If you have seen any of our other projects coivering timber joints you will probably have gathered that they are integral to the success of the project at hand. If your joints are loose or un-square then this will make for a shoddy and unsightly overall job.
In this project we take a look at the shoulder and rebate joint or lapped joint as they are also known and see how ideal they are for making furniture items, boxes and other solid shapes.
What are Shoulder and Rebate Joints?
On looking at this type of joint, and if you are familiar with other types of woodworking joint, then you may think it looks a little bit like a butt joint, but the main difference between the two is that the rebate joint has a section cut out of each joining piece, whereas each section of the butt joint just butts together.
The advantage that the shoulder joint has over the butt joint is its strength as the rebate provides a much greater fixing area and, once glued, forms a solid corner.
If you need even more strength in your joint you can combine the adhesive with screws, nails or even dowels that will further reinforce your corners.
The lapped joint does have a few small disadvantages however in that the grains of one of the joining timber sections will be visible but if you are using a good quality timber then the end grains can actually be made into a feature if cut carefully.
Choosing the Correct Timber for Your Joint
As mentioned, the success of the overall job does come down to how well your joints are cut e.g. how square they are, how sharp the cut is (whether the grains are cut rough or smooth) and also what timber you use.
The actual timber used can have a huge bearing on the final finish in that if it is very rough, full of knots, if it's suffered water damage, if it is bowed etc.... then the timber is actually what will be seen at first glance so you will want to make sure what ever you use will be visually appealing.
That said, if you are going for more of a rustic or worn look then this might be something you are aiming to create but again, the timber you use will need to be selected carefully to match this look.
In most cases you will probably want a clean and smooth finish so you will want to look out for the following:
- Overall Condition: Make suer the timber is planed and smooth, free from any splits and water damage if it has been left outside or in damp areas
- Bowing: If timber has been stored upright, leaning against walls or other vertical surfaces then over time it will bow. In some cases (depending on how bad it is) it can be straightened out again but tihs will take time and add unnecessary hassle so it's best to get timber that's good to go from the off
- Knots and Imperfections: In some cases, knots can be used to very good effect depending on the object being made but in most cases they can be a pain as you can guarantee where ever you need to make a cut a knot will be right in the way so avoid them as muych as you can
What Tools are Needed for Making a Shoulder and Rebate Joint
As we have firmly established by now, the quality of any finish is pretty much down to the tools and materials you use and the time and care that is taken. As certain level of skill is also obviously involved, but with practice, this is certainly something that can be gained.
Looking a little closer at the tool aspect, it is almost always a good idea to buy, borrow or hire the best tools you possibly can. Good quality tools are often sharper, stronger and straighter than their cheaper couter-parts so if you can, buy the best tools possible.
If you don't want to go forking out large sums of money on tools that may only get used once or twice, then hiring is also a good idea. You should be able to rent top quality tools for more than enough time for very reasonable sums of money.
If your only option is the cheaper varieties then this is fine, just make sure they are as sharp as possible, dead straight and square.
How to Make a Shoulder and Rebate or Lapped Joint
If you would like to make your very own shoulder and rebate joint, work through the steps below:
Marking out Each Lapped Joint
To mark out your cutting lines, the best tool to use is a marking gauge, but if you don't have one to hand, a pencil and ruler is fine. For the purposes of this project, we will be using a pencil and ruler.
Firstly, measure the width of the end of your timber. This is the section that will butt up to your second piece. With this measurment taken, divide it by two and this should then give you the centre of the timber. Using your ruler, measure the centre point and mark it with the pencil. Do this for both sides and then mark a line between the two points with your pencil.
If using a marking gauge, use the measurement for the half way point of the width of the timber to set the pin the exact distance from the stock of the gauge. Position the stock flat against the edge of the timber and score a line across the end face. This can sometimes be hard to see so use your ruler and pencil to go over it.
As we are aiming to effectively cut a “square” out of the end of the timber, you will now need to transfer this measurement down each side of your timber. Using your ruler and pencil measure down and mark the middle point on each side for the depth of your measurement, joint the marks together and then mark the middle point along the line. Now draw a line down to joint the two points.
