Foundry Tools Part 2

Foundry Tools Part 2

Cast iron crucible lifting handle

Here is part 2 of my foundry tools section.On the left is the crucible lifter I made to suit the cast iron saucepan I am using as my new crucible. The tongue on the end fits into the slot on the saucepan and provides a positive point to rotate the crucible for pouring and the "s" shape stops the handle from slipping out. The loop on the bottom slides down and locates over the handle to support the other side when lifting and pouring.

Handle fitted to crucible

On the right is the handle fitted to the crucible. The handle on the side provides leverage when pouring the metal into the flasks. To use the handle the tongue is slid into the slot and the handle lowered and the loop is slid over the handle of the crucible, to release the crucible the loop is slid back and the handle raised to release the tongue. The crucible is held securely at all times and cannot slip and spill hot metal everywhere.

Crucible sitting in furnace

           

The next photo shows the crucible sitting in the furnace. The support is designed to hold the side of the crucible with the loop and allows the tongue of the handle to still be inserted.The other side has a square handle fitted with a block of steel on the bottom that sits against the side of the furnace to stop the crucible from slipping off the support.

Steel crucible sitting in furnace

 On the right is my steel crucible in its support in the furnace. The crucibles are held up this way for two reasons. The air is fed in from the bottom of the furnace and so the crucible cannot sit on the bottom, and as I am using wood as fuel, there has to be space under the crucible for the wood. The next photos show the pouring handle for the steel crucible. Again I wanted something to hold the crucible securely without the chance of slipping. I devised an over-centre lever to lock the arms on the pins on the side of the crucible when closed. To release the crucible, the lever is released and a spring opens the arms far enough to clear the pins and release the crucible. This handle has been modified to fit the larger steel crucible as the original crucible was smaller. This involved making up some longer arms to go around the bigger crucible and bolting them into the holes that fitted the small one. Two pins on the arms fit into holes and stop the arms from turning when the crucible is lifted.A nut was welded to the bottom of the crucible so a hook could be used to tilt it to pour the molten metal.

Arms open to fit to crucible

Arms closed

Handle closed on crucible

Hook used to pour metal

A couple of fire pokers

Selection of tongs

        
Above we have a selection of tongs. The ones on the left are used to hold the hot casting by the sprue to remove the sand. The BBQ tongs are handy to place metal in the crucible without splashing hot metal around.The next set originally had straight jaws,but were bent down and extensions welded on  to grip my steel crucibles to place them in the furnace. The last ones are end nippers used to remove flashing (sharp edges where the drag and cope meet around the pattern) The photo on the right shows a couple of fire pokers. The thin one was my first one and was easily bent, so I made a stronger one.

Skimmers

Here we have several skimmers for removing the dross (slag) from the top of the molten metal. Two of them are old forks fitted with long handles, the other is a steel plate with holes drilled in it welded to a long rod. The forks are not the best as they are stainless and as can be seen in the photos, are starting to dissolve. The steel one works better, but the rod is too thin and bends when the dross is bumped off. I recently made a more substantial one out of thicker steel and this works well.

New skimmer

New skimmer

 Here are a couple of photos of the new dross skimmer I made. The head is made from a piece of angle iron shaped to match the side of the crucible and has holes drilled in the base for the molten metal to run through. The handle is some 10mm square steel I had at the time, round would be suitable as well. The handle at the top was made in a loop so it was easier to control when scooping out the dross.

Green sand stirrers

Modified paint stirrer

Next we have some of the tools I tried for mixing green sand and conditioning it again after casting.These were all used with a 12mm electric drill with a gear reduction low speed. Smaller quantities may be able to be done with a smaller drill, but it is pretty hard on the drill. Of the three designs the leas effective is the centre one, which is just round rod bent to shape. Next I bought the paint stirrer on the right from a hardware store. It worked better, but the drill had to be run in reverse or it just pulled out of the sand and it didn't break up the lumps very well. I then welded on the two thin metal wings as in the second photo, and this improved it again. After some research I made the one on the left out of round stool with a bar welded on the bottom. I added wings to each end and sharpened the leading edges, This one worked the best of all, but it was still hard on the back bending over using the drill. I then decided to make a sand muller to reduce the back strain, but at a pinch you could get away with something similar to the two better ones to do your sand mixing.

