Archive for the Category ◊ Techniques ◊

Author:
• Sunday, February 23rd, 2020
levelling table legs

In theory, the bottom tips of all four legs of a table should be in the same plane so it can sit on a flat floor without wobbling. Remember, however, the words of Yogi Berra, “In theory, there is no difference between theory and practice. In practice, there is.”

Now, if you made uniform leg lengths and mortise-and-tenon positions, you should have a flat base after assembly that requires no adjustment but stealth gremlins almost always prevent such perfection. 

On the other hand, consider that rarely is a floor flat over the area on which the table stands, so making the four legs true is really just playing the odds. Furthermore, a table, especially a large one, may flex when you place it on the floor to produce an automatic correction. The same goes for chairs. Therefore, all of this is often of no concern at all – in practice. 

For a small table though, this issue may be a significant concern. The small area of floor on which it stands may indeed be flat, the table may not flex much, and it feels creepy when it wobbles a lot. So, let’s look at how to assess this. 

It is best to do this with the top attached in its final configuration, which contains any flex in the frame induced by the top piece.

The simplest method is to put the small table on a true flat surface such as the table saw. If such as surface is not available, you can turn the table upside down and use winding sticks on the tips of the legs. Note that this may introduce error if the frame of a larger table flexes a bit differently than when it is right side up. In any case, for a larger table, I do not go hunting for a very flat floor, which probably does not exist; I just do not worry about the whole matter.

For small tables, I do like to get it pretty close. You can take off the error from the one long leg, as determined by how the table pivots on the flat reference surface, but I prefer to take off half that amount from each of the two long legs.

OK, if you have done everything just right in the shop and now place the table on the floor where it will live, which is not likely to be flat, and it wobbles enough to be annoying, what do you do? Shim it. A layer or two or more of tape such as duct tape is just fine – in theory and in practice.

Category: Techniques  | 4 Comments
Author:
• Saturday, January 18th, 2020
cross-rail joint finished

Dry fit the joint with just two dowels. Using all five dowels makes it remarkably difficult to disassemble. However, check every one of the long grain holes to make sure it is full depth so you don’t get a surprise when finally closing the glued-up joint.

I find it less stressful to glue up in two stages. I apply glue in the holes, and then tap in the dowels in one of the tongued components. I limit the depth of the dowels with a registration block. When this subassembly has dried enough to keep the dowels stable, I complete the glue up by applying glue to the other set of holes, plus a little bit on the dadoed piece, and then push the whole thing together. 

This joint must be clamped from the ends. I have found it strongly tends to stay accurately square but, of course, I check it anyway, and adjust the clamps as needed.

When the glue is dried and conditioned, I plane flush the outer edges. If made accurately, which is very likely if the dowel jig was made accurately, this joint will turn out neat and strong, and it will stay that way.

Much of the work in making this joint is in making the dowel jig, which is reusable for a joint of the same or less width. The joint also works with large width rails because there is no conflict from dimensional change due to moisture cycling.

This has been a good joint to have in my repertoire. You might want to give it a try.

Category: Techniques  | Tags:  | 2 Comments
Author:
• Monday, January 13th, 2020
drilling setup for cross-rail joint

Drilling the holes for the cross-rail joint is easy as long as you keep track of reference points and orientations.

First, attach the jig to the first side of the joint. Use the reference cleat to set the jig in place in the dado, and clamp it there. Pass a snug fitting transfer punch or brad-point drill bit through the fixation holes to make dimples in the floor of the dado. This creates reliable centered marks to drill minimal-depth pilot holes for the screws. Screw in the fixation screws, which only project about 1/4″ into the workpiece, and then remove the clamps.

With the jig now securely in place in the dado, you can prepare to drill the dowel holes. I have found no good way to accurately secure the jig onto the end of the tongued piece, so it is best to insert and clamp the tongued piece in the dado on the opposite side of the dowel jig in the orientation it will be when the joint is assembled. Thus, the holes will be drilled, guided by the jig, through the dadoed piece and into the tongued piece, all in one step.

The photo above shows the setup in the vise. Note the support block that helps keep the components at 90°. 

