Casting AL molding box

[ironman]

Hi everyone

                   For a change I melted some aluminuim and made a molding box. This video would interest beginners about how I made the parting line without trimming any sand. 

[vtsteam]

Ironman, that's a first rate flask. Modular -- so simple, and conservative of materials and molding technique compared to other aluminum versions I've seen.

I got a little confused at 5:20 by what you were removing (the handles) since it looked like you had already removed the loose piece. But finally figured out that the loose piece was actually in 2 parts, one of them (I'd missed) was transparent (a handle pattern), and that part had been left in the mold when you removed the wooden part (a greensand core pattern).

Wonderfully simple and straightforward and versatile all around. What I think of as elegant in design and construction.   

[ironman]

I had a quite a few people asking about the very same thing when they saw the video.

I think some that look at the video havn't had much experience making sand molds and missed that the handle is a pattern and has to be removed from the mold.

[Mayhem]

Thanks for posting that Ironman

[vtsteam]

This has been on the to do list for awhile. I finally have the time to start on some new flasks.

The pattern so far. Need to make the loose pieces yet.

[micktoon]

Top quality video Ironman  , I can see what people mean about the handle pattern section of the video but made sense once I knew about it , Thanks for posting 

  Cheers Mick

[ironman]

Your boxes will last a longer with iron.http://madmodder.net/Smileys/default/happy0065.gifhttp://madmodder.net/Smileys/default/happy0065.gif

[vtsteam]

Ironman, question:

You put your locating pins in the box sides instead of the handle. Is there a reason for that or just personal preference?

I ask because I was thinking that a pin with threads on the end through the handle could be used to clamp the flasks together, and eliminate a bunch of adjustable clamps that you use.

The only reason I can think of why I might not want to do that is that in your practice you clamp the top and bottom cover plates together, not just the flasks.

And maybe that is because with such shallow copes the sand could push up inside the flask.

The plate and clamp setup you use would prevent that.

Thanks in advance for your answer!

[vtsteam]

Today's progress -- not as far as I'd hoped. Didn't manage to cast anything. Just made the handle pieces and a larger wooden flask to cast the new aluminum flasks in.

Maybe tomorrow......

[ironman]

Yeah you are right.
 
Because the cope is so thin a plate has to cover the cope to stop the mold distorting and rupturing. The reason I use thin boxes is less sand needs to be used.

With the pins it is up to you which way you do it.

 There is a huge advantage with a forum because if a idea comes up it can be modified and improved for for all who read this post.

[vtsteam]

Thanks Ironman!

Hmm, thinking about this -- the need for plates adds a whole new wrinkle to this. If I had lots of aluminum, I guess I could cast plates. But I'm starting to run low, and casting 4 or 6 of these boxes plus the same number of plates is a lot of Al. Maybe all I have.

I'm wondering what else could be used for the plates that's easier to come by. I guess plate steel, but 1/4" probably minimum thickness, and I'd have to buy that.  Probably $60 for 6 plates.

I do have some 1/8" steel plate I could use, but that seems too thin.

Too bad concrete spalls with spills, and wood burns. Any other ideas?

[awemawson]

I just used 20mm shuttering ply, which is the cheapest you can buy, and regard it as expendable. Usually lasts 10-15 pours then goes on the bonfire

[vtsteam]

Thanks Andrew. then that sounds good -- we're speaking of iron pours here just in case you were thinking Al --- but I have unlimited wood supply of any dimension because of the sawmill.

Maybe green wood would be better even than dried?   I recall something about the old timers using a green oak branch for stirring the melt, and green oak used for skimmers. Maybe I can find that reference -- Terry Aspin?

[awemawson]

I used the same method for aluminium, brass, bronze, and iron. It's only splashes and drips after all , and they are 'outside' of the critical area anyway (ie outside the cope). I am fortunate that I have a large pile of steel copes and drags in a range of sizes from very small to really quite large, but I reckon when I actually get round to starting up again I'm going to have to sand blast them. They've been stacked outside for six years already

[tekfab]

I do have some 1/8" steel plate I could use, but that seems too thin.

Rob made some nice ones out of sheet, looks to be about 1/8, he did add a  swage which i guess that apart from stiffening the structure also adds a "retention" hollow for the sand.

Mike

Edit : Just checked "Beating Steel into Submission" thread and it was 1/8" sheet, sorry i don't know how to do the link thingy  :-(

[vtsteam]

Andrew, great, thank you -- that's a great help! 

