Putting up my shelves

[Rod]

John,

I should have put a smiley on your part. :-)

Dennis is doing what he often does.

[John Rumm]

Scales measure weight (i.e. the force that pulls masses toward each other), not mass[1]. Hence, as was commented elsewhere in the thread, the volumes of the samples would be different, and this would effect the amount of air displaced and hence the uplift from that, and also the distance between centres of gravity and hence the strength of the gravitational pull.

[1] The fact that they read in units of mass is only because they perform a conversion between weight and mass making assumptions about the strength of the gravitational field.

[John Rumm]

If you use something of decent thickness like 1" thick window board, and stick 2x1" battens on the wall right round the back and both sides you should be ok. If you want to use something thinner then you would need a lipping on the front.

[dennis]

Where does the bath come in?

Where does the water come in?

Does it weigh the same though?

You are getting things out of context.

[dennis]

I can't imagine any lead shape that will float in the air in a normal room, maybe you could describe it?

[Rod]

In water.

[stuart noble]

The point of my original remark was that people *stack* plates in kitchen wall units without giving a thought to the fixings

[dennis]

Its *you* that is trying to be serious.. the rest of us are having a bit of fun. If you must be serious, please try and be sensible.

[dennis]

How are you going to get water to stay on the shelf?

[Rod]

The bath (ibid).

[dennis]

Did the OP want a bath on his shelves?

[Andy Hall]

It's called doing the job properly with a solution that is easy and inexpensive and will have no difficulty whatever in taking the weight, versus trying to calculate what really can't be calculated properly and is therefore a guess at best and a bodge at worst.

[Dave]

Huge snip.

I did my kitchen about 12 to 14 years ago (don't laugh) using MFI carcasses. The way that it is screwed to the wall is through a chip board batten that is behind the back panel, that is doweled into the side of the carcass and using 4 screws to go through the back panel and batten, into the wall. Cupboard is 300 mm wide and standard upper cupboard depth and height. I remember being very sceptical about the strength of this having worked in the aerospace industry, but several years later, I have never had to take one down to correct it from coming off the wall and the one I have just looked at is full of glass, pyrex and plates.

I know a little about stress, but not enough to calculate the forces in this context, as far as shear and tensile values go.

Dave

[Dave]

Me eds aching and my ears are getting sore from the whooshing sounds that are becoming increasingly louder. I'll move on to the next thread if you don't mind :-)

Dave

[stuart noble]

The sheer strength of a screw isn't in doubt and, if the wall can't support the fixing, a squirt of resin isn't going to change that. I've pulled those things out with a claw hammer before now.

[Andy Hall]

My point about the various mechanical frictional fittings (e.g. Rawlbolts and their ilk) is that the hole has to be very accurately the right size and there is a risk of splitting a block or even a brick when tightening them. I have done this before now.

OTOH, it's easy to go for a 110mm stud and get a very solid resin fixing. There are even solutions for cases where the block or brick have a hollow core and where a conventional plug and screw would be decidedly dodgy.

The discussion is almost pointless. You can drill a hole not particularly accurately and clean it. Fill it with resin and insert stud. Clean off any that is ejected at the surface. A few hours at most and the entire job is complete with very inexpensive fittings. All that remains is to fit the shelves and frames if used to the studs. The whole exercise is simple, quick effective and inexpensive. It really isn't worth titting around with questionable mechanical fixings which a) may damage the wall and b) may give way under load.