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Thanks BLACKHAND!

Here are two more companies that sell casting products used by 40K enthusiasts.

MicroMark is in the United States. They sell a lot of modelling tools as well as casting materials.

Sylmasta is in the United Kingdom. They sell a nice casting kit that I will order online since I live in Germany right now, and I had to get rid of a lot of my other materials before I moved from the US.

I hope to get back to casting in November. I'm sculpting some things (40K bases, bits, and Mordheim bits) that I want to cast.

Thanks JB, have added Micromark to the OP, feel free to post any pics of your moulds and technique when you get casting in November.

When casting are there any harsh fumes or need for ventilation?

Red Corsair wrote:When casting are there any harsh fumes or need for ventilation?

Depends on the products used, I wouldn't have thought there would be too much chance of fumes with Silicone compounds but a with resins there could possibly be a greater possibility. The products I use for instance have no fumes and very little smell at all, the silicone is often used for making moulds of body parts and is safe for contact with skin.

Of course when sanding or drilling resin you should make sure not to inhale the dust, I have had people suggest using wet/dry sand paper and submerging the piece to be sanded in water while sanding... at the very least wear a mask or work outside.

Goes without saying that working with any chemicals, be it resin, silicone or glues, you should probably work in a well ventilated space.


I will however cop the the fact that I work in a 3x6 space under my stairs that has absolutely no ventilation or natural light

Just read a review of something called "blue stuff" by Ron over at "From the Warp"

http://fromthewarp.blogspot.com/2011/10/my-attempt-at-molding-and-casting.html

Might be something of use to you guys, if anyone does try it let us know how it went!

Thanks BH I really appreciate the response : )

Can someone tell me what the minimum requirement for an air compressor is to do pressure casting?

I assume you mean a vacuum pump for degassing. If so, no.

Red Corsair wrote:Can someone tell me what the minimum requirement for an air compressor is to do pressure casting?

It will depend on the size of the chamber, and how fast you want it depressurized.


The following advice comes from Sersi who has a thread dedicated to pressure casting.

Sersi wrote:There are several important features to selecting a good vacuum pump:

1. Your vacuum pump must be able to draw 28 - 30 inches of mercury, or 1 Bar. The closer you can get to 30", the better. Most likely, your gauge won't ever get to 29" unless you have a serious air compressor with a Venturi Generator or a super vacuum pump. However, 27" or 28" is sufficient; you'll just have to run the pump a little longer.

2. You want to get a 3 CFM pump at the minimum. I have a 7 CFM pump, but 5 CFM is sufficient and 3 CFM is fine for mold making and casting. CFM stands for cubic feet per minute. This is how much air the pump can displace, the lower your pumps CFM rating the longer you will have to run it to de-air your silicon rubber. Since most rubbers have a short pot life (pot life - is how much time you have to mix, de-air, and pour it into molds before it starts to harden) of 30-45 minutes. Most pumps that your will find on line will be 0.25 to 1.5 CFM pumps, while cheap avoid these as they will take forever to de-air silicon. I vacuum my rubber twice, after mixing and again after its been poured into the mold box. I do this to remove any air that may have been trapped against the model when the rubber was poured. My 7 CFM pump takes ~ 90 seconds to achieve vacuum with my Belart desiccators.


Cost:

$180 + $43.25 S&H (Re-furbished / E-bay)
$600 new (you can find them on sale for ~ $300.00)

Thanks for the repost JB, and yeah Sersi is really someone that you want to watch when it comes to sculpting and casting, his stuff is pretty stunning.

Thanks guys, but I was referring to the pressure pot though not the degassing chamber ha ha, this stuff gets confusing.

Yea I am ordering the pressure pot but don't know what size air compressor I will need for it... I have the vacuum, expensive but well worth it I hope ; )

A pressure pot would be a degassing chamber, as the intent is to remove air bubbles by means of a vacuum.

I don't see any benefit to adding more air into a cast. Perhaps you could link to wherever you are getting this idea of positive air pressure?

Thank you so much!


I have been looking all over for a simple casting technique as i hope to start producing some of my own little bits and bobs for sale ^^

http://www.dakkadakka.com/dakkaforum/posts/list/243074.page#758869

The purpose of degassing with negative pressure (vacuum) is to remove air from your silicone rubber and resin mix....

The pressure pot is for positive pressure to force the resin into the mold and shrink remaining air bubbles so you capture a higher detail in the product... They are entirely different principles being applied from two different items. If you look at the link I provided from sersi you will see he recommends and uses both items but doesn't list what size compressor he uses...


