Highland Woodworking Blog

Ok, so do you have a card scraper sitting around in your shop collecting dust? If you do, don’t think you’re alone. I’ve talked to a large number of woodworkers across the country that are in a similar boat. I’ll provide you with some easy to follow instructions that will hopefully make the card scraper one of your go-to tools from this day forward. Oh, one caveat… The quality of steel in your scraper can absolutely make or break this success. I know first hand, as I had a card scraper in my shop early on, and no matter what I tried I just couldn’t get it to work properly, or if it did, it would only last a few strokes. I finally decided on a whim that I’d buy another card scraper, just to see if it was me or the scraper. Well, I’m sure glad I did, because the second one worked like a charm. I’ve even gone back to the original one (yep, I still have it for times when I want to dig in and do something I wouldn’t really want to do with my good scraper) and applied the same techniques, but to no avail.

When you first get a card scraper, the likelihood is that its edges will be similar to when you buy a new handplane. Not too bad, but certainly not to the level where you get your best results. The first thing to do is to file the two long edges of the scraper. I use a scraper file/burnisher made by Glen-Drake, which provides great results and helps make it easy to accomplish. Before getting started, I made a spacer block the same thickness as the distance from the file surface to the outside edge of the handle (see photo below). Make sure you test your spacer by placing the file on it, while the handle is on the bench. I put a light source behind the block and made sure no light was leaking through towards the handle or the end.

In the photo above, I have the handle of my file resting on the workbench surface and the file clamped in my bench vise. When clamping, I hold the scraper against the spacer so it is the same height above the bench. With the scraper at this height, it’s simple to keep a flat and square surface on the scraper edges. All you have to do is keep the handle of the file on the bench while moving it down the scraper surface with light pressure. One little trick I use is to coat the edge with black Sharpie so I can tell if my file is taking material equally across the edge of the scraper. One other thing I do is hold the file in a similar position to that in the photo, rather than trying to move it down the scraper from the tip of the file to the handle. The way I hold the file tends to have less chatter on the scraper, so less junk to remove later.

Above is a photo of the scraper’s results if used immediately after filing the edge. As you can see, it’s mostly dust, but there are little “almost” shavings. I thought it would be nice to have the comparison between this stage and the final surface.

The next step is to knock down any burr that either previously existed, or is now there from the filing. Depending on the type of stones you have, softer being a bigger deal, I sometimes use the same file with a pass or two to remove the burr. This is simple and quick. Another option is to use a diamond plate or even a hard 1000-grit stone (like the Shapton Glass series). After you have eliminated or at least reduced the burr, it’s time to hit the stones. Place a thin ruler on one edge of the stone so that side of the scraper is lifted ever so slightly, placing your efforts at the opposite edge. This focuses the work where needed, rather than basically working the whole surface of the scraper. Work on your 1000-grit stone first and then move up to 8000-grit or 10000-grit. The end result should be a very narrow polished band at the edge (hard to capture with a camera), on all four long sides of the scraper.

Next, make a wooden block (unless you have a piece of high density plastic, which I like better) that is almost as tall as the scraper is wide, and make certain the edge of the block you use is square to the bottom surface. This is to support the scraper on the stones when up on edge. Again, use the same 1000-grit/8000-grit stones, but make sure the scraper is oriented as if you were drawing a diagonal on the stone, and push as if moving straight down the stone. With the scraper angled to the movement it helps prevent creating a groove in your stones. If the scraper was oriented straight up and down the stone, the grooves would occur readily and by the time you finished, would be substantial. As usual, work each grit until the scraper has a consistent surface (a dull grey on the 1000-grit and a polished surface from the 8000-grit).

Now you’ve finished the prep work, so it’s on to creating the cutting edge. Well, that’s really not exactly true. The cutting edge is already there and you can test this if you’d like. It’s not as aggressive as it will be after the next step, but it will take a shaving. Just remember that the angle at which you engage the wood is different.

