Drilling aluminium

[Bill]

Son has made a frame to cover his circular fish pond, and now is going to fit several triangular aluminium sheets to make it utterly impervious to his new baby son.

He nees to drill something like 15, 10mm holes in the 3mm thick aluminium sheets. His drills have failed (he says they just jam) and he is coming to borrow some of mine on Sunday.

The sheets are 5m x 3m, and won't go anywhere near any bench drill we have, so he is trying to do the drilling beside the pond using hand held drills.

The 'net is full of random contradictory advice, and I've looked at the diyfaq.

I seem to remember using something like paraffin as a drilling lubricant for this sort of job, but the net suggests variously dry, 3-in-1 oil or WD40. There are also contradictions about size and number of increasing pilot holes ( 0 to 4).

Any suggestions as to the best approach gratefully received. So far I've only found one 10mm HSS drill here to offer him.

[Dave Plowman (News)]

10mm might well be greater than the capacity of at least some cordless drills.

But starting with a smaller hole then gradually increasing it will reduce the load.

A stepped hole cutter will also probably make a cleaner hole.

[Tricky Dicky]

Paraffin is the recommended lubricant. Aluminium is notorious for tip weld on drills and once this happens drilling becomes difficult. Incorrect rotational speed and excessive feed are contributing factors.

Richard

[Fredxx]

You beat me to it. I would say any lubrication will do.

[tabbypurr]

The big problem is the bit jamming into the ali. That's caused by unsuitable bit geometry. That can be solved by grinding the leading edges of the bit so they are upright instead of sloped, so they don't dig in.

If that's beyond him, just take it slow in a hand drill or cordless on low gear and pull up on the drill at the slightest hint of it digging in, ie if it starts to get progressively stiffer as it goes round a fraction of a turn, stop & pull the bit up.

Cone shaped bits have the advantage of having a better edge geometry for ali.

I'd be leary of the effect of any lube on the fish.

NT

[Bill Wright]

I've had to do a lot of this. Centre punch, then drill a 4 or 5mm pilot hole at very slow rpm, then use a step drill also at very slow rpm. It takes time. No need to lubricate if you take your time. If the step drill has steps smaller than the thickness of the material complete the hole from the other side. In any case turn the sheet over and tidy each hole with the step drill, used momentarily.

A normal 10mm HSS drill will be next to useless.

A battery drill won't be much use; you'll just get angry. You need a decent mains or 110 drill.

Bill

[Martin Brown]

Pignet or other mesh would be a lot easier.

Simple way is drill pilot holes of 5mm diameter. Centre punch them first to make sure they don't drift and be prepared for a snatch when the drill breaks through. Putting a piece of wood on the underside helps.

Then depending on how much torque his drill can manage increase the hole size to 8mm and then to 10mm (or strainght to 10mm). My drill would quite happily put 10mm holes into 10mm thick aluminium the main problem I had was snapping off 3mm drills in the job on much deeper holes.

Trying to take it all out in one go is probably too much for all but the heaviest duty rechargeable drills and will snatch viciously when it breaks through on the other side. Aluminium is a soft metal so you need a fairly sharp drill and to keep the cutting edge clean.

A bit of lubricant doesn't hurt but is by no means essential and doesn't really matter what it is.

[Brian Gaff]

The problem is there are a lot of different sorts of ally sheet. Most are of course alloys as the original tends to oxidise fast and is quite soft. I have to say whenever I've done large holes one small pilot hole and a high speed drill for the main hole but not pushing too hard as this is when it gets itself stuck. its not a single person job though, as has been discovered ally does tend to just produce swarf that gums up the works and everything tends to go around together.

I used to make my own aerials but nothing of the scale proposed I have to say! Brian

[Brian Gaff]

Yes the fish, surely if one is covering the water with an opaque substance the fish will be dead in a week anyway. Brian

[Jeff Layman]

Out of interest, where did you find 5m x 3m sheets? They would weigh at least 120kg and cost around £500 each!

Or did you mean 5ft x 3ft?

[Tim Lamb]

I'd be a bit concerned about the lack of light on the pond? Weldmesh?

[Roger Hayter]

They tend to escape silently while you are doing something else. Once may be too many if there is an accessible pond.

[Nightjar]

That or a plastic mesh is the more usual solution. Suspended just below the surface, it can be virtually invisible but still prevent drowning

[charles]

I once saw a dog, onn a very hot day, jump into someoen's front garden pond. Thre was such a mesh. It was quite difficult to extract the dog.

[Bill]

All communication was by text, and he definitely said 3m x 5m. It's a round pond, so they are triangular. I have no idea where he got the sheets and haven't yet seen them.

I did think of suggesting that I bolted a bench drill to some ply and took it to the job, but today (Sat) it's pouring with rain.

[Bill]

In message , Tim Lamb writes

There are no fish. The cranes ate them.

The pond had a leaning, rather weak, fountain, which has now been made vertical and stabilised. The pond surround has also been stabilised and a new liner fitted.

I think the ali frame and cover are because he is fed up with the whole thing and wants a solid respite for a few years.

[Bill]

Thanks, Bill. I'll send this over to him and we will have a think before starting. I have some step drills.

[Bill]

Thanks Martin. Will pass this on together with Bill Wright's suggestions.

[Huge]

Fill it with soil and bog plants.

[Nightjar]

Pebble filled ponds are also quite effective with a fountain.