The Importance of Making Joints for Building Wooden Playhouses
You cannot get far in building a playhouse without making joints. Some of the simplest assemblies may involve no more than putting one piece of wood over another and gluing, nailing, or possibly bolting the two pieces together. It’s not just wooden playhouses as furniture, boats, and houses all require joints.
There have been joints ever since man started using wood as a construction material. Properly made joints were used before the birth of Jesus Christ, and there must have been cruder ways of joining wood parts long before that time.
In fact, many of today’s joints also were utilized several thousands of years back. Of course they were rather rough-looking, but still the same when it comes to functionality. Precision depends both on the craftsman and the quality of his tools.
Probably the joint with the longest history is the mortise and tenon. The idea of a projection on one part going into a socket in another part must have occurred to many early craftsmen. The ways in which the joint has developed are detailed here.
Wood is not the most durable material, and some woods have a short life. Some oaks and other hardwoods may have a long life as can be seen by church furnishings in many European countries, where joints can be found that would be made in a similar way by craftsmen today.
In fact, many of today’s joints also were utilized several thousands of years back. Of course they were rather rough-looking, but still the same when it comes to functionality. Precision depends both on the craftsman and the quality of his tools.
Probably the joint with the longest history is the mortise and tenon. The idea of a projection on one part going into a socket in another part must have occurred to many early craftsmen. The ways in which the joint has developed are detailed here.
Wood is not the most durable material, and some woods have a short life. Some oaks and other hardwoods may have a long life as can be seen by church furnishings in many European countries, where joints can be found that would be made in a similar way by craftsmen today.
Joints
Ever since man started using wood as a construction material, he has had to develop ways of joining one part to another. At first he may have merely levered parts against each other while they were pushed into the ground. As he began to make simple tools, he managed to cut parts from one piece to take another part.
Joints may provide a mechanical lock between the parts of a playhouse, so they will not pull apart—at least in one direction. They may be arranged to provide surfaces for gluing better than if the parts had been laid on each other
Joints may provide a mechanical lock between the parts of a playhouse, so they will not pull apart—at least in one direction. They may be arranged to provide surfaces for gluing better than if the parts had been laid on each other
Mechanical Strength
Mechanical locking joints came first as glues were not trustworthy until very recent times. A common method of locking is a pin through. This is seen in timber-framed buildings, where mortise and tenon joints form most of the connections.
There are holes drilled across the parts so a pin may be driven through. In a modem joint the pin might be a piece of dowel rod, but in old houses the drill used was not efficient. The hole might even have been made by burning through with a hot iron rod.
Into this went a roughly rounded and tapered peg that held by friction and was usually left with its end projecting, so it could be driven further if the parts loosened. A more recent development uses the peg to tighten the joint.
The hole in the tenon is made slightly nearer the shoulder than in the mortised part, then a tapered peg driven in draws the tenon further into its mortise. Another way of mechanically locking a joint is with wedges. A wedge may go alongside a part to increase its tightness, but it is more effective if it spreads the wood to prevent withdrawal.
This is usually done by driving one or more wedges into the cut end. If a mortise is cut tapered, the wedges then spread the end of the tenon so it is too wide to pull back. In old construction these joints can be seen with ends and wedges projecting slightly, so there is surplus length available for driving the wedges further if needed.
There are holes drilled across the parts so a pin may be driven through. In a modem joint the pin might be a piece of dowel rod, but in old houses the drill used was not efficient. The hole might even have been made by burning through with a hot iron rod.
Into this went a roughly rounded and tapered peg that held by friction and was usually left with its end projecting, so it could be driven further if the parts loosened. A more recent development uses the peg to tighten the joint.
The hole in the tenon is made slightly nearer the shoulder than in the mortised part, then a tapered peg driven in draws the tenon further into its mortise. Another way of mechanically locking a joint is with wedges. A wedge may go alongside a part to increase its tightness, but it is more effective if it spreads the wood to prevent withdrawal.
This is usually done by driving one or more wedges into the cut end. If a mortise is cut tapered, the wedges then spread the end of the tenon so it is too wide to pull back. In old construction these joints can be seen with ends and wedges projecting slightly, so there is surplus length available for driving the wedges further if needed.
Shrink Fits
Another way of tightening mechanically uses the moisture in the wood. Newly cut wood contains a considerable amount of sap. Seasoning dries most of this out, but there is always a small amount of moisture present in prepared wood.
Wood tends to absorb and give out moisture according to the amount in the atmosphere. As wood is seasoned and the amount of moisture is reduced, the wood shrinks. In some woods the amount of shrinkage is considerable.
If anything is made from green wood, it will be less in width and thickness in a few months. Shrinkage in the length is not significant. Green wood is newly cut and unseasoned wood; it is not green in color.
Wood tends to absorb and give out moisture according to the amount in the atmosphere. As wood is seasoned and the amount of moisture is reduced, the wood shrinks. In some woods the amount of shrinkage is considerable.
If anything is made from green wood, it will be less in width and thickness in a few months. Shrinkage in the length is not significant. Green wood is newly cut and unseasoned wood; it is not green in color.
If a hole is drilled in green wood, it will become smaller as the wood dries out. This property was used in chair making, where the size of a joint might be small and all the strength possible was needed. The legs and back might have been made from green wood, but the rails were seasoned wood. If the rail end was driven into a hole in the leg, the leg would shrink and tighten the hole on the rail end.
This property could also be used with seasoned wood parts. The small amount of moisture in the rail end was dried out in an oven, and then the parts driven together, so subsequent taking up of moisture in the rail would expand it slightly in the hole.
Doing this and using an unseasoned leg combined the effect. There was a risk of splitting, and unseasoned wood cannot be relied on to remain true. It may have warped or twisted as it dried out, so sometimes a poorly shaped children’s playhouse was produced.
Expansion and contraction due to moisture are also associated with wedges. If a wedge is dried out in an oven just before driving, it can be expected to thicken a little as it takes up moisture again and thus becomes tighter.
Improved accuracy and tools came about and that’s when craftsmen of old founded the eye-pleasing dovetail principle. This is a joint that’s not only easy on the eye; it is also highly functional due to its slight taper that can’t be pulled apart in a single direction. Examples, shown throughout this website, range from single tails on the ends of strips to multiple joints between wide boards.
There are many variations where the joint details are better hidden in one or both directions. The dovetail joint is widely used in mass production including store-bought wooden playhouses and drawer sets. A variation is able to be cut by precise machines, especially in the area that links the sides and the drawer fronts.
This property could also be used with seasoned wood parts. The small amount of moisture in the rail end was dried out in an oven, and then the parts driven together, so subsequent taking up of moisture in the rail would expand it slightly in the hole.
Doing this and using an unseasoned leg combined the effect. There was a risk of splitting, and unseasoned wood cannot be relied on to remain true. It may have warped or twisted as it dried out, so sometimes a poorly shaped children’s playhouse was produced.
Expansion and contraction due to moisture are also associated with wedges. If a wedge is dried out in an oven just before driving, it can be expected to thicken a little as it takes up moisture again and thus becomes tighter.
Improved accuracy and tools came about and that’s when craftsmen of old founded the eye-pleasing dovetail principle. This is a joint that’s not only easy on the eye; it is also highly functional due to its slight taper that can’t be pulled apart in a single direction. Examples, shown throughout this website, range from single tails on the ends of strips to multiple joints between wide boards.
There are many variations where the joint details are better hidden in one or both directions. The dovetail joint is widely used in mass production including store-bought wooden playhouses and drawer sets. A variation is able to be cut by precise machines, especially in the area that links the sides and the drawer fronts.