Resin Casting

[B-52 GUNNER]

Hey Guys,

I was wondering if anyone could give me step by step instructions on how to resin cast.

I read an artical in FineScale Modeler about how this guy made a vacuum chamber out of a pressure cooker pot and a refidgerator compressor.

Has anyone made one of these before?

If so, how do you put it together?

If not, What do you use to degas your TV and resin?

I'd also like to know where you can find supplies cheap.

Thanks in advance,

Scot

[tom64ss]

http://www.macrossworld.com/mwf/index.php?showtopic=41

[B-52 GUNNER]

tom64ss,

Thanks, but it doesn't say anything about Vacuum Chambers.

Do you know anything about degassing?

Scot

[fulcy]

Uhm, do NOT use a pressure cooker as a vacuum chamber. The person who said to do that in Fine Scale Modeler is an idiot, and doesn't know how much danger they are putting themselves in. I think it was cobywan who made a vacuum chamber out of a pressure cooker, and the pot imploded on itself, and I believe gave him a couple of cuts and scratches. A pressure cooker works at a couple of psi, and is made of thin enough metal and glass that it could never stand up to 28" of vacuum for long.

My suggestion? Don't look for the cheap way out - you will screw it up. I spent about $400 on my vacuum casting setup, and I'm not scared for my life every time I use it. Check out ebay, and look for one of these VACUUM PUMPS, something about 1/2 hp and moves about 6 cfm should do you just fine - I spent about $150 on a refurbished one, and it works like a charm. Now, as far as a vacuum chamber goes, try searching on ebay, and you'll find a few, but none of them are that nice... And, I can't find the link to the really nice ones that I'd love to get. But this is a start...

[fulcy]

Another thing, don't disregard that article that tom pointed to - and don't rely on a vacuum chamber to give you good casts. You should learn how to make molds that don't require a vacuum chamber to be free of bubbes first, and then use the vacuum chamber to augment this knowledge, and to improve your technique...

[valkyrietestpilot]

which part do you need vacum for? is it after the resin is poured in the molds to keep it's shape? reason i ask is,if you know anybody w/ access to any type of CAD equipment,then you should be able to make molds easily out of something sturdy.i bumped into resin guru chris barretta at otakon this year & we talked for a long while.he operates a shop w/ extensive CAD gear & he said you can pretty much make anything you need w/ that.he didn't mention about the specifics of resin casting,but is vacum absolutely needed to make parts?

[fulcy]

which part do you need vacum for? is it after the resin is poured in the molds to keep it's shape? reason i ask is,if you know anybody w/ access to any type of CAD equipment,then you should be able to make molds easily out of something sturdy.i bumped into resin guru chris barretta at otakon this year & we talked for a long while.he operates a shop w/ extensive CAD gear & he said you can pretty much make anything you need w/ that.he didn't mention about the specifics of resin casting,but is vacum absolutely needed to make parts?

It's primarily needed for degassing thicker mold rubbers, and casting resins. You'll introduce air bubbles into the rubbers or resins when you mix the two parts together. A vacuum chamber will help remove this trapped air, and help the resin flow into all the holes and details of your molds.

When you say CAD equipment, you typically need a high end computer and a CNC - either mill or lathe. This equipment doesn't come cheap - and the molds that you can make from these need to be polished, and typically made from aluminum. Regardless what the mold is made of, if it is designed poorly, a vacuum chamber can still be useful in removing unwanted air (unless you are talking about injection molding - in which case I know of no one on these boards who has access to that kind of machinery...)

