crucible furnaces for boro

[jiminyrootkit]

ok, so i know everybody and thier dog has looked into this shit, apparently with minimal success, as i don't see anyone with a batch pot in thier garage (except maybe abe from precision ;) )
but i'm looking into it anyway.

who's done some research on the matter? did you get anywhere? what was the snag you hit?
there are obviously places batching boro, so it CAN be done.

i've been lead to believe that 3000F is the temperature mark i'd be shooting for for liquid clear. anyone know one way or the other for sure? i really really don't wanna build something only to find out it's not hot enough. :mad1:

so far, 3000F bricks are pretty easy to get, and not prohibitantly expensive.
looks like molydisilicide elements are the only thing that's gonna get hot enough...i have yet to get a price quote on these, as they are probably a custom fabrication, so i need more specifics.....i bet this is gonna be the pricey part.

and then, crucibles.

i've no idea what soft glass crucibles are made of, but i understand they don't stand up to boro... i've heard talk of platinum crucibles, and i know they can be bought, but shit man, platinum is bloody expensive.....this has to be overkill, doesn't it?
there are other materials that can easilly handle the heat, namely zirconia....which is commonly used for hight temp crucibles and is rated up to 4000F.....anyone know of a reason that this WOULDN'T work?

i guess i'm just trying to get a grip on everything i need to know before i jump in and try to hack something together.....trying to avoid any big pitfalls that i've overlooked and someone else would be willing to point out.

-f

[Greymatter Glass]

getting thr glass to 3000 isnt hard... what's hard is getting something to hold it in, as you've noticed....

You can use the bricks themselves as your tank, but they will corrode very fast with all the fluxes used in boro.

You can build a slightly longer lasting tank with silicon carbide kiln shelf linings sealed with Al Zircon paste, but you'll get contamination around the edges of the batch.

A more exspensive, but cleaner way, is to use any high quality pressed crucible (laclaide cristy, guadalupe, the czech guys, etc) and you'll get usually 1, but sometimes 3-4 firings out of a pot before it cracks.

I've been thinkiong of a way to reclaim the platnium ceramics from Catalitic converters in cars, but it's still not cheap to get a used core... $75-100 a pop and you'd need a LOT of them.

And then, there's the platnium crucibles that start at around $5,000 and go up from there, and they can still break if you crash them.

GL with it....

-Doug

[Udai Hussien]

Please forgive my ignorence gentlemen, are you batching glass? or trying to make like a boro furmace? to gain a gather, pull out and work like soft glass? is there a Pontil tha tcan withstand the heat?

[jiminyrootkit]

what i want is a clear dip.
hot enough to be fluid so i can rapidly build up layers of clear on prep.
i don't want to gather like soft glass, just the ability to, say, dunk the prep for a stickstack and have it clearcoated, melt the end shut on my torch, and add layers of clear to the outside, deepening the encasement.....
i dunno how feasable this is, or what kinda problems i'll run into, but by damn, with as easy as it looks to be to build the kiln and get the elements to get it 3000F i'm not likely to let a little think like a damn crucible tell me i can't have it ;)

and if it turns out it really doesn't work, i have a nice electric casting furnace for pretty much any damn metal i can think of.....shit, those temps would pour cast iron.
-f

ps. what about (i'm guessing they're pressed) zirconia oxide crucibles doug?
according to a manufacturer of high temp crucibles:

Zirconia (ZrO2) can withstand the high temperature up to 2200oC and has very good resistance to thermal shock and chemical errosion.

or high purity alumina? you can get a litre alumina crucible for like $150 sposed to be good to 3150F or so....

[Marc VandenBerg]

I believe your going back to some of the early problems "Man" encountered 5000 years ago. It takes a-lot-o-freakin'-heat to melt sand. Soda Lime glass came out of necessity for what was reasonably effecient at the time. Soft glass as a material both works and melts without going to extremes. From my experience with boro and quartz, they don't work well outside the flame for extended periods of time. And your finding out the costs alone could make the venture ineffeceint. Being a lampworker and furnace blower I have always been skeptical of the Boro offhand studio, but at the same time would love to see it. It would be cool to see large items that are functional, artistic, and boiling heat friendly.
Just some thoughts
Marc

[HNelson]

Might not be what your looking for but here's my 2 cents!!!

