Surface prep... sandblast vs. grind?

[Big Barn]

I can't say for certain which is "better" but I ALWAYS use the grinder. Most likely because of impatience.

Terry

 

[adventure bob]

basic electricity says either way is good: conduction is based on electrode contact with the base metal. now if we're talking about paint that's a whole different animal for prep...

 

[oliver1555]

Here is a pic of my setup. Lots of mods to the HF cabinet thanks to Tacoma Company. But overall idea is portable and transferrable dust collection. The dust deputy mounted on a sealed bin above my shop vac. Welded up a light weight support frame and all on casters. Basically a pre filter before my vac. Probably worth a separate thread if folks interested but I can move this between tools. Blast cabinet, miter saw, router table, etc. I also have a dust collector (in the background) that is soft plumbed to my table saw and jointer, and with a bit of finesse, my wood planer.

I am interested in seeing how you did your dust collection system!

 

[PILOON]

Depends on what components you are prepping for paint.
When I got my pre owned snowblower I dismantled it and did a complete sandblasting.
Within hours I primed it with Tremclad primer and to this day (10 yrs) that primer still holds everywhere but inside the chute but since I have a gravel drive that's to be expected.
Blasting provides that toothy surface for finishes to adhere to. And primer the required surface for the harder wearing finish coating.
Powder coat to me is the worst coating as it flakes and rust forms under 'til the finish comes away is small sheets just like the old style automotive undercoatings did.
I also have had success acid etching new steel B4 priming and painting.

 

[Gary Fowler]

Depends on what components you are prepping for paint.
When I got my pre owned snowblower I dismantled it and did a complete sandblasting.
Within hours I primed it with Tremclad primer and to this day (10 yrs) that primer still holds everywhere but inside the chute but since I have a gravel drive that's to be expected.
Blasting provides that toothy surface for finishes to adhere to. And primer the required surface for the harder wearing finish coating.
Powder coat to me is the worst coating as it flakes and rust forms under 'til the finish comes away is small sheets just like the old style automotive undercoatings did.
I also have had success acid etching new steel B4 priming and painting.

For painting, you need the media blasted surface as Piloon states. As for cleaning for welding, what ever floats your boat as long as the rust and contaminates like oil/grease, paint etc. are removed from the welding surface. If you cant get to the corners with a grinder then blasting is what you need to do. If you have the equipment to do it with, blasting is likely just as fast or faster than grinding.

 

[dragoneggs]

Sorry my original post was meant to discuss welding prep differences... not painting. Agreed that blasting and solvent wipe generally best for painting. I am assuming there is little difference in the weld quality but was curious if there is any 'scientific' o real world comparisons.

 

[Jeepnford]

I don't think it matters as long as it's clean for mig and tig. I'd go with whichever method you prefer.

 

[Fallon]

I prefer using my blast cabinet to a grinder as a general rule. That's more for painting, but as welding generally comes before paint if something is welded I blast earlier in the process.

Leaves a nice even textured surface & deburrs stuff a bit. Not as "smooth" as a well ground surface, but more even. You often can see grinder marks through paint, but can't discern sandblaster texture or any un-even sandblasting.

I go for a more coarse grit blast media. Faster blasting & gives a coarser texture for paint. Not as good as finer media for a nice finish or softer material (aluminum) though.

 

[PILOON]

FYI, when I blasted my snow blower I went to a facility that provided huge CFMs of air and sold the media by the bag, they had blasting stations all set up with tables etc. I seem to recall that my outlay was in the $60-80 range, Good deal! Compressor air was by the hour and media by the bag and they provided the hoods and breathable air via mask as well.
I also blasted a couple of vehicles there as well.
It was also there that I discovered that you could blast multi coats of paint off of furniture for re finishing at a fraction of what paint strippers would cost, it is all in technique by trial and error but after an inch or so you learn fast.

Hey, I also once sand blasted a 30 X 40 log cabin and that in ab 8 hr time frame.
Turned out real nice. Windows and trim details only require simple duct tape to mask as the sand bounces off of the tape.

 

[muddstopper]

FYI, when I blasted my snow blower I went to a facility that provided huge CFMs of air and sold the media by the bag, they had blasting stations all set up with tables etc. I seem to recall that my outlay was in the $60-80 range, Good deal! Compressor air was by the hour and media by the bag and they provided the hoods and breathable air via mask as well.
I also blasted a couple of vehicles there as well.
It was also there that I discovered that you could blast multi coats of paint off of furniture for re finishing at a fraction of what paint strippers would cost, it is all in technique by trial and error but after an inch or so you learn fast.

Hey, I also once sand blasted a 30 X 40 log cabin and that in ab 8 hr time frame.
Turned out real nice. Windows and trim details only require simple duct tape to mask as the sand bounces off of the tape.

I wish there was a similar sand blasting facility around here. I have been all over the S East and dont think I have ever seen such a facility that would rent the baster and a place to work. Seen plenty of large blasting businesses, but no diy places.

I have one of those small blasting cabinets to glass bead small parts, I dont have the cfms to to do any big blasting projects.