[valkyrietestpilot]

exactly mr fulcy.CAD meaning computer aided design.i know a few of these techno-fabricators from my hotrod hobbie.i'm just going on a hunch,but aren't you military mr. B-52 GUNNER? if so,start making nice w/ the guys at the machine shop were you serve.no good military base is without a good machine shop.i believe they have them on aircraft carriers as well.if they have the ability to make surgical intruments,then those guys work w/ high quality stock.instuments are made of VERY pure stainless & aluminums.they have the ability to polish to a mirror finish if they can make instruments,so you might have some resources at your disposal after all

Edited August 9, 2004 by valkyrietestpilot

[valkyrietestpilot]

oh,chris barretta told me he only lurks here once & a while,but he DOES have access to that kind of CAD programs & lathe equipment.he is a custom tool fabricator for black & decker's R&D program.he told me that he can make anything you could possibly want for a valkyrie or any mecha.lucky dog

[fulcy]

exactly mr fulcy.CAD meaning computer aided design.i know a few of these techno-fabricators from my hotrod hobbie.i'm just going on a hunch,but aren't you military mr. B-52 GUNNER? if so,start making nice w/ the guys at the machine shop were you serve.no good military base is without a good machine shop.i believe they have them on aircraft carriers as well.if they have the ability to make surgical intruments,then those guys work w/ high quality stock.instuments are made of VERY pure stainless & aluminums.they have the ability to polish to a mirror finish if they can make instruments,so you might have some resources at your disposal after all

Only thing is, it depends on the part you are making too - it depends how small they are, and how intricate they are. If it's a block of -blah- then yeah, it'd be easy to machine up. If it's a little tiny cockpit with all the instruments and such, that might be too detailed. A good point of reference - if you have access to a 3-d modeling program, you can design up your part, and send it to a shop that will machine the mold for you - out of a chunk of aluminum, and will cost between $2000 and $3000 for the smaller parts. Why so much? It takes time to machine aluminum - and even though these machines are computer controlled, you need an operator there monitoring the machine, and making sure it's cutting where it should cut, and not messing up. These operators will typically be making $20 to $30 an hour, and if a mold takes 20 hours or so to make, you think he's going to spend that much of his time on something just because he's your friend? Probably not... But you may be able to talk him into doing it on the cheap - but it's still going to cost some money, in which case it might be easier to do it yourself...

[fulcy]

oh,chris barretta told me he only lurks here once & a while,but he DOES have access to that kind of CAD programs & lathe equipment.he is a custom tool fabricator for black & decker's R&D program.he told me that he can make anything you could possibly want for a valkyrie or any mecha.lucky dog

Other thing - was he talking about machining the parts, or the molds for the parts?

[valkyrietestpilot]

from the way he was explaining it to me,he could do it either way.make molds,hardparts whatever he wanted.he made some kind of custom joints out of brass for his gundam mecha that he entered into the model contest at otakon.it allowed sick articulation in the feet of his zeon mecha

[valkyrietestpilot]

yah,i see your point about it costing alot to have a shop tool you up a mold.my friend chris has an edge,cause he's the big boss in the shop he's at.i'm sure you remember him from the old days here.he made the original 1/55 heads,heatshields & other parts here on macrossworld.there use to be a link to his parts & installation instructions on the first page of this board.he's friend's w/ shawn i believe too,cause he asked about him first when we started our chat.

[cobywan]

There is nothing wrong with using a pressure cooker as a vaccuum chamber. There isn't enough atmospheric pressure to do you harm. But never use a pressure cooker as a pressure pot;

http://home.comcast.net/~cobywan/Templates/Whoopsie.htm

[fulcy]

There is nothing wrong with using a pressure cooker as a vaccuum chamber. There isn't enough atmospheric pressure to do you harm. But never use a pressure cooker as a pressure pot;

http://home.comcast.net/~cobywan/Templates/Whoopsie.htm

Ah, I knew it was one or the other that went kablooie on you... Though, I still have reservations about using a pressure cooker as a vacuum chamber - cast metals in pots aren't as strong as normal metal - but it could also be the vacuums you guys are drawing to - I go down to at least 28 or 29 inches of mercury - enough so that my resins and mold rubbers boil over....

