Archive for ◊ March, 2021 ◊

Author:
• Friday, March 19th, 2021
pre-threading good

This is just one of those simple little matters that somehow seems to go unattended.

A small solid brass hardware screw, such as a #4, is not very strong and can be easily torqued past its breaking point, leading to all sorts of profanity filling the air of even the most peaceful woodshop. A commonly recommended way to avoid this frustration is to pre-thread the pilot hole with a steel screw, which is stronger.

The steel screw should have the same thread pitch as the brass screw for which it is preparing the way. Otherwise, the preparatory threads will be misplaced and so the brass screw will have to cut most of its own threads anyway. The two sets of misaligned threads may partially merge and probably weaken the wall of the hole in a situation where you want all the holding power you can get.

In the photo above, the steel and (antique finished) solid brass screw threads correspond perfectly. (It is difficult to photograph this in position so please take my word for it.)

Below, the steel screw is a slightly finer pitch and so will cut threads out of sync with the (antique finished) solid brass screw threads. Yes, they are close but that’s just the problem. Not only does this defeat the purpose of the preparatory threading but I think this will also weaken the wood wall and reduce holding power. 

pre-threading no good

A maker of one the best, if not the best, quality hinges supplies such incorrect steel screws with their brass screws. So, beware and check for yourself. 

OK, what if you cannot find a proper steel screw in your Miscellaneous stash? Not a big deal. I find that with proper care, the brass screws hold up well. The key is to first test the screw procedures in scrap wood. 

With or without preparatory threading, there is a good chance you will find you have to use a pilot hole that is slightly greater than the root diameter of the brass screw. (The little steel screws can break too!) I also enlarge the upper part of the pilot hole with my Czeck Edge awl to accommodate the unthreaded portion of the screw. It also helps greatly to dab a bit of wax or Slipit into the pilot hole using a sliver of wood (better than on the screw itself) to reduce the torque required to seat the screw. I do not think this reduces holding power. 

Part of good craftsmanship is preventing little matters from becoming big headaches.

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Author:
• Friday, March 19th, 2021
pin the panel

This is a simple, reliable way to keep the floating panel centered in a frame-and-panel construction. Without anything to keep it centered, a panel usually shifts to one side because one groove grips it a bit more than the others during seasonal movement. This leaves the field and the gap around it off center, which looks less neat.

In fact, this is the only way I ever do this. I like that there is no need to deal with any extra procedure during glue up such as inserting Space Balls or placing a dab of glue in just the right spot to keep the panel laterally centered. Because there is virtually no movement along the grain, only minimal clearance is needed in the grooves in the rails, so the vertical position of the panel is essentially constant.

When the clamps are off and the glue set, carefully center the panel laterally, and mark each rail at its midpoint between the stiles. The 3/4″ 18-gauge brass brads (Hillman item #123743) are 0.051″ in diameter, so drill a pilot hole with a 3/64″ or #56 wire gauge drill bit, which are about 0.004″ less than 0.051″. Drill from the back side and stop safely short of the front surface. Place the hole near the edge of the frame and within the tongue of the panel. 

Gently tap in the brass brad. You may want to nip off the point first to get a bit better purchase in the front side of the rail. When it is seated, nip off the excess with flush cutting wire cutters, and file away any remaining protrusion. Of course, pin the panel in the top and bottom rails.

That was easy.

Category: Techniques  | One Comment
Author:
• Monday, March 08th, 2021
sharpness for accurate work

When considering the benefits of beautifully sharp tools, what usually comes to mind is a smoothing plane producing a cosmetically flawless surface on the wood. This is often the impressive conclusion of a sharpening demonstration.  

Sometimes it is the joyful ease of pushing a sharp blade through the wood that compels us to accept our sharpening chores.  

No question, these are important reasons to hit the stones. However, I suggest that the foremost and most common reason to use a sharp tool is to be able to work accurately. I’m guessing that may not be what you usually have in mind when you go to the sharpening bench, but consider this: you pretty much always want to work accurately when you pick up an edge tool. You assume that.

It’s simple: a sharp tool immediately cuts the wood, and cuts just where you want. (And in small increments if needed!) The result equals the intention.

A dull edge is more likely to be diverted by the fiber structure of the wood, or tear the wood before it cuts it. Forcing a dull tool can cause you to overshoot or just miss the mark. Of course, all of these problems and others reduce accuracy.

Here are a few examples. The final shavings with the jointer plane to produce an edge-to-edge joint must be easy, thin, and precise to produce that square edge with a tiny camber. Just a very few thou matter, and if your blade cannot easily pull thin shavings, you cannot dial in that accuracy.

Similarly, trying to shoot an accurate end grain edge with a dull blade is like trying to produce calligraphy with a crayon. 

Consider paring a hinge mortise or a tenon cheek. You intuitively know that you want a sharp edge. Less obvious, consider chopping to the baselines of dovetails. You know the dull chisel is slower but think about that first entry where you want to avoid push back against the gauge line. Accuracy requires sharpness.

The same goes for sawing. Sure, the sharp saw is faster but most important, it is accurate.

And so forth. 

Working wood is way more fun than working tool steel (aka sharpening), so we need a darned good reason to get over to the sharpening bench. The foremost and most common reason is to work wood accurately.

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