Backyard Casting

I know quite a number on here cast their own stuff and I also know quite a few people would like to try it but don't know how or where to get the materials.

I needed to do a bit of casting today so I thought I would do a bit of a pictoral "How To". Casting is not for everybody and to be honest, you only need to do this a couple of times to realise those expensive castings may not be so expensive after all. In fact they may be a bit of a bargain.

Materials. You are going to need some "stuff". Whilst most Casting "stuff" is as old as the hills you are going to need some simple, but basic ingredients. First off, you need the Metal itself. I assume you are going to use Aluminium and old castings along with a bit of good ally material in the form of offcuts will be fine. Then you need a crucible. For casting Ally this could be one of those stainless containers from the supermarket, but don't expect this to last too long, a couple of pours at most is the general experience. I don't know, I have never tried it. I have a couple of good crucibles.

Then you are going to need a Flux and a degassing agent. You can't really go far without these two basic chemicals. I suppose you could possibly use Borax but again I have not tried this. I buy my flux and de-gassing tablets from John Winter Foundry supplies who are one of the shopping partners on this site. They cater especially for the home foundry in one department and also they are the only supplier I know of who supply Oiled Green Sand. I prefer oiled sand as it gives good definition, holds together well, stores well and al the other good things you want. Doesn't come out of carpets easily though as it tends to stick, being oiled an all. You have been warned

Outside everything else, the most indispensable piece of kit you need are a pair of leather gauntlets. You might get away with a pair of gardening gloves. You probably won't. A pair of good gauntlets are not that expensive. Shop around but believe me, you don't want to be cutting corners. Then you are going to need a furnace, I made my own, pair of good tongs for the crucible, I made my own, a drag and cope (the two halves of the mold former, again - I made my own. In fact you can make everything you need yourself if you so wished.

So, let's get on with it, first up, fill the bottom bit with sand:

Then place your pattern in it. I am doing this a bit ass backwards, because I made a simple pattern from a piece of pipe in one piece. A quick look on Utube will show you how it all goes together with a split pattern but this job is in no way precision casting because today I am making Lead Hammers. Close enough is good enough.

The white powder you see sprinkled everywhere is plain old Talcum Powder. Fruits of the Valley I think this was, smelled nice anyway:

There you go, pulled the two apart and now laid the shaft ready in the drag, the bottom part of the mould. I have also now made the runners for pouring the metal in the Cope, the top part of the mold:

Edited By Oompa Lumpa on 07/09/2014 22:57:33

Now, the lead is ready to go, it is well molten and now I am going to drop a de-gassing tablet in it:

You can see I have used my special Foundry Ladle to remove the dross in the pic too and that grey lump is a de-gassing tablet - and what is the strange tool next to it, looks like it fell off a Dalek - all is revealed here;

It is a stainless sink strainer that I have made into a plunger - I use all the best tools as you can see. Common sense dictates that you bon't look directly over the crucible when plunging. It is quite volatile and can be violent. Not dangerous at all if you are careful. The one cardinal rule is that your tools nust be dry. Do not for instance begin casting outside when it is raining. (and as a word of caution - don't try this inside a building unless it is the size of an aircraft hangar). Also, do not pour over the vent hole either, move around so the pour hole is right in front of you:

And here it is, a lead hammer:

Lead is easy to work with, I first started casting with lead when I was about twelve, going back a bit, but once you move up to aluminium, everything doubles, twice the heat, twice the protection and so on. Casting Bronze is yet more hazardous and Casting Iron is another ball game altogether. Here are a couple of ingots from today's casting, they are both shiny but the one on the left is lead and the one on the right is aluminium. Their shape reveals their very different characteristics.

You can also see some bits of iron pulled from the aluminium melt, a trigger and a couple of grub screws, one way to dispose of unwanted scrap guns!

Is home casting "worth it". Well, that depends. If it is a special one-off that nobody has, it may be your only way to get that part. If you want to pass a couple of hours right back at the basic level of metalworking, it is hard to beat. Blacksmithing is it's equal and occasionally I can be found doing work on my anvil. I find it very relaxing. It is not for everyone, it can be messy, it is certainly dangerous and it is hard work and usually, when you are finished all you have is a bare casting. But then that was the idea, wasn't it?

I am not suggesting for one second this is how you go about casting or even any of the techniques I use are correct. This is how I do it and it works for me.

graham.

Thanks Graham, you have just spurred me on. I have not done any casting since I was at school (ally and brass) but have been working on patterns for the Gingery shaper some of which I will cast at home though the main side parts I think will be from sheet as per Dias Costa's lovely machine. Also part way through building the Gingery furnace (well I a very old and empty gas cylinder cut in two, and a bag of vermiculite sat in the garage) with a few minor changes - to be fuelled with either propane or charcoal. I thought to use the recipe given in Mikesworkshop. Just need a couple of forty eight hour days to bring it all together.

David

I would argue the need for degassing tablets. I did some casting at evening school some 40 years ago, we degassed the metal and the resulting casting was full of bubbles.

Over the last few years I have produced approximately 40 castings in aluminium at home and have not done anything to degass the metal. None of my castings have shown any bubbles. when machined.

Whether you degass or not have a go at casting it is very addictive! It also can save you a lot of money, I am currently building a rotary table and the cost of materials if built from bar stock was over £40 but with castings the only real cost has been the fuel for the furnace and that is under £5.