The final marking stage is to mark a line across the wide face of the timber to complete the square shape that will need to be cut out. As you have already marked across the depth side, you can use these and simply join them together across the width of the face.
Before you do, it is a good idea to just check the measurements with your ruler to make sure all is correct. Once you have checked, use your ruler or if you have one, a tri-square to make your line. The tri-square is the prefered tool to use as you can then be sure all is square.
Once you have made all of your marks you should have something that resembles the image below. If all is correct then you can now move onto the cutting stage below.
Cutting Away Waste Timber to Create Lapped Joints
To ensure that the timber does move during cutting, you will need to clamp it up tight using a vice or Workmate before you begin.
In terms of which cuts you do first, this is entirely up to you, there is no real order that they should be done in. For the purposes of this project, we will cut down the top line first.
Position you timber upright in your Workmate or vice and make sure that it is level. Slacken off the grip slightly and place a spirit level flat on the top and wiggle the timber a little until it is dead level and then re-tighten again.
To make your cut, the best tool to use is a tenon saw as the rigid top brace of the saw ensures that it cuts in a nice straigt line. If you don't have one you can use a normal jack saw but you will need to take your time and keep an eye on how the saw is cutting as they can easily go off-line.
Start your cut at the farthest end by angling the saw slightly downwards and as you cut, gradually level it up so that you are cutting in a flat, straight line. By making sure that the saw flat and level you should then avoid cutting down too far past your marking lines.
Take your time when cutting and stop regularly to check your progress and make sure you are cutting along your lines and not straying off of them.
Once you have cut down to the depth of your lines you are now done with this side.
Loosen off your vice or Workmate and remove your timber and then flip it on its side with your final cutting line pointing upwards. PLace it back in your vice/Workmate and tighten it up, again, make sure it is dead level before gripping it firmly.
If you have one to hand, the ideal tool for making this cut is a bench hook. This is simply a piece of timber with a stop edge at one end you can butt your timber up to while you are cutting.
With the timber gripped firmly, start cutting. Again, stop regularly to check your progress and make sure you are following your lines.
As you get close to the end of your cut, go really carefully. Once yo hit the first cut you made the waste section of timber should become loose and allow you to remove it easily. Once removed, your cuts are complete and it's on to the tidying up stage.
Now that you have completed one half of your joint, it's time to create the other. This is exactly the same process as the steps you have just worked through above so work through them again to create the second half of the joint.
Tidying up Your Rebate and Shoulder Joint Cuts
In the majority of cases, no matter how sharp your saw is, you will have a few rough edges and surfaces to tidy up and depending on how whether you are working with the grain f the wood or across it, will depend on how you do this:
- Working in Same Direction as Grain: The best tool to use here is a shoulder plane. Place your timber down on a flat surface and clamp it down using a G-Clamp. Before clamping up, place a small piece of scrap wood along the top of joint so that it is flush with the edge to use as a guide. Place the plane flat on the lap and run it across the surface. Only remove a very small amount in each run and check you fit with teh other half of your joint to ensure that you are not taking too much material away, causing your joint to be loose
- Working Across Grain: When working across the grain, you should use a very sharp bevel edge chisel. Place the timber on top of a scrap piece of timber (to protect work surfaces if the chisel slips) and clamp it down firmly. Holding the chisel level with the edge of your join, gently tap down with a carpenters mallet to remove any proud spots and rough patches. Again, only remove a small amount at a time and check the fit of the two joints regularly to make sure you haven't taken away too much
If you still have a few rough patches you can tidy up further using a very fine grade sandpaper such as 400 grit or more, but becareful not to take off too much!
Joining Your Timbers Together
With all cuts successfully made and tidied up, you now have to fix the joint together.
This is done firstly using a good quality wood adhesive. Coat all faces of the joint with the adhesive and then fit them together. To ensure nothing comes loose while the adhesive is curing, clamp the joints firmly together using suitable clamps.
With everyting clamped up, leave for the adhesive manufaturers recommeneded time for it to dry completely. Once this time is up, remove your clamps and you're done! Top job!
Now that you have made your fist shoulder and rebate joint, why not check out the other types of timber joints in our other projects below and expand your skills even further!