Abrasive Blasting Air Compressor Requirements

[Beriant]

Hello!

I recently bought a 30+ year old car from NY that I am fixing up / restoring. Right now I am blasting the rear suspension components to get rid of all the rust and prep for refinish.

I have been running into some problems with my media blaster and found this forum through some searching, looks like a sweet place so I decided to make an account and ask the community a question.

I believe I know the answer but I wanted to get some feedback from people with more experience.

I have a 20 pound pressure pot blaster and I am using 70 grit glass beads however I am consistently running into an issue where the media stops coming out or the rate at which it comes out diminishes very quickly, maybe 45 seconds at best before the air pressure drops too much. I am setting the valve on the pot to 90 PSI and have my compressor on max(150 PSI).

It seems that after looking at some specs, my air compressor just is not up to the task. I was able to get the job mostly done but what should have taken 1 hour took 5-6.

So the question I have is, does media blasting even on this small of a scale, always require very high CFM capable compressors? Even If I bought the most expensive air compressor at Harbor Freight it does not even come close to reaching 10 CFM.

The only compressors I am seeing that are 10 or more, cost several thousands of dollars and require 240 and really and it seems like 10 CFM might not even be enough. Am I missing something here or is this just how it works?

Thanks

 

[theoldwizard1]

So the question I have is, does media blasting even on this small of a scale, always require very high CFM capable compressors? Even If I bought the most expensive air compressor at Harbor Freight it does not even come close to reaching 10 CFM.

The short answer is YES ! Blasting and sanding both require a lot of (CFM) but less pressure than other tools. The CFM depends on the equipment. Remember, as you use you send blaster, you are wearing the ID of the tip and requiring even MORE air !

I am far from an expert on this topic, but glass beads do NOT sound like the proper media for rust removal !

 

[kaymccampbell]

You will need a 240v compressor to get decent cfm. The biggest HF compressor should do better, but will not be as fast as a $2000 IR from Tractor Supply, which will not be as capable as a diesel powered trailer compressor. With media blasting, bigger is better.
I would swap media to black beauty for bulk blasting. It's cheaper, more aggressive, and should make your task a bit better.

 

[Beriant]

The short answer is YES ! Blasting and sanding both require a lot of (CFM) but less pressure than other tools. The CFM depends on the equipment. Remember, as you use you send blaster, you are wearing the ID of the tip and requiring even MORE air !

I am far from an expert on this topic, but glass beads do NOT sound like the proper media for rust removal !

I assumed that might be the case, thanks for the information. I did notice that after I went through my first tip, bought some backups to swap out.

I decided on glass beads based on local availability and not wanting to damage the underlying surface in any way. They worked really well for the aluminum pieces that just need to be cleaned but it is noticeably more difficult on the steel components that have rust build up.
I also needed something environmentally friendly as I am unable to contain all of the media( Using a home made shelter).

It's insane how much more expensive glass is compared to something like coal slag, 50 pound bag at tractor supply is $13 compared to the $70 for the glass.

 

[Beriant]

You will need a 240v compressor to get decent cfm. The biggest HF compressor should do better, but will not be as fast as a $2000 IR from Tractor Supply, which will not be as capable as a diesel powered trailer compressor. With media blasting, bigger is better.
I would swap media to black beauty for bulk blasting. It's cheaper, more aggressive, and should make your task a bit better.

I wish I had 240v in my garage, I saw those IR compressor's and they seemed to be the cheapest available that support high CFM.

I considered a fuel powered compressor but I just don't think it will be worth the hassle at this point, probably better off just putting up the cash to have 240v installed and get the IR.

 

[kaymccampbell]

I assumed that might be the case, thanks for the information. I did notice that after I went through my first tip, bought some backups to swap out.

I decided on glass beads based on local availability and not wanting to damage the underlying surface in any way. They worked really well for the aluminum pieces that just need to be cleaned but it is noticeably more difficult on the steel components that have rust build up.
I also needed something environmentally friendly as I am unable to contain all of the media( Using a home made shelter).

It's insane how much more expensive glass is compared to something like coal slag, 50 pound bag at tractor supply is $13 compared to the $70 for the glass.

Coal slag is at least as environmentally friendly as glass. It's a waste product of another process, glass beads are made for one purpose.

 

[Beriant]

Coal slag is at least as environmentally friendly as glass. It's a waste product of another process, glass beads are made for one purpose.

Hmmm good to know, I did some quick googling earlier and the process to dispose of it scared me off but I am going to look into this some more.

