Air compressors and soda blasting

[BadLeeroyBrown]

First post here, so forgive me if I make any mistakes -

I just picked up a used Craftsman 30 gal/6.2CFM/175PSI air compressor. Aside from normal things - Airing up tires, blowing out PC cases, blowing off woodworking workspaces, etc - I also am going to try to get into sandblasting.. Or rather, soda blasting. As a hobby, I restore cast iron cookware. I currently have my electrolysis and lye tanks set up, but I'm hoping soda blasting will help with some of the harder peices I've got, and maybe speed up the process all together.

All that said, Harbor Freight has a 'soda blasting' tank/gun for $150, but it claims the recommended CFM is closer to 8. I know my new compressor is underpowered for this, but what does that translate to in actual use? It's not going to be something I'm doing daily, or for long periods of time.. If I can get it to effectively do its thing for a short period, take breaks every few minutes..

Ideally, I'd get a 240V unit that can do something closer to 10CFM, but my breaker panel will need to be replaced/upgraded to allow for that, and that's not something in the budget for me at this time. My next alternative will be to pick up another similar 6.1ish CFM compressor and run the two in parallel, assuming that'd accomplish what I'm wanting. I've seen mixed things in my searching along those lines.

 

[Matt018888]

Any kind of Blasting uses a lot of air. Ideally to blast anything, you need to start with an actual 5hp unit or up(In my experience). That said... You can always try it. I'm sure you will be pausing waiting for the compressor or compressor's to catch up. Personally I would just upgrade to a larger compressor. You can find deals on marketplace all the time. If a panel up grade isn't in the budget, could you swing the cost of a 220v transfer switch for the time being? If you have a 220 oven of something you could add a transfer switch to the panel and switch as needed. Not ideal but would do the trick until you upgrade. If you do rund duel compressor it may be beneficial to run both off a single pressure switch, which may require some relay work. You can still run two PS but they will have to be tuned to similar Cut on and cut off pressures. Iv also heard many people using cheap harbor freight compressor pumps and building decent compressor out of old used ones. Just remember if you buy anything used to hydrostatic test it, this can be done with a simple water hose and a grease gun. Compressors store a amazing amount of energy.

 

[Steve_P]

I'm not sure what you're trying to accomplish, but baking soda is a very mild blasting agent at typical cabinet pressures. I've used it to blast aluminum carburetors, and it barely changes the surface finish. If you are going by the results of others online that are doing the same thing that you plan to, then ignore me and proceed.

If you run two compressors, they may have to be on separate circuits as you'll be limited to 15-20A per circuit.

 

[GeoBruin]

First post here, so forgive me if I make any mistakes -

I just picked up a used Craftsman 30 gal/6.2CFM/175PSI air compressor. Aside from normal things - Airing up tires, blowing out PC cases, blowing off woodworking workspaces, etc - I also am going to try to get into sandblasting.. Or rather, soda blasting. As a hobby, I restore cast iron cookware. I currently have my electrolysis and lye tanks set up, but I'm hoping soda blasting will help with some of the harder peices I've got, and maybe speed up the process all together.

All that said, Harbor Freight has a 'soda blasting' tank/gun for $150, but it claims the recommended CFM is closer to 8. I know my new compressor is underpowered for this, but what does that translate to in actual use? It's not going to be something I'm doing daily, or for long periods of time.. If I can get it to effectively do its thing for a short period, take breaks every few minutes..

Ideally, I'd get a 240V unit that can do something closer to 10CFM, but my breaker panel will need to be replaced/upgraded to allow for that, and that's not something in the budget for me at this time. My next alternative will be to pick up another similar 6.1ish CFM compressor and run the two in parallel, assuming that'd accomplish what I'm wanting. I've seen mixed things in my searching along those lines.

Welcome to the forum.

Your question is a common one and it's been discussed here a lot. It also generates a lot of discussion (argument) because there are those that believe any kind of blasting requires a 5+ HP compressor and some even higher.

I've been on both sides of this as I started out with about a 7 CFM compressor, then decided to get into blasting, and only much later upgraded to a larger compressor. I have also been a vocal supporter of modest blasting with smaller compressors, including all the various mechanisms for "getting around" upgrading your compressor and/or electric panel.

The first thing I'll say is it does depend on what you're blasting. If you're blasting large things, blasting with too little air is going to get tedious very quickly. Fortunately, it sounds like you're focused on cast iron pans which seem reasonably achievable.

Next most important thing: the air consumption of any blasting setup is a function of the air pressure you're blasting at, and the size of the orifice you're blasting out of. If you're blasting at much higher pressure, you will use much more air. You should check the recommended pressure for the type of blasting you're doing. Your compressor is rated at 6.2 cfm at 90 psi, but you're only blasting at 50 psi, your compressor's air delivery at that pressure will be higher.

Similarly, if you're using a large orifice tip, you will be flowing a lot more air. You can obviously work faster with a larger tip, but if you don't have the compressor to support it, use a smaller tip. With regard to the HF soda blaster specifically, I don't know that different tip sizes are available, so this may not be an option for you.

Given the above considerations, you will likely still be waiting on your compressor if you're trying to blast constantly. That's not the end of the world if this isn't something you're going to be doing all the time. But if you want to increase your air without upgrading your panel and getting a 240 volt compressor, here next best option really is to add another compressor to the system. Stated above you will need to be careful about running two compressors on the same circuit. If you have a second circuit, you can run another compressor rated at 5-7 cfm and effectively double your air flow. Just a couple things to be cautious about

1) even if both compressors are on a separate circuit they are presumably going to be drawing from the same sub panel or even main panel and having them kick on at the same time could be less than ideal. Do that end, see if you can change the kick on pressure of one or the other so that they're not starting at exactly the same time.

2) most compressors in the class you're looking at are really not rated for truly continuous use. So while you will have more air than you did with a single compressor, you're still going to be using quite a bit for blasting and they may run nearly continuously. Just be cognizant of the temperature and make sure you're not overheating them. It's probably still worth it to take a break once in awhile.

3) There are plenty of threads here on how you can plumb the compressors to achieve your desired output but the main concern that's always brought up is to make sure if there isn't a check valve or something in your system, that you don't have one compressor with a higher PSI pump inflating a tank with a lower max pressure rating.

Good luck and let us know how it goes.