on 24/03/2004, Charles Middleton supposed :
Hi,

Ive got a few questions on projecting rawl bolts....

Is a projecting rawl bolt one that has a a screw thread projecting out from
it on which you can mount things such a bracket of some description.

If this is what I think it is Ive seen a few on the web and its exactly what
Im looking for. However, it looks as if you put onto the thread say your
bracket then you tighten a nut onto that to secure bracket against the wall
lets say. What I cant understand is what you do to actually expand the rawl
bolt once it is in the wall. How do you turn the thread to expand the bolt?

Thanks in advance,

There are two models of the common rawlbolt. One has a projecting
threaded stud, onto which you tigten a nut after slotting the item to
be fixed over it first. The other end of the stud has an integral wedge
shape which forces the wings of the outer sleeve apart to grip the
sides of the hole.

The second type is similar the above idea except that inplace of gthe
stud, it uses a bolt which screws into the threaded wedge. This type
often needs a little extra hole depth in the wall to allow the end of
the bolt protrude, whereas the first type doesn't.

The tubular outer sleeve in both types consists of four cast lontitudal
plates held loosely together by a spring, so they are able to be
expanded. The wedge has four flat sides which locate against the above
plates to prevent the wedge from turning as the bolt (or nut) is
tightened.

For most jobs either type can be used interchangably. To actually use
them, you drill an appropriatly sized hole of the correct depth. You
then insert the rawlbolt, tighten it up so it locks itself firmly in
the hole, then gently remove the bolt (or nut) after which you can
finally offer up your bracket.

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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org