It may be the black beauty can get me by and get the job done with what I have. I was able to get about 90% of the surface cleaned but this won't be the last time I need to use it.

 

[Beriant]

Thanks to you both for your responses, with the black beauty, is that safe to use on steel and aluminum in terms of not damaging the metal?

 

[theoldwizard1]

I decided on glass beads based on local availability and not wanting to damage the underlying surface in any way. They worked really well for the aluminum pieces that just need to be cleaned ...

That is probably the best use !

A loaned a friend my old 2hp 240v Craftsman compressor so he could parallel it with another 2hp 240v compressor and sandblast though multiple layers of paint on a large brick wall. Took several week working part time.

 

[kaymccampbell]

Thanks to you both for your responses, with the black beauty, is that safe to use on steel and aluminum in terms of not damaging the metal?

Black beauty for the steel, glass for the aluminum.

 

[GeoBruin]

First, a note on matching your jet/top combo to your compressor flow rate. Depending on the gun you're using, you can get a smaller jet and tip that will be better matched to your compressor output so while they will not remove as much material, you will not outrun your compressor as quickly.

As for compressors, 240 power and a 5hp (or more) compressor is obviously the best way to get where you want to be, but it may not be the most practical way if you don't use a lot of other air tools or do a lot of blasting. I'm a big fan of running a "peaking" compressor for those times when I need more air. If you have more than one electrical circuit in your workspace, you could get a small compressor from the likes of California Air Tools that makes 5ish cfm and plumb it in line with your existing 10cfm compressor to get 15 ish cfm which is a big step up from where you're at.

Just a thought.

 

[Beriant]

First, a note on matching your jet/top combo to your compressor flow rate. Depending on the gun you're using, you can get a smaller jet and tip that will be better matched to your compressor output so while they will not remove as much material, you will not outrun your compressor as quickly.

As for compressors, 240 power and a 5hp (or more) compressor is obviously the best way to get where you want to be, but it may not be the most practical way if you don't use a lot of other air tools or do a lot of blasting. I'm a big fan of running a "peaking" compressor for those times when I need more air. If you have more than one electrical circuit in your workspace, you could get a small compressor from the likes of California Air Tools that makes 5ish cfm and plumb it in line with your existing 10cfm compressor to get 15 ish cfm which is a big step up from where you're at.

Just a thought.

Great idea, I had recently moved to a more quiet compressor but still had my old one laying around. It's not in the best shape but it works.
Got some brass fittings and plumbed both compressors into my dryer/filter unit and then out to the pot.

I also bought the HF 40 pound blast cabinet, wow that cabinet is complete garbage. Assembly was a nightmare, the gun *****, the siphon tube is horrible.

So I went again to the hardware store for some fittings, I drilled out the inlet hole in the cabinet and plumbed my pressure pot into the cabinet but its also removable in case I need to just use the pot.

A lot of frustration, hours, and dollars I ended up with a decent enough setup to get my pieces done AND I did not have to deal with the absolute mess I made the first time around.

 

[dnschmidt]

The correct answer is YES. 240V 7.5 HP is what is needed. My 5HP 80 gallon Quincy can barely keep up and it puts out 17.5 SCFM. It seems that everybody that comes on this site thinks that they can do anything with tiny compressors. That's never been true that will never be true as Physics doesn't give a **** about what you'd like to do. Why do you think body shops of any size have big screw compressors? Because they need them. A good spray gun like a SATA requires 17 SCFM at 30 PSIG. Air sanders take just as much at 90 PSIG. That’s the way it is and nothing changes the Physics of what's needed to produce that much air. Don't forget the refrigerated dryer, desiccant dryer, filters, regulators, piping and valves needed to complete the system especially if you want clean dry air which in the industry is abbreviated CDA and is often required by air tool manufacturers. Making a lot of air costs a lot of money. Life *****.

 

[finn]

I never had luck using an inexpensive pressure pot type blaster. I much prefer an inexpensive Crafrsman suction blaster that I bought almost forty years ago. The pressure blasters seem to plug up easily.

for years I used the suction blaster with a common Sears Craftsman belt driven 120/240 v compressor. Not fast, and there’s more wasted media with that type blaster, but it works, with patients.


A quality cabinet blaster with a 5hp compressor is more satisfy to use, of course.

 

[dkmc]

Physics doesn't give a **** about what you'd like to do.

This should be engraved on a large rock in front of every science building at various prestigious universities across the country.
Or, I'd settle for a T shirt.