Portable foundry furnace

Casting | | |

Fully portable bronze furnace.
Smallest gas powered leaf blower I could find - plenty of air at idle.
Stainless cover with refractory slathered kaowool weighs less than 20 lbs.
harbor freight weed burners are way simpler than making your own.
Oddity is the giant refractory pillblock, I found that then built the furnace around it.

Portable Bronze FurnacePortable Bronze Furnace
Portable Furnace "Off"Portable Furnace "Off"
Portable furnace bottomPortable furnace bottomone man tongsone man tongs


Frank Castiglione's picture

Opening Doors

Hi Scott,
I can't comment on something I have no knowledge about except that because of your posts, I'm gaining knowledge. So thanks so much for sharing, eh...
Frank


visitor's picture

Fully portable bronze furnace

Scott, I'm a sculptor from Benicia, California, so we are practically neighbors.
I've wanted for some time to be able to (occasionally) pour a small amount of silicon bronze at my home workshop, but just didn't have the space to set up a permanent foundry. It seems that you have come up with an ideal solution, and would love to visit you to see this firsthand and get some tips on how to do this. Is there a way to reach you directly?


ScottTheSculptor's picture

contact

I just turned on the "contact" tab in my profile.

(and fixed the bad address in "my website")


keithh's picture

Your setup and work

HI John; My name is Keith and I hope to do some shell casting this summer. At present I am working on a wax figurine and having to learn that art process.
After seeing your setup and discussion about the binder being used I thought to write you about it.
I have read collodial silica is the binder that is in use mainly although I am certain there may be others .
I have found a supplier for the wet version ( in large quantities) and wonder if you have any information on the dry version, which I can get in reasonable quantities.
I have a book written by a New Zealander regarding the shell process from his local.
I wonder about your crucible and did you manage to make it yourself?
Finally, I have work to do on the burner / blower ( my Reil burner will not do it ) and the Kaowool hot side liner.

Anyways, I would like see some of your work and will hop off the your blog shortly and see what you have listed.
Many thanks for posting
Keith


ScottTheSculptor's picture

Dave's not here

ebay "clay graphite" crucible (though I'd rather have a SiC).

Refractory mold making is another complete subject.
Spruing paths and processes are easier to show than say.

easiest is to get your waxes done, take them to a foundry for spruing and shelling. Then pour the finished shells yourself. easiest - not cheapest :-) If you have spruing down then they just need shelling and burnout.

you mix the "dry" silica flour with coloidal silica (plus other stuff) to get the ceramic shell mix. It has to be continuously stirred to keep it from setting up.

coloidal silica is also used to stiffen kaowool.

I have never figured out why people prefer making their own propane burner when the harbor freight weed burners occasionally go on sale for under $20 - with hoses and valves!

I figure the two burners are overkill. I can slump an everdur ingot in less than 30min from startup.


johndach's picture

Why make your own burners

Scott,

If the weed burner works for your set up I think it is just great and the way to go. However, when I am casting, I am melting 90/100 of bronze and after the first melt (takes about 1 hour 15 minutes) the second and all other melts take about 45 minuted for 90/100 lbs. Cannot get that out of a weed burner. Plus I like having a near instant on/off valve (a ball valve) got the gas and I like to also have a needle valve past the on /off valve for "fine tuning" the flame. The home built burner is easily "rebuilt" when the end gets too "crusty" by sawing off the end and welding on a new piece of pipe (I have been using the same burners for 20 years, just the ends have been replace as needed). I can also get far more BTU's out of my homemade burner than the weed burner ever could put out and I need it for my setup.

So if it works for your setup, GREAT. If one needs more BTS's than it is easier and FAR cheaper to build the burners than to buy them.

Just my 2 cents!!!!!!!!

John Dach
john@MLCE.net
web site: http://www.MLCE.net and ctmandalas.com


johndach's picture

Your setup and work

Keith,

First, we are now in NW Washington (Sequim) on the Olympic Peninsula. Colloidal silica binders are primarily CS but there are a number of proprietary ingredients in CS binders available on the market. If you are going to try ceramic shell, I DEFINITELY recommend that you work with a binder from one of the manufacturers (I have experience with Remet and R&R materials). Colloidal Silica is wet if it to be used for shell operations so you are stuck with this. "Reasonable quantities" is a bit tough unless there is a foundry, foundry materials supplier or school using the materials that you are after and that they are willing to sell you some smaller amounts. 55 gal is about the smallest amount that can be had from the manufacturers unless you can work out something special with them.

