Vacuum Chamber Recommendations for Resin Casting

[MichaelK]

Hi everyone. Not sure where to post this; forgive me if this is the wrong place.

I plan on resin casting terrain and various scenery elements for miniature wargames. I'm planning to move on from simple flat pour molds and into two-part molds for more complex pieces.

I want to purchase a vacuum chamber. I think this will be best, given that some of the pieces are small, and would require an annoyingly large number of vents to ensure I don't lose details to random air bubbles.

The whole setup is purely hobby-scale, not industrial capacity. I do not have a garage, work shed, or other sort of large area for this. Literally doing this in my basement... It's 99% likely that a vacuum chamber is overkill for my purposes, but whatever!

I'm trying to find a quality setup, somewhere between the "Gut check says that's highly questionable" ~$100 rigs that show up on eBay/Wal-Mart/etc. when googling for "vacuum chamber", and the $500 industrial setup offered by Smooth-On.

I have had a lot of difficulty finding any sort of good guide, though. Can anyone point me in the right direction? I understand there are various different types of vacuum pumps themselves, but I honestly don't know what is right for my purposes. I bet it would never see more than a thousand uses, ever, but I also don't want something that will give me trouble.

Heck, for all I know, somebody is going to say that rotocasting is the way to go...

Any advice, pointers toward guides, or other nudges in the right direction would be greatly appreciated!

 

[basementdweller]

Paint pressure pot mod into vacuum chamber. Most affordable way and sufficient for your needs. A simple search on the term will give you multiple diy guides and videos.

 

[ZeroSum]

Do you really need a vacuum chamber? Or is a pressure pot what you really want?

 

[Valor]

Do you really need a vacuum chamber? Or is a pressure pot what you really want?

THIS. To cast clear resin you're looking for a pressure pot, not a vacuum chamber. Harbor F sells a 2-1/2 gallon pressure paint tank for $100. You swap a few of the connections, get a cheap air compressor and you're in business.

People get this mixed up a lot. A vacuum chamber is typically used for degassing silicon mold rubber. Not all, but some of the Smooth-on rubbers (like Mold Max) requires degassing. The idea is you are pulling air OUT of the mixed silicon so you have smooth molds.

When you cast clear resin you want to do the opposite. The pressure tank is going to compress the tiny bubbles remaining in your resin until they are microscopic. This way your resin looks clear.

I bought this vacuum set up and really love it:
BACOENG 3 Gallon Vacuum Chamber Kit with 3.6 CFM 1 Stage Vacuum Pump HVAC

https://www.amazon.com/dp/B00W8ZU5FK/ref=cm_sw_em_r_mt_dp_2zlRFbJQF3Z37?_encoding=UTF8&psc=1

 

[Jkirkon]

THIS. To cast clear resin you're looking for a pressure pot, not a vacuum chamber. Harbor F sells a 2-1/2 gallon pressure paint tank for $100. You swap a few of the connections, get a cheap air compressor and you're in business.

People get this mixed up a lot. A vacuum chamber is typically used for degassing silicon mold rubber. Not all, but some of the Smooth-on rubbers (like Mold Max) requires degassing. The idea is you are pulling air OUT of the mixed silicon so you have smooth molds.

When you cast clear resin you want to do the opposite. The pressure tank is going to compress the tiny bubbles remaining in your resin until they are microscopic. This way your resin looks clear.

I bought this vacuum set up and really love it:
BACOENG 3 Gallon Vacuum Chamber Kit with 3.6 CFM 1 Stage Vacuum Pump HVAC

https://www.amazon.com/dp/B00W8ZU5FK/ref=cm_sw_em_r_mt_dp_2zlRFbJQF3Z37?_encoding=UTF8&psc=1

This is exactly correct.
I have the same vacuum chamber posted above, and the same HF pressure pot setup. It works great.

Making the silicon molds, the idea is to lower the atmospheric pressure in the silicon mold material to remove bubbles before you pour silicon into the mold box. This lessens the possibility of bubbles/voids in your molds. You will only use the vacuum chamber to remove the bubbles in the silicon before you pour it into the mold. You don’t need to let the silicon cure while under vacuum.

Pressure pots are used to cast. Increasing the pressure forces the resin into all the nooks and crannies of the mold.
You will allow the resin to cure while the mold is under pressure.


I use smooth on products to mold/cast. I have found it’s a good idea to use the vacuum chamber for the mold material, even if smooth on says it’s not needed. In my experience, I’ve got better quality molds that last longer.
Using a pressure pot may, or may not be needed, depending on the part you’re trying to cast. More complex parts benefit from pressure casting, whereas simpler parts, such as relatively flat or smooth parts, you may be able to get away without using the pressure pot. This will depend on several factors, such as the size and complexity of the part, relative humidity/temperature, and they type of resin used.
I tend to use slower setting resins with a low viscosity. They flow well into the molds, and take a longer time to set up. This seems to allow any bubbles to work their way to the pour/vent spouts of the mold and away from the part. This has merely been my observations, your mileage my vary.

 

[BrundelFly]

Use the VAC to suck air out of your RTV. You cant PRESSURE CAST resin...UNLESS you have Vaced your silicone

 

[Valor]

Use the VAC to suck air out of your RTV. You cant PRESSURE CAST resin...UNLESS you have Vaced your silicone

Also this