Shuttering - The Hempcrete Topic: Designing and Building with Hemp-lime - page 286

Long heavy-duty screws are ideal for fixing temporary
shuttering.
The heads of these heavy-duty screws are usually hexagonal nuts (supplied with a match-
ing socket bit in every box), or they have a recessed torx or 'star' drive (and are supplied
with the corresponding bit). In either case there is usually a flat at the bottom of the head,
before the shaft of the screw starts, so the head sits on top of the face of the board instead
of being pulled through into the board.
You may need to use impact drivers to put these screws in, and pull them out, especially
if your screws are a bit over-long for the job. Normal cordless drill-drivers come in a huge
range of specifications, and some of them will be up to the job, but even if they are they
will be slower than an impact driver. A very low-torque drill (+/-500rpm) is sometimes
useful for tackling screws that refuse to come out.
Be careful to periodically check the hex socket bits that are supplied with the screws, as
these do get rounded out over time, and using a worn socket can round off the hex nut on
the head of the screw, making it difficult to get in and out. It's a chicken and egg situation,
but at a price of around £1 per screw, you will do better to keep an eye on it, and throw out