Sometimes things slip through the cracks. Too often in my case I guess. I recently mentioned that rawlbolts are not always the best choice and that coach bolts are often better. Somebody, might have been Peter Moss, asked what coach bolts are. Can’t remember whether I explained, so here goes. Put at it’s simplest a coach bolt looks like a big Fischer plug. But it is more than that. Most plastic plugs are just that, plastic, which perishes over time. For long life you need nylon plugs which don’t perish. The bolt is really a big wood screw but has a hex head. An 8mm screw fits a 10mm plug. They come in various lengths. For safes you want them as long as the brick thickness will allow. I use 10mm screws with 12mm plugs for safes. About 120mm long is OK. Remember that the whole 120mm does not penetrate the wall because of the thickness of the safe, washer and often a spacer between safe and wall. I’ll come to that later.
The best place to get coach bolts is Ramset who must have a depot or agent in all cities and towns. Ramset is well known in the construction industry and is a supplier of all sorts of fixing screws like chemical anchors and the like. If memory serves they told me that a 10mm coach bolt has a pull out strength of 4 tonnes in concrete.
Some will tell you that installing a safe is an easy half hour job. Depends what sort of job you want and I’ve never installed one in less that two hours. The longest took five hours. The ideal position is a flat wall thick enough to accept long bolts but I seldom had that advantage. Mostly a cupboard is the only available place and most people want them concealed anyway. In Cape Town most cupboards have a masonite back which is usually some way of the wall, so the masonite back is pulled out of line when the bolts are tightened. On a plastered wall you can’t see where the brick joints are so it is hit and miss whether you drill into a suitable place in the brick. There are various kinds of brick. Some are hollow extruded. If you don’t drill those in the right place the bolt won’t get adequate grip. In one case I had to drill new holes in the safe because it could be fitted in only one place and the holes I drilled in the brick didn’t allow enough grip. Fortunately there were a few bricks left over from the construction, from which I could gauge where to drill the new holes. Which is why matching holes had to be drilled in the safe. I’ve had other bricks that were so soft that they crumbled when the bolts were tightened. That was solved by chemical anchors.
It’s a good idea to enlarge the holes that are usually in the safe. Also to drill more of them. They are sedom more than 8mm, maybe 10mm if you are lucky. It is notoriously difficult to drill a hole in an exact position in brickwork. It takes only a millimetre or so error to make installation impossible. The answer is to enlarge the holes quite a lot to allow some latitude in positioning the safe. I make them at least 15mm. Then you use a big washer. Two or three of those big disc washers called fender washers works quite well, alternatively those 50mm square x 5mm thick washers used for roof construction. Both cover the hole and distribute the load over a wider area.
Most safes come with two holes. That might do for those tiny one handgun safes but not for rifle safes, which should have at least four or six for the bigger safes. I provide one at each corner, about 50mm inboard from the corner to allow access for spanners from the inside, and two halway down.
Rigidity, or the opposite (flexibility) is a function of material thickness, shape and size. A small safe will be less flexible than a big one. Rifle safes will flex quite a lot. Most walls are not perfectly flat. The result is that tightening the bolts will often pull the safe out of straight enough to prevent the door closing properly. That’s why spacers are often needed between safe and wall. My own safe has been installed in five different flats or houses. In addition I’ve installed quite a few for other people. Every one has needed spacers. They can be thin enough that steel washers will do, but sometimes two pieces of 3mm masonite has been necessary. Believe me, it takes a hell of a lot of cut and try to get it right.
Anyhow, that’s the bare bones. There’s a lot more to it, so I don’t where the notion comes from that it’s simple. But maybe I’m too much of a perfectionist.
[Originally posted to SATalkGuns -- Admin]