skull shifter update and lost wax casting info

[chromedRAT]

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.

[Upchuck]

looks like special effects for another alien movie

[chromedRAT]

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.

[Jethro]

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

[chromedRAT]

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...

[chromedRAT]

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...

[noboD]

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

[VanHook]

Originally Posted by noboD

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

[hudsoncustom]

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

[chromedRAT]

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.

[CG]

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.

[InDaShop]

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.

[max wedge]

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!!!

[rustfarmer]

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

[chromedRAT]

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.

[cruzr]

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

[brainfrz]

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

Jon

[TxRat]

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

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

You do AWESOME work man.....

[Bear Metal Kustoms]

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

[Flathead Youngin']

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.....