Crucibles were purchased from a foundry supplier in Oakland CA and/or from other suppliers or the manufacturer. I was more interested in safety, working on getting good castings, etc. rather than building "everything" myself (though I did a lot of building of the kilns and foundry tools rather than purchasing them, but this was due to the fact I had the machinery and abilities to do so and thus saved a good deal of $$.) A #30 SC crucible was $90.00 and to me, well worth the money if for no other reason than the safety of having a crucible that was produced by a company making 1000's of them and that I could be reasonably assured it would not fall apart with a charge of molten bronze.

The burner is really simple. A piece of 2 inch black steel pipe (heaver rather than thinner walled), a home made gas nozzle, homemade gas supply line with on/off ball valve and a needle valve for set and forget fine gas control/adjustment and a home made blower attachment with gate valve for air flow control and blower/motor attached to the "burner pipe". Pictures available upon request.

Kaowool use/how toos for kiln/furnace construction also available upon request.

"My" section of the MLCE.net site is still under construction but any requests for information, plans, pictures, sources, thoughts, etc. are welcomed and will be happily answered. Phone calls, Skype and iChat, EVEN snail mail are fine too.

As to "My Work" ........... I learned the aspects of art casting/foundry work to do my wife's art work. I consider myself more of a technical person than an artist, but my wife disagrees so,,,,, I am what I am and do what I do. If I can help or be of service to a person to help them along in their chosen direction, I am happy to do so. I keep no secrets and tell all that I know (at least all that I know I know!!!).

Hope I can be of help and inspiration.

John Dach
360.681.4240 (happy to call you back if you do not have toll free long distance phone service.... I do, in the US and Canada)
john@MLCE.net
web site: http://www.MLCE.net and ctmandalas.com


ScottTheSculptor's picture

thread

can someone tell me where the start of this second thread referencing "your setup and work" is.

And why it's tacked onto *this* thread?

I was thinking this site was just quirky - not completely broken.


Rich Waugh's picture

Scott, I did some poking

Scott, I did some poking around and I can't figure out why the other comments ended up here, either. It seems that keithh posted a "reply" to John here and John answered it.  Why keithh posted it here, I don't know - John has a separate blog entry for his furnace construction thread. 

My best guess is that keithh mistakenly posted his questions to John on your thread and John spotted them, figured out what keithh was looking for and answered here, figuring that keithh would look here for the answer.

As far as I can tell, the issue is not with the site itself, just a quirky concatenation of events.

Rich Waugh

ArtMetal Moderator


johndach's picture

a quirky concatenation of events

Rich, you hit the nail on the head with what you figured out, as far as how/why my posts were here. As to why/how Keith got on this thread, I cannot say, I was just replying to his note.

Scott, I think your unit is slick..... Too small for my casting but totally GREAT for many others I am sure. I don't think that Keith or my reply to Keith is too far off what you started, I thought it was a start up of furnaces,tools and how toos and the like. Sorry if I stepped on a toe. Are you shell casting?? How much are you pouring per pour and what metal/alloy. Shell or investment?

John Dach
john@MLCE.net
web site: http://www.MLCE.net and ctmandalas.com


ScottTheSculptor's picture

sorted

I just wanted to see the other furnace!

Figured it out, wasn't easy.
The other thread wasn't.
That's why I couldn't find it, so went ahead and answered.
It was an image.
Didn't try replying to it to see if it posted here.

so,

You mean a weed burner *without* forced air?
I get to aluminum melting temperatures without adding air.
Yours? ;-)

Just everdur so far in this furnace. Though I have extra crucibles for other metals and spares.
Went for more, shorter lasting clay graphites for the metal flexibility. I couldn't afford that many SiC's :-)

Furnace is adjustable.
I use #16 and #20 A shape clay graphite crucibles (budgetcastingsupplies).
Inner shape is beehive so it necks down as it gets shorter.
Bottom diameter of crucibles are within a half inch and that's where the flame swirl is aimed.
Beehive shape swirls and helps full combustion.
I've tongs and shanks for the #20s.
The one man tongshanks(?) for the #16 has a ring on the far end for a chain hanging from an A frame (11' little giant ladder + pipe with clamps) or for a 2nd man with a hook. Can one man freehand it under half full.