And mike found it: http://madmodder.net/index.php/topic,3545 -- will give that a read! 

(note, to link just go to the page you want to link to and highlight and copy what is in the top of you browser for an address. Then go to the post you want to put the link into, and paste it right in. -- hope that helps.)

And since it's raining today and no casting, I've been trying to find the thing about "green oak stick" for stirring. Can't find anything. So nobody try it, for safety sake.

I did find stirring the melt with a pine stick (presumably dry) in Gingery's Charcoal furnace book -- (for aluminum) -- he says it is supposed to improve the melt, but he didn't notice any difference. Also B.Terry Aspin in The Backyard Foundry p. 85 shows a wooden rake for skimming the melt (iron) -- he says oak and beech are suitable -- (presumably dry). I don't know where that memory of "green oak stick" comes from. So best ignored.

But re-opening Aspin's book brought back all of the excitement of first reading it, and the wealth of information in this little book, wonderfully illustrated. Great drawings of pattern making, core boxes, coring, for steam and workshop tool making. And coincidentally, making flasks -- including many different types of construction -- sheet metal, cast, and what really surprised me, concrete.

Now I'm not interested in making concrete flasks. But I'm wondering about the cover plates anew. Seems like there are mixed opinions about concrete spalling and splattering grit and molten metal all over the place when hit with hot iron.

I'm thinking the reason for the mixed reviews is differences in concrete mixes, bubbles and moisture content of the concrete itself, rather than everybody arguing right and wrong from a firm standpoint.

Concrete can absorb water if mixed in some proportions, and is pretty impervious in others. In fact Portland cement, mixed neat is waterproof -- and is used in waterproofing tanks and swimming pools. So I'm wondering about this -- I always get curious about this kind of stuff -- especially when there are big disagreements by believable people on both sides of a debate -- I often wonder, maybe they're both right, but not talking about the same thing.

If concrete plates could be used for pouring (and if of the right mix and kept dry indoors) they would seem like a very good, nicely massive, inexpensive cover plate material.

[awemawson]

At my last place I had a purpose built 'fireproof' building about 20' x 15' for casting - the floor was concrete and the furnace was in a pit at one end. The apex of the roof was a 10"x6" steel beam that I had a runner on with a block and tackle for the heavier stuff.

All my pours were on that concrete floor. I just laid out my copes & drags in a line on their boards, and if I was being particularly keen I'd sprinkle moulding sand between the flasks, and either side, but usually I didn't. The damage to the boards was not much to be honest - ok they'd burst into flames and smell awful, but knock the dribbles off and a handful of sand and when the smoke had cleared it was fine !

Worst time was when I had a 'helper' who insisted on chatting and not concentrating, and managed to drop a crucible of bronze. Oh boy did that go EVERYWHERE ! I have a ceramic chip forge, which stands on a heavy bent sheet steel base, and it ran under it in a thin puddle gluing it to the floor! Luckily I insist on proper foundry boots with fireproof soles so we were ok. Never did ask him to 'help' again

[vtsteam]

Sounds like the "spalling" explosion of concrete and metal -- often warned about -- didn't occur though -- or did it?

If it was done right, a 9x 12" cover plate probably couldn't hold a signifigant amount of spilled metal at all -- ironman uses a half circle cutout above the sprue in the plate, and those edges could be beveled as well.

Or if the top cover plate was slightly convex or even flat sloped toward the sprue pouring hole, seems like there would be not much chance of any spilled metal staying on it.

[awemawson]

Here you are Steve, don't bother making flasks, borrow some of these (I bought the contents of a foundry that went to the wall some years back):

[vtsteam]

I'm going to have to build a boat to get em!  Nice, though.

[vtsteam]

Well after all this I paid a visit to the shed where I keep my aluminum. After checking what I had, it seems I would use up nearly everything to make 6 of these -- frugal as they are -- by the time you count sprues, long runners etc., I'm guessing 5 pounds minimum each melt. And with a single large flask to cast them in it's going to take a lot of time and fuel to do 6 pours.

So I think I'd rather save all those resources for doing more interesting work. If I had a couple hundred pounds of scrap aluminum, it would be different. Maybe I will at some point, and will take up where I left off here.

[awemawson]

Got any sheet steel and angle iron lying around?  Fabricate some.

Or alternatively use wooden ones and reckon to replace them relatively often.

[vtsteam]

Wood it is, Andrew. I'll leave this thread since it's real topic is the very fine flask design by ironman.