Sanding & psi

[reallylongnickname]

I will be putting on epoxy primer. Is it necessary to remove every last bit of the original paint and primer that you see? (disregard the flash rust)

Also, in the second pic, the sander is rated at 90 psi. Is that 90 psi while in operation? (At rest it's about 100 psi. When operating, it's about 60 psi)

 

[texasking]

There is a point, on all sanders, that all increased speed does is burn up sandpaper or grinding discs faster and create heat. What psi that is, is different depending on the tool. That psi won't hurt the tool unless it is run wide open all the time. I have a regulator on the wall that feeds the hoses I normally run air tools off of, set to 100psi. Impacts and air ratchets need all of it, grinders need most of it, da sanders get regulated down at the tool. All the paint and primer needs to come off. That grinder with a surface conditioning disc would make quick work of it. then go over everything with 80# da.

 

[Big Dave]

I like to take things a bit slower than wide open. Depending on what you’re sanding, there is always a sweet spot, like Texas said. For really hard black rust, I go very slow, for laquer and enamel, slow enough to not turn it into a gummy mess. You just have to play with it to see.

 

[shine]

just enough to turn it . try 35 lbs .

 

[reallylongnickname]

Thx guys for tips. What your looking at here, is metal that I powerwashed today after it sat weeks in a vat of molasses and water. I dont like sandblasting. The power wash will remove 2/3 of old paint and primer, but not all. If there is too much flash rust, it can be reset by returning back into the vat. This is where sanding is necessary.

 

['68 Coronet R/T]

Most of those parts would fit in a sandblast cabinet.
That's not at all like blasting with a pressure pot.