Sprue cutters

In gate cutters

 On the left are a selection of sprue cutters. These are just lengths of copper tubing which are pushed into the sand to cut the sprue (opening to feed the metal into the mould) The plastic ones were out of an old cistern vale and are tapered. The end of the pipe can be sharpened to cut the sand better. On the right are some in gate cutters made from old spoons. These are used to cut a channel to get the metal from the sprue to the pattern. I have since made better ones shown in the next photos. These were made by folding some thin metal around suitable round rod to make a "U" shape. Then a handle was cut out of wood and shaped to suit, and attached to the "U" shaped metal with a small metal thread bolt.

Metal and wooden handle

Metal bent into "U" shape

Metal fitted to handle

Top view

3 different size cutters

Small sand sieve

On the right is a small sand sieve I made out of PVC fittings and a metal trivet from a camping store for sieving the sand into the mould to cover the pattern. The trivet was cut to fit inside the PVC cap and is held in place when the other fitting is screwed into it. The centre was cut out of the cap , leaving the "O" ring and its seat in place. A handle was made up out of some aluminium tubing and bolted to the side with metal threads. A PVC cap can be placed on top to keep the sand in when it is shaken. I have found that the trivet doesn't make the best sieve due to it basically being flat steel drilled full of holes. Sand seems  to go through wire mesh better, especially if the sand is damp. I have since replaced the trivet with fly screen mesh and the sand will go through this better. If I can find some more suitable mesh, I will replace the fly screen and it should work better again. A normal cooking sieve can be used as well, although the mesh is fairly fine in those too. The use of PVC fittings is still one way of making a small sieve, and could be made simpler and cheaper by using a glue on cap and piece of PVC pipe rather than threaded fittings.

Trivet cut to fit in PVC cap

PVC cap cut to suit

Bottom of sieve

Inside sieve

Completed sieve

Sieve with  handle and cap

Following are a few of the miscellaneous tools that I use when doing my foundry work. Some can be made at home or purchased cheaply.

Various sand scoops

Water spray bottle

The sand scoops are used to shift sand around and the spray bottle is used to add water to the green sand. Both are cheap enough to buy but the scoops can be cast if you desire.

Fillet tool

Dross skimmers

On the left is a rod with a round point used to smooth filler to make a radius on joints in patterns. They can also be made by attaching a suitable ball to the end of a rod. On the right are a couple of potato mashers that could be used for dross skimmers.

Rack for muffin trays

Muffin trays

 Left are the muffin trays I use to pour metal into ingots for future use and on the right is one of the racks I sit the trays on when pouring ingots. These are old shelves out of a stove or fridge and stop the wooden bench from burning.

Muffin tray and rack in use

Some moulds ready to pour

 Well that is about all the small tools I use in my foundry at the moment I will post updates if I find any better ones or make modifications to improve them. Next I will look at the larger items such as the sand muller, riddle and ball mill. If anyone has a question or would like more details on anything I've done, please leave a comment and I;ll try to help. Also the photos can be enlarged for more detail by clicking on them.

Foundry Tools

Foundry Tools

In this post I will show some of the tools and casting boxes I use. All my tools are homemade or adapted from things that can be bought cheaply and will do a certain job. I have found when I go shopping I always look out for things that I can cast or use as tools in the foundry. Some have been very successful and some not so good. Second hand, charity shops or $2 shops are all good sources for either cheap tools or items that can be cast.

Rapping tools and carving tools

Venting tools

On the left we have rapping tools for loosening the pattern in the sand. A screw or pin is placed into the pattern and the U shaped tool is rapped back and forth to loosen the pattern for removal.Also shown are old knives used to cut or shape the sand in the casting boxes. On the far right is a tool with a rounded wooden blade used to smooth any rough surfaces or loose sand.
                       In the photo on the right are some different sized knitting needles used to vent the sand to allow the gas to escape when the metal is poured into the mould. Other things such as bicycle or motorbike spokes can be used as well.  

Sand rammers

On the left are several sand rammers I made for ramming the sand around the pattern. The two on the left are made with different lengths of steel bar welded to pipe handles with large bolts welded in the other end. The one on the right is a lighter one that I cast up in aluminium. The pattern for this was made by screwing a square piece of timber to a round handle with a chisel end cut on it. The transition between the square and round pieces was shaped with body filler.

Metal risers

On the right are several sizes of risers used on top of the sprue where the metal is poured in to give some head pressure to feed the casting. These can also be made by ramming sand into the space between a large and smaller piece of pipe and then removing the inside piece. I have seen tin cans with the top and bottom cut out used as well. I first used plain pieces of exhaust tubing which in most cases were able to be removed from the cooled metal as It shrunk enough to release the pipe. I then decided if the pipe was split it would be easier still to remove and I clamped the split together with a suitable hose clamp.This worked well, but the clamp tended to seize up from the heat after a while. I then came up with the design above with two nuts welded either side of the split. One nut has the thread drilled out and a suitable metal thread screw is used to tighten the split. The thread does need oiling to remain free, but it doesn't seize up as bad as the hose clamp did.

