How to gate and runner a car frame?

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jscarmozza
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How to gate and runner a car frame?

Post by jscarmozza » Tue Oct 02, 2018 3:12 pm

I was thinking about casting a frame for a 1" scale caboose, but I can't quite figure out how to gate the mold. A few years ago I cast a few frames for 1/2" scale cars and it worked very well. That frame was similar to a ladder and I gated with a riser into each ladder rung, but this frame is much bigger (32" long) and will have 4 longitudinal rails along with the rungs. If I gate the 1" scale mold the way I gated the 1/2" scale mold I'm afraid that the metal will cool in the runners and not fill the lattice of the mold. If I try to fill the mold from one end, I'm concerned that if the metal doesn't freeze before filling the mold it will wash away the mold sand. Any thoughts on how to make this pour?
John

DavidF
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Re: How to gate and runner a car frame?

Post by DavidF » Tue Oct 02, 2018 11:04 pm

you need to add a picture of whats needs to be cast, and tell us of the cross section thickness. But im betting that you can pull it off without any help :)

jscarmozza
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Re: How to gate and runner a car frame?

Post by jscarmozza » Wed Oct 03, 2018 8:00 am

Attached is a photo of a 1/2" scale car frame that I made a few years ago, the 1" scale frame I want to make is similar but bigger. I acquired a set of LE caboose plans, and since I've wanted a caboose, I figured they would be a good starting point. After studying them, I realized that the LE version was all castings; which brings me to a few decision points. If I plan to make just one caboose, it's not worth the effort of making all of the patterns, I'll just fabricate. If I plan to make a few, do I have the skill to pull it off? A year or so ago I tried to duplicate some LE cab castings with disappointing results, the details came out well enough but the core shifted and the roof casting had a non-uniform thickness. I like making patterns, but would hate to go through all of the effort just to find that my casting skills weren't up to the task. I was talking to my buddy last night and we decided to make a caboose side pattern, dimensions but without detail, and do an experimental pour...easy enough. The casting that has me really worried is the frame. It's big, with the runners, risers and everything else, it's approaching the 8lb capacity of my crucible and I just don't know if I can run a 32" long casting. I wonder if tilting the flask up on one end and pouring downhill would be the way to go on the frame casting?
John
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DavidF
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Re: How to gate and runner a car frame?

Post by DavidF » Wed Oct 03, 2018 10:04 am

Strictly based off a visual/ mental estimate I'm thinking you don't have the melt capacity once the runner, gates, and risers are added...
Do you have a friend with a furnace? or perhaps a second furnace? Im thinking that if you had another person and you both poured form opposite ends at the same time, that would make life easy. Another possibility would be to use a horn gate into the center of the casting or add a cheek to your flask so you can gate into and under the center of the casting if there is a acceptable location to do so.
Tilting the flask may work, but 32" is a lot of distance for the melt to travel esp if the cross sections are thin....

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steamin10
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Re: How to gate and runner a car frame?

Post by steamin10 » Wed Oct 03, 2018 12:39 pm

Dave F is hinting at the approach i would use. 32 inch to run is along way for a melt to travel and is asking for problems. Cold shuts and sand washing will be the norm.

I have had success with tilting the flask a bit to let the metal puddle and then rise like a tide through the casting. The metal will tend to skin but allow the center of the poured area to extend to the open space available. All that is needed is to allow a little more space in the pouring cup to push the metal forward and be easy to hit with a heavy stream. Pouring fast is always a good idea but needed here to prevent cold shuts and freeze offs on the ladder like structure. Try it and see how it goes. I would like to hear about it.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

jscarmozza
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Re: How to gate and runner a car frame?

Post by jscarmozza » Wed Oct 03, 2018 5:32 pm

DavidF, you're correct...I'm right at the volume limit of my no. 8 crucible; I may have to buy a larger one. I have a two man ladle and a one man ladle, so if I beat the bushes I may be able to find a third man to try a double pour. I have a big Johnson (furnace that is) and I think I can fit two no.8 crucibles in it. The double pour may be an option. The cheek approach pouring into the middle sounds like a neat option too.
Big Dave, good to hear from you again. I may buy a bigger crucible and try the tilted flask technique first since it's the simplest. If it doesn't work I can try the previously mentioned techniques. This probably won't happen for a few weeks, but I will absolutely keep you both posted on the results.
Today I made a flip top flask and a test pattern of the caboose side panel and put a few random details on it to see if the details come out. The largest panel section is 6"X 12" X 5/32", pretty thin, so I'm going to try Big Daves technique of standing the flask on edge. I'll let you know how that works out also. Thanks for the advice and insights, John

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Re: How to gate and runner a car frame?

