Progress report - sandblasting done!

[Simon TR4a]

I went over to watch on Saturday afternoon. The inner tub was mounted on a rotisserie, a huge trailer-mounted compressor and very large hose. The guy wore a helmet like a deep sea diver; I have only seen small scale blasters before with a little electric motor and tank of compressed air so I was quite impressed. Epoxy primer went on right away to prevent rust.
This revealed rather thin floor panels so I will have to replace both, and some minor dents to be taken out so obviously not as close to painting as I had hoped, but at least he is working on it again!
Simon.

 

[trfourtune]

hey simon,
what did they charge to blast the tub?
rob

 

[Simon TR4a]

Rob, it was built into the price charged by the painter, so I don't know.
He subcontracted it as he just has a small unit for doing parts. The medium used was not the normal black sand but a light colour, almost like beach sand but finer. I think he said it had aluminum oxide in it, but I may have misunderstood.
Simon.

 

[mcguijo]

I would have thought that Aluminum Oxide would give the sand a silver color. It may have been strict sand. I've toyed with the idea of blasting my tub. I've heard the horror stories of panel warping but believe that there is not a straight piece on the inner tub of a TR3 that could warp. My biggest problem is that I can't find any info out there on the details of such a process, i.e., what size compressor is used, what pressure, what size sand hopper, what size nozzel, etc. Has anyone come across this information before?

 

[trfourtune]

i have my own small pressure sand blaster. if you're going to do a whole tub you will need the largest compressor you can find and huge tank. for my small unit i need to maintain a MINIMUM of 100 psi. 20scfm @ 120psi is not enough so you have to wait for pressure to build. 20 scfm @ 100 psi is about the largest single phase compressor (240v) you can get(6 HP). with mine 3/16" nozzle is about 2 square inch area for about 2 seconds-ie slow. you should also have a fresh air supply mask to avoid silicosys. this job is NASTY!! i would farm out a whole tub. military tests have been done stating that you need to seal the metal (epoxy prime) within 3 minutes before oxidation starts in the metal.(humidity would need to be low). my tub is going to go to a chemical stripper(once i finish fixing it first). caustic dip followed by phosphate. the company is called redi-strip near vancouver canada.
if you must do it yourself then rent an industrial diesel compressor (these are the 12 ft lg pull behind a big truck type)with 400 pound blasting tank. full body suit fresh air supply and a quarter ton of aggragate.
you will have to build a booth with filters to contain the mess or your neighbours will call the epa and sue your behind!today is friday for me at work so /ubbthreads/images/graemlins/thirsty.gif /ubbthreads/images/graemlins/thirsty.gif /ubbthreads/images/graemlins/cheers.gif /ubbthreads/images/graemlins/cheers.gif /ubbthreads/images/graemlins/grouphug.gif /ubbthreads/images/graemlins/canpatriot.GIF
rob

 

[PeterK]

I rented a Diesel 4cyl. unit for $300/day. I went through 1100lbs of media doing the frame, inner tub and other hard to sand areas. Notice the size of the hose in the picture; this is one of those machines that you see blasting bridges along the highway. We did it in the field off the mowed turf and there's no evidence of media anywhere. The touch-up I did out front later is still in the lawn though!

If you do this, you have to be careful about getting the surface hot. I just moved around a lot shooting along the panel not at it and didn't have any warping. But getting the stuff out of the frame was a pain.

 

[MadRiver]

[ QUOTE ]
The touch-up I did out front later is still in the lawn though!

[/ QUOTE ]

Years ago when my dad and I sandblasted the tub on my Healey, we did it using my father's sandblaster and black sand, right there on the crushed stone driveway. That stuff stuck around for *years* and I bet you can still see some. My late mother never forgave us! /ubbthreads/images/graemlins/blush.gif

Funny thing about the Healey body tub, which is welded to the frame. There are enough nooks and crannies that black sand still occasionally trickles out of some unknown location, twelve years later! /ubbthreads/images/graemlins/grin.gif

 

[71tr]

I blasted my frame and suspension parts in the back yard with a 2hp 6gal compressor and a portable sears brand sand hopper and gun. It was a pain in the rear waiting for the compressor to catch up and having to put a water filter on the gun due to the high humidity. I simply hung a couple of tarps from the back deck and on the ground to deflect and catch the "starblast" media which I then ran thru a screen and recycled thru the gun. While it was a slow process I am so pleased with the results. The entire frame and all parts cleaned to bare metal, primed and repainted appropriately.