interfered with the High Pitch Setting Device from ever coming to market. The first was World War I. From 1914-1918, the market for woodworking tools for civilians greatly contracted. I can't imagine anyone wanting to invest in what was a tweak for doing high-class work, when to be a success you would first need to create a demand, advertise, and get the ball rolling. But during the war that wasn't happening.

After the war there was another important factor. The 1913 patent adjuster gave new life to Norris. While before the war Norris tried desperately to compete with wooden plane makers and Stanley in the mid-to-low price tool market, after the war the company decided, rightly so, to take their adjuster and stick to the high-end. The overwhelming number of Norrises that survive from the post WWI period are the higher-end models. And as anyone who has been fortunate enough to use one of that era's higher-end Norris models knows, the performance on difficult wood is so good that adding a back bevel seems unnecessary.

If you happen to come across and actual sample of the device, or even a picture of one, please let me know.

 A rendering of how I think the device was intended to be used
A rendering of how I think the device was intended to be used


Join the conversation
10/02/2019 Derek Cohen http://www.inthewoodshop.com
Joel, there are three assumptions you make, which are incorrect:

1. "The problem with bevel-up planes is that you can easily change the angle of the bevel, but if you use a secondary bevel, over time the effective planing angle will go higher and higher when you don't want to." You assume that the sharpener will lift the blade to work the edge of the bevel. This is what happens when you freehand a secondary micro bevel. However, when honing a BU plane blade, the best method (since accuracy is important) is to use a honing guide. This will maintain the desired bevel angle.

The article I wrote on this over a decade ago now: http://www.inthewoodshop.com/WoodworkTechniques/TheSecretToCamberinBUPlaneBlades.html

2. "Finally, a back bevel on the blade opens the space in front of the iron, increasing the mouth and thereby defeats the purpose of having a back bevel in the first place." When the cutting angle is raised to 55 degrees and beyond, the size of the mouth has no impact on the quality of the planing. You could open the mouth even further, and it would still have no effect.

This is the same result as when setting a closed up chipbreaker (to control tear out). The mouth actually needs to be opened to allow the shaving to pass by the chipbreaker (otherwise the escapement simply jams up).

3. " With David Charlesworth "Ruler Trick" (that puts a tiny back bevel on your iron), using a thicker ruler allows you to create a back bevel of enough angle to create a performance difference." The typical Ruler Trick adds a back bevel of around 2/3 of one degree. Even a thicker ruler will not create much more than this (David's computations). The Ruler Trick is not about performance. It is not a real back bevel - not of the type you described earlier. It is used to by-pass flattening the back of the blade.

Regards from Perth

Derek
Derek,
1 - Good point.
2 - I certainly won't argue that at the higher angle the mouth size isn't a big deal - this is one of the attractions of higher angle planes. But the mouth does get wider. If you go to all the trouble of having a plane with a whisper mouth (that is an iron of the right thickness for that plane) and then you back bevel it you are barking up a completely different tree. It can work out fine, but the higher planing angle is a different approach than a fine mouth and the effect isn't cumulative.

3- With one or two rulers I would agree -but with a 1/4" piece of bar stock you are raising the blade quite a bit. Not for the reason Charlesworth uses a thin ruler, but the technique is the same - even if the intended result is different.

Incidentally or maybe not incidentally I don't own or use any bevel up bench planes except for several mitre planes. I just don't like the feel of them. I also don't have any back beveled plane irons. As I have a mid-1930's Norris A5 I have never found anything I could not plane as long (in the extreme case) the iron was sharp. I do have several higher than Norris angle planes by Clark and Williams - and they are awesome. This blog entry was really a look at a historical curiosity than an argument for or against a back bevel on an iron. So I didn't feel the need to try lots of blade combinations or alternations.
10/02/2019 Steve D
Your first diagram has the "effective angle" drawn as the clearance angle [Fixed - thank's for catching the error -jm]. I think cutting angle (90-rake angle) is more meaningful than "effective angle" and you probably would have caught your error using more specific wording.

In the ad for the device it looks like the two ends are made to allow two different corrections to the cutting angle.

With a 25 degree bevel and 45 degree bedding you would end up with a cutting angle of 70 degrees by just flipping the iron over. Of course you would have to figure out what to do with the chip breaker and huge mouth.

The method pursued by Norris maintained conventional mouth and chipbreaker parameters to a large extent.
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