Oh, and here is the link for the really nice vacuum chambers...

http://www.abbess.com/vac/vacuum-econo.html

[captain america]

If you really want to pressure-cast, you can get a brand spanking new 2.5 gallon pressure tank by Campbell Hausfeld from your local Home Depot, or equivalent home renovation chain. Great big $80 US/$120 cdn, and it can safely take pressure to 50psi without batting an eyelash. If you need more than 50 psi of pressure to get decent castings, you simply aren't doing it right.

Vacuum pumps & chambers: you can get these for a song on E-Bay compared to what I paid for mine 7 years ago. A lexan belljar & base are what the simplest vacuum chambers are made of, and they work flawlessly if not mangled or abused.

As for CNC machining & 3D modelling. Pure overkill. Unless you need aerospace tolerances, and display models don't, you can get absolutely superb masters sculpted by hand for a fraction of the price.

[B-52 GUNNER]

Thanks Guys for all your advice.

I contacted the guy who made the vacuum chamber out of a presure cooker pot and I am waiting to here from him.

He has a website: Small Art Works

and he makes some very high quality models so I hope he knows what he is doing.

As for my name here on Macross World...

My Dad was a B-52 Gunner and I took that name to honor him.

I do have access to friends that work at General Motors tooling dept. and at General Electrics Jet engine plant that can make me small parts.

I was also wondering if you can use a PIAB Vacuum generator to produce the 28.0 to 30.0 inches of mercury needed to degas the RTV and resin?

Thanks again,

Scot

[Akula]

I live in the same city as Mr. Small... but wow... that article on making moulds is great! it's a lot of questions answered!

[cobywan]

By the way, My vaccuum chamber is made out of a rolled sheet of .060" styrene glued into a tube of about 10" diameter and 24" tall. Seriously...a metal pressure pot is fine for vaccuum. But canning pots are sheet metal and get crushed after three uses. Even the enameled steel ones.

[B-52 GUNNER]

Cobywan,

Here is a photo of my pressure cooker pot.

It has grind marks on the sides that make it look like it's cast aluminum.

I also have a PIAB vacuum gauge attached to the lid.

Would this hold up to 28.0 to 30.0 inches of mercury better than the sheet metal pots you told us about?

If the picture is too large I'll edit it.

Scot

[cobywan]

That canister will work fine for vaccuum. You will need to put a rubber gasket on it though. I use a flat plate of 1/2" polycarbonate sheet with a hose for vaccuum as a standard lid that I put onto whatever container I need. A large container takes longer to evacuate than a smaller one does. I put the caulking seal on the canisters.

[whytwolf]

On the subject of resin casting, is there anyone out there who would want to/be able to make molds and cast some Macross scratch-build projects for me? I'm interested in selling some limited run kits, but I don't have the capability (yet) to produce the high quality casts that I've seen here.

Sean

[B-52 GUNNER]

Cobywan,

I was thinking about using the lid that came with the Presure Cooker because I can mount the gauge to it directly.

I know that the reason for having the clear top is to see when the degassing is complete, but for what I'm going to be using it for I can just create the vacuum and then let it sit for several minutes.

Would that be ok to do or should I still get the clear top?

Scot

[cobywan]

If you have a guage you can tell when you have enough draw. But be sure that the container you have your rubber in is three times the volume of the rubber you put into it. The amound of volume the rubber takes up under vaccuum is frightening. You don't want to loose any of your precious bodily fluids... No wait, that's precious silicone rubber.

[Myersjessee]

I asked a casting supply store if I could vac a pressure tank and they said it was reinforced backwards for that...and while I could do it it could collapse so they suggested against it. Obviousley they had a stake in that "solution" as they sold me a vac chamber...but I decided I didn't want to mess around when it comes to implosions or explosions.

[Valkyrie]

I've tried using a 2.5 gallon paint tank as a vacuum chamber once for a friend, and it seemed to work fine. I just had to get a little creative in how to set up the guages and valves and all so it could act as both a pressure pot and a vacuum chamber. As a vacuum chamber, I had no problem reaching 28+in/hg with my 6cfm vacuum pump.

