air compressor purchasing help

jediknight0

New Member
Frequent lurker, occasional poster here.

So I've been using liquid resin for years for various replica projects and computer case modding, but I want to step up my game. I've been looking into either getting a vacuum chamber or a pressure pot and I think I've leaning toward a pressure pot... but if I use a simple venturi pump (for $15 for harbor freight) going from pressure pot to vacuum pump is simple. But both require a good air compressor.

So any recomendations for cheap, good, and possibly local (i.e. sears, home depot, lowes, harbor freight) air compressors?

Ideally my requirements (in no particular order) are:

1) physically small
2) high CFM
3) cheap
4) lightweight
5) low AMPS (short story: my garage shares one 15 AMP circuit with half my condo and it's hard to change for variosu reasons)

I know - some of those requirements are at odds with with other. I'd say high CFM & low AMPS are probably the most important.

Any help? Thanks in advance.
 

JFB64

Active Member
I've looked at you five requirements and I think #5 low amps will be your deciding factor. Compressors draw a lot when they start up and a shared 15 amp circuit might not be enough to power even some small portable compressors. I've been on job sites with a 4 gallon Porter Cable compressor that was too much for the house current and wouldn't start. Having to go with a smaller compressor will mean it will take longer to charge a big pressure pot. It may also not be powerful enough to pull the vacuum you want when used with the HF venture pump. I have one of those HF units and a 8 gallon 1HP compressor and I use them to evacuate a 10 gal. It took a long time, several minutes, and was almost too much for my compressor and I couldn't get the tank to the vacuum I wanted. I was probably asking too much from this set up, my point is that the HF unit is slow even with a bigger compressor. Someone at one of the big box hardware stores may be able to help you with questions on power consumptions of various models. You are just going to have to shop around. Good luck.
 

Superkrates

Active Member
RPF PREMIUM MEMBER
Unless you're degassing silicones and resins that have thick viscosities, you really don't require a vac chamber at this time(Smooth-on makes special silicones that do a good job at degassing themselves)

Simplifing the compressor issue:

• you can use any compressor that pumps over 40psi (pressure most commonly used in resin casting). Bigger compressors just mean faster pump-up times for this application.

• If your compressor tank is smaller than your pressure pot, also employ an external tank equal to, or greater than, the volume of the pressure pot. (this would pump a 2.5 gal pot but probably not a 5 gal pot: 3 Gallon Air Compressor - 1/3 HP, 100 PSI, Oilless)

• Plug your compressor into a 10amp surge protector power strip to avoid tripping the garage breaker (in case of overload, the surge protector will trip before the garage breaker)
 

jediknight0

New Member
Thanks for the replies!

Unfortunately, I just realized how loud various air compressors (including the cheap HF one) actually are... and that isn't going to work. I do have a garage to work in, but the garage shares a wall with my neighbors and is directly below my kids' bedroom (with a 2.5 year old and a newborn). Since I only get a few hours a week to do my hobbies and it's usually midnight to 2am, I'll need something quiet.

So I guess cheap will be close to impossible and low amps will be hard...

I'm leaning towards something like CALIFORNIA AIR TOOLS 1650A | GMC Generators or CALIFORNIA AIR TOOLS 6310 | GMC Generators. Expensive, but the make more reasonable sounds and are below 5 AMPs & 8 AMPs respectively. Thoughts?


Also, I'm trying to decide on a proper pressure pot. I'm thinking of the ones from CA Technoligies specifically designed for casting but can't decide on the size. One of the things I want to cast is a ring with an OD of 9 inches and thier 2.5 gallon pot claims to have an ID of 10 3/8 inches... not sure if that's enough. Thier 5 gallon pot isn't too much more expensive (some places) and is like 12 inches diameter, but I'd rather not have an air tank big enough to fill 5 gallons...
 

exoray

Master Member
You can always put a box over the air compressor, it's common practice in smaller shops to put them in a closet or small sectioned area or closet to cut down on noise...

If you make a simple plywood box say 6" bigger all around vs the compressor, and covered the inside with some acoustic foam and then dropped it over the compressor the noise levels will drop DRASTICALLY... As long as you don't run it constantly you don't have to worry about it overheating...

As for the pressure pot you have to decide what is right for you the CA Tech models are nice because they are turnkey but you can make one with a little effort and save yourself a bundle of money... If you watch craigslist you can likely pickup a used 10 gallon paint pot for $200-300, spend a few extra bucks modding it and you are still well bellow was a CA Tech's 5 gallon cost...
 
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