casting bronze.pdf

8/14/2019 casting bronze.pdf

1/13

The waste oil foundry strikes again......This time bronze falls to it's fiery furey!

You know what... aluminum is nice but after awhile it just seems, how do I say it... "old

hat." A guy like me wants more from his foundry. Sure I've melted bronze before but

furnace size and fuel costs have always limited it to 1 or 2 pounds. Free waste oil fuel and

burner developments have made easy bronze casting a reality. So now its time for some

action! -June/20/2005

CAUTION! Metalcasting can be dangerous! Working with hot molten metal cancause serious burns and/or fires. Additionally the surfaces of the furnace radiateintense heat. The heat sources are another potential hazzard. Working aroundburning and/or hot oil/grease (as with oil burners) can be dangerous, especiallywhen proper safety precautions are not taken. Water should never be used to putout an oil or grease fire. Use dry sand or dirt. Because of the variations in materials

and workmanship there are no guarantees on the information in/on this web site.This information is simply what I have been successful with in my own experiments.I will not assume responsibility for any injury, loss, or damage that may result fromfollowing the instructions, advice or plans on this web site. There are alwaysdangers in foundry work and they have been pointed out whenever possible but it isnot the purpose of this web site to, nor is it possible to mention all known orunknown dangers.


2/13

This is an ingot of silicone bronze.I bought it online from Budgetcasting supply. The benefit of thisis that there is no (or only trace

amounts) of zinc and lead. So thereare no toxic fumes when melting it.lso since there are no metals!aporizing out of the bronze" thealloy doesn#t change as regularbrass or bronze can.But I ha!e to admit that I $%&%T li'e the appearance of siliconbronze castings. It loo's orangish

rather than the goldenyellow coloror regular bronze.I ended up mixing this bronze withsome regular bronze. ainlybecause this ingot wasn#t enoughto completely fill the mold for thecasting I was ma'ing and I was toocheap to buy more of this alloy.


3/13

I decided to *'ic' it up a notch* byadding an oil heater to thefoundry. Some coo'ing oil is ratherthic' and creamy and this heater

turns it all into a loose li+uid. lsoduring the winter this is almostessential since the oil is !ery thic'(high !iscosity) when cold.I call this the *hot tan'* (the smallcylindrical thing under the bigtan') The electric water heaterelement only heats the oil in thissmall tan'. Then as oil enters the

burner" new (cold) oil enters fromthe main tan' to replace it and isheated. To protect the elementthe oil exits from the top so e!enif the large tan' is empty the hottan' will remain full.This system is more energyefficient than heating the maintan'" it only ta'es about , minutes

to get the oil to o!er - degrees/It burns well and is easy to ignite.0ressure is relea!ed through themain tan' and any water in thesystem boils out.


4/13

This is the new oil heaterassembly. It#s based on the designused to warm up old fashined blowtorches. The reason for this

change is that two consecuti!eelectric elements burned out forno 'nown reason. I don#t ha!e timefor ridiculousness li'e that so Iwent with the simple method asshown. 1ust pour some flammableli+uid in the pan and light it. Theflames will heat the oil in the hottan'.

t 2.33 per bottle I can easilyafford to use 45- a pint bottle ofrubbing alcohol each furnace run toheat the tan'. nd I really only usethis in the winter anyways. But Iha!e successfully melted metal6IT7%8T a heater when thetemperature was below freezing (itwas 4,9 :.) and the oil burned well.

Thinning it with gasoline wor'sgreat also if no heater is a!ailable.


5/13

I also decided to step my game upand use a refractory crucible. Thisone is claygraphite and waspurchased on ;bay. The worst part

about using a claygraphite crucibleis that you ha!e to temper it in thefurnace before use. This is done byheating it to - degrees :. for -minutes then letting it cool to roomtemperature.;!en though this step is neccesaryto remo!e moisture before thefirst use of the crucible" I#d much

rather be able to


6/13

7ere are some patterns for thebronze castings I intend to pourwith this foundry run. These aresome of decorati!e paper weights

of popular symbols. These patternsare freshly coated withpolyurothane and drying on myspecial drying board. It#s basically


7/13

Bronze melting part 2

I've melted bronze several times in a steel crucible with no trouble. However theserefractory crucibles aren't as conductive of heat so my first bronze attempt with it was

mostly a failure. This time I'll crank a few more BTUs from the used oil burner and get

the metal nice a hot.

