MadModder
The Shop => Metal Stuff => Topic started by: vtsteam on June 06, 2013, 08:35:16 PM
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Cupolas normally use ladles instead of crucibles. The ladle is often a metal pot with a ladle wash of refractory to protect it. I thought I'd open this thread to get feedback and ideas on making them.
I'll probably just put down some random thoughts here. Feel free to join in on the topic.
I've found that when I made a crucible out of 4" diameter iron pipe for melting aluminum that it wasn't easy to pour with compared to some other shaped crucibles I have.
A straight narrow cylinder seems to pour all at once rather than gradually like a "bilge" shape in a conventional crucible.
I think the same thing would happen with a ladle made from 4" pipe. Or maybe worse. Because you have to line it, which effectively makes it even narrower and proportionately taller for its volume.
Another problem with a pipe crucible is that to fully empty it you have to tilt it at a greater angle. At least it seemed that way to me. The greater the angle, the further away from the sprue hole it needs to be held.
Since the flow varies as you pour you have to move it horizontally to adjust for the change. All in all it tends to make for more misses and miss-pours than a bilge or tapered cone shape.
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It seems to me that crucible proportions have been worked out over time to ease pouring and accuracy.
So I think a ladle shaped with a bilge, along crucible proportions might be something to try to make.
Well one way to make that would be to pour it. But since I can't do that yet, I was thinking about maybe trying to weld one up.
Would it be possible to make one with dart shapes welded together?
I have some 11 ga. (approx 1/8") sheet that I could jigsaw into the dart shapes -- maybe joined at the widest part, and then maybe weld those together to get a good approximation.
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Another thought is the teapot type of ladle.
These look like a watering can with the spout tight to the main body. Their advantage is that they are self skimming. So they would make pouring easier for a one man operation.
The problem with them as I see it is, how do you line it?
Particularly the part where the spout joins the main part. I'm guessing that the lining should be about 1/2" thick.
(http://www.acetarc-engineering.co.uk/images/ladle-slflp/pic1.jpg)
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In my case a teapot would be rather small, which might make lining even harder or even impossible.
Here's a big one!
(http://farm5.staticflickr.com/4026/5148420516_efaf51562f_z.jpg)
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Right now I'm thinking about ladles to hold about 10 pounds of iron.
Probably good to figure out how much volume that actually is.
491 lbs/cuft
so
10/491 = .02 cuft or 34.5 cu in. (or 566 cc)
Let's see how tall a 4" dia pipe that would require:
4 * PI * h = 34.5
h = 34.5/ (4* PI) = 2-3/4"
Wow! That's not much -- is that right?
So a 4 inch deep piece of 4" diameter pipe would easily hold 10 lbs?
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Okay, suppose I did use a piece of pipe, I would have to subtract the thickness of the lining to get the true capacity.
So assuming the lining is 1/2 " thick, then the diameter is really 3" so we get:
34.5/ (2.25 * Pi) = 4.88", say 5"
So you'd want a 6" piece at least.
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I have a couple of A6 crucibles -- not strictly speaking "bilge" type, but shaped better than a straight pipe.
Dimensions are:
6 1/8" tall x 4 5/8" top diameter x 3 3/8" bottom diameter.
This is supposed to handle about 13.2 pounds of brass. Not sure how much iron. Well, I could figure that out. Let's see...
535 lbs/cuft brass, 442 lbs/cuft for grey iron (hey, that's different than what I found online earlier 491 lbs cuft....? Oh well..)
442/535 * 13.2 = 10.9 lbs, okay say 11 lbs, so A6 is about right for my furnace assuming a 10 lb charge.
Okay.
So say an A6 crucible is about 1/2" thick -- that's about what a steel ladle imitation of that shape should be with an allowance for the lining thickness.
So I could use the A6 crucible as a model for making a steel ladle.
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I was trying to find proportions for B4 crucibles -- these are about the same capacity as the a6, but with a true bilge. Unfortunately I can only find the bilge dimensions for larger sizes. The bilge dimension is the widest part.
Well I guess I could interpolate that from the larger sizes. Just get a typical proportion of the top diameter for the bilge.
Okay, a B10 crucible has a top diameter of 6/14" and it has a bilge diameter of 6-5/8".
So the proportion is 1.06. The bilge is 106% of the top diameter.
Okay going back to my A6 dimensions, the top was 4-5/8". That means if I want a "classical" bilge, it should be about:
4.625" * 106% = 4.9", or about 4-7/8"
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Okay, so I've got 4 dimensions for my bilge shaped ladle to handle 10 lbs or so of iron:
Height = 6-1/8"
Top diameter = 4-5/8"
Bilge diameter = 4-7/8"
Bottom diameter = 3-3/8"
Is that right?
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Since it's raining. I'm just playing around with an older free version of Google SketchUp making crucible patterns. Here's a real simple one -- just two rings, but it does give the bilge shape and has a pouring spout. If you made this, it would actually turn out round rather than faceted into an octagon, though you would see the join line as a hard edge between the two rings.