For drilling the holes in the joint, I use a hand-held electric drill and a DeWalt Pilot Point bit. Well made, its diameter is a good match to the high quality brad-point bit that I used to make clean holes across the grain in the jig. The DeWalt produces a little tearout drilling cross grain in the dadoed piece but that will not be seen and does not matter structurally. More important, it advances strongly through the long grain of the tongued piece, where a brad-point bit (essentially a cross-cut device) tends to bog down and burn. 

A good drill stop is a must for this work. I do not like any commercially available stops, and so I use shop-made stops (described here), which have never let me down. When working out the drilling depth, remember to take into account the jig and the dadoed workpiece. I drill 1/16″ – 1/8″ extra deep into the tongued piece to allow for excess glue. 

This is the joint so far:

cross-rail joint

Once you have finished drilling from the first side of the joint, detach the jig and reattach it to the dado on the “second” side of the joint. The cleat stays against the same edge of the dadoed piece but the opposite drilled face of the jig sits on the floor of the dado on the second side. The second tongued piece is set into proper orientation in its dado and the setup is clamped and registered the same as for the first side of the joint. 

For this second round of drilling, the holes in the dadoed piece already exist, so you are just going through them directly into the long grain of the tongued piece.

Here is a reminder of what we are trying to produce:

cross-rail joint

This is more difficult to describe than to do. This method ensures that all the components are drilled in the actual position they will be in the final joint. And that is why the dowel jig is made to be useable from both sides. 

Next: assembly and completion.

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Author:
• Sunday, January 12th, 2020
dowel jig for cross-rail joint

The dowel jig for this joint is simple but it must be accurate. Use a fine-grained, very hard wood. I used some of my old stock of bubinga, one inch thick. The width of the jig must fit snugly into the dado, 5/8″ in this case. A little extra length helps in handling the jig.  

Make sure: all faces are flat and straight, the width and thickness are uniform over the full length, and adjacent faces are dead square to each other. Most woodworkers will use a table saw to make this little block of wood, as I did. Please be cautious working such little pieces, and make use of an appropriate work handling device. I like the GRR-Ripper for such work. It’s worth it. 

Use a good brad-point bit to drill the 3/8″ holes. The drill press must be set up to drill true at 90° because the jig will be used from both drilled faces. If the holes or the body of the jig is out of square, the joint will be inaccurate and difficult or impossible to assemble. 

The spacing of the holes is not critical but leave enough room for pass holes, countersunk at both ends, for two #6 x 1 1/4″ fixation screws. Attach a cleat with little screws at the end of the jig. It extends about 3/8″ beyond each drilled face, and will reference it to the edge of the workpiece. 

This is how the dowel jig will sit in the dado:

dowel jig for cross-rail joint

Next: using the jig.

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Author:
• Wednesday, January 01st, 2020
cross-rail joint

Here’s how to make the joint described in the previous post.

The joint starts with back-to-back dados. These must be precisely aligned because the dowels that extend across the joint will afford virtually no wiggle room when the tongues enter the dados. I didn’t take a photo of the dados before I drilled the holes but you get the idea.

For the 7/8″-thick stock used here, the dados are 5/8″ wide and 1/8″ deep. This leaves a 5/8″-thick web through which the holes will be drilled. Since the 3/8″-diameter dowels are 2″ long, there will be 11/16″ of dowel length to penetrate the long grain of each of the two tongued components.

For a 1/2″ dado, I would use 5/16″-diameter dowels to leave enough meat around the dowels in the tongued components. 

How you make the dados is up to you, but accurate stock preparation is important for all methods. Handwork is doable: knife the lines, square them around to the other side, saw, chop the waste, pare the walls, and router plane the floor.

For machine methods you will be referencing from both long edges, so they must be exactly parallel. I used a 5/8″ downshear router bit, and a sled to move the work across my router table. A dado blade in the table saw would also work.

I used the same router bit and the router table to make the tongue in the other two components, sneaking up on the length and width to get a tight fit. If you make the tongue too long, or later reduce the depth of the dado with finish planing, it is easy to correct this by shooting off the excess tongue length. Just make sure the tongues are not too long (it’s a one-sided tolerance), which would prevent the shoulders from meeting neatly. 

So, now that we have the double dado joint, we are going to bind the whole thing together with dowels. Note that the glue surfaces in the tongued components are long grain-to-long grain. That, plus the multiple mechanical locks make this a very strong joint. Here is “half” of the joint:

cross-rail joint

Next: Making and using a simple dowel jig to make precisely aligned holes in all the components.

