Looking for advice about casting fundamentals

CatamountRob

CatamountRob

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Any tips on casting from a boat CRob?
Did I ever tell you about the time I hooked my math teacher through the earlobe while we were fly fishing? Probably not. It was a royal coachman and looked pretty good there.
 
kimba

kimba

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Hi Abe
Just been looking through this thread again.
Glad all seems to be going well.
Without throwing a spanner in the works , I don’t agree to keeping the resovoirs separate.
As long as the total weight is bigger than the total weight of the crowns .
Also you DO NOT want a button after casting. Just have the resovoir complete with a little of the spruce left. A large button will cool quickly as the casting arm spins and suck alloy away from the resovoir and crown.
Also when casting large span bridges if you have a button it can contract the sprues slightly leading to ill fitting castings.
Hope I’m not confusing the issue just trying to help
 
HonestAbe

HonestAbe

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I appreciate all advice given and I'm trying different things out.

I'm also a welder and I don't know if this principle applies to casting, but there are multiple ways in welding to achieve good/acceptable results. Like if I picked up another welder's machine and tried to weld with it I might have trouble with their settings. My process here is to gather everyone's best practices, experiment a little, and find what works best for me.

I think my biggest weakness here is that I'm not the one doing the metal finishing, so I have to rely on feedback from that. What I really want to do is get to the point where I'm making the least work for them possible. If I can keep getting farther ahead of schedule I might be able to get some time to learn the finishing side of things but as I'm sure you all know, it's hard when things are busy and you're being pulled in 10 directions at once.
 
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Michael @ Beyer Dental la

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I would google around for info on casting with different fuel sources. Many years ago, when I was still new to this world, we were using acetylene(!!!!) to cast with. It was dirty and we were having miscasts. I started googling and found a father son duo who had a great article about casting with different fuels and found out real quick that acetylene should not be used :). We changed over to propane and oxygen. Natural gas should be fine also.

Spruing is the other big concern. Making sure you have big enough reservoir is key. Also keep in mind how your molten metal is flowing. I try to limit the mount of directional changes the flow has to make before it gets to the margins.
Work on spruing. I have bee using acetylene for over 30 years and no problem. Thick castings require bigger spruing.
 
HonestAbe

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Any thoughts on when to replace O2 bottle? I'm at 500 psi left in the tank atm but was noticing some odd things adjusting my flame yesterday. Like I got it dialed in to where I wanted it but it was way more finicky and sensitive (tiny turn of knob, sudden big change in flame kind of thing).
 
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Willard

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Maybe be a problem with your regulator
500 psi I wouldn’t consider low
 
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karlanm

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Quick tip. Find the density of your metal in g/cm3, weight crown and sprue, and then multiply by density and then 1.3. Too much metal causes porosity issues and too little is heartbreaking
 
HonestAbe

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Overall things have been doing well, did end up with a little pit of porosity on one crown near the sprue connection and right on a contact which sucked but I'm not certain why it happened.

What is the industry standard for how much weight gets added to the bill to account for the kerf?
 
HonestAbe

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Still getting porosity sometimes at the sprue location and I'm not sure why. I can't tell if it's adjacent to where the sprue is or directly where it meats the pattern. My gut is telling me it's something to do with the way I'm attatching the sprue (too broad perhaps? will get some closeup pics of next ones I do) but others here are insisting it's because my button wasn't big enough.
 
CatamountRob

CatamountRob

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Try a bigger reservoir, not a bigger button. You don’t want more than 1/4” of investment over the top of your pattern.
 
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