I'm experimenting with a minimalist ceramic shell process. Will document it here if it works out. Also sodium silicate bonded sand.

Where in Oakland do you get your refractories?
I'm 35 miles North.


johndach's picture

Melting metals..............

I could see aluminum without added air (1200 Deg F but bronze needs about 2200+ deg F and air for best combustion and LOTS of it is needed.

SiC crucibles have always been my standby. They last a long time if taken care of and are strong at melting temps. I got #30 at at Pyro Minerals in Oakland. I don't know the cost today. I also bought a case of them from a supplier that was having a sale but I do not know/remember the name. They ended up costing $85 each shipping included.

My lifter was made to accept different radius "grabbers" for different sized crucibles, easily changes with a loosening of a bold on each side and a new/different unit put in place. The pouring shank was home built and also made to "accept" different diameter crucibles with 3 bolt loosening/tightening operations. Was easy an works well. All pouring was done as a 2 man operation.

Pyro Minerals. http://www.pyromineralsinc.com/

Good luck with your melts and pours..................

John Dach
john@MLCE.net
web site: http://www.MLCE.net and ctmandalas.com


keithh's picture

Wow, sorry Scott

HI Scott. It looks like I messed up on your thread. I though I was responding to John's thread and wondered why I recd the reply I did. I'll do better next time. :)

Hope you are understanding...

Keith


jiminycricket's picture

forge construction...

Hey, working on my first forge, was wondering about the opening up top. Noticed yours (and about every other one I've seen) has a relatively wide mouth - is there a reason for this? Do you think it would get hotter with a smaller opening at the lid? I was thinking less would be more, but I'm new to this after all =)

PS- I'll add a picture so you can see what I'm working with when I can figure out how...


ScottTheSculptor's picture

balance

the real size of the area that the air exhausts is the space between the top of the crucible and the underside of the lid - hole doesn't *have* to have any more area than that. but a larger hole convenient for stuffing odd size chunks of scrap in.
the air temp just past the lip is far above any loss at the surface of the metal.
no effect until the hole gets ridiculously large.

Only time I've "banked" a furnace (closed down the exhaust with a pillblock) is to slow bake in a new liner with the gas valve hardly open.


johndach's picture

furnace construction...

There are a number of things to consider with exhaust. Space between the lip of the crucible and the top is one. There has to be enough so that you are not choking the flame/flame path and causing back pressure to build and then get flames blowing out any and all other holes in the furnace. The actual outlet has to be big enough so that the same problems are not occurring within the furnace. If the burner is a forced air unit verses a naturally aspirated unit, more gas/air/combustion by products have to be able to leave the furnace, in an unrestricted manner, so that the new, fuel/air mix being introduced into the furnace can be..... introduced, and done so without back pressure that would blow combustion flames out other holes than the top exhaust. I know there is a formula for figuring out the exhaust hole size that is "developed" thru what the inputs are going to be but I do not have that formula available. If I find it I will post it.

If it is a forced air feed the hole will have to be bigger, but there is a limiting factor on how small the exhaust can be for a naturally exhausted furnace too.

This is at least what I have experienced. I did make a lid with too small of an exhaust hole and I did have problems with flames ejecting from unwanted areas but fixed this by opening up the exhaust just a little bit. You can easily demonstrate this simply by choking off the exhaust hole on a properly operating furnace (either naturally exhausted or forced air operated) and watch the results for yourself. Or if you have a forced air unit, turn up the air/fuel flow until you see the "forced out of other holes" flames. If the exhaust hole in a forced air furnace is (too big) it will allow one to put too much air/fuel mixture into the system and you will start melting the furnace but the furnace could be operated at lower inputs without furnace damage but there may likely be more BTU waste.

This is just what I have experienced in my melting activities. I have no specific or higher education in this area, just a good deal of trial and error, self directed research, help from other successful casters and finally a great deal of success.

John Dach
john@MLCE.net
web site: http://www.MLCE.net and ctmandalas.com