However internally, it would be smooth since you would line it with 1/2" of clay refractory, and could round the corner out.
This is the same size as the A6 (with bilge added) from the dimensions in the last post.
I might actually try making this.
(http://www.vtsteam.com/Ladle/Crucible1.png)
ps. I'm not a SketchUp expert -- this is as much a learning exercise as anything else.
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why not make a rudimentary "one shot" crucible out of clay and the first thing you cast is a laddle?? =)
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why not make a rudimentary "one shot" crucible out of clay and the first thing you cast is a laddle?? =)
A "bilged" ladle is not the easiest thing to cast actually, thin wall, needs a core, and is compound curved. Not the best first iron casting project. And I wouldn't trust a pure clay ladle I made, though I could easily use a metal pot or pail or steel pipe ladle, lined with clay refractory mix in its place.
But more importantly, like the question, "Why would you build a lathe when you can buy one," I might think about trying to make a shaped ladle this way because I'm simply curious and interested in it, enjoy practicing with SketchUp, and because it is going to be raining continuously for 2 days.
:D
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Here is some crucible sizes
http://www.budgetcastingsupply.com/Crucibles.php
Tom
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Well u build a lathe coz its fun making tools and machinery. And buying them is either expensive or chinese rebranded crap. :)
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Here's a pattern for making the ladle -- I've made it so it will print out on A4 paper for others here. I'm labeling it a B4 because it is similar to the size of B4 crucible (or A6 with a bilge added).
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Print out and, tape sheets together, and cut them out with scissors:
(http://www.vtsteam.com/Ladle/Crucible2.jpg)
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I glued them to some aluminum sheet and cut them out with tin snips to make patterns. I'm sure i'll make more than one, so patterns are handy to have:
(http://www.vtsteam.com/Ladle/Crucible3.jpg)
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Then I used the patterns to mark out some 1/8" plate I had. The plate was cut out with a portable reciprocating Bosch jigsaw, which, with a bimetal blade makes short work of this stuff. Frankly, faster than a bandsaw, and a lot easier to maneuver on a big sheet of material.
(http://www.vtsteam.com/Ladle/Crucible4.jpg)
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A little bending, a little cussing, a littl hammering, a little welding, not to mention some grinding and....
(http://www.vtsteam.com/Ladle/Crucible5.jpg)
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An enjoyable little job by the time it was done. I'm impressed with the unfold tool add-on to SketchUp. The pieces fit together perfectly:
(http://www.vtsteam.com/Ladle/Crucible6.jpg)
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:clap: :clap: :clap: :clap: Very nice Steve :thumbup:
Rob
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That looks brilliant. :)
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Very clever
:thumbup: :thumbup: :thumbup: :thumbup:
John
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Well done , the unfold tool looks like it would be handy to have , thanks for posting :thumbup:
Cheers Mick.
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Rob, Neo, Double, Mick thanks!
The unfold tool is by Jim Folz and is available here:
http://sketchuptips.blogspot.com/2007/08/plugin-unfoldrb.html
I use it with an older version of the free version of SketchUp (version 7.1). Along with tools for exporting DXF files and the PhlatBoyz CAM CNC Router output plugin, it makes free Sketcup a much more powerful tool.
For those who want to do similar things to the crucible design without using a CAD program, there is an online program to generate the projected shape for cutting out cone sections from sheet metal here:
http://www.i-logic.com/conecalc.htm.
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Rob, Neo, Double, Mick thanks!
The unfold tool is by Jim Folz and is available here:
http://sketchuptips.blogspot.com/2007/08/plugin-unfoldrb.html
I use it with an older version of the free version of SketchUp (version 7.1). Along with tools for exporting DXF files and the PhlatBoyz CAM CNC Router output plugin, it makes free Sketcup a much more powerful tool.
For those who want to do similar things to the crucible design without using a CAD program, there is an online program to generate the projected shape for cutting out cone sections from sheet metal here:
http://www.i-logic.com/conecalc.htm.
I wish I knew about this earlier. There's been a few times in the past where this tool would've saved me a bit of bother. I'm sure i'll get a chance to use it at some point too so thanks for posting it.
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You're welcome S. Heslop!
Just now trying to figure out which I should do: make a pouring shank of the ring type to fit the new pot, or just weld a long Tee handle directly onto it?
Any opinions out there?
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vtsteam
Here is a video of a cupola exactly like yours and they use the exhaust vent to preheat the ladle
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Yes that works well there.
Boy, they have a lot more height and they're using coke. I'm really doubting whether I will have enough heat to melt iron at all with my setup. :(
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Just shows what you can do when Health & Safety stay away for the day :lol:
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You have to love how American's cheer for anything and everything :clap:
VT - I guess there is only one way to find out if yours works. If not, I'm sure you could add more hight. Or is the issue that you want to use charcoal and not coke?
Also, what were they doing at around the 9-10 minute mark? Was that a small blower they were adding?
I wonder how Rob is going...
