Sandblasting middle aged iron

[Rick Fisher]

I picked up this old Delta Scroll saw.. The 20" version, cast Iron model.

I have been thinking I will restore it . . paid $88.00 for it ..

Anyway .. I have a customer who sandblasts wooden signs.. he said bring it over when its all apart and he will blast it and prime it .. Much easier than stripping to bare metal by hand..

I wondered about the cast iron top.. Its terribly rusty.. He said he has done cast iron frying pans.. never noticed any damage..

Has anyone sandblasted a cast iron surface ? I am skeptical but have no idea.

[Chris Parks]

It will be ok. The only dings in it will be from any rust that has eroded the top and you remove by sandblasting. The best bet would most probably be to get the top surface ground after blasting if it shows any pits or dings.

[Larry Edgerton]

Protect any bearing surfaces. I use that rubber stuff you dip handles in and just leave the bearing in if it is going to be replaced.

Sheet metal will become distorted. Soda blasting works for that. I learned that the hard way, ruined a 49 Chevy.

Larry

[Chris Parks]

Larry, the operator ruined the Chev, is he still walking? I have had more than one car sandblasted but the operator needs to know what he is doing or you finish up with stretched and bent panels. Yes, all bearing surfaces need protection as Larry says, with a low pressure system as you envisage using tape will do it. I know of a guy who can strip finish off wood and not damage the wood, he just knows what he is doing.

[Cary Falk]

What media is he using to sand blast with? Walnut shells, glass bead, and soda will be non abrasive to cast iron and aluminum while still removing paint and rust. Aluminum oxide not so much. Sandblasting with sand is hazardous to your health. I have used glass bead and soda.

[Chris Fournier]

Blasting will save you tons of time and the outcome is superior to the alternative of messing about by hand. I have done this on several pieces with quite a bit of sheet metal (heavier gauge than car body panels) and it came out beautifully.

[Larry Edgerton]

Larry, the operator ruined the Chev, is he still walking? .

I was 19, and the operator was me. Seemed like a good idea at the time.......

Larry

[ian maybury]

It's the way to go, but needs doing right. Bearings need a lot of protection (best just to take them out as masking isn't truly reliable), sheet metal curls up like a crisp with too much pressure/too coarse a grit. Too coarse a grit/media produces a very coarse/rough/high friction surface, and can shift enough metal to mess up fits.

There's lots of less aggressive media options about that if correctly chosen (e.g. at one extreme walnut shells get used on aluminium parts and produce a nice satin finish) can do pretty much whatever you want. The key is to find a service provider with the right option available, and who knows what he is doing.

Motorcycle and car restoration people tend to be well clued up on the topic, and on who has what...

ian

[Thomas Hotchkin]

Rick
If you are going to outsource sandblasting. Go to someone that uses Plastic Media in place of sand or glass. There are over 9 different grit hardness in Plastic Media. most of them will not damage aluminum, steel or cast iron. It will leave a clean surface but will not remove stains. Most sandblaster do not use it because once used it is not reusable, turns to dust. I have used it on turbo aluminum compressor wheels for cleaning. Stanley handplanes to remove rust and paint, and small cast iron part for my Northfield jointer. Tom http://www.plastic-blast-media.net/plastic-blasting-media.html

[Myk Rian]

Don't blast the table. Use PB Blaster and a scotch-brite for that.
Cover/tape all machined surfaces, and caution the operator about them. Don't let the inside of the crankcase get blasted.

[Peter Aeschliman]

I'm in the planning phase of a Landcruiser FJ40 restoration. I've called a few shops about media blasting. The shop I will probably hire uses plastic media for paint removal, but it's too gentle to remove rust. For that, they use sand...

If you do soda blasting, which won't warp your panels, my understanding is that you have to spend extra time cleaning the surface afterward because it leaves a residue. Also, i've heard that it leaves a pretty smooth surface, so you might have to rough up the bare metal to provide some tooth for the primer.

Disclaimer: I have no experience with media blasting, so I'm just regurgitating what I've learned through my research.

[Rick Fisher]

The fella uses sand .. Not really surprised, he never struck me as a guy who needed to save for retirement ... if you know what i mean ..

[Larry Edgerton]

I'm in the planning phase of a Landcruiser FJ40 restoration. I've called a few shops about media blasting. The shop I will probably hire uses plastic media for paint removal, but it's too gentle to remove rust. For that, they use sand...

If you do soda blasting, which won't warp your panels, my understanding is that you have to spend extra time cleaning the surface afterward because it leaves a residue. Also, i've heard that it leaves a pretty smooth surface, so you might have to rough up the bare metal to provide some tooth for the primer.

Disclaimer: I have no experience with media blasting, so I'm just regurgitating what I've learned through my research.

Check on having the body, or even the frame for that matter dipped. It is an acid bath that will take off the paint and all of the rust, even in areas where you can not see. There is one in Detroit I have used that does the dip, cleans, dries and dips in an epoxy primer electrostatically applied to a uniform thickness. I did a 65 GTO with this process and was very happy.

Larry

[Kevin Presutti]

If you could take the bearings out the least invaisive way to remove rust and paint is electrolosis. If you go the blasting route I would glass bead the top as it removes the rust and is not as prone to remove the cast iron as sand. IMHO