Weekend Projects - Arched laminated clock archive

Friday 19 June 2015

Ellis Hein creates this unusual clock which enables you to get a true corner on time

Gallery

Einstein once remarked that he had put a clock in every corner of the universe. This project is not so ambitious as that, but it does allow you to get a corner on time.

For this project, in addition to the turning tools, you will need a blank measuring 95 x 95 x 150mm, hardwood to make a blank, jointer, heat gun, a scroll chuck, woodworm screw for the scroll chuck, live centre for the tailstock, large cone centre for the live centre, drive centre, drill chuck, 45mm and 10mm Forstner bits and a 45mm clock insert.

Tools used:

Diamond parting tool

Square-nose scraper

Round-nose scraper

10mm bowl gouge

Hollowing tool

STEP 1

For this project the round is only visible by being absent. You will remove it and leave the square. Glue up a blank measuring 95 x 95 x 150mm. The clock pictured in this process is composed of two layers of oak (Quercus robur) measuring 20mm each, one layer of red gum (Liquidambar styraciflua) 38mm, and then another 20mm layer of oak. You can use my suggestion or alternatively, you can come up with your own combination of hardwoods

STEP 2

Once the glue is dry, run your blank over the jointer to clean up the glue joints and to make it square in cross-section. Trim the ends to make the blank 115mm long. When the blank is ready, draw a diagonal on each end such that the lines are joining the same pair of corners. Use the other two corners to locate the centre of the blank on each end. Use a bradawl and punch a hole 25mm (1in) from the centre on the diagonal line. Mark the other end the same way except that the punch mark on opposite ends should be on the opposite sides of centre, both on the diagonal line

STEP 3

Use a wood chisel to cut a recess for three of the four prongs of your drive centre. One recess, the one on the diagonal line and nearest the corner, must allow that prong of the drive centre to penetrate deeply enough for the two cross prongs to get a good bite in the blank

STEP 4

Mount the blank between centres such that the axis is running through the punch marks. Bring up the toolrest and rotate the blank at least one turn to make sure the blank does not catch on the toolrest

STEP 5

Set the lathe to a slow speed, and use a parting tool to cut in about 25mm to mark the ends of the legs. The longest leg should intersect the block where the corner joins the end. This will produce one leg that is 115mm long, the opposing leg is approximately 55mm (21/8in) long, while the other two are approximately 83mm each. This will make your clock tilt at about 24 degrees off horizontal when it is standing on its legs

STEP 6

Shut off the lathe, pull the toolrest back, and remove the blank. Next, mount the blank between centres so that the axis now runs through the centres of the ends of the blank. Position the toolrest at the tailstock end of the blank, and use a round-nose and a flat scraper to begin hollowing on the tailstock end. Leave a suitable spigot that you can grab in your scroll chuck

STEP 7

Remove the blank, remove the toolrest, and replace the drive centre in the headstock with the scroll chuck. Grab onto the spigot with the scroll chuck and use the live centre in the tailstock to centre and support the off end. Reposition the toolrest along the side of the blank. Rotate the blank at least one turn to check for clearance. Set the lathe to a medium speed - approximately 800-1000rpm. Use a 10mm gouge to cut a curve on the end of the blank. Make this curve using a series of shallow cuts. Begin on the outside of the blank and cut around the corner onto the end. The next cut begins closer to the headstock and comes around the end, terminating closer to the live centre. Your final cut should travel all the way up the leg and make a smooth transition around the corner and across the end of the blank. Cut along the legs just enough to round over the corner

STEP 8

Replace the live centre in the tailstock with the drill chuck. Remove the toolrest. Set the lathe to a slow speed. Mount a 35mm Forstner bit in the drill chuck and drill a 10mm deep recess for the clock insert

STEP 9

Replace the 35mm bit with a 10mm Forstner bit and drill a pilot hole - for the woodworm screw - on the same centre. Drill no deeper than absolutely necessary. Fit a live centre with a large cone centre and support the off end of the clock. Set the lathe to a medium speed and sand the curved end of the blank. Sand the legs with the lathe turned off, rubbing in the direction of the grain. Apply a beeswax finish to the sanded portion. Set the lathe to run about 1500rpm, then hold a block of beeswax to the spinning blank. Use a piece of absorbent paper to melt in and remove excess beeswax. When buffing the legs, grab a length of paper towel by each end and stretch it across the spinning blank. Repeat the process then remove the blank from the scroll chuck. Mount the woodworm screw in the chuck

STEP 10

Now cut a circle of thin cardboard to act as a washer to prevent damage to the top of the clock, fit it over the screw and screw on the blank square to the chuck. Set the lathe speed to a slow to medium speed and begin hollowing out the interior with whatever tool affords you the most control. You get a ghost image of the legs. These 'ghosts' have a substantial presence if they catch a hand, your hair, an article of clothing, or a turning tool

STEP 11

The curve you cut on the outside will guide you in cutting the contour of the interior. You want an even thickness all the way as will be revealed by the remainder of the flat side of the blank. Note the pointed protrusion in the centre of the interior which covers the pilot hole you drilled for the woodworm screw - do not remove it. Cut down in stages about 8mm at a time making sure you blend in each previously cut section with the next

STEP 12

Repeat the procedure until you get to the depth of the pointed protrusion in the photo above, step 11. As you get near the depth of the screw, make swinging cuts from the centre of the hollow left, then to right, to create the shape required

STEP 13

Once you have roughed out the interior, clean it up with light, shearing cuts with your chosen hollowing tool. Use a light touch when cutting along the legs; they are fragile and will flex away from the shear cutter. Clean up the interior of the legs with a rolled up piece of sandpaper. Do this sanding with the lathe off, and the rest of the un-sanded surfaces. With the lathe turned off, wax the interior by using a heat gun to warm the surface of the wood and rub the bar of wax over the warm surface. Reheat the surface to melt the wax and rub over the surface with an absorbent cloth. You now need to remove the clock from the screw chuck. Put the clock insert in its recess and your clock is now ready to be displayed in your chosen location


Briony Darnley

Tagged In:

Weekend Projects , Ellis Hein


Diagrams Click an image to enlarge

Handy Hints

1. Every time you reposition the toolrest, check for clearance between the turning blank and the toolrest by rotating the blank at least one full revolution
2. Always cut curves such that you are progressing more deeply into the grain of the timber. Cutting the other way tends to lift the grain and causes chunks to split off the blank
3. Clock inserts to fit into a 45mm (13/4in) hole are available from many sources and retailers. An internet search will turn up the outlet nearest you