Sandblasting sheet metal parts
 

At what air presure should I have to sandblast some sheetmetal parts such as a radiator shell so as not to get any warping of the sheetmetal parts themselves?

Thanks.

Pluck

Re: Sandblasting sheet metal parts
 

I guess air pressure may have something to do with warping but heat created in the blasting process is what causes damage. As long as you do it gingerly you should not have a problem. If the surface is delicate you may want to use walnut shells. I typically use black diamond that i get at TSC, but it leaves a pretty rough finish.

Re: Sandblasting sheet metal parts
 

The first step is to strip any paint that is on the Sheet metal. Then sandblast the part. Most of the time I use 90 PSI. and regulate the blasting by the distance I keep the nozzle from the work. If the part is really delicate I'll keep back 12". Normally about 6" from the work and just go lightly back and forth and up and down many times until it's clean. Go easy and take your time and you end up spending less time do metal repairs. Paint stripper is made to remove paint. Sandblasting is for removing rust. the two should never meet.!! Paint has great adhesion to the surface that's why people warp the panels as it creates so much heat by the time the paint is sandblasted off the metal.
Hope this helps. "The Old Tinbasher"

Re: Sandblasting sheet metal parts
 

Also keep the nozzle at an angle to the metal, not straght on. If it is a thinner piece, ive dropped the pressure all the way down to 40psi. Nothing truly gets rid of rust in the pores like blasting, in my opinion. For fine work I use glass beads.

Re: Sandblasting sheet metal parts
 

I have blasted a lot of sheet metal with my outdoor blaster over the years and the method I use is a lower pressure and a going on an angle from further away if that makes sense. Basically shoot the sand from a 45 degree angle rather than a 90 degree angle.

Re: Sandblasting sheet metal parts
 

Great advice from posts above. I’m not too fond of black diamond but other sands have gotten so expensive. Anything silica has been banned I think
Not heard good about soda blasting and may not apply to standard blasting system...not sure
Big thing is keep the sand pattern moving and don’t dwell on a spot as that’s where the heat builds up

Re: Sandblasting sheet metal parts
 

I never had problems running the compresser at 45 lbs pressure for tin, I use a smiths compresser, set the governer to regulate max pressure with large enough nozzle----- the nozzles from the "weak"electric compresser when they get worn move I move them up the line, I have a water tank with a 100 foot coil for moisture condenser and then to 10 gallon water separator-- wet air goes in the middle, dry air out top, water leaking out drain valve( bad valve that never totally shuts off so the drainage is automatic, all connected with 25 foot hoses so compresser is upwind
I use a tip turbine compresser to inside the hood, gives positive pressure to keep most dust out, on hot days the hose gets coiled in a tub of ice water to be a crude form of air conditioning

I keep the bead blast cabinet at 45 too, the glass beads last longer before turning into dust

Re: Sandblasting sheet metal parts
 

I have found that blasting is expensive and messy. I blast but don't dwell on it, just get the heavy rust off and then spray with muratic acid which makes the rest disappear. Then neutralize with a solution of baking soda and water. Let it dry and you are ready to prime. Be careful using muratic acid as it is nasty stuff. A good wiff and you won't have to trim your nose hairs for a while.

Re: Sandblasting sheet metal parts
 

When I restored my 29 AA, I completely dismantled every piece of cab and running gear, sandblasted, 2k primer and urethane painted then reassembled it. My compressor is JD diesel, 125 cfm and 100 psi. I regulated it down to 60 psi, backed of 12 to 18" at a 45* angle. Some industrial suppliers only carry one size sand like 20/30, that's too course, I use a fine sand that looks the same size as common table salt, I buy in bulk 4000 lb. All my porcelain tip are 3/16" diameter, when they're wore out to 1/4", it reduce the pressure and spreads out the sand. You wont have any problem with pieces like the radiator shell, the problems come with the hood and door skin, do these last. I did the doors in side and out but did not spend much time on them, this is called dusting, I did not have any problems. I don't think the metal stretches because of heat, take a chipping hammer and put a needle point on it and strike the metal a thousand times, its the impact not the heat.
carry on

Re: Sandblasting sheet metal parts
 

After using a paint-stripper, use feed-grade molasses. It works well as a rust-remover and is guaranteed not to warp anything. Use a 6:1 mixture (water:molasses) strength and submerge for 10 days. You won't be disappointed.

Re: Sandblasting sheet metal parts
 

Kurt do you have any pics of your set up. Sounds interesting.