Flasks

Wooden moulding boxes (flasks)

Next we have a selection of casting boxes, (flasks) both wooden and steel. The ones on the left are just timber butted together and screwed on each corner. Angle iron brackets are bolted to the sides and pins to align the drag (bottom) and cope (top) are welded to this.
                 I have seen many casting boxes held together with clamps or weights on top to prevent them lifting apart when the metal is poured in. I came up with the idea of using eye-bolts with a couple of nuts locked together to hold mine together. A suitable hole is drilled in the angle iron on the cope and another matching one is drilled and tapped in the cope. The nuts are run up the eye-bolt far enough so the bolt screws into the threaded hole and then they are locked together.When the flasks are assembled the eye-bolts are screwed down and hold the two flasks together.
       Some people also cast their own metal flasks, but I haven't tried this. I would recommend gluing (liquid nails etc) as well as screwing wooden flasks as the joints will work loose over time. Although I have both wooden and steel flasks, I would recommend metal flasks if possible, although both will work well. One advantage of metal flasks is they will not burn if molten metal is spilt on them. As you can see my wooden ones have black burn marks on them.

Closed flask with eye-bolt removed

Longer flasks open

Longer flasks closed with eye-bolts

The above photos show two different styles of wooden flasks, the longer ones have a different set up for aligning the two flasks. The cope has wooden pegs that fit into the space between the blocks on the cope. The eye-bolt arrangement is similar to the other flasks. The detail is shown in the photos below.

Flask alignment peg on cope

Detail of drag blocks

Steel flasks closed

                                                

Steel flasks

Flask base board

   Above is a base board for the flask which holds the drag and pattern while the sand is rammed. A top plate ( without the rails on the bottom) or second base plate is used on top of the drag when it is turned over. Sometimes you may be able to sit the flask on its side and switch the base board to the other side of the flask, but if the pattern is loose in the sand it can fall out

Crucibles

When I first started out melting aluminium I decided to try stainless steel bowls as crucibles. These were normal thin bowls used for cooking etc. Although they worked for a while, they soon developed holes and after having molten aluminium run into the bottom of the furnace, I decided they were not suitable. I found the hotter they got the quicker they developed holes. I had a look on the internet and found others that were using welded stainless pipe, so I made up a couple to try. The only stainless pipe I could get was approximately 3mm thick and while it certainly lasted longer than the thin bowls, it still developed holes. After repairing one by wrapping more stainless around the outside, I did some more research and found that molten aluminium dissolves steel, so I then decided to make some thicker mild steel crucibles to try. As I was using the aluminium to cast art items and not machining it, I wasn't too concerned about a bit of steel dissolving in it. The mild steel crucibles worked better, and didn't burn out like the stainless. After using them for some time however, they did start to rust and flake. Even scraping them out before using them didn't help much and I would still get flakes in the metal. It is possible to line them with a wash to keep the metal away from the crucible, but by all accounts this doesn't last very long before it needs re-applying.

Stainless crucibles

Mild steel crucible

Cast iron cooking pot

        After considering buying a proper silicon carbide crucible, I had another look at some foundry sites and found that cast iron could be used, in fact some people cast their own crucibles out of it. It will still dissolve into the melt but was not supposed to flake like mild steel - the reason it was used for wood stoves and I guess, cooking pots. I decided to give it a go to see if in fact it was any better. Finding something that was both cheap and suitable was a little bit of a challenge. I first thought of a camp oven, but after looking at one, decided it wasn't tall enough. I then went to a camping store and found a cast iron cooking pot that was more suitable and priced right.With some modification (which I will cover in a future post) it was ready to use. I have found so far it has been a lot better than both stainless and mild steel. It doesn't flake at all, and my metal has never been cleaner, and it has already outlasted the stainless steel. The only thing is the bottom has sagged a little from the heat, and it will eventually wear out, but that is only expected. I think I will try and make a pattern and get my mate to cast some up in cast iron in the future.

       So, my experience with different types of home made crucibles has shown that in my opinion, stainless steel dissolves quickly, according to thickness, mild steel seems to dissolve slower, but rusts and flakes (especially if salt is used for flux) and although cast iron will still dissolve, it doesn't flake, and in my opinion would be the pick of all three for a home made crucible.

        In my next post I will continue with some more miscellaneous tools that I have made and in future posts will post details of some of the bigger items such as the ball mill and sand muller that I have built.