Never try to outsmart a dead guy. If you see something that worked a hundred years ago, don’t try to improve it, that’s not your job. Your job is just not to mess things up. Moderns tend to put way more aggressive a camber on there irons than needed, Lee Valley and Lie Nielson put a 3 in radius on their scrub planes. A camber that size is great for removing wood in a hurry, and on it’s own a 3 inch camber sounds like a great idea. But our ancestors realized that each tool was part of a system of tools used to get them to a finished product quickly. A plane with a 3 inch camber leaves deeper troughs and higher valleys that take more time to remove with a try and smoother than I like. As a result, I like a camber of about 5”-7” on a scrub and 8”-10” on a fore. Both of these will remove wood in a hurry going cross grain, but they leave very little work for the progressively finer planes that follow them.
But what about a try plane? What kind of camber should it use. According to the clue I showed you in the previous entry, it’s about a 12.5. Before I show you how to figure that out. I missed a few things yesterday.
When it comes to the chipbreaker smooth is more important than machined perfection. So do this freehand.
Start the cut on a narrow angle, resting the back of the chip breaker pull the breaker towards you, and rotate the breaker up as you do so to finish the cut on the knife edge of the breaker.
Once the very tip is shiny from end to end, you can smooth up any hollows further back with progressively finer paper.
By the way for most restoration My progression from rough to fine sandpaper, goes as follows. 80, 220 400, 1500, 2000. I only go up to 400 on not cutting components as it gives things a dull shine without being to attractive to fingerprints. Another finer point is I start with 220 to get an idea of the material I have to remove before I decide to hog off waste with 80 grit.
But I hate sandpaper let’s talk about steel. To figure out the arc the the original blade was ground at, I use this ridiculously simple jig. Yep, just a nail, a stick a string, and a pen. You can adjust the length of the string by winding it around either the pen or the nail. You don’t need a ruler, although it helps if you don’t have an existing camber to go off of. To find a camber pull the string as tight as it will go and set the tip of the pen on the farthest edge of the center of the arc. While holding the pen vertical rotate the pen to an outside edge of the arc (it is easier to hold the pen vertical if the sting is low on the pen). If the tip is past the blade then you need to shorten your sting of it is on the metal you need to lengthen it. When the pen follows the arc you are ready to trace an arc on the back of the blade (this shows up better on a clean blade, which is one of the reasons I start flattening the back at this stage…the other reason is flatting the back all at one is mind numbingly boring).
I will not grind to these lines but I will use them to create my new arc. The secret to doing this smoothly is to grind a flat that you use as a reference surface for the rest of the grind. Make sure that your support is tall enough that the tool touches the stone slightly above the center line. This helps save steel and prevents tool grab. Don’t be temped to take the corners off all at once, you’ll just gouge your stone. Instead keep the blade flat on the stone and and feather the grind so that You work more on the corners than in the center.
When done the end looks like this.
But this is the more important part.
By using this edge as a guide you can tell where material needs to be removed through the grind to create an even arc on the bevel. All you have to do is make this arc look straight when you look at it on end. To do that more material needs to be removed from the ends than the center. Once it’s straight, you can work this while keeping things even until you have created a bur on the entire back of the blade. This takes some time and some steal so I don’t recommend changing arcs often, I would rather just have spare blades with differing arcs if I need them.
The joys of working with vintage gear. I think I spun my hand around a few times after the handle fell off.
A quick repair.
And I get back to work. The same tips for grinding the end apply on the bevel but as you are removing more steel take you time and don’t overheat the tool. I keep my fingers close to the edge so I can tell when I need to do something else for a moment. Sharpening two irons at the same time is a good way to keep you steel cool and keep working (which is why I got a scrub in the last post)
As you can see the edge is flat across the bevel which means I have a nice even bevel at this point.
Now I just need to get a burr, and we are well on our way to making shavings.
-- Make furniture that lasts as long as the tree - Ryan