I recently (FINALLY!!!) got my casting studio all set up, and started in with the actual casting using a Smith Little Torch and an oxygen/acetylene setup with a centrifugal casting machine. I’ve a couple bad casts and a couple great sessions with no problems, but not today. The torch keeps blowing out. Today it got so bad that I finally had to just stop the session entirely because I could not keep the torch going long enough to actually get the metal to the liquid casting point. The torch was doing this the other day and I thought I’d fixed the problem with a little cleaning and adjusting of the height of the flame from the metal. But again and again today it kept blowing out. What the heck is going on?
Are you getting the torch flame to close to the melt that it is blowing itself out. I am not sure why this happens other than there is not being enough gas or O2 pressure or flow to maintain the flame. If both gases are regulated, try increasing the flow of both. Otherwise, change the angle at which you apply the flame to the melt so that there is less back pressure from the flame to the tip. Good luck…Rob
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John, which tip are you using? Too much gas or oxygen pressure can cause the flame to travel away from the tip and blow out. That’s more of an issue with the smaller tips, probably much less likely with a multi-orifice melting tip.
Rob’s suggestion that the torch tip may be too close to the crucible is also a possibility, especially if the pressures were approaching ‘too high’ for a stable flame.
It isn’t something I do, but you should be able to wave the torch around a bit without the flame going out. If you try that and the flame goes out dial back on one or both regulators and see if that helps.
Neil A
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Try turning the gasses down. If you’re exceeding the tip’s capacity, it’ll blow it out.
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I’m using the rosebud tip for the Smith Little Torch. Too much gas… ok, looks like I’ve got to play around with the gas pressure. I learned elsewhere about the distance from the crucible being an issue, so I’ve tried to keep it close but not too close. that’s what seemed to be the issue a few days back but yesterday was just nuts. Gas pressure. Thank you for the tip.
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thanks. I’ve been trying to do keep the tip close but not TOO close, but that didn’t do a thing yesterday. The PSI on both tanks is at around 10. But now it looks like I’ve got to play around with the gas knobs on the torch to get it right.
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I’m sorry that you’re having so many problems! Getting your casting set up and working has been quite a challenge
As I remember it, you’re doing centrifugal casting. Think of the crucible like a bowl. It’s very easy to angle the torch so the flame shoots back out of the crucible directly into the torch tip. That’s going to mess up the flame and probably blow it out. You have to angle the torch so the flame bounces out the other side away from the torch tip. Does that make sense? Also, at all times, never touch the torch tip to any part of the crucible. I tell people that the torch tip needs to always be about 3/4" - 1" away from any part to the crucible. That can be a challenge because you also need to always keep the flame moving, but you’ll learn to dance with it.
I’ve done a lot of casting with the Little Torch rosebud tip, but I’ve found that it’s a very underpowered torch tip for more than say 1/2 to 1 oz of silver. If you’re casting more than that, you’ll probably be frustrated. It’s not that you can’t do it, but it’s a challenge.
Like others are saying, you need to play around with the pressures. Too much pressure will definitely blow out the Little Torch rosebud flame.
You say that you have an oxy/acetylene set up. Why don’t you use that? Or at least try it. Lots of people cast jewelry in centrifugal casters with oxy/acetylene welding torches. I grew up doing centrifugal casting with an oxy/acetylene torch. Again, it’s very common. If you have that set up, I’d definitely recommend trying it.
Right now, from what I can see your biggest hurdle is to start getting some successful castings. Once you start seeing what works and what doesn’t, then you’ll get information about how to make everything be more efficient.
One last thing. I’ve found that centrifugal casting is a fairly forgiving process. There are numerous opinions about how to do it and what works and what doesn’t. It’s definitely one of those situations where there are sometimes different answers to the same question and they’re all correct. You need to find what works for you. Keep trying! Always be safe. You’ll figure it out.
Jeff
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This is my experience in melting metal for use in my shop.
First of all I don’t do a lot of casting. When I do it is one off stuff done in Delft Clay. Mainly I am melting to create ingots that I can roll into wire or sheet. I have an Invacaire Platinum O2 concentrator and a propane Little Torch. When I am doing a melt I work with a Paige Melting tip. I can melt up to 25 grams without a problem but more than 30 and it becomes very iffy. I would say that underpowered may describe my problems, which are few, with that torch/tip/concentrator combo . I have to be realistic about what I am trying to do and the size of the project. The tip may be very capable of blowing a flame strong enough for a large melt but with my 1lb propane can and the O2 concentrator I can’t dial up the pressure needed to sustain the heat over a broad enough area in the crucible. Where the blow out occurs with me is when I try and get the torch close enough to the melt to increase the heat. Blow outs like this would happen in the Boatyard I worked in. Usually when cutting a thick piece of plate. And triggering the O2 blow when the gas pressure was too low for the job. I have a Prestolite plumbers torch that can do a large melt if I need to but I haven’t had to light it up for over a year.
The lesson for me is I have to match the work to the capability of the tools at hand. This is something I am historically not good at. Good luck with this.
Don
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Don…You may have noticed the O2 cylinder hanging around my shop. I connect it to my Meco with the Paige melting tip when I am doing a larger melt. I takes care of the frustration resulting from trying to do a melt with the O2 concentrator. Really big melts are done in the electromelt furnace. I don’t use it very much, but it is there when I need it. I won’t be doing any melting for a while since I just sent all my scrap to Hoover and Strong…Rob
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