Photo: Mario Rodriguez Mario Rodriguez covers the essentials for choosing the best joints for your project. Smooth, accurately mated, grain-slope matched surfaces and good adhesive penetration are necessary (see scarf slope The bottom image shows the layout for a squinted scarf joint, which avoids the feathered ends of a through slope; the squint is cut at an angle so that the butted areas are not solely end grain; however, a squinted joint is unlikely to be applicable in an airframe primary structure.
In addition to the previously mentioned specific requirements, it is recommended that the number of scarf joints be limited as much as possible; the location be limited to the particular portion of a member where margins of safety are most adequate and stress concentrations are not serious; and special care be exercised to employ good technique in all the preparatory gluing, and pressing operations.
Your problem with plainer snipe can allmost be none if you make sure your infeed and out feed tables are leval and if you can adjust your in and outfeed roller pressure just a little bit so you can release some of that downward pressure on your wood one more thing you must make sure all your plainer blades are ajusted so that they are at the persistly cutting at the same depth as all three and don’t have them cutting to deeply or you will have someing new to deal with.
The surface area bonded is minimal and the joint is very weak, so the normal practice is to bond a piece of the same dimension material centred over the butt joint or plywood strengthening plates over opposing faces; much the same as the lap joint above. These joints are typically used for expensive drawer construction, where a solid drawer front is required and only the sides of the joint are visible.
Half laps are used for frame construction and while not strong do increase the glue line(area of glue)and give an oportunity to add a screw or pin to reinforce the joint. The miter joint has two signal advantages over a butt-corner joint: First, no end grain shows, making for a more regular and attractive joint; second, the surface for gluing is increased. This is why corners are also often joined together using tongue and groove joints. The joints mentioned are some of the most common ones used in the woodworking industry. The dovetail joint is one of the most beautiful and frequently sought after joints in furniture and cabinet making.
These joints attach members along an edge to form a corner, in 3-axis joinery, usually a right-angle. Although you are going end grain to long grain the same idea applies – glue is as strong as the wood in most cases, but this refers to long grain gluing, not what you are describing. But even if only nails or screws are used, snug-fitting joints will still be much stronger.
The way to avoid fuzzy wood is to make sure you don’t sand with a paper finer than 150 grit. The natural development of a rebate is a groove, as shown here in a spline joint, which uses a separate strip of wood (the loose spline) to join two pieces of stock via a groove in each. If necessary, scarf joint splicing can be used to obtain the necessary length of clear, straight-grained timber. Let it dry for a few hours and you have a wood panel that is stronger than a single piece of wood of the same width.
Depending on how tightly the notches are cut, you may not need more than a small amount of wood glue to hold them together. As an example, wood is very strong along the grain but against the grain, however, it will easily break. This is used where pieces of wood are to be joined with the flat or wide sides overlapping so as to form an ”L” or a ”T” as shown here. The addition of glue will add some strength, but the joint relies primarily upon its mechanical fixings.