Category: Techniques  | Tags:  | 2 Comments
Author:
• Tuesday, December 17th, 2019
cross-rail joint

For rails that cross over their widths, this joint is very doable, strong, and neat. It has several advantages over other options for this situation. (Note this is distinct from rails crossing over their thicknesses, face to face, where the familiar half-lap is a good choice.)

Let’s take a look.

Each crossing member has strength distributed over nearly its full width, and there is no unsupported portion of the width. Furthermore, there is mechanical resistance to twisting in all directions. This is superior to a cross-halving (or “cross-lap”) joint, which is just a vertically oriented half-lap.

This is a strong joint with substantial long grain-to-long grain glue surface – more than 8 square inches. Note that the five dowels are long and continuous from one side to the other side of the joint. Cross-halving joints yield minimal long grain apposition.

It is much easier to conceptualize and execute this joint the than refined but elaborate cross-halving designs that involve stepped notches, sliding double-dovetails, or tapered notches. They make my head hurt. 

For an enduring neat appearance as well as strength, the pieces entering the dado have outside shoulders. This differs from some versions of the cross-halving joint that are designed to correct the problem of unsupported width, and involve a dado that houses the full width of the entering piece, which can leave gaps when the housed member shrinks in thickness.

cross-rail joint finished

Woodworkers of all stripes will be pleased to know that this joint can be executed by hand, by machine, or a combination of both. In fact, you will see that a single shop-made jig can be easily adapted for use with various workpiece thicknesses and even various widths. 

Full disclosure: a disadvantage is that it must be clamped from the ends. This could be awkward for very long pieces, though that is not a likely application. 

Next: How to make it. As with all woodworking, it’s a matter of being accurate when it counts.

Category: Techniques  | Tags:  | 4 Comments
Author:
• Sunday, December 15th, 2019
dovetail markers

Here are the dovetail angles that I use. There is more than one good way to do almost everything in woodworking, and there are many situational exceptions, so these are not absolute. I do, however, know that they work. For the most part, they conform to what is usually written and taught, but here I also offer explanations for the various options.

My go-to angle for through dovetails in most hardwoods is 7:1 (8.1°), such as for a carcase or box in cherry, maple, or walnut with stock thickness of 9/16″-13/16″. It has enough angle to form a strong mechanical lock but not too much to produce fragile tail corners or overly fussy fitting. Vulnerable tail corners can be annoying in the making stage even though they are shielded after assembly. 

carcase dovetails

For more brittle, harder woods such as the curly oak shown below, I prefer 8:1 (7.1°). This helps to prevent chipping at the corners of the tails but still provides enough mechanical lock because the wood is less compressible. For the ovangkol small chest shown in the second photo below, I used 7:1 but the wood proved to be harder and more brittle than I first thought, so maybe I should have used 8:1.

red oak dovetails
ovangkol dovetails

For softer, more compressible woods such as pine or aspen, 6:1 (9.5°) works well. The steeper angle produces more mechanical lock, and chipping is not a concern.

Half-blind dovetails are a different matter. The shorter length of the tails usually requires a little more slope to create a good mechanical lock. 5:1 (11.3°) works well in most cases. It also just looks right to my eye. This study drawer with poplar sides and pear front that I keep in my shop is a good example. Using a harder wood for the sides and/or a thicker front (longer tails), I would consider 6:1, ultimately going with what looks right.

half-blind dovetails

Through dovetails in thin stock deserve similar consideration. Very generally, for thin pin stock (shorter tails) consider using a bit more slope than for similar circumstances in thick stock.

Interestingly, in all of this, the mechanics and the aesthetics seem to dictate the same answer, and not, I think, by coincidence. 

I have been using the shop-made bubinga markers shown in the photo at the top for many years. Unlike most commercially produced markers, they allow you to mark the entire length of the line on the face grain and end grain with one positioning. I detailed their construction in an article in Popular Woodworking, November 2009, issue #179.

Category: Techniques  | 5 Comments
Author:
• Sunday, December 01st, 2019
shooting tips

Another question from a reader: “My trouble in shooting is (I guess) in advancing the wood.  I often find myself in a situation where I’m feel like I’m pushing the wood very firmly against the toe of the plane and still not getting any bite from the blade.  This problem seems to come and go and I have yet to diagnose what I’m doing wrong.”