0ouring the metal is probably myfa!orite part of the metalcastingprocess. But unfortunetly this onedid not go so well. The metal is not

hot enough. The bronze shouldglow red as should the crucible.ost li'ely the metal will not fillthe mold...%h well" at least my pouring shan'wor'ed properly. But it was !erywobbly. It is after all only madefrom 45-* steel rebar and someother scraps I had laying around/

(Click photo for larger view)

I was right" the metal cooledbefore filling the mold. %nly theziggurat (ncient ;gyptian steppedpyramid) casting turned out. ainlybecause it#s basically a solid chun'of metal.=et#s try this again shall we>?o to the@ 0re!ious page &extpage


8/13

CAUTION! Working with or around burning and hot oil/grease can be dangerous,especially when proper safety precautions are not taken. Water should never beused to put out an oil or grease fire. Use dry sand or dirt. Because of the variationsin materials and workmanship there are no guarantees on the information in/on thisweb site. This information is simply what I have been successful with in my own

experiments. I will not assume responsibility for any injury, loss, or damage that mayresult from following the instructions, advice or plans on this web site. There arealways dangers in foundry work and they have been pointed out whenever possiblebut it is not the purpose of this web site to, nor is it possible to mention all known orunknown dangers.

I thin' this is interesting.7ere is some spilled bronze.The bronze spilled out thecrucible and into the bottomof the furnace where itdrizzled out the drain hole.&otice how the copper hasstarted to separate fromthe bronze alloy. aybe thisis a result of the otheralloying metals burning awayor


9/13

7ere#s a glimpse into thehot (to put it mildly) innerchamber with the crucible inplace. If you loo' inside the

crucible you#ll see an oldbronze plumbing !al!e withpieces f copper tubing stillsoldered in place.The copper tubing meltedalong with the bronze sothis metal must ha!ereached at least 43degrees :. 6hen melting

!al!es be sure to remo!ethe handle if it#s not alsobronze. any are potmetaland they burn up andproduce toxic zincfumedsmo'e. Beware of melting alot of soldered copper orbronze


10/13

It doesn#t loo' li'e it butthis is indeed bronze beingpoured. I#m casting apersonalized insence stic'

holder for a friend of mine.7ere name is Y!ette and onetime she told me how shehas trouble finding thingswith her name on it (li'e 'eychains and stuff).6ell... when you#!eharnessed the power to meltand pour metal that problem

no longer exists/ 7ey... Ine!er see my name on 'eychains either/(Click photo for larger view)

t bronze and iron meltingtemperatures typicalhomemade refractory mixes

will :Y/ &otice how theinterior of my furnace isburnt and glazed.

Page contents copyright 2005 by L.Oliver II - www.BackyardMetalcasting.com


11/13

7ere#s a loo' at some of thecastings after they#!ecooled for about an hour. Idecided to cast them in

smaller groups rather thanall at once.The mass of three castingson the left weighs about C.Apounds and the other massof castings is about Cpounds. The round castingsweigh close to 4.A poundseach and the rectangular

ones are a few ounces less.7ere is a bronze casting andthe cutoff gates. &oticehow clean and solid theinside of the casting is.There are no gas poc'etsnor bubbles. 1ust cleanbronze.The small thing on the left

is actually a small riser. Itwas at the opposite end ofthe casting as the sprue andwas meant


12/13

7ere are some of myfinished bronze castingsafter the gates were cutoff and they#!e been

cleaned up a bit with a file.The can still use some morefiling and a brushing with awire brush.In the center is theinscence stic' holder (ahefty ,.A pounds/) Idesigned for a friend withsophisticated design taste.

The inscence stic' is stuc'in the small hole at the topend. I thin' she#ll put it inthe center of her dinnertable designed by acclaimedfurniture ma'er =enoile!ilo. (ctually there#s nosuch furniture ma'er...that#s


13/13

7ot babes really dig a guy that can castmetal//$ecorati!e bronze castings ma'e great

gifts for hot chic's/ =et#s say you wal'up to a girl you#!e been watching andhand her a nice bronze casting(especially something with her name onit/). You follow up with a line such as@*7ey baby I made this for you in my artstudio/* That is pure gold/ You#llinstantly earn bonus points in her mind/

7owe!er there could be too much of agood thing... Suppose for example sheresponds with@ *%h I really li'e a guywho can melt metal/ Dan I come see yourstudio>* %h no// This is disaster if@. You still li!e with your parents.B. Your *studio* is nothing but a ragedyfurnace in the corner of the yard and a

couple burnt flas's. nd5orD. Both of the abo!e at the same time/In such a situation you must thin' fastto a!oid complete embarrasment. 6hatusually wor's for me is one of thefollowing lines. *8h sure... You can cometo my studio. 7ow about the Thursdayafter next summer>* %r *ummm" yeah o'

are you free on the Cth of ugust-43>* &e!er underestimate the powerof the foundry...?o to the@ 0re!ious page.

casting bronze.pdf

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