TR2/3/3A Sandblasting

[DavidApp]

Hello All

I sand blasted my rear wing yesterday and I am not sure which got hotter, me or my compressor. I could not touch the compressor tank when I was finished it was so hot and I was working outside in 90+ degrees in Georgia so it was a miserable experience.

This got me to thinking that I need a need a bigger compressor and or outsource the blasting work. Talking to a local auto body guy who does some blasting he said he used a wet system because the dry blasting will distort body panels. I have not heard anyone else here mentioning panel distortion when blasting.
Any thoughts on wet blasting?

If I get a new compressor I will skip several steps John took and go straight to an Ingersoll Rand. My current compressor is a 25 year old 5 HP Sears unit. Missed a nice one on the Government auction site, it got too high for me.

David

 

[CJD]

5 hp is good, but the "duty cycle" is what you need for sand blasting. All the Sears compressors are only, like, a 20% duty cycle, so keeping them alive is a chore. Later, when you get to spraying paint, the heat will cause a lot of water condensation. So, look for a compressor set up with 100% duty cycle. They, unfortunately, start at about $900, but are well worth the investment. I've tried Sears, Campbell Hausfeld, and some Home Depot off brand. Changing the oil every day I blast got about a year out of each. I even blew up my Ingersoll rand after 4 months, but it has a 3 year warranty. I plan to get plenty of use on that warranty!

Soda blasting is easier on the metal, but sand blasting will not hurt your panels so long as you are using fine sand...which I'm sure you are with the Sears compressor. An industrial blaster company will always use to coarse a sand at to high a pressure, to save their time. They will destroy your panels.

I prefer the surface you get from sand, as it will permanently hold your primer and will never peel. As you found, blasting is the most miserable job there is! It does improve as the temps go down so you're not on the verge of heat stroke.

 

[ed_h]

I use an IR 5 HP compressor with a pot blaster, and don't think I could distort a panel if I tried. Further, I don't see how wet blasting would be less prone to distorting panels. It shoots more mass at the panel, suggesting it might even be more prone to causing distortion, given a big enough compressor.

Ed

 

[DavidApp]

Hello John/Ed

Thank you for the input.

Which IR compressor, SS5L5 or the SS4L5. The reviews seem to favor the SS5L5 as it seems to be an industrial grade machine.

My first bag of sand (Black Diamond from TS was medium) but it kept blocking the nozzle. The second bag was fine which worked much better. I put a large blue tarp around the area and managed to reuse some of the sand.

There seems to be several systems for wet blasting. One is an adapter for a pressure washer that adds sand to the water stream (3000psi) and another that uses a pressure pot with water, fine glass and a rust inhibitor.

David

 

[CJD]

I've got the 5L5. It seems decent...and is rated at 100% duty cycle so long as you use the synthetic lubricant.

I'll have to take some pics of the piping I use to minimize condensation in the lines. It is all copper, and designed with an incline in the 40 feet of piping. The idea is that the copper transfers heat easily, so the hot gas cools in the copper and water condenses out. There are then several low areas where the water accumulates so it can be expelled by opening ball valves. All pressure taps to the line come off the top, once again to minimize water in the working hoses. I then use 2 water separators just prior to the fitting I use for painting. When you plug in your flexible hose...make sure the entire length is laid flat. If part of it is still looped on a hook, water will accumulate in the low side of the loops...and eventually cause spitting on your work (or clog you sand nozzle). When the hose is laid flat, any water that does condense will remain is very small droplets that will vaporize when they exit the nozzle.

I know this all sounds like severe overkill...but if you paint, it is very worth the trouble. Once you have a decent air set-up in the shop, you start accumulating a lot of air tools, since air tools last longer and work harder than electrics.

After I killed my new Ingersol Rand in 4 months of blasting...I went to Northern tool and bought a cheap Chinese fan to blow on the compressor head while it is running. I tapped it into the same pressure switch that cuts in the compressor motor, so it only blows while the compressor is working. Probably not necessary if you follow the instructions and keep the compressor 24" from the wall, but I could only fit the big tank in the garage corner...so I suspect lack of circulation is what killed it. With the fan it gets plenty of cooling...and so far so good.

 

[ed_h]

I have the 5L5 also. Clogging could be moisture, or it could be pieces of grit a little too big for the nozzle. I use (and re-use) ordinary sand, but I have to screen it. Even screened, I can't use the smallest nozzle that came with my pot blaster.

All the moisture control is probably worth the effort if you have high humidity. Clearing a moisture clog in the pot blaster is a pain. I don't go to the extent that John does, but I do have occasional moisture clogs on very humid days.

I think anything based on a pressure washer could definitely distort a panel.

Ed

 

[TomMull]

After dealing with all the issues above, the mess, overworked compressor, recycling media and the personal discomfort, I no longer blast anything that won't fit in the blast cabinet or too big for the spot blaster. I've found a good shop and I send the stuff out. It's a bit costly but allows you to put that time into something else.
Tom

 

[carpecursusII]

I just had a car blasted with crushed glass. I am very impressed with the price and the quality. No doubt the user is a factor in the quality of job but for $700 I get an entire TR3 blasted. My blaster does the wet blasting and I like it, the process also shoots a chemical on the metal to prevent the flash rusting that usually happens. The water helps keep the panel cool and prevent distortion.

 

[CJD]

I'm with you, Tom. If I could I would farm out the whole blasting job. I keep it at home so I can do it when I want...keeps it on my schedule instead of someone else's. Plus there's an endless supply of small parts that pop up.

 

[DavidApp]

Did you see the machine they used? Look like this?

https://www.youtube.com/watch?v=Fc_wfu-0McU

There is a local guy that does wet blasting. I will see if I can check out how he does it.

David