Garden Clock Cover

Tuesday 11 November 2008

Mike Jordan gets us thinking about design with this garden project

1.The finished cover in situ

This is one of those nice little jobs that allow you to exercise your skills on a "one off" item that is unlikely to be available from any other source. The customer was a longstanding friend who was frequently to be seen doing bricklaying jobs at my house when not indulging his passion for gardening. The clock was a gift that he wanted to fix to a wall and protect from the weather with some sort of roof. His sole contribution to the design was to mutter "oak" and "you'll think of something" while making a roof shape with two hands. I decided that a small porch type construction with some shapely "gallows brackets" to support it would be appropriate.

Angles, curves & gallows

Roof pitch

A pitch of approx 33 degrees seemed to suit the job in hand. I decided to make the top surfaces out of 12mm (1/2") ply in the first instance and see what a temporary assembly looked like.

A full size drawing was made of the front elevation and side view on a sheet of veneered MDF to check the appearance, and allow the sizes and angles to be lifted off (pic 1). From this drawing, a cutting list was prepared, and my store of short lengths of kiln dried oak was raided for the materials, all of which were face and edge planed and thicknessed to size. The shorter lengths required were left as longer lengths for safety and ease of handling (pic 3).

Gallows brackets

The gallows brackets were first, a mortise and tenon joint being used between the horizontal and vertical rails (pics 4 & 5). I left the existing 9mm (3/8") chisel in the mortising machine, and reversed the work piece, in order to get a 15mm (5/8") wide mortise. When this joint had been dry assembled and checked for square, the shaped angle bracket was placed on top of the assembly and the shoulder lines were marked on in pencil and then squared round and knifed in (pic 6).

I left the angle bracket in its square shape until after cutting the tenons on the ends, and when the tenons had been completed, I drew on the required curves. For aesthetics, the curved shapes were allowed to run thinner in the centre of the bracket.

The curves were cut on the band saw and cleaned up using a sanding device in the lathe; the tenons were trimmed square as required, before returning the finished angle bracket to its original pencil lines to mark on the sizes of the mortises. The mortises were cut at 9mm (3/8") to match the tenons and the brackets dry assembled.

For the two 100mm (4") wide "rafters" at the back, mortise them into the vertical rails of the gallows brackets and fasten together at the top with a loose tenon. To solve conflict between the two mortises at the top of the vertical rails cut away a small part of the rafter tenons to allow the smaller tenon on the gallows bracket to pass through (pic 7).

Finials & rear rafters

The finial was turned to size and mortised out to take the facia boards; the three components being dry assembled and placed face down on the working surface.

The rear rafters, which had now been glued together at the top and cut to shape on the bottom edge, were dry assembled with the vertical members held in place with a sash cramp. This assembly was now placed face down on top of the facia to allow the positions of the rear mortises to be marked through, used to locate the mortises in the back of the facia boards. The position of the mortises was moved inward to make the front tenons bare-faced (pic 9).

These blind mortises were drilled out with a forstner bit and squared off with a chisel; the matching tenons were cut using the cross cut for the shoulders and band saw for the cheeks.

Decoration

Holes

The decorative holes were cut with the router fitted with a 6mm (1/4") two flute cutter and 30mm (1 3/16") guide bush (pic 9). When I was satisfied with test hole, the template was cramped to the front of the facia boards and plunged through 6mm (1/4") at a time. The facia boards were given a shaped bottom edge using the band saw and the resulting edges were cleaned up with spoke shave and sandpaper.

I cut screw holes and slots in the rear rafters to allow the completed item to be lifted off the wall if required (pic 11); the bottom edge was finish sanded using a spindle moulder.

Cove moulds

I decided to run a small cove mould on some of the square edges using an inverted router (pic 12). To help prevent the accidental moulding of the wrong bits, I marked the parts of the edges to be moulded with a black felt tip pen.

Gluing

Once everything is hand-planed and sanded, glue up! The rear rafters, which had already been glued together, were glued and cramped to the vertical parts of the gallows bracket to make a rear sub assembly, the front fascias and finial forming the front assembly. After the glue had set, the remaining parts were glued, assembled, and left overnight (pic 14).

The roof

In the absence of a tame plumber I was obliged to have a go at the roof covering. A search of the deeper recesses of the ironmongery cupboard produced a supply of galvanized felt nails which would serve to fasten the sturdy lead covering in place. When the lead had been cut and shaped to fit, it was placed to one side while the whole construction was given an initial coat of exterior varnish, suitably thinned with white spirit to ensure good penetration. All that was left was to apply a final exterior varnish, and fix the whole construction to the wall!

Finishing off

One final piece of decoration was added in the form of two turned imitation "fixings" at the bottoms of the gallows brackets. These were turned using a "four jaw" chuck on the lathe. A 12mm (1/2") spigot turned on the back of each "button" was glued into a blind hole drilled in each upright.

The 12mm (1/2") ply for the roof didn't look adequate anymore, so I increased it to 18mm (3/4") and screwed it in place.

Glossary Rollover a term to view its definition

  • Bandsaw
     

    Bandsaw

    Bandsaw

    Bandsaws have a relatively small footprint and are often the first choice of machine as they can perform a variety of operations. A good quality machine accurately adjusted, with sharp blades can do rip cutting including deep ripping or even thick veneers, it can cut tenons for joints and various awkward shapes including tight curves if a narrow blade is fitted. For solid timber it is usual to fit skip tooth blades, these have a gap between each tooth thus allowing waste to clear quickly. For thin ply or MDF a fine tooth blade is needed.

     
  • Router
     

    Router

    Router

    Most routers are plunge type, which means the motor body is plunged to allow the cutter to enter the workpiece and make the cut. There are a few fixed body types which are normally pushed into the work from the end of the workpiece as the cutter is already projecting beneath the baseplate. Routers use special high-speed carefully balanced motors that drive a spindle in which a collet is fitted at the bottom end. The spindle runs in special high-speed bearings and the collet can be interchanged depending on what cutter shank size is in use. A collet is different from a chuck in that it can only hold a specific shank diameter whereas a chuck can be adjusted to suit any diameter within its range. The collet is the most critical part and the best machines have much better more reliable collets. This is important as cutting speeds can be as high as 27,000 rpm depending on the cutter type and size. Routers work best with some means of guidance such as a fence or guide bush.

     
  • Cove
     

    Cove

    Cove

    A concave curve found on the circumference of spindle work

     
  • Forstner Bit
     

    Forstner Bit

    Forstner Bit

    A specialist bit, similar to a sawtooth bit but without the teeth. They cut a parallel sided, flat bottomed hole. These bits can cut overlapping holes. The photo shows a Forstner bit on the left and a saw toothed bit on the right

     

top tips

The cutter needed for the job was a bearing guided small cove shape; I hadn't got one small enough, so chose to use the bearing end only on an ogee shape cutter. You can see from the pictures that only the end of the cutter was allowed to protrude through my makeshift inversion table. Try to be careful, but burn marks can be scraped and sanded away if needs be

Diagrams Click an image to enlarge

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