My dashboard has a hole where a push-button used to be; it's about 20mm in diameter.

I now want to fit a different button, but it will need to have a recess of around 25mm diameter, 5mm deep, around the original hole.

Can anyone suggest a way of cutting this recess?

What is the dash made of and how thick is it?

Oops!

Marine ply, around 12mm thick.

[Edited on 9/3/09 by David Jenkins]

maybe a router with 25dia plunge bit

25mm flat wood drill bit?? Might need to glue a piece of wood to the rear of the dash temporarily to allow the wood drill to centre on that.

link

Draw it up and dremel it if I were you. Score the line through the first ply with a stanley knife so it doesn't splinter, then use a fine router-type bit.

Caveat - only if you have a steady hand mind! If not, go with the above.

cone cutter drill bit?

file?

I'd glue a bit of wood accross the back of the hole. Drill a centre in that and then use a 25mm hole-saw and prise the piece off after. Dremel would be second choice because it needs a steady hand.

adrian

I think the quickest and easiset way is to glue a piece of wood on the back to hold the tip and use a (nice sharp!) flat wood bit or holesaw.

I'm thinking of changing my mind... I might drill right through (rather than creating a step) and then mount a plate behind the hole. The button's shroud can then fit through the dash, rather than sit on the surface.

I'll probably use an amalgam of the ideas you've all posted - I'll turn a wooden plug to fit in the existing hole, then use that to locate a flat bit.

Thanks to all,

David

(now go and answer my question in Electrical re. starter solenoid current! )

I would have just clamped a second piece of wood to the back and used that to centre a hole saw.

second the cone cutter (step drill )
will work every time
cheers
colin

Hi

If you want to maintain the step then use a bearing guided router bit, the finish will be as good as your original hole.

Regards Mick