4 x 3 tips for dowelling with wooden dowels
4 x 3 tips for dowelling with wooden dowels
When it comes to wooden dowels, many people first think of drilling the holes for the dowels. However, this is only the second step. Mistakes can easily be made when marking out the positions. And even after drilling, wooden dowels can be tricky. Here you will learn how to mark and transfer dowel positions precisely, how to drill holes for wooden dowels accurately, what you can do if a dowel hole does go wrong and what you should bear in mind when assembling.
How big should wooden dowels be?
If possible, the diameter of a wooden dowel should be 1/3 of the material thickness used (example: for 18 mm board thickness, use dowels with a diameter of 6 mm). The length of the dowel also depends on the material thickness and also on the type of dowel connection. If the dowels are visible from the outside (open dowelling, where a hole is drilled completely through a workpiece into the counterpart), the length of the dowel should be approximately three times the material thickness. If dowelling is concealed (the wooden dowels are not visible from the outside), you can choose a length between two and two and a half times the material thickness. Wooden dowels are often not available in exactly the right size. In this case, it is better to opt for a slightly larger diameter than to use a dowel that is too short or too thin.
How are the positions of the dowels marked?
3 tips for marking the dowel positions
- Mark reference edges
To be able to mark the position of the wooden dowels exactly on all workpieces, define a reference edge on each workpiece that serves as a starting point for measuring and marking. In the simplest case, this is the edge with the carpenter's triangle. You can also mark the outside of the corners where the dowel joints are to be positioned (dowelling machines such as dowelers or domino routers and dowel gauges are usually positioned on the outer edge).
The positions can be marked precisely using classic marking tools. - Marking dowel positions with a rule and compass
There are numerous tricks on the internet for marking the drill holes (with adhesive tape or strips of paper, etc.). However, if you want to be precise, classic marking tools are still a good choice. First mark out the centre line on the edges and end faces using a marking gauge. Then define a starting point (centre of the workpiece or a fixed distance from the reference edge). Now set a compass to the desired distance between the holes and use it to mark the positions of the dowel holes, always starting from the starting point. - Measure only once
Transferring measurements is more accurate than measuring them again several times. You can mark the centre line on all workpieces. However, the positions marked with the compass are then transferredwith an angle or, after drilling, with so-called dowel markers.
What should I bear in mind when installing wooden dowels?
3 tips for drilling
- Correct sequence when inserting wooden dowels
For concealed dowels in solid wood, drill into the end grain first, as the drill bit runs more easily here. Even if the hole is slightly misaligned, you can then transferthe position with dowel markers. For open, visible dowel joints, clamp the workpieces together as they are to be assembled and drill through the longitudinal timber from the outside. With board material (chipboard, MDF, OSB, etc.), the order in which the holes are drilled is of secondary importance.
Dowel gaugesmake it easier to drill the dowel holes accurately. - Drill dowel holes deep enough
Wooden dowels push some of the glue in front of them when they are inserted. The total length of the hole should therefore be approx. 3 mm deeper than the total length of the dowel. This creates a "glue chamber" that can absorb excess adhesive. - Countersinking holes for wooden dowels
After drilling, you can slightly chamfer the top edge of the holes with a countersink. This makes it easier to apply glue and insert the dowels, the workpieces slide together more easily during assembly and the countersink creates additional space for glue to ooze out.
How can I correct an incorrectly drilled dowel hole?
3 tips for after drilling/before assembly
- Use test dowels
To test whether the joints fit and are drilled deep enough, it is best not to use normal wooden dowels, as they may swell in the joint when you try to put them together, possibly get stuck and break off when you try to pull them out. Instead, make a few test dowels. These are wooden dowels that you sand down a little on the outside or drive through a dowelling iron with a 0.5 mm smaller diameter. These test dowels can then simply be pulled out of the holes by hand.
Use a dowel saw to saw off the dowel flush with the incorrect hole. - Correcting a misaligned hole
If a hole is not in the correct position, you can plug the hole with a wooden dowel. Once the glue has dried, saw the dowel flush with a dowel saw and plaster the surface. You can then drill a new hole in the correct position using an auxiliary template (hardwood block with a hole of the same diameter as the dowel holes) or a dowel jig. - Always chamfer wooden dowels
Always chamfer both ends of wooden dowels cut from dowel rods or round timber or shortened dowels (e.g. with a pencil sharpener). Straight sawn wooden dowels are more difficult to insert into the holes and push the glue in front of them. With bevelled ends, the glue spreads better at the tip and in the grooves.
Does the wood glue go on the dowel or in the hole?
3 tips for assembling dowel joints
- Always put glue in the holes, never on the dowel
Wooden dowels swell slightly due to the glue so that they sit firmly in the joint. If glue is applied to the dowel, the dowel may swell before it is inserted into the hole. Therefore, always spray the glue all around the hole, e.g. using a glue bottle with a spray nozzle.
With a thin spray nozzle, the glue can be distributed all round the hole. - Insert the wooden dowels into the deeper holes first
If possible, the wooden dowels for larger parts and complex workpieces should be inserted into the workpieces with the deeper holes first. As the shorter part of the dowel then sticks out, the workpieces can be aligned and assembled more easily. - Use weatherproof dowels outdoors
Beech is less suitable for outdoor use. Beech wood warps comparatively strongly and is not very weather-resistant. For outdoor furniture, you should therefore use weatherproof dowels made of sipo-mahogany, bangkirai or special dowels (e.g. KNAPP dowels).
