“I am Spartacus!”
Spartacus, what have the romans ever done for us?
“The aquaduct?”
sorry couldn’t resist…
‘Bionk’ is a very apt description of a footy ramming John…
Yeah, too bad, we could probably ge:icon_smokt it dirt cheap from the soldiers in the middle east; if they can collect some and ship it home.
The only problem with the depleted uranium is that it’s still slightly radioactive. self-lighting keel bulbs = night sailing?? :smilebig:
I agree that there’s too MUCh paranoia about lead. The only time it’s that bad for you is when you ingest it. Are there any toxicity studies on lead fuimes (from melting it?)
What about silicon carbide? It’s non-tonic, and widely used in tools. It might be tough to machine or cast tho.
thx
Take a look at this link http://www.pca.state.mn.us/oea/reduce/sinkers.cfm
1/4 way down the page is a list of bans in various states and countries at the time. The general thrust appears to be to stop ingestion of lead by birds, small mammals etc. Ingestion being considered there as the main threat rather than ‘leaching’ of lead from a larger object into the aquatic environment.
Graham
On top of all that, I’ve even heard of some r/c boater ( fast electric racers, I think) not being allowed to operate an r/c model on a lake because they’re using Nickel-Cadmium batteres! “Cadmium is toxic, and if your boatsinks, the whole lake will be polluted!”
Yeesh :mad:
TomoHawk, you are kidding right?
If not, just a quick reference: http://manbir-online.com/diseases/lead.htm
or: http://www.aafp.org/afp/980215ap/stauding.html
Gio
I’m referring to the smoke you see from the crud in your lead when you’re melting it.noia and misunderstandings, just like the electric & gas boat people when they talk a beryllium oxide props being toxic.
As nice as tungsten sounds it is way over the density of lead at 19250kg/m3. Plus, IMO, dealing with a fine powder would not make you imune to hazourdous situations. Lead is pretty nasty stuff and the fumes are quite dangerous when melting them. The worst part is the accumalative aspect to your body.
Seems to me that the best alternative is the lead free pewter that is available now thru jewelery suppliers. It runs $10-$12/lb and is easily obtainable. It has a density of 7279kg/m3 which is less than lead (11340kg/m3).
Now, there are other alternatives too. One is Bismuth, but some of the alloys do contain lead. Bismuth is a alloy that is used for fine detail casting because it is a fusible alloy and expands as it cools as opposed to most metals that contract as they cool. One of the biggest advantages of these alloys is that they are eutectic, which means that they melt at a lower temperature than the parent metals they are made from. Some alloys will melt in boiling water, but others will melt anywhere from 100* to 300*. The density of bismuth alloys are 8857kg/m3
Bob
I think we all need to get together and agree on one value for the density of lead. I’ve seen 3 or 4 different values so far in this topic. For our use, it should be 11.34 g/cc
Tomo, where the heck did you get THAT number? Every chart I’ve seen has it at 11340 kg/m^3 or 11.34 g/cm^3.
Your number would make it slightly more dense than wet peat (1.12 g/cm^3)!:lol:
–Doug
Oops. A typo. Add a 1 to the beginning: 11.3 g/cc It’s from the Periodic table of the elements.
Since we use it in relatively small amounts, It’s better to express densty in grams/cubic centimeter, in stead of kilgrams/cubic meter.
A little more research: there seem to be things on the market called ballast replacement compounds. These are epoxide/tungsten pre-mixed putties of exactly the density of lead. They are used to make ballast/balance weights in production/laboratory equipment to replace existing lead components. From product information sheets (sorry, I’ve lost the list of links), they are no more hazardous in health terms than any other filled epoxide - at least as far as the UK CoSHH people are concerned - and therefore presumably Brussels.
They do have the advantage of being cold mouldable, so it is easier (and healthier) to produce precision bulbs than using hot cast lead. There is no performance advantage whatsoever.
Any more feedback?
I thought the idea was to use a denser material to create keel bulbs that are smaller than lead ones?
How do those epoxy putties cure? Do you know if there is any shrinkage?
thxer
As far as I’m concerned, the only good reason for getting involved with tungsten in blulbs is legal/environmental/health & safety. We can do without any subsantive changes.
A sintered pure tungsten bulb is tiny: it is also VERY expensive!
I don’t understand how you can change the specific grafity of a material. I thought that would be impossible. Do you have a link to a page related to that?
Bob
Bob. My point is about what we say is the ‘material’. Is it the potted goop that you buy as ‘ballast replacement compound’ (i.e. a pre-made up tungsten powder/epoxide composite) or is it the tungsten on its own? There are no magic density changes: mix epoxide (SG about 1.9) with tungsten (SG about 19) in the right proportions and you’ll get a mixture with SG 11.34 or whatever the magic number is.
Tungsten is also very expensive to buy as rod, and is rare in the diameter you would need for a Footy ( about 15mm.) For example, a 10mm rod 30mm long is about 4-5 quid.
And just try to melt it! I think you’d be better off with steel rod, which yould get for free, like I have, but I just like to use the lead.
As an aside, the tungsten putty is also used for sheilding in X-ray rooms, atomic particle accelerators and nuclear power sites.
Tomohawk my dear friend!
Read what I’ve been saying: we’re talking about epoxide putties filled with tungsten powder, not sintered tungsten components: those are VERY expensive.
The putties are not particularly cheap, but I think that those who wish to look after their health and respect the environment should be allosed to do so without a performance penalty. I am not suggesting that the overall maximum density of the bulb should be changed - just that we allow it to be made of a composite that contains a component that is denser than lead and one that is less dense than lead. There is no performance implication whatsoever.
I was confused as some people wanted to go with the denser material, like solid tungsten, for the performance edge, and some (like you) just want an alternative to using lead.
I see no reason against it, but like lead, it takes some knowledge of how to make up the putty (if it isn’t already made up in a pot) and form it with a mould. Not everybody can do that well, and should probably be best left to someone with the pertainent skills & equipment.
One interesting thing- Tungsten putty is used for fishing. So it is getting more accessible to the ordinary person. This shop may be near
you: http://www.shortferry.co.uk/endtackle/results.asp?cat=RBS