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Oil fired crucible furnace

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MetalCaster:
That looks like a good pour.  I am not sure about the small blowholes though, what type of sand are you using (water or oil-based?).

And the amount of slag you are getting sounds a little excessive.
I get very little slag and only need a light skim, but I start with clean iron.

Looks like you are on a roll.

And very conservative fuel usage too.

vtsteam:
Re-cast the part again today to try a few more changes:

First change, built a new cope 2" deep in place of the older one 3.5" deep.
Second change, increased the size of the riser from 1.25" dia to 1.5" dia
Third change, increased the size of the well under the 1" sprue to 1.5 dia
Fourth change, made the path of the gates more square than curved
Fifth change, dusted the mold cavity with plumbago

Total furnace melt time from lighting to pour 1:15
Diesel fuel used: 1.25 gal

Results were a general further improvement over the last pour. Finish was greatly improved, though corners were more rounded (result of blacking). There were still a couple of minor holes, though they looked like they would be removed when the surfaces were machined, and the channel bored to 1" dia.

The main problem that came up was again my mis-estimate of the amount of slag/vs metal in the pot, and a nearly short pour as a result. I did not fill the sprue and riser completely, though they filled sufficiently to make a good casting.

I really need to slag out the crucible while in the furnace, rather than out, so I can get a better visual take on the amount of metal in the pot -- and can add more if needed. The slag is very puffy so it takes up a lot of space. The slag used to appear much smaller when I used a flux which liquified it. Now it's got the appearance of cottage cheese. Last pour I scraped it in the furnace and added more metal -- there was plenty for the pour. This time I didn't scrape it beforehand and assumed I had enough metal.

I had no trouble with the shallower cope, and I think it is going to be an improvement. I think the riser and gating were good, except that the gates could have been bigger -- the pour went unusually slowly. Possibly because of the lower head pressure of the thinner cope. I think a completed pour with more metal might have made a very good part.

MetalCaster:
Nice work.

vtsteam:
Thank you, Pat.

In answer to your earlier questions:

The greensand is traditional silica sand and bentonite, per ironman's formula.

The iron is from broken up cast iron radiators. The pieces are thin, and so probably would make more slag than thicker iron.

awemawson:
Cast Iron radiators of the finned 'school' or 'hospital' type are usually a high phosphorous iron and as such should be very fluid when pouring but rather hard to machine. From what you've said earlier your castings machine nicely which is at variance with this - just an observation.

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