PH3 and larger screwdrivers

In article , Fred writes

PZ3 is common for larger size screws, I have driven moderate length #12 screws with these heads and they have been fine but I've had bother with larger frame fixings that use PZ3, the bit just can't transmit the torque reliably without the risk of destroying the screw thread.

For larger fixings I now pay a little extra for torx head screws and I've not had a failure since.

Googling for Pz4 suggests they do exist, dare you search higher?

I have both pz3 and pz4 on my toolrack made by stanley and bought many years ago

Think I may have once used the pz3 but cannot recall ever using the pz4

Regards

I had to buy one many years ago to adjust the hinges of a car. Can't remember what the car was, nor where the screwdriver is at the moment. That was the largest one I ever bought.

Probably, but I have never come across anything bigger than a size 3 head.

What's the widest flat blade

When I was on the tools working on Tornado development aircraft, the forward jacking point blank was approaching an inch and a half head diameter. Your average DIY screw driver would just make a mess of the slot in quite a short time.

But surely, a screwdriver could never be considered a chisel, even though a screw driver is used in many situations other than screw driving :-)

Dave

No 3 is standrd on flatpack fittings

NT

Screwfix turbogold 6mm, and Spax 6mm screws, both PZ3.

Thanks everyone for the replies so far. A lot of people are posting about PZ3. I think they are quite common; I was wondering more about PH3: has anyone ever seen or used those?

Re. PZ3 I have encountered them on 12 gauge screws. What do you consider a moderate length? I think I have used up to 4 inch screws without problems.

I tend to use hammer fixings rather than frame fixings, though is their really any difference? The only difference I can see is that frame fixings have those two protrusions at the end, which I think are supposed to stop them rotating, though why would rotation be a problem when they are a symmetrical design? I read somewhere that hammer fixings use a stronger screw to take the force of being hammered but I wonder whether manufacturers really use two different types of screw in frame and hammer fixings? Wouldn't it be cheaper and easier for them to sue the same in both? I accidentally hammered in some frame fixings the other week (I wasn't concentrating when I bought them) but they seem to have survived!

Thanks.

Really? Do you mean for cam locks, like these:

I've got a Pz4 (Wiha) and used it a few times for door frame fixings.

Screwdrivers have flat ends to their blade, so never.