skull shifter update and lost wax casting info

better late than never, i guess, guys. working around the day job and all of that has been a bitch, but now that i'm on summer vacation i've got all the time in the world. so here goes, an update thread, and a little bit of an explanation of how this casting works. expect this to be updated here and there as i complete some things.

first off, a group shot of all of the wax skulls on their wax tree. the bright red thin wax lines are all vents, which will eventually allow air to escape so that the entire shifter knob will fill out. these things require alot of venting, as you can see, and each one is attached by melting/welding it to the piece and another vent going up to the top of the cup.

i think everybody's knobs oughta be visible in this one, with 16 of the 32 pilots i am casting this go around in the front, followed by firemen, more pilots, and some others in the back. up until this point is what took so damned long, as there was alot of work in getting the few imperfections incurred in wax casting fixed and ready for this stage. doing 97 knobs and some other things, and it really filled up my time.

 

looks like special effects for another alien movie

 

after all of the waxes are "chased (what we call the clean up work)," "sprued (attached to the 'tree' for dipping)" and vented, i then start the ceramic shell process. each piece will be dipped in a ceramic slurry up to 9 times. the first two coats involve a thicker solution with very fine particles, onto which very fine sand is sifted for body and strength in the ceramic. the next two coats use a slightly coarser sand, and the remaining coats use coarser yet sand and a runnier slurry with less fine particles in it. the final coat is a "sealer" and eliminated the sand application to seal in the layers and sand so that it cannot be rubbed off.

in this picture, the trees of shifters are visible with just the first coat on them. in the lower right corner is a small shot of the slurry tank, which must always spin to keep the particles agitated. sitting still for only 5 minuts can cause the particles to settle, which can bury the agitator paddle. the bottom literally starts to rise as this happens. if there is a power outage, it takes 24 hours to chop up this settling AFTER we pry the agitator paddle out of each tank. that's a pretty rough task in itself.

just before i came in tonight i finished the second coat and should finish up the ceramic shells by sunday or monday. my next post will talk about melting the wax out of the shells, and then casting after that.stay tuned if'n ya wanna.

 

I must have been sleeping.... I never saw all the other kinds you make.You have any more firemen left?They all look awsome!!

 

one last note, you might notice how yellow-green the tank is, and how the trees of skull sare a little orange. we use a dye additive that is orange in the absence of water and yellow-green when in the presence of it. one of the ingredients in the slurry is distilled water, and this allows us to be certain that shells are dry. when my dad first started casting bronze, we hadn't discovered this, and the shells were snow white when they were sopping wet and bone dry... makes it alot easier to get it right, because repeated wet coats cause weak shells. with bronze, there is much more pressure than aluminum, and blow-outs are more likely if a weak spot in the shell exists. the bronze is poured at over 2000 degrees, 300 lbs. at a time. that amount of metal at that temperature can be interesting, i'll save those stories for another time.

also note that everything, the sprues, vents, and skulls are being covered with ceramic, and this shell will grow with each dip until it is about 1/4" -3/8" thick...

 

i'll cast more firemen in the next pour, so far the 9 i included with this one are spoken for. next pour won't take near as long to make happen because i'll have all day and night to get things done. summer vacation rocks...

 

Thanks for the update. I was wondering about the Bombers just the other day.

 

Awesome post! I was wondering about this process. Cant wait for the finished product! Chad

 

Wow, that is a crazy process. You should make some chromed Rat shift knobs....for old time's sake.

 

haha, only "chromedRAT" i have at the moment is the spray-painted mummy rat from the back seat of my old 50 pontiac!

i also wanna add, that if anyone PMed me since may 16th, i just dumped about 20 some PMs i had saved thinking they were sent messages. stuff like reservations for knobs and whatnot i have safe and secure, all recorded in my leger book, but other stuff like addresses and correspondences mighta been lost. not much to worry about as i know who wanted what, but just wanted to get that out there...

a few people wanted to see the fireman and i hadn't posted a picture of it on the board yet. here goes... serial numbers on him will be on the area below the fireman's cross on the front of the helmet.

 

very cool, i can hardly wait to get the ones i ordered. i really like that you posted some of the process of making them.

 

Josh, those Fireman helmets look sick!!!! I can't F-in wait to surprise my buddies with those. Thanks again for working with me on the 'staches, and the Truck/Station Helmet #'s.

 

Badass!!! Reminds me of what I did earlier this year, making a mold of a mummy mask for my band. The damned thing pretty much rotted away so I had to copy what was left of it. Casting monster stuff RULES!!!

 

The firemen looks awesome. Can't wait!!!!

 

here's the next step of the process. in the lower right you can see the shells with wax still inside them, ceramic dipping recently completed. i've made sure the tops of the cups have been cut off to allow wax to drip out, and drilled a few vent holes in the main sprues so ease these things as the wax melts. the main picture is of the loaded kiln, wax dripping and burning out of the shells. this kiln is a large stainless chamber with a propane burner and reaches 1500+ degree f. a hydraulic ram from an old garage lifts the rack of shells into the kiln where it is held by a pair of levers and the ram retracted. wax runs out the grating that makes the floor of the rack. after the wax stops, about an hour later i pulled the shells, slightly glowing from heat, out of the kiln and rolled them to a safe spot to cool. the white shells in the lower right are the freshly burned-out shells, now ceramic molds. gonna pour tomorrow or thursday, stay tuned.

 

I have a "pilot" , and everytime i get in the car i smile, the shift knob is the highlight of my Roadster !

 

What a cool process and thanks for sharing. Love the shifters.

Jon

 

TECH-O-MATIC!!!!!!!!!!!!!!!!!!!!!!

Can't wait to get a bomber skull and whatever else I reserved.

You do AWESOME work man.....

