Rolling Chassis - Dustless vs sandblasting

U

Usafexplorer

Member
Performed a couple sandblasting searches on various sites and seems to be a plethora of opinions on how far down to strip a chassis. Some say all the way and other claim a rolling chassis with suspension and axles are fine to leave if your rebuilding the brakes anyways as the sand gets everywhere. I originally planned on leaving the axles intact and blasting as a rolling chassis but I'm open to suggestions either way for those with experiences or opinions that want to share.

Thought I read everything then came across dustless blasting which is applied wet and reduces the heat factor and the particulate getting into everything (supposedly). Curious what everyone in the Model A community thinks or has experience with to assist in making a decision as we have both mobile services in our area.
 
I like sandblasting as it is the tried and true method. It is messy but you get a mechanical bond from the etching and the chemical bond from the primer.

I think it is the best way to do things. This all depends on what you are doing with your chasis. If you are restoring a car you have to do it the right way and either take it apart and have each individual part sandblasted or shortcut it slightly and blast the rolling chasis and then take it apart and sandblast each piece.

Sand getting into a model a chasis isn't really a problem unlike later cars with box frames. Even then, compressed air can get almost all of it out. Now if you leave the brakes, suspension components, and differential in, it will get in some of them.
 
I had my chassis frame chemically stripped! When I picked it up I walked passed it thinking someone has a nice looking frame, It was mine! I could see forming lines in the metal from the factory. Epoxy primed and epoxy paint looked like new
 
Big hammer said:
I had my chassis frame chemically stripped! When I picked it up I walked passed it thinking someone has a nice looking frame, It was mine! I could see forming lines in the metal from the factory. Epoxy primed and epoxy paint looked like new
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That's another option I'll have to look into, didn't realize complete frames could be chemically stripped. Thanks.
 
If you sandblast it all together there will be lots of areas you cannot get to.
Also, there’s going to be lots of trapped sand everywhere.
I do blast units like rear ends together but if backing plates on, lots missed.
If pull hubs and plates be sure and tape up races and protruding axels
 
The problem with chemical rust removal is that the chemicals get into area, like items that are in close contact with each other - like some assemblies – i.e. brake drums, and can't be removed with the rinse the companies use to remove the rust removal liquid. At least that is what I encountered a number of years ago when I had some parts "dipped", done in rust removal chemical tanks. I had some brake drums done and they seeped out a white material that looked like the stuff that accumulates around battery terminals for years afterward.


As far as removing rust from steel, sandblasting is by far the best technique I have found. To do it right, the chassis and sheetmetal sections should be totally disassembled. I have sandblasted 3 chassis' and the sheetmetal for the 3 bodies. I have a TIP USA made pressure sandblaster that works great - messy but great. I use a fresh air system to prevent sand dust from breathing in and coveralls to mostly prevent the sand for getting in my shorts and other places. I have NEVER seen any sheetmetal warping after sandblasting. I sandblast at 80# and never at a perpendicular position -i.e. at an angle. Plus, sandblasting provide and excellent base for the epoxy primer I spray on soon after the sandblasting is done.
Just my experience.
Rusty Nelson
 
Dustless blasting is a huge improvement over dry blasting. Blasting media stays localized, you don’t need to be in a full media suit, and the liquid is a rust inhibitor that extends your need to prime it for several weeks, as long as you keep it dry.
The liquid also prevents heat from warping sheet steel. I also found it is more consistent with less missed or partially cleaned surface than dry blasting when components are stripped.
 
Soda blasting used to be (may still be) popular.
I’ve heard a great problem with primer bonding after soda blasting
I won’t be doing soda anyway

Wrndin seem to be on exact same page
 
If'n it was me I'd go w/a stripped chassis, it's not to hard to change a rolling chassis into a stripped chassis.
 
Media blasting is going to give you the best anchor profile to apply an epoxy primer that will last a lifetime, whether that be powder or liquid paint. Disassemble as much as you can and protect areas you don't want blasted using duct tape or white blast tape. Once blasted, unmask and clean up missed areas using a grinder and/or 36 grit flap discs.

Disassemble complete leaving just the frame to be blasted. Blast other components separately protecting where needed. This will not only allow you to blast and paint components completely before reassembly but it will allow you to inspect parts as you disassemble for blast and identify any issues with them along the way.
 
Here in Southern Iowa we have a company that strips using heat and sand in a big vat. It heats things up to about 400 degrees and injects air at the same time. When they open the doors on this thing it looks like the gates of hell with the flames, heat and rolling sand. We take things over there all the time. I watched a hood for a 1947 ford come out looking like it had just been stamped. No warpage, and no paint or rust. I don't know if they have anything like it where you are, but we like the system.
 
First lets just dispel a myth.

It is NOT heat that warps the metal!!

It is the mechanial beating of the surface that causes it to expand. You control the surface expansion via speed of the media and the amount of media in the stream. Also by running at an angle.

The idea of it being heat is just so wrong on many levels. The expanding gas is cooling the surface. To cause heat induced warpage you need to get above around 600 degrees. Feel the surface of the metal, it is not hot.

I have done many hours of blasting sheetmetal. When I use the Smith's compressor I run 40LBS and crank the sand to where I can just see it in the stream. Event he French sheet metal which is thinner did not warp.

On the other hand, I have run 40 lbs with one of those cheap siphon blasters and it would warp sheet metal like crazy, but there is too much media.

When they say media gets everywhere, that is likely best taken as an understatment. You tend to find places you did not think could hold media when you sandblast. You can tape off and area and think it is sealed and still some gets in.

If I blast a part that will house moving parts the part gets flushed after it gets the paint before it gets moving metal.

Simple rules that I have found doing more sandblasting then the average guy. The science of warping is not my opinion. It is verified fact.
 
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