Fitting a blind to an aluminium window frame

[diceboy1]

Hi

I've got 2 blinds which need to fix directly to (new) window frames (aluminium). There is no room to drill the bracket fitting into the wall or the ceiling (we have coving) so the only option is to drill into the frame.

I've been looking at various websites and would appreciate some tips on the best way to do this- e.g. using a metal drill bit or self fitting screws? And any other advice as I'm not a DIY expert!

Thanks

 

[Burnerman]

For this you need to use self tapping screws.....these are hard screws that cut into the aluminium itself.
The trick is to drill the hole to the same diameter as the shaft of the screw, not the external screw diameter.
Ensure you don't get close to the glass, which will extend into the aluminium frame somewhat.
John

 

[diceboy1]

Thanks John.
Are you suggesting that we first pre-drill the hole to a size marginally smaller than that of the self tapping screw shaft using a toughened drill bit?
Are self tapping screws the same as self fitting or self drilling screws?
And I assume plastic rawl plugs aren't needed as part of this option?

Thanks again, I don't know if you can tell but I'm a bit of a novice

 

[Burnerman]

No worries mate, we all start somewhere!
The drill bits you need are HSS (high speed steel), sometimes called jobber drills. You don't want to use self drilling screws here, likewise , plastic plugs .....great for masonry, no place in metal!
An example.....if you use a screw with the outside diameter of say 4mm, then the drill size you need is around 3mm, maybe 3.5 if the frame material is thick - greater than 3mm, say.
So - the theory is, you drill a small hole in the aluminium frame and then you screw a self tapping screw in, which cuts it's own thread and hold your blind bracket firmly.
As ever, a bit of practice on some scrap alloy is a good move if you have such a thing.
John

 

[JohnD]

by chance, I was doing that only yesterday

Some self-tappers have a pointed end, and some are sort of blunt-ended. In my case the holes were rather tight, so I ran some pointed screws through them a couple of times. You need a perfect-fitting screwdriver, in exactly the right size, that is not worn.

If you hold the drill in front of the screw, you should be able to see the threads, but not the shaft. It is not so easy to drive a self-tapper through an aluminium extrusion, as through thin metal sheet.

BTW, small sizes of drill (3mm and below) are easily broken if you drop the drill, or withdraw it carelessly from the hole. You can buy small sizes in packs of 5 or 10 in the same size if you are clumsy, like me. Can be cheap from an engineering merchant on ebay. I very seldom damage larger sizes so end up with incomplete sets otherwise.

 

[Burnerman]

True self tapping screws have a pointed tip.....those with a flattened tip are used with Spire nuts.
John

 

[diceboy1]

Ok- thanks this is really useful stuff!

Can I run a couple of other questions by you both...

1) I read somewhere that when drilling metal you should make a preliminary indentation with a pointed tool to help stop the drill bit 'walking'. Do you think this is a necessary step?

2) Is a 4mm width screw is a good size to go for in this case? (I'm using 3 brackets to fit a 160cm roman blind of pretty average weight I'd guess)

3) Any idea what would be a good length of screw to go far? I'm assuming aluminium window frames aren't solid and I wonder whether I should try to keep screw holes to the interior aluminium layer only or if it's OK to drill through to the gap in-between? Or should I keep going until I feel the drill hit the next layer?

 

[Burnerman]

To drill metal you use a centre punch to mark the work and stop the drill bit skidding away.....the tip of a drill bit is actually flat but only really noticeable on larger drills.
4mm screws sound about right.....you can of course drill a test hole in some timber and see how the screw grips.
The screw, if it has a length of 20mm say, needs a pilot hole along it's whole length.....it can't pierce metal on it's own.
Tip - fix one bracket with one screw and see what sort of purchase you get.....you should be able to tighten the screw firmly but not allow it to strip once it's fully in. If this happens, the pilot hole is too big.
Hope things go well!
John

 

[diceboy1]

Thanks for the advice John, this makes good sense. I'm going to be trying to put the blind up this weekend, I'll let you know how it goes!

 

[foxhole]

No drill bit required.

http://www.screwfix.com/p/easydrive...tracking url&gclid=CLTm9P3-g9ICFSsz0wodJDkNxA