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I'm trying to drill some 10mm holes in 1mm thick aluminium, I first drill a 4mm pilot hole and then use a 10mm HSS standard metal working drill bit but the holes are really misshapen

Here's an images to show what I mean (sorry for the low quality)



So my question is, what can I do in order to get perfect (or near perfect) 10mm holes?

Thank you!

Was the drill skipping around?

You could clamp the metal between TWO bits of wood, drill through the top wood, straight into the metal - it will act as a guide and stop your bit skipping.

Make sure the bits are nice and sharp too....

BG

All is not lost. You can still make them round.



Cone cutter

BillyGoat wrote:Was the drill skipping around?

You could clamp the metal between TWO bits of wood, drill through the top wood, straight into the metal - it will act as a guide and stop your bit skipping.

Make sure the bits are nice and sharp too....

BG

Hey

No, it wasn't really skipping but it was vibrating quite a bit.

The drill bit should be sharp as its brand new.

I think I'd find it differcult to be millimetre accurate if I were to drill through a piece of wood and then into the aluminium

Any better drill bits for this type of work, or perhaps a 10mm hole saw bit for metal work?

someone-else wrote:All is not lost. You can still make them round.



Cone cutter

Hmm... cool I'll look into those.

Thanks

SCREWFIX £21.89

You can also get "stepped" cutters, but they cost considerably more.

A pillar drill is best, but without one step up in sizes drilling a bit at a time and do not use cheap drills

Grind the angle of the drill much shallower if you have a bench grinder.


Slow the speed of the bit down too I expect.

merlin50 wrote:A pillar drill is best, but without one step up in sizes drilling a bit at a time and do not use cheap drills

Yeah don't have a pillar drill so will try those cone drill bits

Hitch wrote:Grind the angle of the drill much shallower if you have a bench grinder.


Slow the speed of the bit down too I expect.

Unfortunately I don't have access to an angle grinder, I don't do much DIY :/

I will slow down the drill speed though

Don't look as though you drill right though

Rustyy117 wrote:

BillyGoat wrote:Was the drill skipping around?

You could clamp the metal between TWO bits of wood, drill through the top wood, straight into the metal - it will act as a guide and stop your bit skipping.

I think I'd find it differcult to be millimetre accurate if I were to drill through a piece of wood and then into the aluminium

Drill a 4mm pilot in the wood and metal separately, align them (using the bit), clamp them then drill through all three with the 10mm?