CASTING PARTS FROM TIN OR ZINC?

[Kegan]

Hi everyone

I am new to casting but have been collecting materials to melt for a long time. I have only just recently gotten a house and a workshop and am planning my first foundry/furnace build in the next few month.

I have collected cast aluminium and cast zinc and tin items. Ive been learning to tell the difference lately, density seems to be a tell tale indicator. Items like belt guards can be made from aluminium quite easily and the material seems to suit such applications. But items like the base of machines, lathe beds and such call for a heavier material like cast iron. Take the Quorn tool cutter for example.

So has anyone used tin or zinc or zamak or alumimium-bronze to make parts for projects like the Quorn etc? I noticed my Myford ML7 Apron is made from a metal that is not aluminium or cast iron, correct me if I am wrong.

If this topic has been covered sufficiently please accept my apologies and point me in the right direction. If you have experience with any of this please share. I like to experiment and my budget is tight so I like out the box ideas. Simply buying ingots of the right type of material is not an option for me at this time.

Thank you for your time

Kegan

[A7er]

Hi Kegan.
I am not 100% sure, but I don't think you would find many workshop bits and bobs made from cast tin. I would think it was too weak, and too expensive!
Aluminium can be a lot stronger, and cheaper. An alloy such as ZL12 is very heavy, machines well and is readily available. Many amateurs use aluminium car wheels to save trying to buy ingots.
Zinc is something else. It forms 88% of ZL12, the other 12% is aluminium. Many casters steer clear of using it because the fumes from melting zinc can be a bit dangerous. I don't know how dangerous, so please read up on it. Zinc is also found in brass, so be carefull melting brass too.
I am trying to buy tin mined here in Cornwall. Rocking horse poo is more common.
One last thing about tin. Pewter has tin in it and melts at about the same temp. I am not sure how to tell the difference between tin and pewter unless there is a hallmark, or some other marking.
Lee

[Alyn Foundry]

Hi Kegan.

I may not be able to provide much information about sand casting with  MAZAK or ZAMAK as it’s more commonly known these days but I use it extensively in metal dies. It has quite remarkable strength and is also a very capable bearing material for our model engines. It has a fairly low melting point and, because of its density allows for easy
“ gravity “ die casting.

If you’re on a budget you can make a very simple “ pit furnace “ by digging a hole in the ground and lining it with Clay. Alongside the pit bury a 2” diameter Steel pipe that communicates with the bottom of the pit. Set some kindling going and then build a fire from dry wood blocks. Put your crucible in the centre and provide a good draft of air from an inflatable bed inflator. An old friend of mine used this system for many years and was capable of melting Iron, Brass, Bronze and obviously, Aluminium.

The beauty of this method means that you’re not trying to lift and manoeuvre molten metal over obstacles. Just lift out to ground level and pour your moulds. For Aluminium almost any stainless Steel pot like article can be used to melt in. For the higher temperature metals I would really recommend the use of proper crucibles.

   Graham.

Pictures of die cast big end bearing shells and gravity die.

[Alyn Foundry]

Lee has made a very valid point about safety.

Brass and its alloys contain Zinc. At high temperatures it burns off in a White cloud and if inhaled makes you feel very nauseous. The “ Zinc jitters “ was a common name for it. Brass founders ague….

With using scrap MAZAK you can keep the temperature low enough for it not to oxidise however good ventilation is highly recommended.

   Graham.

[Kegan]

Thank you Graham and Lee for your responses, much appreciated. Also, thank you for posting pics. Its wonderful to see what others can achieve, it certainly helps to motivate and encourage me.
Kegan

[ddmckee54]

Myfordboy has used ZL12 to cast several parts for his projects.  He's usually using an inexpensive, and SMALL, electric jeweler's furnace when he does it though.  ZL12 melts at a relatively low temperature compared to brass so at those lower temperatures zinc fumes are almost non-existent.  If you've got an electric furnace with PID control of the temperature, melting zinc alloys should produce minimal zinc fumes.

[Dick Morris]

I've used ZA-27, 27% aluminum and the remainder mostly zinc. It casts and machines nicely. It's lighter and, I believe, has a higher strength than the alloys with less aluminum, but the reason I used it was that was the type of ingots I could buy.

I believe the zinc alloys have a strength comparable with cast iron.

I don't remember boiling off the zinc as a problem for me with the zinc alloys but it has been with brass which melts at a much higher temperature.

One thing to beware of with the zinc alloys, just trace amounts of lead in the alloy can cause corrosion and cracking over the long term. This has given it a bad name. Be careful what goes into the pot and with using the same crucible for for zinc and lead containing alloys.

