Casting using bronze swarf

[kelvin2164]

I have access to a lot of bronze maching swarf at a cheap price. However when I fill a pot with solid and swarf, the molten bronze can be poured off, but the swarf is still solid in the bottom of the crucible. The same alloy for the two. I've tried a couple of times, same result. Would be nice to use the swarf and fill the voids in the pot.

 

[aonemarine]

It sounds like your crucible is sitting with its bottom below that of the burner. Can you raise it up a bit with a taller plinth and see what happens?
I have noticed that when I melt silicon bronze that the top was melting fine, but when I poked into the melt with my skimmer I could feel that it was not melted in the bottom. Raising the crucible a bit higher worked for me, hopefully it will work for you.

 

[obrian]

I have not yet tried to cast brass or bronse but I have used aluminum swarf. Here is how I do it. Cut the top off a soda can and pack it tight with swarf. This limits the air in the swarf. Melt some solid aluminum - very hot. Then submerge the soda can in the melt and hold it under with a steel bar. I think that small amounts of swarf at a time is good as it does not cool the melt as much.

I will be watching your post to see if others have an answer.

Dennis

 

[dnalot]

I do like Aonemarine does and elevate my crucible an extra inch when melting bronze. I put the swarf in a short section of pipe and compress it with a 2 ton manual press. It's best to have a small pool of metal in the bottom of the pot before adding the compressed pucks of swarf. You get a lot of dross when melting swarf so spoon of the top of the melt occasionally.

Dnalot

 

[kelvin2164]

The bottom of my pot is level with the top of the burner.
I have noticed a couple of times with my castings, a lot of sharp inclusions in one end, almost a porous casting in the one spot, which baffled me at first. Now I realise these are regions of unmelted swarf. Maybe not worth the trouble and pay 25% more for solid maching off cuts and be sure of the casting quality.

 

[ddmckee54]

Stupid question, but why don't you melt the swarf and cast ingots, then use these ingots to cast your part. It might be an extra casting step but you'd probably get a cleaner casting that way.

Don

 

[nel2lar]

Don
wonderful question. That is what I do and I stir the molten metal to make sure there is no hard spots or lumps. Brass and bronze have so many different alloys and the color of the mater is effected by that, so I like to melt all my scrap and chips at one time and pour small pigs or ingot. The bigger the center is the longer it takes to melt, but a nice pre-heat and stick it in the molten material. Once the metal is about 3 or 4 inches deep it will start to melt the preheated ones much better.

When using chips they must be completely dry and free of oil or any other cutting fluid. I have even used a aluminum can about 1/2 full and pressed, works well for me.
Nelson Collar

 

[Silvergoose]

New to this very interesting hobby so I must ask this question.

How is the best way to insure the swarf is clean and dry? Are chemical cleaners used, if so which one. Also where is the best place to get crucibles, make/buy?

Thanks