My question was in regards to the PSI rating required for the second item the pressure pot (he lists the goal to be reached, 40PSI, but not the best compressor size to get here in time)...

Corsair

http://www.harborfreight.com/1-8-eighth-hp-40-psi-oilless-airbrush-compressor-93657.html

This one does 40psi, and it's borther does 58.

http://www.harborfreight.com/1-5-hp-58-psi-compressor-and-airbrush-kit-95630.html

Thanks for offering the advice Aerethan, this is pretty much over my head

Red Corsair wrote:Thanks guys, but I was referring to the pressure pot though not the degassing chamber ha ha, this stuff gets confusing.

Yea I am ordering the pressure pot but don't know what size air compressor I will need for it... I have the vacuum, expensive but well worth it I hope ; )

Oops sorry , I should have read your question more carefully. You should probably just send a Private Message to Sersi to find out what pump he is using. I was planning on just using the air compressor that I have in my garage but I changed my mind after reading that I should get one with an air tank.

Aerethan wrote:A pressure pot would be a degassing chamber, as the intent is to remove air bubbles by means of a vacuum.

I don't see any benefit to adding more air into a cast. Perhaps you could link to wherever you are getting this idea of positive air pressure?

I'm not an expert on the use of pressure pots in casting (all gravity for me so far) but have been researching it (like Red Corsair) before I purchase the required equipment.

From what I've read, degassing works best when making the molds but pressure works better for the resin during the actual casting. A vacuum apparently can play hell with the resin, causing it to end up outside the mold and all over the vacuum bell. A vacuum also messes with the curing time making the process more unpredictable. Pressure, on the other hand, requires another set of equipment (pressure pot and air compressor) and can be dangerous if you don't properly seal the top of the pot. I'm thinking that I'll go with a resin that requires a longer demold time to give me plenty of time to get the filled molds into the pot, seal it, and get the pressure up to the required PSI (40-60 according to most of the sources I've read or viewed).


BLACKHAND, are you planning any more casting this year? I'm ordering my new casting materials (still gravity casting) this week. I'm planning to make some one piece molds of bases, movement trays, and vehicle stowage. It's not much but I felt I had to do something after seeing Foda_Bett's plog of Warhound wonders (including much casting).

Not planning on any major casting projects in the near future JB, have a six month old and a 4 year old who are (quite rightfully) taking up most of my downtime

I am planning on a scratchbuilding a rubbish skip and casting it for use as cover on my Infinity table but nothing more complicated than the moulds I have down previously.

Thanks for mentioning Foda_Bett's plog, I have been trying to think of his name for the last couple of days to suggest that Red Corsair have a look at it. The pics of his degassing setup are about all I know about pressure casting and he sure as hell looks like he knows what he is doing.

Ya I asked Sersi that question before about the pressure pot for the resin.

He wrote:
"You need a pot that can be pressured to at least 40 PSI, more is always better"

I endied up trying talc powder instead of spending $200 or so on a pot.

I have to say I'm kicking myself for not trying it earlier!! Talc Powder is Magic!! Thanks Blackhand for the tip. I have no Idea how it works but it keeps the bubbles off the surface. Even a bad resin mix looks amazing. Mind you, the bad mix was very brittle.
Talc on a good cast makes the resin flat and not shiny like a cast without Talc. Though I found it eaiser to clean and the primer sticks to it better. Details that I couldn't get before, come out perfect.

I use OOMOO 30 and sometimes Talc alone can tear small bits of rubber, So I use a light coat of release agent, then add the talc powder when dried.

If your new to casting and want the bubbles gone without buying that pressure pot I'd give Talc a try first.

Yeah, I am not sure if the talc breaks the surface tension of the resin bubbles or just bonds to the resin to make it cover the surface of the mold completely but who cares? It works!

And I've become quite used to the textured surface it gives, paint adheres really well to it.

Pressure casting does not force resin into molds. Increasing the pressure decreases the size an air bubble will be. Under enough pressure even a very large bubble in relative terms it forced into a very tiny bubble. If you look closely at Forgeworld resin you can see some of these very tiny bubbles in the final product. Since it is impossible to completely degass your silicone before you pour the mold, or your resin before you pour it pressure casting becomes extremely important.

You cannot normally use the same vessel for both pressure casting and degassing. The equipment required to create and maintain a vacuum is much more expensive then the equipment to pressurize a simple vessel. I use this for pressure casting http://www.harborfreight.com/2-1-2-half-gallon-pressure-paint-tank-66839.html along with a compressor I normally use for airbrushing. You can get a complete pressure casting setup from harbor freight including the pressure tank and a cheap compressor for under 150 dollars. A legitimate vacuum degassing setup is upwards of 600 dollars.