 

I can't wait to get mine.. I still get #27 pilot for the chrysler... right??? Now I am getting excited.. EVILT

 

The pics DO NOT do these justice!!!! I was lucky enough to be the winning bidder on one of these at the Rallly in the Alley this past Sunday. I'm really stoked about putting it in my roadster. My little baby girl held it in her hand all the way home from the get-together and she had it even when she slept in her car seat......I may have to get another one.....

 

alrighty! so i poured around 100 lbs. of #356 aluminum today, and here's how it went. first off, there's a large picture of my pouring rig. the two sets of tongs, one for lifting, one for pouring, were made by my dad when he first started casting bronze. they've upgraded to a 300 lb. crucible and an overhead hoist to pour with, so when i set out to build a casting setup, these were just about right. the inset picture is FLAME ON in my little furnace. i built this thing myself a little over a year ago, if memory serves. the blower and burner behind the furnace is a pretty antique item. reconditioned and refreshed when they started pouring bronze and like the tongs, not big enough anymore. the burner pipe i rigged up myself from the design used by my father. we use propane gas and this little refractory blanketing furnace gets the job done pretty damned quick. more after dinner...

 

so the chicken stir-fry was pretty good... up next is the actual pouring. when the aluminum reaches temperature (a hair under 1300 works pretty good), the furnace is opened back up and the full crucible is removed with the lifting tongs, visible in the lower left hand corner. the crucible is then set down on a block with a piece of cardboard on top of it. the cardboard is to create a "carbon barrier" to prevent the crucible from sticking to the block and screwing things up pretty good. the pouring tongs are laid on the ground with the ring around this block at this time. after the lifting tongs are removed, the pouring tongs are lifted upwards, engaging the crucible, and the retaining latch is closed to hold the crucible when it is tilted at an extreme pouring angle. i do one tree of shifters at a time, and maybe one or two small pieces with a tree as my crucible holds abotu 25 lbs. max. for the next pour, the crucible is set back down by the pouring tongs and picked back up with the lifting tongs and replaced, with cardboard underneath every time. the fella on the right is yours truly, and my best bud Beck is helping out on the left. everything else i do myself.

 

last, here's some finished castings of the new stuff. most everything turned out great. a few rough spots on a couple, but it looks like nothing i can't take care of when i go over these with the dremel and files during metal work. first off, the whole group of em...

 

detail of the WWI german

 

Man that is awesome. I'm putting in for the tech-o-matic. Is this a family trade you learned?

 

WWI doughboy with the stainless steel cigarette. most WWI helmets had a crimped metal rim around the edge of the helmet, but the one my grandpa bought me when i was 10 or 11 was apparently a very early production helmet and didn't have the edging, so it wasn't there when i used it to make this shifter knob. i really dig the dent in the top of the helmet.

 

last one for now is a detail shot of the fireman. CG and rustfarmer both asked me about doing a fireman, and i decided to make a mold of it and cast several, which were all spoken for pretty quick. in this run i did 1-8 and 13, and 13 worked out to being a single pour, which is what we see here (already had a full tree with the firemen on it). there's a hood around the back of the skull under the helmet like the one i borrowed to sculpt from. i dig this one too. serial numbers for these are all under the fireman's cross.

Roothawg, yeah, it's the family business. we've been on the same farm for 200 years here, but sold our dairy herd in about '96. my dad got a job at the autozone distribution center and hated it (jumping jacks and crap and "team" this and "team" that drove him nuts). his best friend since 1st grade started sculpting a few years earlier while recuperating from having his foot cut reattached after having it cut off when a drunk hit him on his sportster, and by 1996 had gotten a commission to do a 30 or 40 ft sculpture group up the side of the world cultures building at california university of PA. it had about 15 7-8 ft figures from different historical periods weaved into a grape vine up the side of the building, cool piece. needing some technical expertise, he asked my dad to help him.

fixing and fabricating things on the farm builds some pretty decent skills, and he did well. while working on this piece, they hatched the idea that they would start a bronze foundry to cast Alan's work and my dad would run the foundry. we then got a commission to do the zanesville bicentennial monument in 1998 (4 7 ft figures from the area's history) and the foundry had begun to sustain itself.

we've done probably well over 100 lifesized and larger pieces since then for Alan Cottrill and other artists and there's currently 4 full time employees. coolest part about this whole thing is that probably 90% or more of the technical tools and machines we use were built by us, right here. i think the only things that were made by someone else are the ceramic tanks, and they've been improved heavily anyway.

i helped out here and there early on, and regularly starting in '99 when on summer breaks from college. learned every step of the process that way. skipstitch on here asked me about aluminum casting in 04 and i decided to try it out because i wanted to make a shifter knob for my car. it took some research and trial and error to figure some thigns out, aluminum is persnickety. did a few sketches of shifter knobs i'd like to have and decided to cast some stuff, starting with the regular skull i advertised on here in january, and i've been busy ever since filling HAMBers' orders!

i'm pretty amazed, actually, but i really like what i'm doing, even when school's in session and my foundry time is limited to evenings after teaching. every single piece has been handled by me individually at least 6 times, start to finish, so it's a pretty in-depth process, and every piece is consequently one of a kind in some slight way, and i serial number every one of them for that fact. anyways, i'd better go put the little furnace away if it's cool enough, and i've written a novel anyway...

thaks for all the compliments, guys. i should have all of these finished and ready to ship in less than two weeks.

 

is everything already spoken for or do you have anything left?

 

1. Are you getting any shrinkage or problems with dross? I like to fill from the bottom when I cast aluminum. The Gates point up from the sprue tree.
2. what are you using to degrease or brake the surface tension?
3 are you using Rancosil products?
Pogo

 

one of the coolest threads ever!