John wrote:

The Medway Handyman wrote:
Hi All

Just received some 10 x 100mm Turbo Coach Screws from Screwfix.

The catalogue description reads:
"Make any job faster with Zinc-plated, Yellow-passivated Coach Screws,
combining the unique design of the Turbo Screw along with a self-cutting
point. (May require pilot holes in harder substrates.) Unique Rifled Shank
for Easier Driving & Reduced Splitting, Self-Drilling Point".

You simply cannot drive these into softwood without a large pilot hole!!!!
Let alone 'harder substrates'.

I tried with my 14.4v driver (loads of torque), a 350w mains driver and a
500w variable speed drill. No chance at all, they go in for about an inch
and thats it.

Screwfix have responded to the problem by offering a credit without
collection to be fair to them, but I'm still going to lose time on a large
decking job. I've ordered some 6.3 x 100 Exterior Timber Screws at double
the cost in the hope they will drive OK.

Never trust a catalogue description!

I've just built a pergola using M8x150 Turbo Coach Screws from
Screwfix. They went straight in to treated softwood using a variable
speed mains drill. I did final tightening (1/2 turn or so) by hand
using a socket & ratchet. No problem there.
My cheap 16V battery drill wouldn't look at them but I didn't expect it
to. The mains drill did get hot so I had to cool it by either running
off load for a minute every couple of screws or arranging my work to
give it time between uses. A two speed gearbox driven drill would
probably have coped better.

I use those 8mm coach screws as well in similar material. 8x100 and
8x120 in my case. Like you I haven't found pilot holes necessary, I'm
using a Metabo 12v cordless to drive them which I chose specifically
because it can deliver up to 50Nm of torque.

--
Chris Green