The only problem with this method is that you have no way of seeing what's going on inside the pot when you're vacuuming. And with all the expansion that goes on inside there, it helps a LOT to be able to keep an eye on things. That's why I like my vacuum chamber a lot more than the paint tank. It has a 1" thick clear acrylic door, so I can see everything that goes on inside it

[B-52 GUNNER]

Cobywan,

How much would a piece of 1" thick clear acrylic cost?

It would have to be 1.5' square.

Also, If I wanted to make the highest quality lenses what type of clear resin do you recommend?

Scot

Edited August 14, 2004 by B-52 GUNNER

[B-52 GUNNER]

Also,

What type of material would you use to make the original out of in order to make the mold.

I was thinking of using aluminum.

Scot

[valkyrietestpilot]

B-52 gunner.that's really cool you took your user name in honor of your old man's former gun position.i was unaware they had gun emplacements on the "strato-fortress".i thought she was up to high to have to worry about fighters.did he serve on 1 when they first came out or did he serve time in 'nam in 1?

cool thread btw.i hope your getting all the info you need for your project

[B-52 GUNNER]

My Dad was a B-52 Gunner from 66' to 78' where he retired from Castle AFB as an Instructor.

He served before, during, and after Vietnam; mostly during the cold war flying with pretty silver cylinders in the bomb bay.

During Vietnam, two Gunners shot down Migs. Afterwards the Gunners were allowed to keep one of the barrels from their tail gun. If you ever goto the U.S. Air Force Museum in Fairborn, Ohio they have one of the barrels on display.

The B-52 had a .50 cal. Quad Cannon in the tail until I think the G and H models when they had 20mm Vulcan Cannons I beleave.

One final note:

When you hear people call the B-52 "B.U.F.F." (Big Ugly Fat Fellow) they are wrong.

The real nick name is "B.U.F" for (Big Ugly F****r).

Edited August 14, 2004 by B-52 GUNNER

[valkyrietestpilot]

well,my dad served 2 tours('67 & '68) in the bad bush('nam) w/ the 101 & 82nd airbourne divisions.seems your dad provided some air support for my dad in addition to "operation lineback" perhaps?

Edited August 15, 2004 by valkyrietestpilot

[B-52 GUNNER]

My Dad was in Nam as a Gunner in 70".

Making monkey meat and tooth picks. (Bombing Jungle)

But he was a Radar Tech for Recon Drones in 65" 66" 67".

Cool FireBee Drones; But that's another story.

So back to the main topic:

RESIN CASTING!!!

Help me Cobywan , Your my only hope!!

I need a reply on the last 2 questions I posted PLEASE!!!!!!!

Scot

[B-52 GUNNER]

Here is a photo of my pressure cooker pot and the refridgerator compressor.

I have a PIAB vacuum gauge and a compressor coupling attached to the lid.

Can anyone tell me the best way to attach the compressor to the pressure cooker?

[Valkyrie]

ouch... looks like it won't be easy.

My best guess is to put a flare fitting on the intake tube, and from there, attach a flexible hose from the flare fitting to the fitting on the chamber. But to put a flare fitting on the tube, there's a tool you need to use to flare out the end of the tube.

For clear parts, the only stuff I've used is Smooth-On's Clear Cast. It works well, if you can get all the air out of it, but it's slow. Even the quickest curing stuff (which says it cures in only a couple hours) takes up to a week to fully cure, if you're casting thin parts like a canopy.

As far as martials for your originals... the sky's the limit. If it works well for you, use it.

There's a few materials, such as wood and plaster, that could couse problems if you're using urethane mold material (which I personaly hate), but even then you can avoid problems by spraying them with a sealant. Just read the paperwork that comes with your mold material and you'll be fine.

[B-52 GUNNER]

Valkyrie,

OK, Here's the REAL IMPORTANT QUESTION!!

Which tube is which?

Thanks in advance,

Scot