Edited By norman valentine on 08/09/2014 08:46:02

This link is good for anyone contemplating home casting

http://www.backyardmetalcasting.com/index.html

Good crucibles can be made from empty “non refillable CO2 (disposable) cylinders cut in half - use bottom end - Take care when releasing any pressure left in cylinder

Hi Graham,
One warning you missed out although you show that you have the paving blocks covered was not to work directly on concrete as it can explode if molten metal is spilled on it. I have tried using stainless steel containers and they do only last a short time. I think they dissolve slowly in molten aluminium and start to leak. I have seen it recommended to heat them for a time to form a good layer of oxide on the surface before melting the metal in them. I think it is a good idea to post information on techniques like this to tempt people into trying them.

David, I used the recipe for home made refractory in "Mikesworkshop" in my small furnace and it works very well. I don't know if it would stand the temperature required for casting brass or bronze.

Les.

Hi David,

I am not sure about the use of vermiculite in the recipe on my website. I have always used perlite. My information is that vermiculite is not heat resistant enough but I have never tried it so I do not know. I have made two furnaces using the mix on my website with perlite and both have been satisfactory. One is now 7 years old and it is still in good condition after dozens of melts.

Mike (of Mikesworkshop)

Norman, thank you for the comments. My experience is slightly different to yours and it just goes to show, casting remains one of the "mysterious arts". With lead at low temperature I have never had an issue though I have had with Aluminium.

Les - You are quite right, you must have something between the molten metal and the concrete. If the molten metal hits concrete it is quite likely to explode, sending shards in all directions. In this instance though, as I was working in "her" parking spot, if anything had hit the concrete blocks it would be a toss up which would explode first, the concrete or the missus!

I have my molds which I first bought as a schoolboy a long time ago secreted away and I will take some pics later today so you can see where I started with this.

graham.

Very interesting Graham. It took me back many years to when my old friend and I attempted to cast some 5" Simplex cylinders from non-ferrous machining chips. As a crucible we used a piece of 5" diameter thick walled tube with a plate welded on one end. This was then lined with a thick wall of fire clay.

We made a ground level hearth from loose bricks and used coke as the fuel. When the fire was going well we used wife's vac in reverse mode to get a good draught going.

We had already had a pattern made and the sand was in the mold box ready for pouring. We used a two handled thing we had knocked up that looked like this l-----o------l for holding the crucible. We were surprised that our "melt" did not fill the crucible to where we had expected but we poured anyway. Every last drop went in and at the end - ugh-ugh - only smoke came out of the vent hole.

After cooling we knocked out three quarters of a perfectly formed cylinder. We had seriously underestimated how much of the chippings would be needed. We must have melted 3/4 of a bucket which we both thought would be plenty.

Our sand, also red, was gifted to us by a local precision casting business, they described it as "Maidstone sand".

That was my one and only experience of casting and in the end I machined the castings from solid gunmetal ingots which I "found".

Since then I have acquired some more suitable gas torches, hoses and bottles and intend experimenting again at some point albeit on a smaller scale.

Thanks for your informative post Graham.

Rik

Mike, many thanks for the heads up greatly appreciated. I was under the inpression they were similar. When I can get to the back of the garage I will check to make sure just what I have. Cheers David

In my (very limited) experience of casting we used Mansfield sand...

Rod

Hi Graham,

My understanding is that one should not use Borax as a flux with Aluminium, an equal mixture of NaCl + KCl should be used.

Peter.

> an equal mixture of NaCl + KCl should be used.

Three parts Lo-salt to one of Saxa then!

Neil

Graham, you mentioned casting Lead, the pot looks a bit grisly so the best clarifying material for lead is Bees wax!

A piece about the size of an Acorn and stir the lead as the heavier metals go down and stirring mixes the metal and brings up all the dross. Plus all the steel bits from the scrap. You know how to skim off the dross leaving clean metal.

I wonder if the risers for Aluminium need to be quite large to add pressure to the pour? Maybe that is why the corners did not fill out?

Clive, (my only forte is lead bullet casting.)

Very useful that Clive, I will remember that in future and fortunately have a good supply of Beeswax!

Both the lead and aluminium were poured into the open Ingot mold that can be seen in the pics (i hope - if not I will post a pic) so the Ingots were free forming and that is how aluminium ends up. These are small ingots so a bit more pronounced.

Peter, thanks for the information, I was saying I did not know if Borax would work as a flux, I didn't make myself clear. I use a commercial grade and always get good results.

graham.

(sorry, forgot to take pics of my lead molds today as I have had a day from Hell. It happens. Tomorrow is another day).

Edited By Oompa Lumpa on 08/09/2014 21:27:35

Edited By Chris Trice on 09/09/2014 00:31:43

I tried making an RTV silicone mold and it was full of bubbles ( the rtv that is). Is it possible to produce a good mold with out vacuum degassing? If so how does one get rid of the inevitable entrapped air?

Clive

Ditto on the bees wax. An excellent lead flux that has been used in bullet casting for centuries. Years ago I cast thousands of bullets for obsolete cartridges using a combination of plumbers lead and wheel weights. The wheel weights hardened the bullets which greatly reduced leading in the bore of the rifles. I initially used a Coleman naptha camp stove for a heat source which melted the lead in very short time. An 8" tall piece of 6" well casing with a 1/4" plate base welded on made an excellent lead pot. Later I purchased a commercial bullet casting electric lead pot that eliminated the need for a dipper but took far longer to do the melt. Always worked outdoors in a good cross breeze using a respirator to keep from inhaling the fume. Despite all my precautions, I gave it all up when I asked my Doc for a Pb test and the results came back on the high side - 56 whatever that means. At the time I was employed in a paint shop as a sign painter using lettering enamels that contained lead so it is difficult to say which activity caused the high lead count.

Bill

Edited By Chris Trice on 09/09/2014 11:13:16