It is important to maintain a constant pressure level during the entire cure time that your resin requires. Always purchase a compressor with a tank for this reason. http://www.harborfreight.com/3-gallon-100-psi-oilless-pancake-air-compressor-95275.html is my recommendation. You only need between 10-30 psi however this level must remain constant or you risk the bubbles changing size during your resin cure! I pressurize both molds and casts using the same process.

Simple degassing of your resin and silicone can be accomplished with a very inexpensive vibrating table. You can build your own with a simple AC or DC motor and any flat surface. Just place your mixed resin on silicone on the table for a few minutes and nearly all the bubbles will rise to the surface. This combined with pressure casting will produce very professional results for under 200 dollars in setup costs.

Linkdead wrote:Simple degassing of your resin and silicone can be accomplished with a very inexpensive vibrating table. You can build your own with a simple AC or DC motor and any flat surface. Just place your mixed resin on silicone on the table for a few minutes and nearly all the bubbles will rise to the surface. This combined with pressure casting will produce very professional results for under 200 dollars in setup costs.

I've read about the vibrating table before but I haven't seen an example in pictures, much less a how-to-build it tutorial. Do you have one that you built? Could you tell us how you made it?

As much as I think this could go down like a lead balloon I will mention it...

... it was once suggested to me that it was pretty easy to assemble a decent vibrating table with some foam, a piece of plastic or thin mdf and ah, well how can I say this...um a "Marital Aid"....

... of course since my painting and modelling area is under the stairs in a cupboard and also has my computer in it I havn't dared try this in case my partner was to walk in, no real way to explain it

A vibration table is easy to make.

Materials:
A back massager(the head of which needs to be at a 90 degree angle) like this one
http://www.walmart.com/ip/HoMedics-Extendable-Percussion-Massager/14540369
2'x2' piece of plywood
4 FOAM sponges(dollar stores should have them, NOT the kind you use for dishes as they are only springy when wet)
some duct tape


Duct tape the 4 sponges on the bottom, then tape(or you can use metal connectors from Home Depot or w/e) to secure the massager onto the board head down.

Plug in and play.


Automatically Appended Next Post:
http://www.hirstarts.com/casting/advanced.html#vibrate

this is much better than my shoddy instructions

BLACKHAND wrote:As much as I think this could go down like a lead balloon I will mention it...

... it was once suggested to me that it was pretty easy to assemble a decent vibrating table with some foam, a piece of plastic or thin mdf and ah, well how can I say this...um a "Marital Aid"....

... of course since my painting and modelling area is under the stairs in a cupboard and also has my computer in it I havn't dared try this in case my partner was to walk in, no real way to explain it

Funny, very funny but I think I'll go with Aerethan's method. Heck, I'm no glutton for SITCOM humor.

Here you are, I'm sure you all get the idea.

http://www.hirstarts.com/casting/advanced.html#vibrate

I quick tip about these tables. The more viscous your resin or silicone is the better your table will work. You are also looking for low frequency vibrations, too high will just cause more bubbles and worse sloshing around and potentially foaming. The best mold making silicone is a very thick and slow drying. They can be degassed using the vibration table method. Most modern high quality resin is the opposite, very thin and with a fast bloom time. I usually mix and immediately pour the resin.

I thought I would jump in on this and make a post or 3.

I have complete walkthroughs on my blog for all three methods, plus what I would like to think is usefull hobby info.


First up is press molding, it is the cheapest to get started in. I can't post pics (IP issues) of my pressmold projects but here is a link to the PressMold tutorial.
using Instant Mold and either GreenStuff or ProCreate putties
http://warfrog.blogspot.com/2011/05/saving-ebay-finds-by-casting-your-own.html for around $24.00 at the warstore you can get everything you need to get started making small bits. I strongly recommend this over BluStuff.

Next is silicon molds for resin.
Using Smooth-On's line of silicon. This rubber does not need special casting equipment like a vacuum chamber or pressure pot.
http://warfrog.blogspot.com/2011/11/two-part-mold-making-tutorial-resin.html Walkthrough.


Finally is making molds and casting white metal or pewter. Links to suppliers are in this tutorial
http://warfrog.blogspot.com/2011/10/white-metal-casting-tutorial.html

Great tutorials, thanks for posting!

The Idea with the syringe in the mould is brilliant!!

Using a syringe was a tip that I think i picked up from Aerethan, I just decided to go ahead and make my pour gates with them.