Post by jscarmozza » Fri Oct 19, 2018 2:08 pm

I made my experimental pour today with a new larger crucible (10# AL) and it went fairly well and was, as usual, a learning experience. First thing I realized when making the car frame pattern was that a 32" long pattern was going to be too big for me to pour and handle, flask weight wise. I decided that I would make half a frame and just bolt the two pieces together. I also made a trial car side pattern with a rivet panel and and a few scribed lines to mimic vertical boards just to see how much detail would come out. The side panel was 6" X 12" and 5/32" thick. I poured the car frame in the conventional horizontal manner but with a sprue extension (tomato can) and very generously sized sprue, runner and in gates, I also vented at every intersection of the car frame longitudinal and transverse members. The side panel was poured using Big Dave's standing on edge method. As you can see in the photo, the frame turned out well, but the side panel has a hole in it. That's because I didn't make the cope properly by ramming it up on the reverse side of the mounted pattern, instead I just rammed it up and screeded it off leaving a high spot that caused the hole. All in all I'm encouraged that I can make the necessary patterns and successfully pour them.
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steamin10
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Re: How to gate and runner a car frame?

Post by steamin10 » Sat Oct 20, 2018 8:36 pm

Not bad, just imperfect. You identified your mistakes and the next run will be different

Innpouring a heavy melt, it is soemtimes advisable to use a pouring rail. taht is simply a sawhorse of needed heighth to carry the weight of the pouring shank above the mold and allow you to set the shank down on it for weight and pour without strain on your arms. Really heavy operations use a hoist or pouring pot to accomplish this. I use a pipe rail with #16 crucibles. It slides easy and gives me good control of the melt pour.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

hoppercar
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Re: How to gate and runner a car frame?

Post by hoppercar » Wed Nov 14, 2018 7:45 am

A much simpler way is to pour smaller end sections, and bolt them together with channel iron

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Re: How to gate and runner a car frame?

Post by Rwilliams » Thu Nov 22, 2018 10:28 pm

Have you tried a thin coating of powdered graphite in the mold to speed the flow of the molten aluminum to all parts of the casting?

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steamin10
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Re: How to gate and runner a car frame?

Post by steamin10 » Fri Nov 23, 2018 2:41 am

I can assure you that to my knowledge, adding graphite dust will do nothing for aluminum. This method is used for cast irons to reduce skin temper due to white iron as the carbon will be picked up when the iron flows over it. If you have ever tried to machine a bad iron casting that has white iron chills, you will know what I mean. They will eat normal tools for lunch.

On the flip side of this, original wheels for early civil war era cars were poured with iron chills around the wheels to make that cooling effect, and harden the cast iron for better wear. Such iron wheels were prone to fire cracks and often failed during service, especially as speeds were going up. They were later replaced with wrought steel, and finally forgings.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

jscarmozza
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Re: How to gate and runner a car frame?

Post by jscarmozza » Fri Nov 23, 2018 9:39 am

The frame pours are coming out consistently good using the methods described previously. The side panels are a different story. Using Big Dave's standing on edge method with flasks made from warped and twisted wood just doesn't get it done. In every one of the panel pours we made last week, just as the mold filled we'd get a run out through the the seam between the cope and drag. Even with four C-clamps on each flask the liquid metal head was too much (and the sand may have been a little too dry). I think the riser/runner being an1-1/4" off the face of the flask is too close to the edge, the sand dries before the metal freezes and with the high liquid head blows through the flask seam even though the sand in the cope and drag are snugged up to each other. Better and larger flasks are in the works. That being said, the partial panels that came out of the failed pours had great detail in the doors, windows and siding boards, so I'm encouraged to continue until I get it right.

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