blow holes

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sawyer massey

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I just started casting cast irion and all my poor's so far have had blow holes at the pooring hole
What am I doing wrong?
 

Brian Rupnow

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Try googling "blowholes in iron castings.
"Such defects can be caused by air entrained in the melt, steam or smoke from thecasting sand, or other gasses from the melt or mold. (Vacuum holes caused by metal shrinkage (see above) may also be loosely referred to as 'blowholes')."
 

sawyer massey

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  • know what causes them .how do I cut down on them ?longer runs dryer greensand?
 

sawyer massey

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Governor casting is great crank not so much think I'll ad some to the diameter iron was lots hot enough an had 6lb left over
Over filled the riser and still did not fill the casting again I'm am starting to wonder if the sand is collapsing as it is only 5/16 thick at this point .
Or should I put it in the top box and fill from the bottom
 

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skyline1

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This looks like a "cold shut" it tends to happen with thin sections, it is caused by the metal "freezing" before it has chance to fully fill the mould cavity

Notice the depression in the top of your runner this is an indication of not enough "head" of metal in the runner.

Extending the runner height should cure this (I used to use old beer cans with the top and bottom cut off)

As you are ramming the cope embed the runner extension in the sand a little around the runner stick and fill with sand so that the runner height extends above the cope

A good large "cup" at the top of the runner will also help giving the casting a bulk of hot metal to draw from.

Wide ingates are a good idea and if you still get cold shuts use multiple ones to "feed" the casting from multiple points.

I had trouble with this too, when I first started casting iron 'til an old moulder taught me the runner extension "trick" so you are not alone.

Some Ferro-Silicon added to your melt will also make your metal more fluid if you can get some.

Hope This helps

Best Regards Mark
 

jimsshop1

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I would like to see your furnace if you don't mind. I have built one and it works great for aly and brass. I just got done casting a 45 lb cylinder of bronze for a special bushing for a WWII surface grinder at work. I would like to melt some cast also. What do you use for starter ingots?

Thank you,

Jim in Pa
 

sawyer massey

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What are you using to melt the cast iron, gas or electric?
I use an oil burner
I would like to see your furnace if you don't mind. I have built one and it works great for aly and brass. I just got done casting a 45 lb cylinder of bronze for a special bushing for a WWII surface grinder at work. I would like to melt some cast also. What do you use for starter ingots?

Thank you,

Jim in Pa
I use electric motor end bells I work in a refinery town and the company I work for rebuilds motor's the 3 I have now weigh over 200 lb each but they are real hard to break up
 

jimsshop1

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Thanks Sawyer,

Have you thought of using a press to break them?
 

sawyer massey

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I would like to see your furnace if you don't mind. I have built one and it works great for aly and brass. I just got done casting a 45 lb cylinder of bronze for a special bushing for a WWII surface grinder at work. I would like to melt some cast also. What do you use for starter ingots?

Thank you,

Jim in Pa[/QUOTE
Here is my foundry its a 22 gallon drum lined with 3" of kowooll rated for 2700 f and coated with 3200 ceramic painted on the pedestal is 4500 fire brick
My next on will be a 45 gl drum lined the same way
As you can see I built up the night about 6" as I needed to raise the pedestal as I could not keep the heat a temp near the Bolton of the furnace helped huge
 

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sawyer massey

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I would like to see your furnace if you don't mind. I have built one and it works great for aly and brass. I just got done casting a 45 lb cylinder of bronze for a special bushing for a WWII surface grinder at work. I would like to melt some cast also. What do you use for starter ingots?

Thank you,

Jim in Pa[/QUOTE
Here is my foundry its a 22 gallon drum lined with 3" of kowooll rated for 2700 f and coated with 3200 ceramic painted on the pedestal is 4500 fire brick
My next on will be a 45 gl drum lined the same way
As you can see I built up the night about 6" as I needed to raise the pedestal as I could not keep the heat a temp near the Bolton of the furnace helped huge
 

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