|Nailing and Screwing - Course: Making of Wood Joints. Trainees' Handbook of Lessons|
Nailing is effected on a firm, not springy support. The nail, when being driven in, is held and guided with the left hand at the shank until it sticks sufficiently deep and tight in the wood. The hammer is taken with the right hand at the end of the handle; hammering is done from the wrist. The hammer must be guided slackily and without clenching. When driving in the nail, the direction of the blows must be the longitudinal axis of the nail. Nailing is done with the hammer face.
Nailing of a lath grid
This simple nailing technique is applied when wood joints of laths and crosspieces (joists) shall be made by means of nails. With determining the nailing points, the required distances to the edge have to be adhered to.
The nails to be driven into the first and the last lath must be upset so as to avoid a splitting of the crosspieces. For upsetting, the nail is put with its head on a firm support and held fast. By slight blows with the hammer onto the nail point, it is upset through which the splitting effect of the nail is reduced.
Each lath is nailed to each crosspiece with two nails. To increase the durability of each joint, the rear nail is nailed with an inclination towards the back and the other nail with an inclination towards the front. The inclined position of the nails shall be about 15° deviating from the vertical. The nail length is at least double as long as the thinner board but shorter than both parts.
Nailing of a halved frame corner joint
This nailing technique is used for subordinated structural parts (makeshift nailing) only.
This nailing technique with overlong nails implies a risk of injury due to bursted out wood fibres and projecting nail points!
The nails are driven in with the grain as to the lower surface with an inclination of 15° deviating from the vertical. The point of the nail is deflected through slight blows of the hammer when it impacts on the steel plate and then penetrates the wood again. The workpiece has to be firmly pressed onto the steel plate (screw clamp). The nail length is about 10 mm + the overall wood thickness.
Nailing of a tool kit
In addition to the simple nailing, the nailing with overlong nails, as well as folding back and hammering back of the overlength is important.
The nails are driven into the laths and boards vertically and flush with the surface. Base blocks of wood are to be used so that the nails do not penetrate the joiner's bench.
The workpiece must not be springy; otherwise there is a risk of slipping off when hammering and so there is a risk of injury!
Nailing is done in the form of a triangle. When folding back the nails, the steel bar must be firmly pressed against the nail shank. It has to be seen to it that a firm support is used so that the nails cannot be hammered out and that the nail head remains Gush with the wood surface. Folding back of the nails is accomplished in the grain direction of the wood. Hammering is done with the hammer face, on principle.
1 nail driven in, 2 nail folded back at the steel bar, 3 nail point hammered back into the wood
The distances of the nails to the edge are absolutely to be observed!
The nail length is at least 15 mm + the overall wood thickness.
Nailing of a wall panel
This nailing technique can be applied if large areas of boards with shaped grooves and tongues shall be produced on a sub-structure of wood. The advantage of this is that the nails are invisible after completion.
The first board on the left-hand side is begun with. After an exact aligning, the board is nailed from the front onto the sub-structure close to the left-hand narrow surface (groove side). On the right-hand side, this board and all following ones are not nailed onto the sub-structure from the front but at the narrow surface through the shoulder line of the tongue.
The nails are driven in at an angle of 120° to 135°. To avoid damages of the wood edges and the tongue, the last blows are made by using the nail punch. The nail head is sunk. The nail length has to be chosen in dependence on the construction.
When several screws shall be driven into a workpiece, then the individual parts have to be secured against shirting.
Pre-drilling and/or pre-cutting is necessary in any case!
To maintain the screwing-in and/or drawing-out resistance, the screw holes must not be pre-drilled too large and not too deep. The end of the insert of the screw driver shall have the width of the screw head diameter. It must fit exactly into the screw slot. When driving in the screw, the screw head and the end of the insert of the screw driver have to be guided with the left hand.
Do never drive in screws with a hammer!
Bore holes for cup square bolts are to be pre-drilled through all parts to be joined with d + 0.4 mm. Cup square bolts are driven in by slight blows with a hammer and fastened with washers and nuts. The length depends on the thickness of all parts to be joined, adding about + 10 mm.
Screwing of a carrying handle to a tool kit by means of counter sunk-head screws
This screwing technique can be used for fastening a board onto another. The screwing points shall give a regular picture but shall not lie in the same annual ring.
After scribing and marking the screwing points at the handle holder, the holes are pre-drilled 12 mm deep with the shank diameter of the countersunk-head screws (3 mm). The bore holes at the front are reamed with the rose bit. After fastening the handle holders to the tool kit by means of screw clamps, the screw holes are concentrically pre-drilled deeper by another 12 mm with the drill dia. 2 mm.
The countersunk-head screws are put into the bore-holes by applying pressure with the thumb (do not use a hammer!) and screwed clock-wise into the wood with a suitable screw driver by applying light pressure. Doing so, the end of the blade of the screw driver and the head of the countersunk-head screw are to be guided with the left hand. Thereby it is avoided that the screw driver slips off the slot of the screw head.
By the screw driver slipping off, the wood surface may be damaged and accidents (injuries of the left hand) may occur. Screw driver handles must be clean, tightly fitting and non-slipping!
Why must wood screws not be driven in with a hammer?
Screwing on of a screw-on brace
By applying this screwing technique, metal mountings can be fastened to structural parts of wood.
The selection of the respective screw shank diameter depends on the prepared holes at the metal mountings. The shank diameter of the screw shall be about 0.4 mm smaller than the hole diameter in the mounting.
The screw length is chosen in dependence on the thickness of all parts to be joined. The wood screws are shorter than the parts to be joined. The cup square bolts are abt. 10 mm longer than the thickness off all parts to be joined so that the washer and the lock nut can be screwed on.
After scribing, the bore holes for the wood screws are vertically pre-drilled about 0.4 x screw length deep with the shank diameter of the chosen wood screws and after that, if hard wood or large screws are used, the same depth is drilled once again with the diameter of the thread core. The hole for the cup square bolt is drilled with the diameter 0.4 + d of the screw through all wood parts to be joined. Here, splitting of the wood fibres has to be avoided when the drill comes out of the wood.
After scribing the hole, take off the mounting and do not guide the drill through the hole in the mounting!
The cup square bolt is driven through the hole in the mounting and the bore hole by slight blows with the hammer and fastened from below with a washer and a nut. The square neck must tightly stick in the punched hole of the mounting.
The wood screws are screwed in with the appropriate screw driver. In doing so, the screw head and the end of the screw driver are guided with the left hand and secured against slipping.