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Posted by Michael Bulatovich on April 29, 2007, 10:59 am
>>
>>
>>>I need to attach what would look like a small shelf (2"a x 3"b x 4"hyp):
>>>to
>>>a plaster wall. It is to support a magnifying lamp with a clamp-on
>>>pivot
>>>arm. The lamps weight is a bit of a beast. The shelf itself is not a
>>>problem, I can make it out of 3/4" plywood, but I do not have experience
>>>with this type of wall. It is not drywall, its the kind of very hard to
>>>knock on stuff, from 70 yrs ago. The small shelf is a <||>, turned 90
>>>degrees, for a beast of a clamp-on pivot arm to the || shelf. A small
>>>horizontal shelf dadoed into vertical pieces bolted into an inside corner
>>>wall will withstand the torque stresses. I have a 1/2" hammer drill and
>>>I
>>>will need to drill into the normal wall (inside corner) both above and
>>>below the shelf at right angles so the clamp-on pivot arm torque forces
>>>on
>>>the shelf will be pushing on the shear of the four fasteners. The
>>>distance
>>>from the adjacent wall will have to be the width of the 1/2 profile of
>>>the
>>>hammer drill (maybe 2" from the inside corners, about 27" up a 8' high
>>>wall). I have a feeling I will need to build a jig for the holes,
>>>probably
>>>with plywood with washers hammered in spaced spade drill holes, so the
>>>masonry bit doesn't jump all over the place. So I will be using masonry
>>>bits, but since I have never attempted such a hold, not drilling in this
>>>type of wall, I don't know what type of fasteners to use, or if I need to
>>>worry about drilling out with HSS-type regular-drill for lath or whatever
>>>might be in there from before I was born.
>>>
>>> So the question is:
>>> What's in there & how do I drill it out (several drills, drill holes in
>>> wood shelf after?)?
>>> What kind of fasteners do I use through 3/4" plywood & into wall (lag
>>> bolts, expanding bolts)?
>>
>>You never said on what the "plaster wall" was supported, though you seem
>>to
>>assume masonry.
>
> I am assuming that he thinks he needs a hammer drill with masonry bits to
> get
> through the "very hard" plaster and then possibly switch to an HSS bit to
> get
> through the lathing strips or "whatever might be in there."
If it's a frame wall, regular bits will do it, but he has to find the studs.
Look for electrical boxes (attached to studs) or for nails in baseboards,
which will also indicate stud locations.
--
MichaelB
www.michaelbulatovich.ca
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