There are at least two possible reasons for this.

1. The blade may not be sharp enough, causing it to skid on the wood rather than cut it. The whole system (workpiece, plane travel, blade edge) may be deflecting, preventing the blade edge from engaging the wood. 

Of course, end grain is harder to cut than long grain. Paring end grain is how many woodworkers test an edge. However, there is another reason why sharpness is so critical that is peculiar to shooting. 

Planing in the usual manner with a bench plane, we intuitively sense that we can extend the working life of a gradually dulling edge by pressing down harder with the plane. Related to this, we find that it is necessary to advance the blade further (depth of cut adjustment) to get it to take the same shavings as when it was sharper, though with more effort. Eventually, we head back to the sharpening bench.  

Brent Beach offers a technical discussion relevant to this. The basic idea is that the extremely narrow lower wear bevel in a sharp blade has less area against the wood, and so is able to generate more pressure (force per unit area) on the wood than does a dull blade with a wider lower wear bevel. The sharp blade compresses the wood and bites into it.       

In shooting, the plane does not ride on the wood, it rides on the edge of the track, and so you cannot regulate the edge pressure against the wood as you can with ordinary planing. The blade has to be sharp enough to cut without your “help,” so to speak. Actually, I have found myself intuitively trying to shove the workpiece toward the plane as the blade dulls, but that is awkward at best, and tends to produce inaccuracies.  

Furthermore, end grain is less compressible than side grain. 

2. Another possibility is that the fence is set slightly greater than 90°. This will cause the workpiece to register against the sole of the plane near the fence but not reach the sole where the cut begins. It only takes, say, a couple thou of error for this to happen. Furthermore, as an insufficiently sharp blade moves along to eventually meet the workpiece, it might push it away rather than cutting into it. (This is another example of the general principle that a tool, hand or power, given the opportunity, will move the workpiece instead of cutting it, and/or move the tool itself.)

The shooting board fence may start out dead-on at 90°, but if it is not very firmly set, it is easy for it to eventually get pushed to greater than 90° because that is the direction of your force on it in use. 

In summary:

1. Sharp – wicked sharp – is a must for shooting!

2. The shooting setup has to be not only statically accurate, but also dynamically stable in use.

Category: Jigs and Fixtures, Techniques  | Tags:  | 4 Comments
Author:
• Sunday, November 24th, 2019
shooting board

A reader described the following frustration he is experiencing with end grain shooting.

“I have a problem getting perfectly square ends when shooting them on my shooting board.

“I have a homemade plywood shooting board and use a Record 5 1/2 on its side to shoot. I’ve checked everything, and everything is square to each other and the plane is sharp, however when shooting end grain the plane takes more off the near edge (closer to the front) than the back edge. 

“Am I doing something wrong?”

If you are getting this inaccuracy despite having everything set up square and true, the glitch may be in the shooting stroke itself. The blade can grab the workpiece on initial contact and slightly pivot it away from the fence at the opposite end. This can easily happen with wide workpieces. 

But first let’s check a few things with your set up.

The sole of the plane should be flat, at least in the critical areas. Use a very wicked sharp blade with a straight, not cambered, edge, and a fine, even blade projection.

The track edge that the sole of the plane runs against in the shooting board must be straight. Ideally, the shooting board should have a snug channel in which the plane travels to prevent it from deviating during its run. (This will not work with a bench plane with a rounded side hump but not as well as with a dedicated shooter.) Wax the channel and/or use UHMW plastic on the running surface. If your shooting board does not have such a channel, take extra care to hold the plane firmly (without tipping it) against the running edge throughout the shooting stroke. 

The fence must be straight, of course. The best way to square the fence is to place the sole of the plane (with the blade retracted) firmly against the track edge, then place a square against the sole of the plane and the fence. This directly assesses the elements that produce the square edge on the workpiece. The fence has to tolerate considerable pressure in use, so make sure it is fastened securely.

The fence also has to be long enough to register an adequate length of the workpiece so the workpiece does not budge during the planing stroke. I sometimes had problems with my old shooting board that had a fence that was too short. My current shooting board’s fence is 11 1/4″ long. Books often show shooting boards with a fence that is too short for furniture work. 