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Mayhem, yes I could add more height with an extension, and yes the idea was to use charcoal made here. We'll just have to wait and see. I could also go waste oil crucible, etc. But my real hope was for a single charge charcoal melter, either cupola or crucible.
Toward the end they broach the furnace shell and refractory with a bar, leaving the blast on which they deflect with a shovel, then drive a pipe in through, and duct tape a second blower on.
Awemawson, that video was absorbing to watch on the other side of a computer screen, but not live, not my cup of tea in just about every way. Great gobs of bot, patted by hand into place, broaching walls with the blast on, a tangle of inexperienced helpers, and a bunch of spectators is not quite how I imagine wanting to work with iron. Concentration is more admirable than heedless showmanship.
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We were talking about making crucibles on my oil furnace thread, and it seemed like it would fit in better here, since the ladle I made could actually be used as a crucible to melt aluminum or any of the copper containing metals.
But also of interest is the possibility of making an iron melting crucible. Neotech linked to a youtube video of a crucible being home made with graphite, using a press. Although this one, in the end was only used to melt aluminum -- no mention of its suitability for iron. And Vince Gingery wrote a book about using a press to make non-ferrous melting ceramic crucibles -- without graphite.
With the right ingredients seems like you could make one on a pottery wheel with a bilge shape, unlike the prior two.
But what interests me is probably the simplest and oldest pottery making method -- coil forming. And it doesn't require a press, or a wheel or any other special equipment. So, I'm thinking about that. Just thought I'd put it out there.
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This is a particularly instructive video about commercial crucible making
But also check out the segment at about 3:14 "rib forming" which looks like it might be appicable to smaller scale crucible forming.
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the biggest problem with coil forming is that its hard to keep the wall thickness the same over the whole shape especially you do the bilge shape..
On way is to mix the clay up and make it more lika slurry and go about casting the shape needed. All needed for casting in clay is a gypsym mold that can be created on wood plug. the two parts is then let dry 1-2 days until they start to be "leathery".. then a thin water film to moist the contact surfaces and you squish em together and smooth out the seem... And then let dry a bit more before burning them in the furnace..
Stoneware is usually burned in 1350 degrees for 4-6 hours depending on surface coat or no coat.. But its a ramped up temperature.. Buut can be done with propane burners and a stopwatch. =)
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the biggest problem with coil forming is that its hard to keep the wall thickness the same over the whole shape especially you do the bilge shape..
I don't think that would necessarily be a problem, within limits. These would not be for sale for home decoration. I've seen some extremely fine coil and pinch work, btw. Not that I'm probably capable of it!
I do know about slip forming, though I wonder if it would work with iron crucible materials, like graphite, etc. Plaster of Paris is used for the molds here.
For long firing time there may be a few alternatives. Sounds expensive for propane. I'm thinking a wood/charcoal fired kiln here. If you could do say a dozen at a time, you could build temporary kiln, like a brick kiln to do the batch.
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I guess the biggest problem toward an experiment would be finding a proper recipe and materials for iron melting. It would be a lot of wasted work if you didn't have those right.
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I think a deep dive into the alloyavenue forum and some good old book reading is in place.. its a goodproject - if one figure it out. =)
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Hi,
The ladels I have used have been hemispherical, with a pouring lip and I have never experienced any problems.
Cheers David
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Oh the laddle thread was converted to a crucible making thread though. =)
Still good to know..
Been looking into mothers ceramic stuff vendors.. seems i could conjour up all the materials needed for trying to make a crucible clay, the glace is another matter.. it would need to be some zirconium based glace to really withstand heat.
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Hi,
The ladels I have used have been hemispherical, with a pouring lip and I have never experienced any problems.
Cheers David
Hemispherical should be a good pouring shape for a ladle. Just like a soup ladle!
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vtsteam Thank you for posting that crucible video it was very informative! It even shows isostatic pressing which I wondered how it was done.
Here is my attempt at using a lump of coke and machined it in the lathe to get the crucible shape. It was used in a microwave oven to melt pewter to pour into a silicon rubber mold.
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Isnt turning coke kinda harsh on the machine with all the powders coming off of it?
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Wow, Ironman, that was quite an experiment! :bow: :bow: :bow: You've found a lot of uses for micowave ovens -- and parts of them.
A place I used to work at used graphite crucibles to do thin film metal deposition on optical filters. As an experiment I once turned one from raw graphite stock for them, but there were too many impurities in it apparently to be useful.
But turning coke is I imagine much more difficult than graphite. Graphite is merely soft, messy and delicate -- but uniform. I imagine coke is not quite so simple. I've also turned graphite to make a hot air engine power piston.
One more example of the amazing stuff you've tried and succeeded with. :beer:
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NeoTech
I covered the lathe with rags to protect the slides and used a vacuum cleaner to suck up the dust before it spread all over the lathe.
Certain coals contain pitch which bonds the carbon to make coke. Pitch is also used to bond coke dust to make carbon electrodes for arc furnaces.
When a crucible says it is carbon bonded it uses pitch as a binder.