fixing plywood to metal

[george (dicegeorge)]

I have some plywood boards to fix to metal frames. My plan is to use self-tappers. Drill holes the width of the centre of the screws. Then use an impact screwdriver? Is this the best way to do it?

[g]

[Dave Plowman (News)]

If the plywood is thin I'd use nuts and bolts - with washers to spread the load over the plywood.

[John Rumm]

You can get self drilling screws which can work well for this sort of application.

[Steve Firth]

OK...

There's an appropriate hole for each size of self-tapper. This is a reasonable guide:

Then use an impact screwdriver?

The last is great if you really mean to mash up the screw heads and shear them off. Use a proper screwdriver or, since there seem to be lots of screws to fix, a cordless drill with a torque setting.

[george (dicegeorge)]

the toilet frames are made of square section metal so I dont think nuts and bolts will do, they'd be bent when we pack it away for the winter

[g]

[Stuart Noble]

Rivets look neat

[george (dicegeorge)]

So why is an impact screwdriver great for screwing into oak, but not into metal?

[Steve Firth]

I can't recall recommending an impact driver for such a task. I've used one to get rusted in screws out of oak.

You're only trying to hold plywood to a metal frame WTF do you need an impact driver for?

[John Rumm]

Are you sure you guys are talking about the same tool?

[george (dicegeorge)]

Yes i meant about using an impact screwdiver, like the blue battery one in the picture, it drives screws into oak.

But would it be suitable for driving self tapping screws into metal framework? Or is there a reason to use a electric drill on low torque setting?

[g]

[John Rumm]

They are often used for fixing drylining to metal studwork - usually without pilot holes. I can't see any real difficulty unsing self tappers into more substantial metalwork - just take care not to drive past "done"

If your cordless drill has a torque limiter and it can muster enough torque to start the screw, then you can use that if you are worried about over driving.

[Steve Firth]

plywood to light metal IMNSHO.

[Pete Verdon]

Seconded. A mate's dad boarded out his vast (as in, space to work on half a dozen cars simultaneously) workshop using hex-head Tek Screws to fix ply to thin steel. No drilling required, just press the screw to the required location and pull the trigger. If the job had required pre-drilled holes in each board it probably wouldn't be finished yet.

Pete