sand blast questions

[Professor Marvel]

I have a couple pieces of cast iron furniture I want to clean up and repaint. I have done 2 with a wire wheel but I would like better results. I can't seem to get into many of the crevices.
I was thinking of getting some minor sandblasting equipment to do this job. As I look more into it it seems that quite a large volume of air is required. I only have a couple pieces and I am in no rush so I don't think I need a sustained amount of air. I have 3 compressors but they are all 120 volt (not sure of the cfm). I thought I could start out with a small handheld sandblaster. If I find it useful I have no problem getting more significant equipment.
My question is -- what size compressor, cfm etc is the minimum I can get away with for this project? I think there is more to sandblasting than I initially thought. Looking for helpful practical information. Keep in mind I have no plans to do any large projects at this point. I also figure if I can play with a small project I will be far better informed if I want to go ahead and get the correct stuff at a later time.
I have run into CFM requirements, blast media (some apparently toxic), pressure pots, hose sizes, guns, nozzles, siphon type, not siphon, valves etc and am pretty confused at this point. Maybe I am better off being satisfied with my wire wheel results.
Thanks for any direction.

 

[bumperm]

Several ways to go I'm aware of, first is a blast cabinet (for relatively small items - they have to fit in the cabinet). Advantages, abrasive gets recycled, no breathing protection needed, can use fine media for delicate items (soda, glass bead) or aggressive media.

Sand blaster with a hopper or pick up tube. Mostly used outdoors, spreading a big drop cloth can help you recycle some of the media (a fair amount will be lost), obviously works for big things, and good breathing protection is a must - you can use sand available from Home Depot etc intended for playground use. You'll be taking a shower afterwards to get the grit out of every body orifice possible. Dust cloud will probably not endear you to close by neighbors.

As you're aware, blasting takes a prodigious volume of air. I run my blast cabinet with a 5 horse Quincy compressor, no issues and it keeps up well. I've used smaller compressors as well, in particular for outside sandblasting . . . more time is spent waiting for the compressor to catch up than is spent being productive. When choosing an outside blaster, be aware that cheap hardened steel nozzles wear out fast, ceramic nozzles are better. This is a major issue when working with a smaller compressor because as the nozzle wears, efficiency drops off rapidly.

And lastly, wet sand blasting using an adapter for a pressure washer - dust is less an issue and I understand it works well, though I haven't tried it.

 

[mikehaugen]

I can't add much to what bumperm has said, but if you are recycling media be aware that it loses effectiveness the more it is used. If time is money then it matters more. My friend used to work in a commercial blastic/painting place and he said they never recycled media. They would bring in a skidsteer in the blasting room every so often to clean up the sand and it would get taken away (probably recycled for another use)

 

[George2615]

I have a HF sand blast cabinet. I think they are about $200. on sale. It requires a lot of air as most sandblasters do. I supply air with a Husky 80 gallon air compressor bought from Home Depot. I forget the CFM but think its around 12-14 CFM. Motor is a 4HP runs on 220V.
HF sells the smaller portable sand blasters for outside use but even with them you'd need at least a 60 gallon air compressor. If you can regulate the air pressure down to about 60 - 70 PSI. the CFM required would be down to 6-8 CFM. I doubt a smaller portable compressor could keep up with the volume of air needed but if you blast a little then wait for it to build back up you'd get the job done..

 

[mikehaugen]

Maybe run all three compressors in parallel?

 

[dodge man]

I had one of the siphon type, it was crap. I have the pressure pot type now and it's much better. Think a head, is a bigger compressor something you would use in the future?

 

[newbury]

One of my best friends in college sandblasted an entire MG with a small compressor, probably < 2HP. Did it outside w/ playground sand on a tarp and took his sweet time.
It wasn't fast but it fit his budget.

 

[PILOON]

What you need is CFM's not PSI's.

I actually did 4 steel 'cofee' chairs with sand blasting. 150 cfm compressor and 3 bags of sand
Also my 60" snowblower.
Both jobs took about 1 hour at a DIY site* that sold sand and provided air.
Later we did a Chevy Van and blasted all rust spots at the same firm.
Blasting IMHO resumes as 50 PSI and 100CFM. with CFM being the magic solution.
OK, I can spot blast with a hand held 'pot' but that's only OK for the odd rust spot on my truck, not fenders or running boards.

*they charged $25/hr for the air + $8.00/bag for media

 

[pmsmechanic]

There is a sandblasting company in out local town. They charge $90/hour and there is no way that I can keep up with their equipment. I drop it off and a couple of days later come back and pick it up. I still have my own for small jobs but the larger ones go to town.

 

[Hiltz]

Years ago I needed an old sheet metal bath tub sandblasted. I ended up taking it to monument business, headstones, that kind of business. It was really reasonable. Maybe an option.