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A little aluminum casting

Started by Don P, May 23, 2020, 08:52:21 PM

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Don P

Sometime in the last week or two we were talking about charcoal and I mentioned wanting to do a little more aluminum casting with it. We had days of rain this week so I scavenged through my scrap piles and got some junk aluminum together and welded up a mold for the mount for my Belsaw guide. I've broken a couple over the years when a board or log gets away and they aren't making any more of them. So I figured I'd try to cast a few and if that works, cast the guide itself which is a bit more complex. My sand and my sand molding skills aren't up to this multi part mold level so I figured I'd try to make a simple 3 piece steel mold to pour into.

Here is the trashcan furnace with a pipe "crucible" surrounded by charcoal. I've got an old tire rim in the bottom that I drilled for the blast pipe to go into then the air goes up through the various holes in the rim. The crucible is sitting on a piece of pipe stuck through the axle hole an inch or two above the rim. I stick it in and pour the charcoal around it. There is firebrick lining the can below and that is old oil furnace masonry lining you see up top' It takes a couple of feedsacks of charcoal to do a melt in it.




That's a link of chain welded to the top of the crucible and there is one on the side near the bottom. I lift and pour by using steel hooks through those.

This is the guide mold clamped up and ready'




If there was extra I've been playing with a walkingbeast geartrain and had the plywood gears around so molded one in damp sand





The melt was part of an old carb, an old shoplight housing, parts of an old floor sanding machine, the end gland from a hydraulic cylinder, real junk and some was pretty low grade stuff. I skimmed a lot of dross off the top before pouring, a whole lot. I'll throw that in with my aluminum cans when I go recycle, it was still very rich in aluminum I just cant get it all and skim that off down to the shiny pool.

These are right after the pour, you can see I ran short on the gear. Well it cleans up the aluminum for next time.







The guide mount unmolded beside the original. Not horrible, it'll work but I have some things to learn.




I still had more scrap and the furnace was hot so I jammed the pipe crucible back in and got it down pretty low, poured in another sack of charcoal and plugged the blower back in. About the time I had started to get melting going again a rain storm came up for an hour or so. I have the trash can lid on the furnace while its melting so not a big deal. I let it pass and added and skimmed. It was about suppertime and I got in a little more of a hurry and didn't put on my welding jacket or safety glasses and the ground had gotten wet... see where this safety message is going ::)  :D
So I'm trying to pour faster to get a better fill in the guide mold and overfill, and some runs over onto the ground. Then the science lesson starts. Did you know that steam is 1700 times bigger than the water it came from? And aluminum at about 1500 degrees makes bodacious steam on wet ground. Luckily there is only one small burn on my neck and once I put my t shirt out I realized I was dang lucky. The shirt is a nice lace curtain, grease rag :D.
So anyway, fun way to spend the day and hopefully made a couple of spare parts for the mill. I'm kind of thinking about some Victorian style slab table legs and I have a couple of buckets of old copper...

WDH

Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Don P

Not entirely sure myself how I made it to 9 :D

Walnut Beast

Nice information and impressive 👍👍👍

Dan_Shade

Woodmizer LT40HDG25 / Stihl 066 alaskan
lots of dull bands and chains

There's a fine line between turning firewood into beautiful things and beautiful things into firewood.

Southside

I am envious.  Have a pile of broken bands that some day I plan to run through a not yet owned forge, which will (in my mind) convert them into an axe or knife.  So your spirit of adventure keeps my fantasy alive!!  
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White Oak Meadows

Diesel 40 Don

Might I suggest the Gingery series on building machine tools from scrap metal.  Google Gingery books for the website where you can buy them.  The first book is on building a charcoal smelter and casting techniques.  I bought the books quite a few years ago, skeptical that they would be any good and was very pleasantly surprised.  They are well written and clearly illustrated, overall good quality.  The smelter book gives enough info to do good castings at minimal expense.  I modified mine to burn waste oil and am very happy with it.  I have cast many small parts for a variety of projects: engine mounts, shaft bearings, pulleys, etc.  Learning to cast aluminum has been a pleasant and profitable experience, not monetarily but in the ability to make a custom part quickly and cheaply.  In your case it is very handy since you need parts that can't be gotten otherwise.  So, keep up the good work and expand on what you can do.  It is a satisfying and fulfilling occupation.    

