Industry Insights: Grain Cuts and Joints
Grain Cuts and Joints
We hope everyone is having a successful 2020 so far. This year, we wanted to give you more of a behind-the-scenes look at what makes us tick here at Shape. This month, we are spotlighting timber and a selection of details; Grain Cuts and Joints. Get in touch if you spot any nice examples of these out in the wild!
Grain Cuts
The way the timber is sliced to produce solid panels or veneers affects the resulting grain pattern, producing varying degrees of wavy to straight lines. The resulting patterns will vary between species of timber, however generally, the typical patterns outlined below should give a good indication of the most common cuts.
Photography by Adam Scott
Terminology:
Bookended – Whilst timber is cut in narrow planks, we often want to create panels that are larger than the width of the plank. To achieve a seamless finish, the planks are bookended, where matching sides are placed adjacent to each other, creating the illusion of a wider panel and repeating the natural pattern of the grain from leaf to leaf.
Grain Matched – When creating a set of drawer or cupboard fronts, it is important to ensure the grain runs consistently between panels. This can either be created by a single large panel (that is often created from bookmatched veneers) being cut into smaller panels, or using a crown cut to dissect the timber into matching sections, which are bookmatched to create the continuous grain pattern.
Crown Cut
Also known as plain-sawn, this is produced by cutting the log in consistent straight strips across the breadth of the trunk. It is one of the most common veneer types, and produces a wavy or arcing decorative pattern in the grain. Due to the timber being cut in adjacent slices, you can achieve a good grain matched finish.
Rotary Cut
A rotary cut cuts the timber in a continuous spiral. As the veneer (a very thin slice of timber, that is bonded to MDF or another substrate) continues, the wavy pattern varies as the lathe traverses the tree’s growth rings. It is the most economical method of cutting as there is very little waste, however you cannot bookmatch the veneers as each section is different.
In the Etch House, rotary cut veneers of Douglas Fir highlight the timber’s iconic wavy grain pattern.
Photography by Adam Scott
Quarter Sawn
Quarter sawn is the standard to produce a straight grain pattern. The log is quartered, and each quarter is then sliced in a consistent direction. As such, you can bookmatch the resulting veneers or planks.
Rift Sawn
The rift sawn produces a straight grain pattern, but unlike quarter cuts it avoids the flaking that can sometimes be seen. This is because the cuts are always made in the direction that is most accurately perpendicular to the tree’s growth rings. As not all parts of the log can be used, this is the most expensive and rare cut, and also produces the most waste.
Types of Joint
We use a variety of methods to join sheets and panels; some, such as dovetails, are implemented for aesthetics as well as strength; others, such as dogbone or tab joints are more practical, and are cut efficiently on our CNC machine. Below are some of the joints that we use most frequently at Shape.
Rebate/Half Lap
We use this joint as a way of extending the length of a panel, sheet or plank. It is one of the strongest ways of joining timber vertically. The rebate is either glued, pinned (as in diagram), or both for added strength. If joined perpendicular to each other, the joint is similar to a butt joint, however a groove is cut into one piece for added strength.
Domino/Biscuit
A domino is used for the same purpose as a rebate, or where anything might need to be joined without any visible fixings. Holes are cut in the panels that are to be joined, and the “biscuit” or “domino” is coated in glue and inserted into the holes. The panels are then clamped together and a tight bond is formed. This creates a perfectly flush joint.
Dovetail
The dovetail joint is an extremely strong decorative joint. It is formed from angled pins and tails that interlock to form the bond between pieces, which can be further strengthened if glue is used (note: a box joint is similar, except the pins and tails are not angled, making it slightly weaker and less decorative). It is one of the oldest joints known to humankind, pre-dating written history, and is a mark of a skilled craftsman. At Shape, we typically use this joint in decorative drawer boxes, particularly in kitchens and dressing rooms.
Mitre
Mitres are typically used to join panels perpendicular to each other. 45° angles are cut into the timber which are then glued together at a 90° angle. It is more decorative than a butt joint and marginally stronger, due to a larger surface area for the glue to bond to. It also conceals the end grain if this is exposed. We frequently use this joint in exposed timber cabinets or door liners.
Butt Joint
The butt joint is one of the simplest joins, whereby two pieces are butted together and glued. In the right application, particularly with plywood or timber with a beautiful grain, this can create a contemporary aesthetic, as it displays the end grain of the material. Dominoes and glue, or mechanical fixings such as screws can be added in non-visible locations and angles for added strength.
Lap Joint
There are a multitude of variations on the lap joint, such as the half lap, mitred half lap, cross lap (shown here), and dovetail cross lap. In a full lap joint, no material is removed from either piece so the resulting joint is the thickness of both pieces. In half laps, some material is removed from each piece, then bonded, creating the same thickness of material throughout. These half lap joints are some of the strongest joints.
Dado
Also known as a housing or trench joint, this is formed by a groove being cut all the way, or partially (known as a stopped or blind), through a panel. The second panel then slots into this groove with glue applied, and the join is formed. This is one of the strongest joints as there are three faces to bond to. We often use them to create the join between shelves and side panels in bookcases.
Dogbone/Tab Joint
Unlike the above, the dogbone or tab joint is most frequently created from joining two panels that were cut on the CNC router. Named from the semi circles created from the cutting path of the router, this is how we most frequently construct cabinets. A notch is cut into one panel, whilst a protrusion is cut into the other. These two are then locked together, then either glued or mechanically fixed, or both. These create incredibly strong carsasses that are very quick to assemble.
We hope this provides an insight into some of the considerations we put towards detailing, and helps you to specify or spot these in your own projects and visits. Please get in touch via our socials below if you spot any of these out and about, we are always looking for inspiration for upcoming projects!
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