SCREWDRIVERS

[graduate_owner]

If you regularly need to remove stuck screws which your normal driver won't cope with, you could try an impact driver. I have an 18volt Makita which is simply brilliant. The torque is just amazing. These things aren't cheap ( I was lucky enough to be given one by someone who was upgrading to Li ion) but they are really useful, not just because of the torque but also because the impact action results in less chance of shearing the screw.

K

 

[dc_ni]

I bought a box of these about a year ago and they do 90% of my screw driving jobs.
I think I have about half left.

Not only are they cheap but seem decent quality. Having a boxful avoids the temptation of making a manky one last a while longer

https://www.amazon.co.uk/DeWalt-DT7908- ... dpSrc=srch

Anyone buying tools from bnq must have money to burn

I'll second the Dewalt bits, got a box of them from a local builders merchants, still have some left.

 

[nabs]

They are designed to cam out once the screw is set, which is why they are common in manufactured goods.

Thought you might like to know that's a myth. It supposedly stems from a mis-read of the original patent but it clearly states they were not designed to do this, in fact the exact opposite!

Phillips screwdrivers in the real world are of course very prone to it.

I had read the same thing about the philips screw head design and uncritically assumed it to be correct - there was a plausible sounding explanation (something along the lines of it being preferable in industry to break a screw than over tighten it and break the part that was being held in place - but now I think about it, that must be nonsense - why would a machinne over tighten a screw?)

Anyhow, I looked at the patent and you are quite right on both counts - the propensity of philips and pozidrive screws to cam-out is particularly galling since a much bettter design was invented 15 years earlier by Roberson.

like philips it is self centering and it has a better grip than pozi-drives thanks to the slight taper on the bit so it can be used one handed/upside down etc .   The snug fit in a deep recess also reduces the chance of"cam-out".

Apparently Ford used them in Canadian produced Model As but switched to Philips after Robertson refused to grant him sole rights and the rest is history (although I read 85% of the screws used in Canada are Robertson - indeed my Canadian Veritas vice came with some included).

 

[Phil Pascoe]

They're the commonest in NZ according to my bil (an ex ship's joiner).

 

[Bob Graham]

Dare I say it? Oh go on then. This has been an interesting thread.

 

[pcolbeck]

If your using an impact driver then as well as bits that are designed for impact drivers you should use a bit holder that's designed for impact drivers. If you don't then the bits wear out quite quickly even if they are Wera or another good brand. Its to do with the way the holder cushions the torsion apparently. WIth Wera its Impaktor bits and holders.
This is theoretical knowledge to me as I only have a dril/driver not an impact driver. I would be interested to know someone's real world experience of this though.

 

[Sideways]

You can get longer (typically 50mm) bits that have a torsion zone built in. If you're using standard short 25mm bits, the impact driver manufacturers (pretty widely I think) recommend that you use a "impact" type bit holder with a torsion zone built into it to reduce the shock.
I always wondered a bit about this as on the one hand the tool makers are making more and more powerful impact drivers and on the other, they and others are selling accessories that seem to mitigate some of that impact.

I bought a Bosch 18v impact and like it as it's one of the most comfortable tools in the hand that I own but they are all much noisier than a drill driver so the driver is what I reach for first for general screwdriving.