Cold Weather Casting?

We are into full bore winter here in Minnesota with current conditions Fair at 16°F or-9°C.
It is going to warm to just below freezing today but along with that comes a chance for snow.
I still have a couple pieces I want to do in aluminum with my wee propane + 20lb tank furnace, another set of 3" tape holder wheels in lost foam and some repair parts for a telescope in Petrobond (once I straighten out the warped 3d prints...)


What are people doing to keep going in the cold? Or is casting a warmer-weather sport?

Curious to the effects of cold on the process of casting. I am also considering going to a regional iron pour and that is in February.

So far I just keep the Petrobond in the house and rammed flasks indoors until just before the pour and covered until the crucible is ready to pour. The lost foam is still new to me, that sand is outdoors due to the polystyrene 'stank' on it. I am still planning to work outdoors today, but would like to explore better inclement weather options.

I could move the furnace to the attached 2-car* garage (*cars are not really allowed in the garage, too many other projects) and enjoy the waste heat and fumes during the melt or move it to a smaller 8x8 foot (2.5 x 2.5 meter) detached, mostly-abandoned shed 100 feet away and really enjoy the heat but also have even more concentrated fumes and low ceiling and partial dirt floor and such. Leaving the rig set up in the little shed has its appeal too but not dragging stuff out there like loaded flasks and pails of sand through the snow.

Has anyone done a heat reclaim / fume exhaust on a propane furnace? I have a wood burning stove and chimney in the garage, I could just stick the furnace in there and have some venting but realize that by doing so the heat reclaim would be minimal, especially if I crack a door or window for intake air.

 

the furnace is unaffected by the cold, at least down to freezing, Petrobond looses green strength when it gets cold ( It will be crumbly) if you keep them indoors in the 50s until you light off the furnace you should be fine, really no concerns about the metal if you get it to pouring temp and work fast you will see little difference

V/r HT1

 

The only factor I've seen affect furnace operation is the humidity: converting all that water vapour into steam burns about 10% extra fuel and takes a bit longer to melt the first crucible from cold.

 

Thanks Everyone, good thing to consider. Casting is on hold for today, ran some errands and broke one of the 3D printed pattern pieces so decided not to rush around or push forward any more today on it. I will also use the original as one of the patterns, with the holes taped closed, just in case I have more trouble with the other printed one.

 

I just never liked burning my face while freezing my butt.

 

I poured a 48" camelback straight edge this morning with temps somewhere in the 26 to 28 degree range. I DID have an unexpected problem---my pressure reducing valve filled with ice from the air compressor line.

I have been aware that there is some condensed moisture in my compressed air line but that was of little concern to me as I only run a pneumatic rammer and a dust blower from the line or use the compressed air to atomize fuel in my siphon-nozzle burner. It is rarely sub-freezing in my neck of the woods and those episodes are usually brief. Recently, we have been breaking local cold weather records for date.

This morning after overnight lows near 22, I set up to pour 46 pounds of iron into the mold I made yesterday. Everything went just fine for the first half hour or so and then I noticed the pressure supplied to the burner was starting to vary inexplicably. I would drop to 10 pounds and then return to the 45 pounds set and then go down to 32 and then back up etc etc. I already had a pot full of just melted metal at that point and sure did not want to shut down. After it dropped down to 10 and stayed there I figured my valve had crapped out and pulled it off the line and replaced it with another one that was handy. When I looked at the intake side of the valve assembly you could see that it was nearly obstructed by ice. Suddenly everything made sense. So, then I placed the valve about a foot from the furnace so that radiant heat would heat it some but not too much and I started periodically opening a vent valve on the air line upstream of the gauge to shoot out any water in the line. From then on the melt went fine.

Lesson learned: watch for ice in air pressure reduction valves and keep the valve warm---easy enough in my case as long as I think of it.

The general scene this morning as the melt progressed:

Ice in the valve:

Ice cleared:

Something to watch for...

Denis

 

Maybe cold weather is good luck? The casting that resulted from the iffy melt this morning came out very well.



The riser recently discussed did its job nicely. You can see central piping. The void extends 1” downward. There are no unintended voids.

Bottom line—-whew! I always breathe a sigh of relief when I get a good casting. This pattern is very challenging for me. Pouring it from the end like this is relatively new. I used to make two more or less central gates. The mold was inclined to be about an inch higher on the far end than it was at the gate.

Denis

 

Jammer- LOL!
Denis-glad it all worked out well. I have like the couple inclined pours I have done after reading about yours.

 

How interesting! Why is it higher at the far end?

I also have a long, thin part that I used to gate from one end and then I changed my technique and had repeated failures. My next attempt will be back to a gate at one end, with risers and chills.

 

I incline flat-pattern molds almost always as I have read and learned through experience that they fill in a more organized fashion that way. A long flat LEVEL mold allows the metal running into it to bounce all over the place in disorganized blobs that, because they are small balls with large surface area/mass ratios, cool quickly and may or may not coallesce finally. Raising the far end causes a pool of molten metal to accumulate at the gate and then progress as a single front to the far end and then to filling level. Level flat plate-like molds are the worst. Cold shuts and incomplete fills are often seen in them if they are poured level.

It would be interesting to see the mold/pattern you are dealing with. Troublesome molds are the best as those are the ones trying to teach us something. (Least ways I try to look at them that way.) It sounds like this is a challenging pattern.

Denis

 

I tried to pour tonight, had issues all the way around. I was not able to extract the small pieces cleanly (they'll clean up...had higher hopes) and something went wrong (too much mud? too small sprue to part joint? ) on the lost foam so those pieces didn't cast. I did not realize the issue with the foam until I had loaded about a pound of aluminum into the bean can with Petrobond pouring cup. I also did not ram up the scope mounts until the furnace was running for the lost foam (last minute trying to consolidate 2 pours into 1) so I worked myself out of time to think about or to repair that mold. The air was just under freezing heading to 10 F (-12 C) later tonight, no apparent issues related to that and propane, other than the tank is probably due to be filled. I did the mold work in the unheated garage and poured outside. Sand was vibrated with an air chisel on a board on the side of the pail. The Petrobond handled nicely as it was mulled on a warm day a couple weeks ago and kept indoors at room temp since. Maybe this event will 'learn' me to make all the molds, and make them well, before lighting the furnace...

 

Thanks Kelly.

 

I tried the tape wheels again. 15 F (-9 C) outside. 40 F (+4 C) in the garage. I used my air chisel with a board between it and the metal bucket to induce vibration in the sand.

Safety note: check you propane fittings for leaks, especially if you break down your furnace after each use. The hose end closest to the venturi was loose enough to hear a hiss and smell mercaptan.

Ran the melt, skimmed, and and checked metal for temp. Meter slowed at 718 C so I put it back in for a minute and skimmed and poured. The small tin can filled and overflowed a bit...oh no not again...then I heard a joyous gurgle and it started filling again and drained the crucible level to the top of the can. Parts are formed and the drywall mud captured details down the the expanded foam beads in the sprue.

Wondering if I am still gating or sprue-ing too small? I don't get much smoke or fire but the sand is ripe with styrene fumes afterwards. I am using hot melt glue to attach things but cannot say what temp (high or low) the glue it is.

 

Thanks Kelly!

 

Just finished a simple pour, 3/4 x 12" round bronze bar. Open shed, temp 40#. I used a
heat gun to blow air through the mold, sprue to vent and reverse. Don't know if the
heat gun helped or not but the pour was good.

 

Glad to hear the pour was good Skratch.
Wondering if those infrared 'heat lamp' bulbs used for food service and chicken brooding would help keep a mold warm when it's cold outside.