Lay the scraper flat on your bench, along the edge, and carefully move your burnisher up and down the wide surface at the edge. If you don’t have a burnisher, a carbide router shank will work, but be careful you don’t accidentally cut yourself on the router bit. This is done on all four edges. **Since I’ve been using the ruler trick on my stones, I’ve omitted this stage and the scraper behaved equally as well.

Clamp the scraper again in the bench vise and get your burnisher.  I usually run the burnisher down the edge, holding it level with very light pressure. I then drop the handle side down ever so slightly and again lightly run it down the edge. I stop when I’m probably around 5 degrees, and it’s surprising at just how little pressure is required on these passes. If you’ve never tried it like this before, give it a shot with just the amount of hand pressure you might apply when shaving. Very light, as you don’t want to dig into your face/leg (men/ladies).

Below is a photo of the same piece of Walnut as in the second photo, which shows the shavings the card scraper produced after going through the full sharpening/burnishing techniques. Decent results after just a little bit of work!

It is also very surprising at just how a little burr does a better job and will last longer than if you create a large burr. Part of that is probably obvious when you think about it, as a thin piece of metal sticking further out is more likely to bend with similar forces.

I hope this helps anyone that has had trouble in the past or for those who have never tried a card scraper before. When you get used to doing the steps it’s usually not more than about 5 minutes to be back to making shavings. If you have trouble getting a cutting edge or keeping one, it may just be the card scraper isn’t of good quality, so just upgrade to a better one and you’re off to the races.

Thanks for checking out my blog and let me know if you have any questions or comments.

Lee

Lee Laird has enjoyed woodworking for over 20 years. He is retired from the U.S.P.S. You can email him at lee@lie-nielsen.com or follow him on Twitter at twitter.com/is9582

In the Down to Earth Woodworker’s most recent October 2013 Wood News column, he discussed the Dado Depth Torture Test, and in this follow-up blog entry, he has the results of his testing.

The Down To Earth Woodworker responds to a reader’s question, “Why do you make your dados 1/4” deep in 3/4” plywood?”

Pursuant to a reader’s question, I tested three dado depths (1/4”, 3/8” and 1/2”) in 3/4” plywood to see what depth provided the strongest joint in each of three potential force directions.

The test demonstrated that to some extent, it is all about the plywood.  So-called “furniture grade” plywood with few plies and many internal defects can fail in spectacular ways.  I suspect that the same tests in Baltic Birch or some other fine grade of multi-ply plywood might have turned out differently.  But “furniture grade” is the type of plywood most of us use for shop cabinets, kitchen cabinets, and bookshelves.

In the shear test, both the 3/8” and 1/2” depth dadoes failed as a result of a split in the plywood between the plies, starting at the dado wall.  The deeper dado weakened the plywood and the downward pressure on the test piece provided the leverage to split the plywood.  The 1/4” depth dado was the strongest.

In the tear test, the 3/8” dado was the strongest, with the 1/4” deep dado coming in a fairly close second.  I suspect that in this test the deeper dado helped… to a point.  As the dado got deeper, there was more gluing surface on the sidewalls of the dado.  But at 1/2”, the dado was simply too deep and the plywood surrounding the dado was weakened to the point that it overcame any advantage provided by the additional sidewall gluing surface.

In the pull test, as the dados got deeper the joint became weaker because there was not enough plywood behind the joint to hold it rigid.  The flexing in the weakened plywood allowed the sidewalls of the dado to give way, and the rest was, as they say, history.  Again, the 1/4” deep dado was the strongest.

Check out the video  below for more details!

