Big crucible

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A few months ago I made an ingot mold for dealing with my scrap problem. See this post: http://weldingweb.com/vbb/showthread.php?t=39850I made ingots until my 20lb ceramic crucible cracked  Big crucibles are expensive. I thought I'd build a steel one and try it... it's bound to last as long or longer than the ceramic one.Tonight while upgrading the plasma cutter software (and needing to make some test cuts) I decide it was time to build a crucible large enough to handle a couple ingots. This is what I've come up with so far. This is a piece of 8" well casing. I figure it should tip out somewhere around 45 to 50 lbs.  Attached ImagesLast edited by forhire; 10-27-2010 at 02:14 AM.
Reply:Nice Work but,..I think you're going to be surprised at how 'Quickly' this crucible is going to 'break down'.  I've seen some steel ones last less than 5 or 6 firings believe it or not..  Most due to the amount of 'Junk' that flakes off into the melt...  It seems to be a real PITA when attempting to get nice clean ingots.  You can always COAT the inside with 'Marcote' or any type of 'Kiln Wash' and that should help significantly.  Also, the Walls will 'Thin' quite quickly, so be watchful of that...Honestly, I think you'd be better off with a 'Graphite' one as they can take a bit more of a beating than the 'Clay' ones and can be fired thousands of times...  The BIG ones are actually not that expensive if you plan to 'melt stuff' over the long term and also affords you the opportunity to melt Brass', Ores, whatever...Either way, I'm Looking forward to the updates!Cheers,Miller Diversion 165120 amp Buzz BoxVictor Oxy/Ace Oxy/LPGSmith "Little" Oxy/LPGHypertherm Powermax 30Lot's of Misc. tools n' crap....
Reply:Originally Posted by jmanNice Work but,..I think you're going to be surprised at how 'Quickly' this crucible is going to 'break down'.  I've seen some steel ones last less than 5 or 6 firings believe it or not..  Most due to the amount of 'Junk' that flakes off into the melt...  It seems to be a real PITA when attempting to get nice clean ingots.  You can always COAT the inside with 'Marcote' or any type of 'Kiln Wash' and that should help significantly.  Also, the Walls will 'Thin' quite quickly, so be watchful of that...Honestly, I think you'd be better off with a 'Graphite' one as they can take a bit more of a beating than the 'Clay' ones and can be fired thousands of times...  The BIG ones are actually not that expensive if you plan to 'melt stuff' over the long term and also affords you the opportunity to melt Brass', Ores, whatever...Either way, I'm Looking forward to the updates!Cheers,
Reply:Isn't the crucible just for melting the metal and then the mold (final part or ingot mold as needed) is for letting the metal cool in and solidify?    The best laid schemes ... Gang oft agley ...
Reply:Originally Posted by MoonRiseIsn't the crucible just for melting the metal and then the mold (final part or ingot mold as needed) is for letting the metal cool in and solidify?
Reply:Originally Posted by forhireWhen I melted aluminum in the clay-graphite crucible it would leave a thin layer of metal on the inside, despite trying to scrape it out. I had never had metal stick to the crucible like the clay-graphite. It happened on the first use. I wasn't letting metal cool in the crucible. I couldn't ever get it clean. I suspect I was suppose to use some type of wash... maybe Marcote to prevent the metal build up.
Reply:Originally Posted by jmanHmmm, yeah that is weird.  It will 'cling' to a 'degree' but that shouldn't be an issue, especially with Aluminum.  My feeling is that the crucible you had was cracked all along.  It would explain the problem with the metal sticking to it and the 'further cracking' as 'moisture' builds up inside while not in use and subsequently fired again.  Also, the VERY problem with the 'Clay Graphite' or 'Clay Silicon'' is they have to be heat treated 'first' before they can be used as some of them DO have a bit of moisture in them...  A Kiln is best for this (as you can ramp up/down and level off and rid the moisture 'slowly'.  Having said that, you certainly wouldn't expect to HAVE to do that and well,.. that sucks.
