Drilling a small hole in an aluminium frame

[FlyingDutchman]

Advice sought:

The canopy of the boat is held in place by small 'mushroom' type of fittings where the reinforced holes in the canopy fit over.
On the windscreen frame made of anodized aluminium, one of the mushrooms is a little out of position.
Last weekend I removed the mushroom and it is screwed into the window frame with a small (3 or 4 mm) stainless selftapper.
Now, I need to drill a new small hole in the correct position and screw in the selftapper with the mushroom.

How do I prevent the drill from running away? Clearly, a centre punch is not an option as I don't want to damage the frame or the windows. Maybe masking tape or some other trick?

 

[noelex]

You can centre punch aluminium with one of the spring loaded centre punch tools. There is no need to use a hammer to produce a small impression, do this over some blue tape and the drill will not wander. I doubt it would be enough force to damage anything else.

 

[FlyingDutchman]

Thanks Noelex, but I don't have a spring loaded centre punch and don't really fancy buying one for just one hole...
Good idea about the tape though!

 

[alahol2]

Drill a hole in a small piece of aluminium strip, 3 - 5mm thick, then clamp it to the frame where you want to drill your hole.. I've done this to start a hole in stainless before.

 

[vyv_cox]

You need to grind a sharp point onto a centre punch, administer a light tap at the appropriate point, then drill a pilot hole with your smallest drill.

 

[noelex]

I think you will find hand pressure with a conventional centre punch over blue tape will be enough to get you started. Use a very small drill to create a bigger depression then the correct sized drill.

 

[30boat]

Run the drill in reverse with a bit of pressure and you'll find that it doesn't have the tendency to run off.It'll make a mark that you can use to locate the drill bit for drilling.

 

[FlyingDutchman]

Thanks all, you have given me the ideas I needed!

 

[rogerthebodger]

hold a heavyish block of metal on the other side of the frame this will take the shock of the hammer hitting the centre punch on the other side of the frame.