<hr style="color: rgb(0, 0, 0);" size="1"> <!-- / icon and title --> <!-- message --> All I've been able to find on the subject of do-it-yourself automotive sandblasting is a bunch of posts saying "don't do it" in one form or another, but I recalled an old mentor of mine. His words of wisdom were" "Some folks learn from reading about it and some learn from watching others do it. But some of us just have to pee on the electric fence and find out for ourselves!" So, I've already found out that ya get really dirty blasting without a full bunny suit outdoors! I've also learned that sandblasting outdoors is a great way to waste a bunch of blasting media, and some of that stuff is pretty expensive. That's why I bought a blasting cabinet big enough to take 15 X 7 inch wheels, that'll handle most of what I need to clean up just now. Bigger stuff, I think I'll pay someone else to do! This brings us up to today's question: How do ya know when you have the proper mix of air pressure and media and nozzle to do the job with the best efficiency??? In about a week of web searching, somewhere back there I would swear that I found the phrase "if you can see the media in the air/media stream, that's too much media" I cannot find that phrase again for all the search tricks that I know, so it's possible that I've misquoted. But I'm sure I saw it (unless, of course, that is not a true statement and I made the whole thing up). And if that's the case, someone please give me a hint about what the correct mixture should look like! My compressor has an eighty gallon tank, and will do 120 lbs per sq. in. so I'm pretty sure it should be OK for the size projects I'll be doing, but it's that "magic" combination of control settings that I would like to find before I waste a whole lot more time and media. Thanks for any advice, tips, references (references would be REALLY good!), or most any other comments except "don't do it!"! I burned that bridge several days ago.
The "trick" to sandblasting is to match the NOZZLE SIZE to the Compresssor's CFM rating. The PSI is great, but it's only a SMALL FRACTION of the equation. Think of the CFM as the VOLUME OF PRESSURE that the compressor can produce. What your key factor is - WHAT is the CFM your compressor can achieve at say 100PSI ???? You'll find out that the blaster used a TON of VOLUME - that will be the key to all this. If you find yourself having it work great for a very short period of time and then it works progressively worse - it's because you have quickly exceeded the capacity of the compressor - in short - the compressor just can't keep up. You will find yourself having to: BLAST - WAIT - BLAST -WAIT etc etc. Having a smaller nozzle dia will help this - but there's no free lunch either - the smaller nozzle will make your blasting time longer, but at the same time your throwing LESS sand - so your fighting a never ending battle. The answer is to match the nozzle to your compressor. The ultimate answer is to have a compressor with a LOT of CFM. My compressor is around 20 CFM at 175 psi and I blast anywhere between 50 psi and up. My nozzle size is too big - I can find myself getting ahead of teh compresor on bigger projects. You might want to check out the TIP TOOLS website - for specific references.
Does anyone have any experience with the (I know) Harbor Freight blasting pressure pot? The one that acts as an air tank to help maintain pressure?
I started with the 40 pound Harbor Freight pot. I think it's usable, but I'm going to keep the blasting cabinet in order to save media and keep myself and the area cleaner. I may use the pot plaster outside when and if I figure a way to somewhat contain the media. At a dollar a pound I can't afford to throw away a lot of pounds of blast media. Then there are environmental concerns and relations with the neighbors As for the blaster itself, see Hemi Rambler's comments above for setting guidance, then experiment. Know this, however: The media WILL scatter everywhere, including your hair, ears and eyes (a hood with viewing window will help, but that stuff goes EVERYWHERE). A full coverage "bunny suit" would be better, but mighty warm in the Texas summertime. After less than an hour of experimenting with the pot, it took an hour in the shower, and another 15 minutes cleaning aluminum oxide media out of my bathtub, since I sure don't want any more that stuff going down the tub drain. I'm considering an outside shower before I do anymore pot gun blasting.
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