Dissolving different metals

[kd0afk]

But not aluminum. Is there an acid that will eat steel and not touch aluminum? I had an idea to fill a box with ball bearing and then aluminum. When the aluminum cools, dissolve away all the balls and be left with a very cool structure. Is there an acid that will eat steel but not aluminum?

 

[Tin Falcon]

IIRC alum will do it old trick for removing broken taps from aluminum castings.
Tin

 

[tornitore45]

Alum works but extremely slow.
Depending on the size of the ball bearing and considering the unfavorable surface to volume ratio against a broken tap it may take a lifetime to see the shiny bottom of the cavity.

Just pouring Aluminum into a box with ball bearings on the bottom will completely encase the ball bearing and negate the corrosive action, unless some method to let some of the ball bearings exposed is used.

 

[goldstar31]

I would agree. Frankly, in the confines of a home workshop and the limited or nil experience of the caster, I say as Gus has- a resounding NO. I recall a works manager of a rather large casting firm when the mould broke and two of his workmen became dust.

Again, I was a qualified sailing instructor and would advise you that being a 'light airs sailor' takes more experience than is generally realised.

Exits to 'Helm hard down and trust in the Lord' holding the jib sheet in one hand and the main in the other whilst holding the tiller with one's third hand and ducking the boom as one gybes and getting the centre board up with your remaining hand as she tips and goes though the wind.
Sorry and all that.

Norman

 

[kd0afk]

I would agree. Frankly, in the confines of a home workshop and the limited or nil experience of the caster, I say as Gus has- a resounding NO. I recall a works manager of a rather large casting firm when the mould broke and two of his workmen became dust.

Again, I was a qualified sailing instructor and would advise you that being a 'light airs sailor' takes more experience than is generally realised.

Exits to 'Helm hard down and trust in the Lord' holding the jib sheet in one hand and the main in the other whilst holding the tiller with one's third hand and ducking the boom as one gybes and getting the centre board up with your remaining hand as she tips and goes though the wind.
Sorry and all that.

Norman

What in the hell are you talking about?

 

[kd0afk]

Alum works but extremely slow.
Depending on the size of the ball bearing and considering the unfavorable surface to volume ratio against a broken tap it may take a lifetime to see the shiny bottom of the cavity.

Just pouring Aluminum into a box with ball bearings on the bottom will completely encase the ball bearing and negate the corrosive action, unless some method to let some of the ball bearings exposed is used.

I wouldn't be just throwing the stuff in a box. I would be nesting the balls stacking them tight.

 

[tornitore45]

I have a problem with the geometry, which I have not worked out completely so I have to be conservative in my statement. A packed sets of spheres leaves interstices that are connected with very little strands of empty space (Aluminum in your case)

The "access" of the corrosive solution is minuscule and the iron volume to be corroded is huge.
Removing a broken tap still require some picking out of particles of the tap that looks like sand.

 

[kd0afk]

Yes the aluminum left over would take on a lace appearance. But it's just a theoretical exercise at this point. It would be very similar to the ice candles I made when I was a hippy

 

[10K Pete]

What if the spheres were made of a 'core' material? Not green sand but
some sort of core material that would be much easier to remove than
steel?

Pete

 

[techonehundred]

As for the Alum, I have used it to dissolve an 8-32 tap in two hours. So depending on the size of the steel balls it would take a while to dissolve. Also, keep the alum/water mixture near boiling and as saturated as possible. One problem is that the Alum/Water leaves a film on the Aluminum so getting that out of the holes would be the difficult part.

 

[tornitore45]

One problem is that the Alum/Water leaves a film on the Aluminum so getting that out of the holes would be the difficult part.

Not knowing any better I used an aluminum pan to do the work.:wall:
You would not imagine the crap i got from my wife.:fan::hDe:

 

[kd0afk]

What if the spheres were made of a 'core' material? Not green sand but
some sort of core material that would be much easier to remove than
steel?

Pete

That would work I think.