Good Compressor for Amateur Media Blasting

WalzAaronFFG

WalzAaronFFG

Joined
Jun 4, 2011
Messages
269
Hi all,

Not sure if this is the right place for this post, but here it goes.

First off, let me start by saying I am not a knife maker or even very handy around the house. I am just a tinkerer and am looking for some advice from people who probably know this stuff pretty well since you all spend a lot of time in the workshop.

I am looking at doing some sand/glass bead blasting and am starting from the ground up. I have no blast cabinet, no gun, no nozzles, and most importantly, no air compressor.

So first things first, I plan on glass bead blasting very small parts on occasion. The largest part I would be blasting would probably be an AR15 barrel or receiver. Most things will be knives and misc. small gun parts. I also will use the compressor with a spray gun for Cerakote and Duracoat and will probably use it for some basic air-powered tools in the future.

I currently am borrowing a very small compressor from a family member (Craftsman 4 Gallon 2HP 3.0 CFM @ 90 PSI) for basic stuff around the house and it's time for me to return it and get something for myself. Everything I am reading is telling me that a compressor of this size will not the get the job done when I start media blasting.

The place i'm getting hung up is: how big do I need to go? I truly don't care to spend a thousand bucks on this "hobby", so what is the minimum I can get away with and still get decent results?

I'm looking at something in the 15-20 gallon range. Probably single-stage due to cost. I found a local deal on this one and am interested in hearing people's opinions. If you think I can get away with a lot less since i'm doing such small parts, let me know.

http://www.northerntool.com/shop/tools/product_200455339_200455339

Thanks in advance for any advice you may have,

Aaron
 
I'd get something with 10 scfm or more, it sounds like a big compressor and is but blasting takes a lot of air. If you can try the one you have now for blasting I would, it may be good enough for what you are doing.
 
Once again I think the pay once cry once rule applies to this particular tool decision. The good news is that "quality" air compressors like serious belt grinders HOLD THEIR VALUE nicely. I have 2 myself, a Craftsman pancake that I bought at a garage sale CHEAP and a bigger, quieter Quincy (not cheap). They serve different needs nicely although my wife scratches her head over why I need 2.

http://www.engineeringtoolbox.com/air-consumption-tools-d_847.html

Good luck

C
 
I have a 5 HP, 60 Gal, 6.5 CFM (I think) @ 100 psi. I sandblast knives using a mix of glass beads and AlO2 at 85 psi. I would not want to go any smaller.

Tim
 
http://m.harborfreight.com/air-tool...-cast-iron-vertical-air-compressor-69865.html

I use this air compressor from harbor freight. It works. For a good sized knife I have to let it catch up once or twice while sandblasting at about 80psi with a harbor freight sandblast cabinet. You can use a smaller compressor, I did for a long time, but I wouldn't buy a smaller compressor than this. I think it's 5.9 cfm @ 90 psi

My previous air compressor was probably about the size you are borrowing now. I did use it for sand blasting for coating prep and airbrushing. It was painfully slow going.
 
With our 13A 230V single-phase domestic mains, the biggest compressor we can run over here without a dedicated supply is 3 HP (continuous motor rating). 3HP seems to give around 15 CFM displacement and around 8-12 SCFM Free Air Delivered at 90 PSI, depending on how well the manufacturer has sorted out the details. The receivers go from 50 litres wheeled to 200 litres static and 150 litres static (about 40 gallons) is the most common.

With a cheap imported freestanding blast cabinet, a 90 PSI regulator setting and the biggest of the nozzles supplied with it (3.5mm?), the 3 HP/150 litre compressor will not keep up.

Going down a nozzle size (3mm?), it becomes reasonably usable; not continuous, but able to keep up in normal use.

Going down 2 nozzle sizes gives continuous operation.

We tend to use the middle nozzle. It seems to get the most work done in any given amount of time.

It's hard to tell how much is the nozzle size and how much is the cheap, nasty cabinet, but media blockages seem irritatingly common. We are using cheap glass beads.

Having used a 3 HP compressor, I would not want to go less than 3 HP, though I suspect pretty much everyone is going to feel the same way; they'll have managed with what they've had, would have liked more and would hate to have less.

It looks like another 20 bucks would get you 3 HP on a 60 gallon receiver. http://www.northerntool.com/shop/tools/product_200455341_200455341.

The Cast Iron pumps are significantly quieter than Aluminium ones in my experience. They usually run slower and seem to be more efficient than the Al ones (higher CFM at 90 PSI for the same power).
 
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It seems that a compressor for many folks ends up getting used more than initially expected. A die grinder with carbide burrs, grinding stones mini flap disc will suck some serious air. I also agree that a quality compressor from a solid company will hold its value very well. These compressors are expected to go 50,000 hours. They have a hefty price but in then end when you have enought air you will be happy. Quincy, Champion are solid manners of quality compressors.
 
Thanks for the info everyone.

Honestly after reading your posts i'm second-guessing this whole thing. I really just wanted to do something on the cheap since I really won't be using this much. I don't build knives and I don't have a "shop". I especially don't have room for a 60 gallon compressor in my basement.

I might be better off paying a local person that does what you all do to help with the limited items I will probably end up blasting.

I have a friend with a compressor that's similar to what I posted in my OP, so I might just order the blasting cabinet I was going to try and see how it does with the lower SCFM rating. Worst case, I have to sell the blasting cabinet and I lose a few bucks on shipping and whatever media I buy.

Thanks again, folks.
 
A 60 gallon will take up about the same space as the Puma you listed. Here's one I just picked up that was on sale at Easter for $419+tax. It just won't be portable. I'd look at some of the popular tool/shop/garage forums & do some research, but when it comes to compressors, it's better to go big because there are so many great tools you can use if you have enough CFM & volume.
http://www.tractorsupply.com/en/store/porter-cablereg;-stationary-belt-drive-air-compressor-60-gal

My initial test has it in the mid 12 cfm range based on some calculations I found online to estimate CFM from the time it takes to fill from empty. It was like 6 min 20 sec to fill 60 gallon tank. Regular price this is still cheaper than the other one you are considering. Also, here's another one similar to that Puma, but with a larger tank & it's cheaper. But I agree with the previous statement, buy once, cry once. I have a California Quiet Air I just bought last year that I could have put the money towards a larger one....but then last year I didn't think I'd be starting a business out of my garage. I'm still deciding if I'm going to keep or sell it, since having a small quiet 115v compressor that's portable may be handy.

http://www.tractorsupply.com/en/store/porter-cablereg;-portable-belt-drive-air-compressor-30-gal
 
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