ROMAN MOSAIC WORKSHOPS - Cutting the Hardie hole

ROMAN MOSAIC WORKSHOPS - Create a Piece of History

Cuting the hole for the hardie

I'm not a carpenter so there may be a better way than this. This is just to show you how I do this and to date I've cut about 20 blocks.

Safety note, make sure the block is fixed when you drill it otherwise if the drill bit catches, the block can spin round very fast!

Mark the centre

Using 2 diagonal lines find the centre of the block. This doesn't need to be very accurate, do it by eye if you want.

Measure your hardie

Measure your hardie at the width you want it to go down to. For my hardies this is about 28mm

Mark the block

Use a pencil and mark a rough square using the measurement above.

Drill size

I use a 14mm width wood drill bit to start a 28mm hole

Drill the hole

Quite simple, make sure it's reasonably straight though!
Make sure you drill further than the depth your hardie will go to. If the bottom of your hardie sits directly on the wood the vibration may crack the wood, over time.

Start the hole with the chisel

Set the chisel in the centre of your line. Make sure you cut a hole which is too small then enlarge it. Don't make the hole too large or you'll need to cut wooden pegs to stop it rocking.

Chisel angle I

Set the chisel with the angle shown here by the red mark

Direction of the chisel

Set at this angle the chisel blade is naturally drawn in, following the shape needed for the hardie.
Work your way around the square checking that you are not making the hole too large.

Chisel angle II

To enlarge the hole I turn the chisel blade around, note the red mark. Then I use this at the angle shown to remove larger shavings of wood.

Clearing the hole

Make sure the block is properly fixed at the base before doing this. I then use the drill to remove the loose shavings. Upend the block and drop it against the floor to clear the hole or use a small gouge or even screwdriver to get them out.

End result

Continue with all the stages above until the hardie is set to the depth you want. As you can see here with a freestanding block i've added a handle on the side. This not only makes it easier to move but also makes it a handy place to store your hammer.

Block width

My blocks are all about 17cm across. The reason for this is so that when you adjust the angle of the block you can hold it with one hand as here and with the hammer just hook the edge of the blade in the other side and move it. Much easier than putting down the hammer and having to use both hands.