Solder..?

Roderick,

not quite

dry weight is density * volume

weight of water displaced is (density of water) * volume

so wet weight is (weight in air) * volume - (density of water) * volume

go through the algebra and you get density = density of water / (1 - wet/dry)

as a worked example, if a lum of stuff had a dry weight of 17 gms and a wet weight of 15.5 gms, its density would be 1 gm/cc /(1-15.5/17) = 11.33 gm/cc

To answer John Fletcher, I was never a jointer, but, as is often the way of these things after working mostly as an exchange maintainer, I did finish up in charge of a cable maintenance group where quite a lot of lead plumbing was still needed. So far as I can recall (I left in 1996) the official way of keeping things neat was the use of plumber's black as John describes. In practice, I think careful use of a shave hook to scrape off only oxide in the target area before soldering limited where the solder travelled, bear in mind that almost no new lead cable was worked on by the time I arrived.

Keeping it tidy is something which I have often wondered about when soldering in recent times, only soft solder currently but I may yet take the plunge to silver solder up my Rob Roy boiler........

Duncan,

You'll note that I said "suspended" in water. Being an empirical sort of guy I have just measured a cut off a rectangular steel bar and calculated the vol at 94.67 cc and weighed it at 737g. This gives a density of 7.79 which seems reasonably correct for mild steel. I then suspended the bar from a thread and lowered it into a bowl of water that was sat on a tared scale. The indicated weight was 95g which equates, to sufficient accuracy, to 95cc. I'll let you do the algebra, I can't remember how.

Cheers,

Rod

That's not what you suggested in your first post ' weigh it suspended in water'. This to me at least means having the lump of lead/steel/whatever hanging from a balance, not what you've just described. Yes this second way measures the volume directly since 1cc of water weighs 1 gm. You need some conversion factors to do it in Imperial units

I thought Yorkshire fittings were so named because they used less solder!

Thanks for all the info guys, some interesting reading there.

This is right off the top of my head so bear with me, I wondered if I could make some small castings with the solder. I know that solder is relatively soft but I wouldnt want to machine the castings just clean them up by hand. I was wondering what I could use for the moulds, would some form of clay work, it would be good if it would as I could make the patterns from wood and press them into the clay to form the moulds.

Or is it a daft idea..?

Ron

Edited By Ron Laden on 24/08/2018 09:34:50

Probably more or less how lead soldiers were made once upon a time.

Just to add; I used plaster-of-paris to cast lead keels for model sailing boats. Best to make sure it's dry though.

Edited By Clive Brown 1 on 24/08/2018 10:30:48

Don’t know, but apple wood is used for forming molten glass, so wood moulds could be used a few times before they deteriorated?

Cuttlefish shell (you know - like budgies gave in their cages) was used for making small single sided castings - press the original pattern into the soft side and pour your solder into the depression that is left.

Alternately try some lost wax casting by covering or investing a wax pattern in plaster inside a short length of copper tube with a funnel like entrance at the top. Heat until the wax has melted away and then melt some solder in the funnel. Clap a metal lid on with a circle of wetted cloth in it (I used to use the lid of a pipe tobacco tin) and the steam will force the metal into the mould. Break out your finished casting. You will need more heat for this though.

This method was used by dental technicians years ago and I attended a demonstration at the Nottingham SMEE in the seventies before trying it out myself with what was then called students metal, however I suspect that you will need absolution from H&S to do it today!

My grandfather lost three fingers off his right hand when he was 14 years old, left with a thumb and little finger he had a long career as a plumber in the proper sense of the word, wiping a joint was no problem and making a lead lined cistern and such things were normal jobs.

Mike

Just an observation, if you had the lump suspended from a spring balance and dipped it in a bowl of water on a scale, the spring balance reading will go down by the same amount as the scale's reading goes up (assuming they are both accurate).

Now, tell me - how can you weigh your head accurately without removing it?

Neil

Why would I want to do that?

Tim