Built Up Boards

The full title is laminated board.

Blockboard: This is a cheaper board than the above and is not so satisfactory for cabinet work. The core strips are up to 25mm wide.

Battenboard.: In this the core strips should not be wider than 75mm. It is unsuitable for good-class veneered work, though is often used for large cabinet backs and the like.
The drawback of both block and battenboard for veneering is that the line of the core strips is liable to show through to the surface of the veneer eventually as the wood dries out. It appears on the surface as a series of waves. The narrower the strips the smaller the waves, and it is for this reason that laminboard is superior to the others. Even in this, however, the waves may show to an extent, though an increase in the thickness of the outer layers in relation to the total thickness has brought some improvement. In any case, it is advisable to sand the board with coarse abrasive paper before veneering to take out any such waves. Various lippings or edgings for ply and laminboard.

A drawback from which all built-up materials suffer is that the joints are bound to show at the edges. This necessitates their being edged or lipped, and a few ways in which this can be done. The simplest lipping, in which the strip is glued on, levelled, and the surfaces veneered. B has an advantage in that it is entirely invisible at one side and is, therefore, handy for carcase work which is not veneered. The lipping does not show at the outside.

A better form of lipping and its application to thicker board for work to be molded could be followed, the choice depending upon the required section. It’s a method of thickness, whereas G is for a fielded panel. Any of the above could be cut by either hand or machine tools. If, how-ever, a spindle is available the section at H is specially satisfactory since the canted edges protect the outer lamination. Clearly it is an impossible job for hand tools.

A point to consider when lipping both plywood and lamin board is whether to veneer before or afterwards. The advantage of the latter is that the lipping is entirely concealed. On the other hand, to veneer first means that the lipping protects the edge of the veneer which is always the most vulnerable part. It is a point to consider in con-junction with the usage the work is liable to receive. A table top subject to much handling, for instance, would be better if lipped after veneering.

Chipboard. Improvements in the manufacture of this make it suitable for veneering, even for un-supported items such as doors. Both sides should be veneered, and in the best work counter-veneering is desirable. In this the under-veneers have their grain at right angles with the face veneers. Lipping is generally necessary except for carcase parts, and most of the methods could be used, though it is advisable to avoid any method in which a tongue has to be worked on the chipboard because there is little strength in it. It is better to have the tongue in the lipping or to have a loose tongue. That at C would be unsuitable owing to the thin strips at the top and bottom being liable to crumble. In the case of a door to which hinges have to be screwed an extra wide edging is needed to give a firm holding for the screws.

The method of veneering is much the same as in solid wood, the surface being coarse sanded first. Some makes of board, however, have larger chips at one side than the other, and it is advisable to have the small chips on the face side.

Chipboard does not take kindly to such operations as planing. It is, therefore, desirable to cut the board to the finished size. From this it is obvious that machine sawing is infinitely preferable to hand-sawing, which necessarily leaves a ragged edge.

To an extent joints can be cut in chipboard, but generally it is better to regard it as panel material rather than for structural purposes. If the latter is necessary it is safer as a rule to joint solid wood edgings to it and cut joints in these. If dovetails are essential they should be coarse with pins about equal in size to the dovetails. Any attempt to cut fine dovetails will end in failure as the material. Counter-veneered chipboard, showing grains of veneers at right angles to each other.

would crumble. Similarly, tenons in chipboard, since there is no grain direction as in solid wood, and the tenon would be liable to snap off. If a job needs a joint for which a tenon would be used in solid wood, it would be more satisfactory to substitute dowels.

Incidentally, veneering both sides of chipboard increases its strength considerably, especially when it is counter-veneered. It acts rather as a form of stressed skin construction. This, of course, does not increase the strength of joints, but it does stiffen the panel as a whole. Veneered panels should be brought to size before veneering, the reason being that if any attempt is made to plane or otherwise trim the edges afterwards the dust seems to be forced in at the sides, so that the veneer is liable to be pushed outward. This, of course, does not happen when a panel is edged, and is an additional reason for edging. The best procedure then for, say, a door is to cut the hardboard to size on the circular saw, less the width of the edging all round, using a saw with tungsten teeth to resist the wear caused by the abrasive nature of the adhesive used in manufacture. It is then grooved to take the tongue of the edging, and the latter glued on

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