Sandblasters

[jamie392]

I am re-doing a project and really want to do it properly this time which means sandblasting a lot of the car. I can't really afford to have this done at any sandblasting shops and was wondering about some of the units they sell.

Are they any good... or are the majority of the pressure units only made to do small sections of metal... how do they compare to the professional units... would it be a rediculous question to think about sandblasting the majority of the car with one of these.

If they are any good, how much CFM would they require. I've been searching for days trying to find this information... and all the places say 9 to 12 CFM. I highly doubt that I could half decently blast a car with that little CFM, considering I believe the professional units use in excess of 50 CFM. I can rent a compressor locally that will put out 25... would it be worth it to rent the unit and buy a sandblaster... would I even be able to black a medium sized car inside and out with the unit. I have used professional blasters before and they just rip through everything at extremely fast rates... but i'm unsure if this will be able to do the same.

What do you guys think, and do you have any experience with using any units in the past?

Thanks a lot
Jamie

[Len]

What are you talking about blasting? Are you talking about the sheet metal or the underside or both?

I'd recommend against "sand" blasting the sheet metal yourself if at all. Blasting the paint off the sheet metal is best done using Plastic Media Blasting... PMB. This is a process best done using professional equipment.

If you want to strip the paint I'd recommend using the process linked below then use the same sander/buffer at the end of the job to polish the new paint.


http://www.autobodystore.com/lac5.jpg
Strip and Paint Link (http://www.autobodystore.com/strip_&_paint.htm)

[jamie392]

I'm not worried about the outside of the car at all. I can strip that fine without any problems. This is a restoration project that i'm redoing. The first time I left the floor pans underbody, etc. They weren't badly rusted but I just stripped whatever rust there was with a wire wheel and used zero rust. The outside of the car was done properly though.

What I want to do now is strip the whole thing right down and I want to sandblast the firewall, underbody, door jabs, truck floors, inside of door panels, basically everything needs to be stripped to bare metal and fixed perfectly. I want it done properly...

Do you think if I rented a 25 CFM compressor for a day, and a standard sandblaster I would be able to strip all of that... or is it no match to the professional units. Also does anyone have a rough estimate of how much sand I would go through.


Jamie

[TimG]

I did my plow truck 6 or 7 years ago,blasted the frame ,floors,etc w a Tip pressure blaster and a Cambell Hausfeild 5 hp 80 gal compresser,13.5 scfm@ 90 psi.
Not sure of the model of the blaster,but it would hold most of a hundred pound bag of sand,the compresser couldn't keep up.
What I ended up doing was getting the smallest ceramic nozzle that would still flow medium grit Black Beauty,and setting my air reg to a hundred pounds or so.
Still,by the time the hopper was empty,I was out of air.I'd sweep up the sand,sift it back into the blaster{Black Beauty is good for 2 or 3 times}.
By then,compresser cycled off,back at it.
If I ever do it again,I'll rent a gas powered industrial compresser,like the tow behind ones you see highway crews use to run jackhammers,have 10 or so bags of sand on hand,and see if I could snooker someone else to do the actual blasting!

[Len]

Jamie
The last time I had a big and rough blasting job I went to a tool rental and rented a tow-behind gas compressor like you see on construction sites and a large sand blaster. It worked great. As long as you don't need to use it on the exterior sheet metal you should be fine however I still wouldn't direct the blast directly (90 degrees) at the sheetmetal parts. Angle the blast so that it strips the paint but doesn't stress the metal too much. Purchase too many bags of sand from the rental place then take back what you don't use, just make sure they're ok with taking back the excess.

[Ron H]

Jamie, This is my first project, so I have very little experience. However, I will tell you about what I have done with great success. I have a 60 gal craftsman compressor somewhere around 3.5 hp. I also have a harbor freight 110lb sandblaster, $159 on sale. I have been using #4 black beauty sand from the local rental store. I am using the fine tip which came with the unit.I have done the door jams, trunk bracing, hood bracing, windor framing, rain gutter, and the hood with good results. Contrary to the instructions I only use 40 to 45 lbs of air pressure. Less than half of the recomended pressures. I also turn the sand feed lever (on bottom of tank) only half open. Then as Len said I use it at about a 45 degreee angle. While at harbor freight get a BIG tarp, I use two. Spread them out and use a few posts chairs or something to hold the edges up. I also have put a tarp inside the car to catcth that sand, makes it easier to recover the sand. The sand will not fly very far. Recycle the sand by running it through a peice of screen wire. I usually use the sand about three times. You will be able to tell when it is "wearing out". I used Len's method on the "flat" panels, but use the blaster around the door jams, windows, trunk lip, rain gutters, and anywhere else on the outside (so far) where there is not enough room for the sander/polisher. If weather permits this weekend I will blast the inside of the car, should take one day. The sandblaster is my favorite tool next to my angle die grinder. I think I can do the inside of my car (57 chevy 4door) with two bags of sand, I have a little rust on the floor. I think the under side of my car and cowl will take two or three more bags of sand. It is tedious, dirty process, but the paint flies right off, because of the low pressure the rust takes a little more time. It is also a pretty big mess. If you don't use the tarps, be prepared for a beach party. Ask me how I know. Although I unknowingly did the top of the hood, since then everyone here has warned me against it. I did not have any wavng or other damage though. So now I use Len's method of low speed on my 7" polisher/sander for the large "flat" panel areas. The first time I used the unit I used 90 lbs of air, way too much, etched the metal pretty good. With 40-45 there is very little frosting of the metal, and the paint comes off like dirt with a water hose. I also use picklex 20 on the bare metal immediatly after blasting. Allow plenty of time, as you will have down time when recycling your sand, setting up and cleaning up applying picklex etc. Ron

[Lost in NJ]

Ron is right.

We run a model A engine converted to a compressor. We run at 40lbs and only turn on the control until you just start to see media coming out. The more media you allow in the stream the higher the probablity you will damage a panel. You can still damage a panel with the sand valve wide open and only 40lbs.

You need a good respirator and expect to be covered head to toe in sand.

I have done 3 cars this way and never had a warped panel. But it is much slower this way.

Godd luck.

[jamie392]

Thanks a lot for all the replies! That cleared everything up!

I was wondering how much black beauty costs for a bag usually?

Jamie

[Ron H]

Ten bucks for a 100lbs. If you use it three times two or three bags will be a long day.