WDH

The picture that I see is you, clad in skins, bending over a fire with a chunk of ore in it, deep in a cave, poking the ore with a stick, 20,000 years ago, and saying "hmmmmm".
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Nebraska

I've never ventured past lead and making weights or basic projectiles. A forge has always interested me as well. Interesting project Don.

moodnacreek

I tried to pour babbit once and lead decoy weights. When I broke the bellsaw saw guide I welded it with a torch and flux core rod.         Interesting post about casting.

pineywoods

Interesting, thanks for posting. Many moons ago, I dabbled in aluminum casting. Used a propane burner out of an old hot water heater and crucible welded up from 6 inch steel pipe. biggest problem I had was poor sand for the molds. Never found a good source for casting sand in small quantities. Dump truck load is a bit much. If I had extra melt after filling my mold, just pour it in an empty tin can for use in lathe/milling machine projects. Be cautious melting any pieces that may be aluminum/magnesium alloy. Molten magnesium is highly flame-able. Best source I found is small engine blocks and Ford transmission cases. 
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Tom King

One of the classes that a friend of mine (now gone) used to teach was Lost Wax Casting.  The final test was to do a wasp.  If you succeeded, you got an A.  You found out real quick the meaning of Wasp Waist.

He left me all his tools, which included a lifetime accumulation of machine tools (he also taught welding, and machining), and the casting stuff, but it's mostly stored in a pile in a building, and I haven't had the time to do anything with it yet.  I need to build another shop just for that stuff, but have been too busy.

I've never done any casting beyond lead for counterweights, but they were just poured into metal cans.

luap

We did some pours of babbit bearings in our shop, a few were large, 6" bores. Very important to preheat the molds. We would chalk the inside of metal molds. I used a pine kindling stick to stir the molten metal. It assisted the dross to seperate. Don't know if Al woud be the same. Damp concrete floor is not any better than a damp dirt floor. I have done a few small pours at home. Scrap Al pistons made good castings. I have read a few of Gingery's books. Fun hobby to enjoy.

Don P

I was wondering if preheating the mold would help with those shrinkage voids, the second one has those as well, I just pulled it. There's also different thicknesses and cover which isn't helping. The chalk is a good tip. There's really no draft in much of the mold so it takes a good hour to work it loose. Wood would flash off too quick at this temp I think. I have a few of Gingery's books, I really like his stuff. As a boy I nearly blinded myself and left my shadow on my mothers kitchen cabinets playing with casting lead on the stove. Moisture and hot metal is nothing to play with.

The mountain behind us is Iron Mt, I know of at least 5 old furnaces, the open cuts are still visible, a couple of lime kilns and several charcoal hearths around the area. I can drag a magnet in the dirt and pick up magnetic dust so there is good ore here but that is one hot fire, I'm not anywhere near that yet. The casting was mostly done in a sand bed floor in the attached building, there is another tapping arch in the furnace like the visible draft arch you can see here.




farmfromkansas

I took a metals class in school, had a part in casting aluminum. Have a pair of bookends to prove it.  We used a really fine sand to pack for the mold, had a sort of wooden handle to pack the sand around the form, then you pulled the form out, and poured liquid aluminum in.  Also helped cast a plaque for the school, made of brass, for someone who donated money for some tree plantings.  Was a fun class, they used a crucible that you picked up with a steel frame, had to be 2 people, one on each end of the frame, crucible in the center and you just poured it into the form.  Most of the forms came out great, I made one for a boot puller, it did not, so had to be satisfied with the book ends. Liquid aluminum would probably burn your foot off if you dropped a bit in your boot.
Most everything I enjoy doing turns out to be work

Tom King

I guess just like for welding, and cutting metal with a torch, wear boots you can shake off quickly.

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