A grippy glove on the hand holding the wood is a huge help in keeping the workpiece steadily registered and in advancing it after each cut. Otherwise, inaccurate registration can creep in, especially with wide workpieces, and especially as you fatigue. As a diagnostic experiment, try positioning a workpiece just right, then clamping it in place, shoot, and see if you get a square edge. 

In summary, your shooting “machine” must be set up accurately, but also must be dynamically stable in use.

Mystery frustrations like this reader is experiencing afflict all of us woodworkers but are rarely addressed in books and other teaching media where the descriptions are often idealized. Rest assured, however, there are solutions. 

I hope this helps, dear reader, but if you are still stymied, let me know. We’ll get it right.

Category: Jigs and Fixtures, Techniques  | Tags:  | 13 Comments
Author:
• Thursday, November 21st, 2019
Veritas shooting plane

Shooting is a gateway skill to precise hand tool woodworking. So get started by shooting with the planes you have. 

The basic requirements are:

  • Mass. You want substantial momentum to firmly and steadily carry the blade through the cut after you get it started, especially for end grain shooting. 
  • The side of the plane should be square to the sole. If you only have a not-so-great plane, use tape to shim the side. I did this with my old Record jack plane when it was the only one I had. [Please see in the Comments section reader Michael’s germane point and my lengthy reply for more details on the squareness issue.]
  • It helps a lot to have a comfortable, secure grip to consistently apply pressure where it is needed. Dedicated shooting planes have this feature. 
  • The blade must be sharp. Sharp! A dull blade is not only harder to push through the cut, but accuracy will suffer as the plane and the blade itself deviate from a true path. 

For end grain shooting:

Best: a dedicated shooting plane. 

Veritas shooting plane

I use the Veritas shooting plane, and love it. Comfortable and accurate to use, it meets all the requirements above. The adjustable-angle handle properly and comfortably directs pressure, and the 20° skew really eases the blade through the cut. The bevel-up design is easy to set up and adjust, and provides excellent support to the blade close to its edge.

Is it worth spending about $350 dollars on a plane just for shooting? In view of all the other expenses involved in woodworking, yes, it is. (See the first sentence of this post.)

Lie-Nielsen also makes a great shooting plane, which I have had a chance to use briefly. This massive tool uses a bevel-down design and a skewed, Bedrock-style adjustable frog. Personally, I like the Veritas design and features, but both merit consideration. 

I use a straight edge blade for end grain shooting – no camber

Good: a bevel-up bench plane. 

Veritas jack plane

The Veritas BU jack plane is perhaps the most versatile plane of all, and a good shooter. The BU design gives good blade support, and makes it easy to swap dedicated blades for its varied uses. You can get a decent grip on this plane for shooting.

Adequate: a bevel-down bench plane. 

I used a BD jack and jointer for shooting for years. I do not consider these ideal but they can get the job done. Don’t let anyone tell you that you “can’t” cut end grain with a bevel-down plane. Use a sharp blade, and set the chipbreaker close to the edge to reduce deflection.

bevel-down jointer and jack planes

Gripping a bevel-down bench plane for shooting may be a bit awkward for some. With the jack, I squish the base of my thumb behind the side hump and plant four fingers on the lever cap. A grippy glove can help. (So then you’ll have one on both hands.) 

For long grain shooting:

Compared to using a plane with the blade on the bottom (the “regular” way) this is just a matter of different manual mechanics. The plane is not running in a track as in end grain shooting. 

So, a BU or BD bench plane is fine, as long as it has decent mass and stability, the side is square to the sole, and you can get a decent grip. And . . . the blade is sharp.

I like my Lie-Nielsen #9 “iron miter plane,” which I’ve dedicated to long grain shooting, because its beefy, boxy design makes it stable through the stroke, and it handles exceptionally well with the “hot dog” grip. This is a bevel-up design with a 20° bed. (Hmm . . . ) Unfortunately, I don’t see it on their website any more. Veritas sells a somewhat similar plane. 

Lie-Nielsen #9

I keep the #9 set up with a straight edge blade, mostly because it is easier to maintain and works well for the thin stock that I’m usually using when long grain shooting. A mild camber, such as for a jointer plane, is also a good option, especially if you will be long grain shooting thicker stock, or if you are also using the same plane and blade for general tasks.