Reply:Wow!That almost looks like sticky 'dross build-up' due to Fluxing...  What you have on that crucible is an 'Excess of Excess'!Once that metal gets stuck in the crucible after a session or two and is allowed to become Cold, it's going to eventually crack the crucible.  I've seen guys clean em' out by leaving them upside down (immediately after a pour) and using a torch to 'rid them' of the excess...  Another way is to complete a smaller, but MUCH 'Hotter' POUR and do it quickly to get that crud off the inside walls.    The thicker the metal builds up, the WORSE your crucible will feel after being heated up for the next session.  I'm interested to see how the 'steel one' holds up...  I think you're gonna' need a few Passes to keep it from leaking.  BTW, what were you using for a Plinth when melting with the Sic Crucible?  Any problems with sticking to the bottom of the Kiln/Plinth?Cheers,Last edited by jman; 10-27-2010 at 02:58 PM.Miller Diversion 165120 amp Buzz BoxVictor Oxy/Ace Oxy/LPGSmith "Little" Oxy/LPGHypertherm Powermax 30Lot's of Misc. tools n' crap....
Reply:Originally Posted by jmanI'm interested to see how the 'steel one' holds up...  I think you're gonna' need a few Passes to keep it from leaking.  BTW, what were you using for a Plinth when melting with the Sic Crucible?  Any problems with sticking to the bottom of the Kiln/Plinth?
Reply:Originally Posted by forhireThe bottom is a three pass weld. I'm no pipe welder so we'll see. I'll make sure it holds water. I've made smaller steel crucibles in the past and had good luck with them even with a single pass weld. My ingot mold doesn't leak.I used a ceramic plinth. Never had a problem with it sticking but I did use a piece of cardboard which leaves a layer of carbon in between.
Reply:http://www.lindsaybks.com/ Hi Forhire, I have been casting aluminum for about 30 years now. Always wanting to improve the quality of my castings and save money at the same time. Through the years I have gotten many how to books, one of the books show how you can make your own crucible at this link, I think you will find this web site very interesting, that is if you don't know about it already. I have built many things from the knowledge I have gained and taught myself from reading these books, although I have not made the crucible yet I plan to, I do have this book on my shelf. Here are a few pictures of what I have built, the first two are castings I used in building my CNC plasma cutting table, the next are showing the table and then the metal cutting lathe I cast all the parts for, lastly I cast dies to press flat sheets of copper to this shape, well hope you enjoy this web site, have a good one, Jeff. Attached ImagesLast edited by Jeff-; 10-28-2010 at 10:11 AM.Reason: pictures
Reply:Jeff, That is some cool stuff. I have a couple Lindsey books (don't we all). Do you have photos of your dies you made for making the copper decorations.This is the progress for today. Cut out a V notch in the pipe with the plasma cutter. Bent a diamond shape to make the spout. Welded it on the outside and the inside. Still need to decide on the lift arrangement.Picture 1: Quick coordinates to cut the shout. Often on simple parts it's faster to write g-code by hand than using cad and converting.Picture 2: V-notched the pipe. The spout in the background.Picture 3: OutsidePicture 4: Inside Attached Images
Reply:Could someone please explain to me what an ingot is and this crucible thing you are talking about?  I hate to sound ignorant but I really have no idea what you are talking about BUT it looks very interesting and the pics are great.  I am just a lowly ag teacher trying to learn something new.ThanksIf you don't use your head you may as well have been born with two backends.That ain't exactly how Papa used to say it.*Linc'n WeldanPower 200 with a Wis. 2 cyl. w/handcrank*Linc'n AC225 *Linc'n ProMig 180*tiny porta torch...
Reply:Originally Posted by Bluesman  Could someone please explain to me what an ingot is and this crucible thing you are talking about?  I hate to sound ignorant but I really have no idea what you are talking about BUT it looks very interesting and the pics are great.  I am just a lowly ag teacher trying to learn something new.
Reply:just spent an hour watching those backyard casting videos... now i want to try it.  geez, thanks a lot, forhire!
