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> I have no idea why on earth we still have slotted engineering screws with a cheeky short cylinder on the end to aid initial contact, to hold electrical faceplates onto back boxes.

I would assume that it's because in areas where it's possible for the head of the screw to get "gunked up" with paint or dirt, that a slotted head is easiest to scrape away the material and restore function. You generally don't need any special tools for this -- you can use the screwdriver already in your hand.

I noticed this feature when watching some wooden boatbuilding channels that specifically use slotted head screws in places where the fasteners are recessed in the wood and will be filled and sealed with wood plugs. The slotted screws can be cleaned out later if repairs need to be made.

I think it's more that electricians typically have an electrically insulated slotted screwdriver in their hand at all times.

If any electrical device were to require a different screwdriver it would be extra effort to go get a different screwdriver when everything else uses slotted.

Must be regional. Over here I picture electricians with an insulated #1 square welded to one hand and a power driver to the other.

Slotted stands out because it's a wallplate-only screw.

> * the real problem is getting the bloody things out again after 10 years of weathering or other age effects. *

Try putting grease on thread as you drive it in. 90% or so of the bolts and coach screws i've removed from hardwood or treated pine are reusable after 15-20 yrs in Oz climate. They were all greased up by my dad going in. The ones that failed are rusted badly & the grease wasn't coated around the shaft. The good ones have signs of corrosion (we use galvanised), but essence of grease and the thread is still there.

We don't use Pozi, but use hex drivers (coach screws & bolts) or their negative female equivalent (bugles), which an allen key fits into. We also pre drill holes.

"Try putting grease on thread as you drive it in."

I appreciate the advice mate. We have quite a diverse set of conditions to deal with. I live on an island that is N hemi. and temperate. You live on a huge island that is continent sized and S hemi.

Pre-drill holes: me too and I think that is a real win.

My golden rule is that the less stressed fix is a good fix.

It's probably time for me to see me relos down south!

> You'll be using torque that can potentially break or at least hurt your wrist if you are not careful with a big drill/driver

Getting an impact driver for woodscrews was a game changer. I used to do theatre carpentry which mostly involved rapidly assembling stuff that a chorus of 20 can dance on. It frequently involved big timbers and large woodscrews. Even carefully piloted, and clearance holed a 4"x12 (80x12) requires a lot of torque and a lot of weight on the drill in order to prevent cam-out and head stripping, and even with practice it was challenging. With an impact driver there's no issue at all. You just learn very quickly to buy impact rated PZ bits for it!

I share the experience that impact drivers seem to require less downward force to keep the bit engaged compared to a drill or hand screwdriver but I can’t work out why this should be the case. If they exert the same torque then shouldn’t they require the same downward force?

The nature of impact is that it comes in many "hits" vs continuous application, maybe? Just guessing.

> For really big wood screws eg joining two sleepers, we generally use hex headed screws …

Known as “Coach Screws” in the UK, if anyone’s searching for them.

For new screws in my experience pozi outnumbers phillips 20:1 at least, and flat heads even higher. Flat heads I only really see inside plugs which I rarely need to remove, even the outside screw for changing the fuse tends to be a phillips, if the plug isn't moulded of course.