Heating elements can be bought from I squared R Element company in Akron NY
Crucibles form Ipsen Ceramics in Pecatonica IL
Boro cullet from Kopp Glass Pittsburgh PA
Tried it!!!!!! did it!!!!!! worked!!!!!!!
Cullet melt and hold @ 2400 degrees f

Happy melting.

Heather

[PyroChixRock]

Being a lampworker and furnace blower I have always been skeptical of the Boro offhand studio, but at the same time would love to see it.

Why don't you just ask Marcel since he already has a boro furnace. ;)

[Udai Hussien]

what i want is a clear dip.
hot enough to be fluid so i can rapidly build up layers of clear on prep.
i don't want to gather like soft glass, just the ability to, say, dunk the prep for a stickstack and have it clearcoated, melt the end shut on my torch, and add layers of clear to the outside, deepening the encasement.....
i dunno how feasable this is, or what kinda problems i'll run into, but by damn, with as easy as it looks to be to build the kiln and get the elements to get it 3000F i'm not likely to let a little think like a damn crucible tell me i can't have it ;)

and if it turns out it really doesn't work, i have a nice electric casting furnace for pretty much any damn metal i can think of.....shit, those temps would pour cast iron.
-f

ps. what about (i'm guessing they're pressed) zirconia oxide crucibles doug?
according to a manufacturer of high temp crucibles:


or high purity alumina? you can get a litre alumina crucible for like $150 sposed to be good to 3150F or so....


That would be really cool accually the way it sounds Just safty would be an issue... I still want to get s triple axis CNC machine...

[Runez]

I agree that would be sick what your describing.... but imagine the raw heat you would have to expose yourself to in order to actually "dip". Ive only been in a hot shop once or twice but that furnace is INSANE heat... not the fun kind of heat when you get a piece of boro raging. I hear you get used to it with soft glass but imagine how much hotter it would be with boro.... Good luck I dont know if id want to do it, but id sure as hell love to watch someone else try!

[jokersdesign]

That would be really cool accually the way it sounds Just safty would be an issue... I still want to get s triple axis CNC machine...

What would you use a CNC machine for when it comes to glass?

[jiminyrootkit]

if all i was ever doing was dipping vertically into a pot, i'd prolly just make a punty with a big ball in the middle to keep a heat shield hung on. heat shield of some sort for sure.
-f

[IrieGuy05]

One time I crushed some clear, and put the clear frit on a brick, then I took that national you got and put on the 31 hole tip and turned it all the way up on that frit and it sorta melted a little.. build a heat tunnel with bricks linned by fiberfrax and put a little clay pot in there with some fine clear frit and rage it with that 31 hole tip, just make sure you got flashback arresters on, that 31 hole tip can flashback like a son of a bitch.

[Udai Hussien]

What would you use a CNC machine for when it comes to glass?


tool and mold manufacture..

[cheng076]

I've melted soft glass in my AIM 64J and the pyro said it was at 2100 deg. I know you can pull boro rods from a cullet batch at 2300 deg easily. As for a crucible I used an Italian flower pot ($0.59) with the hole filled with kiln wash. Got 3 or 4 firings out of it before I dropped it and broke it.
You can stir it with a stainless rod or graphite rod and can use the same for a pipe or pickup rod.
There are some small gas fired 'Turbo Furnaces' I've seen but I don't know how well they work.
PJH

[jokersdesign]

tool and mold manufacture..


Thats cool yo. Duh, I should of know that. I guess when I posted in the early am last night I was awake.

What kind of cnc are you looking at? I looked at getting one, but I never did cnc before so I didnt want to buy the machine and not use it.

Robert