Reply:Originally Posted by forhireI use my crucible to melt aluminum turnings into ingots that will eventually be recast into a usable objects. I create the ingots first to save storage space and time when casting as the ingots are more pure. Each ingot weighs 20 lbs. Most crucibles are made of something like clay-graphite. Steel can be used with aluminum because aluminum melts around 1100 degrees, much less than steel.Check out this site, it should get you up to speed.http://www.backyardmetalcasting.com/
Reply:Originally Posted by forhireJeff, That is some cool stuff. I have a couple Lindsey books (don't we all). Do you have photos of your dies you made for making the copper decorations.This is the progress for today. Cut out a V notch in the pipe with the plasma cutter. Bent a diamond shape to make the spout. Welded it on the outside and the inside. Still need to decide on the lift arrangement.Picture 1: Quick coordinates to cut the shout. Often on simple parts it's faster to write g-code by hand than using cad and converting.Picture 2: V-notched the pipe. The spout in the background.Picture 3: OutsidePicture 4: Inside
Reply:Originally Posted by BluesmanThanks.  So a crucible is just basically a pot to melt some metal in huh?  I found a little cast iron pot with a handle on in and a pouring spout and another thing or two in my shop at work I will try to post some pics up.  From my uneducated observations I'm beginning to think it may be the remnants of a casting kit of some kind.  I found an aluminum chunk that has an impression of some type of fish in it.  When I found it I thought it may have been used to pour fish lures or something out of a polymer.  Don't really know what it or any of the other weird stuff in the shop is doing in a Vo-ag classroom shop.
Reply:Originally Posted by rlitmanSounds like a lead melting pot, and fishing weight molds.
Reply:Originally Posted by BluesmanI was kinda thinking it may be that but I have never seen a fish shaped lead weight.  I have a couple big chunks of lead laying around on my farm, reckon I could melt a batch up and pour it in that aluminum mold?  I mean, I've never done that and don't know the do's and don'ts of the processes.  Are there any risks like fumes or such?  I know lead is poisonous if it is ingested but does it give off toxic fumes when you melt it?
Reply:Added the lifting studs to the crucible. I had some shaft ends in the scrap bin... they looked about right. Turned them on the lathe. Made a little guide by notching some angle iron on the mill to keep them aligned with each other. Welded them on. Now to make the lifting hook and then it's melting time  Attached Images
Reply:Looking good...What are you going to use to make sure that your 'lifting Wire' does not 'slip off' the ends of the spindle ends while completing a pour?  Are you fitting something to the spindles other than wire?  Curious about the 'lifting hook' as well....Cheers,/J..Miller Diversion 165120 amp Buzz BoxVictor Oxy/Ace Oxy/LPGSmith "Little" Oxy/LPGHypertherm Powermax 30Lot's of Misc. tools n' crap....
Reply:Originally Posted by jmanWhat are you going to use to make sure that your 'lifting Wire' does not 'slip off' the ends of the spindle ends while completing a pour?  Are you fitting something to the spindles other than wire?  Curious about the 'lifting hook' as well....
Reply:Hi Forhire, I will post the pictures of the dies tomorrow, could you post pictures of your furnace and burner setup for melting aluminum, just like to see how others melt metal, thanks, Jeff.
Reply:Long as we're on this subject, here is an interesting shot which just got posted, of a bunch of fellows standing around with their crucibles, apparently at the end of a run. Maybe time to dump the cupola? Looks like the blowers are still running, some iron still falling.              "From Scratch; 1901"Hi forhire, here are the photos of the dies I made to press flat copper sheets to this shape, Jeff. Attached Images
Reply:Made the hooks for the lifting tool. Cut them out of some 1/2" scrap and welded them to some 3/4" round bar. This should allow me to get into the furnace and lift the crucible out with a second person. Still need to weld these hooks to the cross bar. More to come as free time permits. Attached Images
Reply:Found a couple old pieces of water pipe. Nasty stuff. Cut a gusset and hook eye out of some plate. Now the crucible can be removed from the furnace then hung from the gantry.  Attached Images
Reply:Finally had a few minutes to put the pour eye on the crucible. Maybe I can start melting soon  Attached Images
Reply:Coat the crucible with Boron-Nitride mixture (applies like paint) and you'll eliminate the "wetting" issue of the aluminmum sticking to the crucible. Will also make your aluminum ingots cleaner as it will prevent the steel from contaminating the aluminum.
Reply:love the thread, can't wait to see how it works out for you!