Cabinet scrapers or card scrapers make a great shortcut to get around using sandpaper to get your wood ready for final finishing.
The basic idea behind these is that you hone an edge onto these so that they can function as almost like a plane on the surface of the wood. So using them is pretty simple, the technique involves just running them over the wood while bending them and kneading them forward. We are going to look at that in a minute.
The hardest part about them and the most controversial part I would say among woodworkers is actually how to sharpen them. There is many different methods and I have one method that works for me. So if you find a method that works for you, stick with it. I'm going to show you my method.
First step is we need to put a flat edge on top of the card and I have made a little jig here to help out with this. You might want to do this as well unless you have perfect control of your hands. This helps you keep the card straight and a 90 degree angle. You're just going to file these down. Now it's hard to know how much filing to do so one tip I would give you is, grab a marker and just put a line. You can do both sides too while we're at it here. Put a line of marker on there so you can see when that disappears, you know you're done. And just file it off.
After a few minutes depending on how flat your card was to begin with, you'll have removed the marker and you know you're ready for the next step. The top is now flat and you want to now level off these sides. In making this top flat on the file, what we have done is we have a created a little bur that's hanging over , a little piece of metal that's pushed down over the sides. We'll want to get rid of that because it has a very jagged edge on at this point from the file.
The easiest way to get out of that is use some high grit sandpaper, this is 800 grit on a piece of float glass. You can actually just do the edge of your card by scraping it, again you'll want to gauge your progress. If you don't know, you've never done this before, how long to rub it on the sandpaper, this will give you a gauge to determine when you're done. You just go until that marker has disappeared.
It doesn't take too long, it's almost gone on this one so we'll be ready for the next step. Now we've got flattened sides, flattened top, we are ready now to do the burnishing on here. Burnishing is a process where you're applying pressure to the top of the card with a burnisher. A burnisher, all that is basically typically a piece of harder then the card so it can push down and almost anneal the metal into a bur.
When I put this in, I'm putting this only about an inch above the table because that makes a comfortable hand position to rest the burnisher and keep it level. The first thing we are doing is just keeping the burnisher at 90 degree's to the top as we run it across. To help keep things moving smoothly, we'll put a little bit of oil on the burnisher and a little bit on the card. We'll use that to lubricate this process.
This takes elbow grease, you're going to be pushing down pretty hard and how often, or how much to do this, and how many times, is really dependent on how hard you push but the goal is to create like I said before a little bur that's hanging over the edge. You will start to feel one form as you do this work.
The final stroke that you want to do on here is to put a five to ten degree angle on this bur. Once you get a good bur formed, you'll feel it, it almost touches your fingers, do that. Just do a couple strokes on an angle, both sides. Then you're ready to pop it out of the vice, and let's try it out. So make sure you get all of the oil off, you don't want oil to get into your wood at this point.
We are going bend it back towards you, angle it away from you, the top, and then you're just pushing. So what I'm doing is catching that little bit of a curve I'm making down in the wood and that's the cutting edge. You'll feel it catch, if it's sharp, it will dig into the wood and that's when you know you're at the right angle to do this work. If your card scraper sharp, you're going to get little shavings and curlicues on the wood. If it's not sharpened enough, you'll see saw dust and you'll know you will have to go back and sharpen it more.
So the card scraper is like a plane and it cut's the wood. You know, sand paper is basically just scratching to wood at different degrees and you don't see it because it's blending with the grain but you get a much smoother finish with the card scraper because it's actually cutting the fiber's of the wood and you can feel it. You'll see it has kind of a glassy feel and it looks smooth, and shiny.