Hey guys, figured there would be some experts in this department in these forums......I bought one of those 110 lb pressure pot sand blasters from harbor freight...now the flow cuts off unless i tap the bottom flow valve, is this because the sand im using is too big, or is there another issue? i filtered the sand that i bought (didn't say the size of sand when i bought it) it filtered very slowly thru a window screen...also the compressor im using, is only 4.9 scfm at 90 psi, or 4.3 at 115...is this way too small for a big project such as the frame of my car?
thanks guys
Nick

 

Are you really using sand or are you using a media like oxide or plastic etc?

 

Is the sand sepecifically for sandblasting use? That stuff is really uniform in size and shape and doesnt' stick to itself very easily. Regular sand (like sandbox sand) is not designed for sandblasting equipment.

 

haha, ya its sandblasting sand for automotive use, but is quite coarse, it was called white lightning, it has no silica in it, got it from a bulk sand place, all dried and very uniform but quite coarse...its too bad if its the sand size because when it does flow for 10 or so seconds before it stops it really eats at the rust quickly. but me tapping with my foot to get the sand to flow again just wastes air and im already under capacity with my compressor.

 

that compressor is a lost cause.

 

Three things are getting in your way, I think......

Your sand probably is too course

Your sand might be too WET (moist)

Most of all I think your conpressor is too small

You car RENT a big compressor to knock back the blasting quickly.

 

Ya JMD i think your right 2X...i know for sure the sand is dry so thats out, I picked up some 30-60 grit glass beads on my way to work so ill try that tomorrow, as for the compressor, your most likely right there too, so renting might be a good option, I do have access to a pretty big 2 stage good old compressor, but would be a pretty big job to transport it to my house.
thanks

 

Way back when I was a kid, I had an old syphon feed blaster, it worked in a pinch but it was slow, I rented a big sandblaster with a 4 cyl gas compressor and got my car done in two half days and 2,500 lbs of sand.

It was a miserable couple of days, I havent sandblasted (outside a cabinet) since.

 

yikes, thats pretty scary, I plan on doing the car in sections so it isn't so bad, but ya if i have to rent a compressor each time, ill have to do it all...heres hopeing. hahaha

 

i did mine on two separate weekends. cowl forward on one weekend and the undercarriage/interior on another. i didn't blast any external panels. i used about 500 lbs of sand but i recycled it a few times. within one day of blasting on each occasion i epoxied that section.

the more you can do in one shot the better. i spent about 4 hours each time rotating the car, vacuuming and blowing with compressed air in an attempt to get the sand out so it wouldn't get in the epoxy. add in more time wiping the car down with cleaner.

my compressor supposedly pushes 17 cfm @ 150 psi. i like to make sure gauge at the tank is showing over 100 psi for faster results. my compressor ran almost continuously and i had to take a break every couple of minutes.

it was the worst two weekends i have ever had with the car. however, i know that the rust pits were clean.