This month I’m taking a closer look at Lie-Nielsen’s Mortising Chisels. While most woodworkers, and even many non-woodworkers, will quickly recognize a basic chisel like the bevel-edged style, the mortising chisel looks a little different. So what’s different about the mortising chisels compared to the bevel edged chisels that are more common? The shape of a Lie-Nielsen mortising chisel is somewhat rectangular, with the width less than the depth from the chisel’s back to its top surface. This creates a very strong chisel capable of handling the unusual stresses applied regularly to a mortising chisel. The mortising chisel is used to evacuate wood, while creating a rectangular void in a board, whose name likely isn’t much of a surprise, a mortise. This allows another board with a tenon of the same size on its end to fit precisely, creating a very strong and long lasting joint, the mortise and tenon joint. With this evacuation process, the mortising chisel is pounded (and I do mean pounded, at least after you get going) down vertically into the wood (a square is really useful to test the chisel is truly vertical) and then used to lever out the waste. Both the levering actions and the strong impulse driving are very tough on tools and a normal bevel-edged chisel would likely chip or possibly even snap under the stresses that are common for a mortise chisel. This is why the mortising chisel is made so stout.

The mortising chisel’s width can be used to determine the size of both the mortise and tenon. This is due to the tight tolerances required to create a proper fitting mortise and tenon joint. As you may have experienced, other woodworking techniques allow you to use chisels smaller in width than the final working area, and a smaller tool may work just as well or even better than one that precisely fits the opening. For example, when you are cleaning out the waste wood between the tails and pins on dovetails, you’ll almost always use a chisel that is narrower than the opening. Using a narrower chisel in this scenario is beneficial as a wider chisel requires more pressure to move through the wood, and this operation is one of surgical precision. This is certainly one example where it might be detrimental to use a chisel the same size as the opening. For a mortise and tenon joint, I find it much easier to obtain repeatable results using a mortising chisel that is the width of the final mortise (at least up to ½” or so), rather than trying to use a smaller mortising chisel, which would require multiple passes along the mortise’s width (for example, using a ¼” mortising chisel for a ½” mortise), and hoping to end up with the consistency in the mortise for a solid fit with a tenon.

The sides of mortising chisels come in two basic varieties: those with parallel sides and those where the sides are cut at angles, so the back of the chisel is slightly wider than the face of the chisel. The concept behind the angled sides is that you can twist the chisel slightly when it is down in the mortise to aid in removing it when it gets stuck. The Lie-Nielsen mortising chisels are designed and made with parallel sides, which I find much more useful and easier to control the direction and overall shape I’m evacuating. I’ve used both styles of mortising chisels and personally found the angled wall version felt like it occasionally had a mind of its own. What I mean is after lining it up with my intended direction it would still end up twisted slightly in the cut, and ultimately off line with my intended mortise. Obviously, the chisel shape can be a personal preference sort of thing, but I am absolutely sold on the parallel side version being the easiest and most accurate in use.

Lie-Nielsen’s mortising chisels are made from A-2 Tool Steel and have Maine harvested Hornbeam handles. The chisels have a socket design where the handle fits snugly into the socket with a friction fit. As the wood in the handle can move, it is always a good idea to pick the chisels up by the socket area, so your sharp tool doesn’t find its way to the hard floor. Usually a quick rap of the handle against your bench will seat the handle so it is nice and solid. Some prefer to use glue to make certain the handle never falls out, but there is another choice that is more middle-of-the-road: Hairspray! I know you’re probably thinking I’ve just lost it, but if you test it out you will find it is amazing what a little bit of hairspray will do to keep the handle in the chisel’s socket. And it isn’t so long-term like glue, as you can still give the handle a sharp smack sideways against a bench to remove it from the chisel.

Sharpening mortise chisels is very similar to other chisels with a caveat or two, but it ultimately works best when shaving sharp like all other woodworking chisels. Lie-Nielsen mortising chisels come with a 30 degree flat bevel to which I add a micro bevel of an additional 5 degrees. This both increases the strength of the tip of the chisel as well as allows you to rapidly hone to a razor-sharp edge. When honing these chisels, there are a number of choices of guides, of which I personally own three and I’ll share my thoughts on each. The side clamping honing guides are simple and can work, but I would make a quick test to verify it is holding and presenting the chisel both square and with no twist, before moving forward. If you already own one, place the chisel in the guide and apply clamping pressure, and with the bevel down on a 1000-grit stone, pull straight back away from the cutting edge once! Take a look at the bevel edge of the chisel and see if the micro bevel is reasonably equal across the width or if the edge might only be hitting on one corner. If the latter is the case, you may wish to look at my next honing guide suggestion. My personal side clamping honing guide provided surprisingly acceptable results.