[Kegan]

Thank you everyone.

Your contributions are most helpful.

Kegan

[Kegan]

Hello all

What type of crucible can I use for zinc and ZA27 etc? I know you need graphite or similar for the higher temperature metals like copper or cast iron. I understand that stainless steel is good for Aluminium and lead as they have lower melting temperatures. Is this true for all metals of low melting temperatures?

Thanks

[Alyn Foundry]

Hi Kegan.
If you’re not concerned about metal contamination you can use just about anything that will take both heat and hold the molten metal.

   Graham.

[Kegan]

Thanks Graham

[fidlstyks]

I always like threads on casting. I started casting in 1980, my dad and I. We made the first molds of just one side, in the old wood boxes with finger joints, using crick sand. Dad then bought all the books he could find, and I learned most of what I know from talking to others abd experimentation. 
   We melted aluminum in a steel ladle in a coal forge. Dad burned a hole in it,and Grandpa put a rivet in the hole so he could still use it.
   We melted old carburetors at first,as they are  pot metal, which is like what your talking about. Zinc and aluminum. We bought new  pot metal once, called Alazac. It would crack in time. Cost a buck a pound 40 years ago.
   I use to make my pattern copis from pot metal as it does not shrink.  But normally use aluminum.
   Burning the zink causes zinc chills. If you ever think you have breathed it in, drink some tomato juice right away, and never soda pop. That would make you real sick.
   Yellow brass is the same way. Red brass has lead in it, and it makes people go crazy like a hatter from mercury poisoning. I have had a time finding new yellow brass or red brass, and not many foundries will cast them. The story is something about the EPA, and pollution. It use to be the only requirement for melting was for old sand disposal, in that one had to pour a little acid on your old sand, write down what colors it turned, which indicates contaminant are present, then dump it back where sand came from.
  Crazy sounding but true.

[fidlstyks]

Hi Kegan.



If you’re on a budget you can make a very simple “ pit furnace “ by digging a hole in the ground and lining it with Clay. Alongside the pit bury a 2” diameter Steel pipe that communicates with the bottom of the pit. Set some kindling going and then build a fire from dry wood blocks. Put your crucible in the centre and provide a good draft of air from an inflatable bed inflator. An old friend of mine used this system for many years and was capable of melting Iron, Brass, Bronze and obviously, Aluminium.

The beauty of this method means that you’re not trying to lift and manoeuvre molten metal over obstacles. Just lift out to ground level and pour your moulds. For Aluminium almost any stainless Steel pot like article can be used to melt in. For the higher temperature metals I would really recommend the use of proper crucibles.

   Graham.

We actually started out melting in a pit furnace, but we used an old cast iron tank heater with a car rim as a lid and coal as a fuel. We melted yellow brass and aluminum.
     I am now thinking I need to build my next furnace as a pit furnace. But one would have to keep it dry. Very interesting idea.
   I wonder how the clay walls would hold up and how to arrange a top.

[Alyn Foundry]

Hi Kegan.

If you’re on a budget you can make a very simple “ pit furnace “ by digging a hole in the ground and lining it with Clay. Alongside the pit bury a 2” diameter Steel pipe that communicates with the bottom of the pit. Set some kindling going and then build a fire from dry wood blocks. Put your crucible in the centre and provide a good draft of air from an inflatable bed inflator. An old friend of mine used this system for many years and was capable of melting Iron, Brass, Bronze and obviously, Aluminium.

The beauty of this method means that you’re not trying to lift and manoeuvre molten metal over obstacles. Just lift out to ground level and pour your moulds. For Aluminium almost any stainless Steel pot like article can be used to melt in. For the higher temperature metals I would really recommend the use of proper crucibles.

   Graham.

We actually started out melting in a pit furnace, but we used an old cast iron tank heater with a car rim as a lid and coal as a fuel. We melted yellow brass and aluminum.
     I am now thinking I need to build my next furnace as a pit furnace. But one would have to keep it dry. Very interesting idea.
   I wonder how the clay walls would hold up and how to arrange a top.

These days there are the new refractory materials available like Ceramic Fibre. Absolutely amazing thermal efficiency but easy to damage. I would suggest a proprietary refractory compound that you make in the same way as Concrete. However you can make your own using a mixture of Silica sand, cement and Pearlite using diluted Sodium Silicate to wet the mix.

Vincent had his pit furnace down the garden underneath a lean too that kept the rain off. It also greatly reduced the exposure to the noxious fumes created during melting.

   Graham.

[Alyn Foundry]

Could someone in admin please tidy up my previous post please? Somehow the quote message has got into a tizzy.

   Graham