While this guide worked decently, the narrow wheel does require some focus so you don’t accidentally take the chisel out of square. The guide in my collection that I prefer to use for these chisels is my Kell honing guide, which has vertical walls that clamp against the chisel and the parallel design of Lie-Nielsen’s mortising chisels allows for a nice solid connection, with very little chance to move away from square.

The last honing guide I own is one by Veritas, which clamps down on the back of the chisel, applying force straight down. I’ve had this honing guide for 20+ years, so it doesn’t have some of the bells and whistles of their newer versions, and in mine the chisel can shift away from square if I’m not extremely meticulous.

No matter what honing guide you decide to use, whether purchased or made, taking a single pass on the bevel side, on your most coarse stone, is useful to verify everything is good. I tend to do this regularly, rather than forging ahead, removing a decent amount of material, only to find my micro bevel huge on one side and barely touched on the opposite. Why waste time and then spend more in recovery mode, when its so quick and easy to verify before moving forward?

While I’ve talked about the bevel side of these chisels, as if it was the only portion of the tool requiring attention, this is certainly not the case. I always hone the backs of my chisels up through 8000-grit, too. It is important to remember that the definition of a sharp edge is two equally honed surfaces meeting at as close to zero radius as you can obtain. If you decide to omit honing the back, since it arrives looking nice and smooth, just remember this will limit the ultimate sharpness of your chisel.

When creating a mortise and tenon, based on the size of the mortising chisel, I always start out with the mortise. I scribe the two end positions of what will be the mortise, as well as mark for one side. There is really no reason to mark the opposite side of the mortise, as the chisel will ultimately remove the material from the mark to its full width. The first few passes with the chisel, you’ll apply a much lighter blow with the mallet, so you can really focus on the placement of the chisel and keeping it as dead vertical as possible. You’ll also stay away from the very ends of the mortise layout, which you save until the remaining mortise is at full depth, since you end up using this portion to leverage up chips from the bottom. After the beginning passes, the walls of the mortise will start to give the chisel support, helping to maintain the vertical nature you worked so diligently to establish early on. Just make sure to keep your focus, so you strike straight down with the mallet and only lever in the straight forward and back. When laying out the tenon, I use a mortising gauge (some have two pins or blades, that are adjustable, while others are of set widths), which I set to the width of the mortising chisel. When setting this gauge, I’ll lean towards being just slightly thick rather than possibly thin, as I can more easily rasp away a little material rather than trying to add some back on. A good fitting mortise and tenon will go together without pounding, but just a gentle push. You want to have a solid fit, but need enough room for the glue in the joint, too. One thing to remember when using the mortising gauge is to mark which face of the board the fence will ride against. As many mortises are not dead center on the board, but slightly offset, so marking from the wrong face could end up with wasted materials or at least extra work. The board(s) that will have a tenon(s) should also get marked for orientation (which face out and also which tenon goes with which mortise) so the fence of the mortising gauge again is against the correct side.

Lie-Nielsen makes their mortising chisels for joinery in a range of sizes from 3/16” to 1/2”, as well as the 1/10″ size, generally used for making traditional European wooden woodworking planes. If you want to make extremely small scale pieces, or just want to have an area of small components in a full-sized piece, you could utilize this smaller chisel in that manner.

I believe all woodworkers should at minimum make a mortise and tenon frame with hand tools, as the focus and skills required can easily carry over on a range of future builds.  You may just find you prefer creating your mortise and tenon joints by hand, rather than using your power tools/machines.

I hope you enjoyed the article and please let me know if you have any questions or comments.

CLICK HERE to return to the September 2015 issue of Wood News Online.

Lee Laird has enjoyed woodworking for over 20 years. He is retired from the U.S.P.S. You can email him at lee@lie-nielsen.com or follow him on Twitter at twitter.com/is9582