Glass bead blasting at home--need advice.

[RallyJon]

I spent the afternoon setting up a cheapo Harbor Freight blast cabinet and attempting to strip the finish off a caliper. I'm using #8 (80 grit I think) glass bead, which was the only grade they offered. My compressor was maintaining 80-90psi pretty well.

Since this is the first time I've done this, I'm not sure what's normal and what's not:

1) It went really slowly. It took about 30 min to do the one surface you see in the photo. I had to hold the gun within 1/2" of the surface for it to work well. Is that just how long it takes?

2) Is the media appropriate for stripping aluminum? What are other options? Anything that would go faster, but still not damage the metal?

Thanks for any tips!

Jon

[911r_parts]

You're trying to get off the hardest paint that you'll encounter.It's going to take a little longer than normal.
Aluminum oxide is the most abrasive media to use to get that stuff off,but you don't want to work the aluminum to much. If you could brush on some paint stripper carefully, it would get you a jump start.
Eastwood has all the different medias and descriptions for each one.

[Scott Clarke]

Jon-
I have a cheapo blast cabinet myself. I find that the bottom of the cabinet (the funel shaped part) is not steep enough to insure that the pick up tube remains covered in bead. I end up stopping to shake the cabinet with the intent of getting media to flow to the lowest point. When the tube has a good supply of bead, it works quite well.

On another note, I sugest that you wear a respirator when you blast, and that you do your blasting outside. I learned this lesson the hard way, unwitingly exposing myself to cadmium. My cabinet hs significant leaks, and it will make a mess of my garage and lungs if left to its own devices. I have found that the liberal application of duct tape helps to some extent.

-Scott

[jthwan22]

make sure you plug all holes and lines. Eastwood sell different size plugs. Duct tape may work if you don't hit it directly

[project935]

Is 80-grit glass bead comparible to 80-grit sand(paper)? If so, I'm thinking the nozzle might be too small ... not enough media flow.

Maybe experiment with some different nozzles?

Keep a rubber mallet handy to tap the hopper to keep the media dropping.

Air supply dry enough? That can cause some media flow problems too.

[Wavey]

Ditto on the "tough paint" comment. That's the biggest part of your problem.

#80 glass bead is WAY finer than80 grit sandpaper - no corelation at all.

More air pressure would sure help - like 125 psi, but your compressor probably won't do that.

A tip for anyone else who buys one of these cheapo cabinets: before you ever put any glass bead in it, seal all the joints from the inside with a good exterior silicone caulk. Mine also leaks all over the place, to the point that I hate to use it anymore.

[Oldporsche]

I use a Harbor Freight Sales cabinet. It's sealed with silicon. I use a Grizzly dust collector. I however have used it with a pressure blaster with pretty good results. The reason being is that the pressure blaster is more efficient with the air and I don't use it timewise as much.

Vibrators can be bought for the cabinets that keep the abrasive moving. If using a siphon feed gun, make sure that there is a good air supply tube getting to the pickup for the gun.



Take a look at this site: http://www.tptools.com/
This outfit has good siphon feed guns. The problem I find is that the quality of most siphon feed guns are pretty poor.


Good luck,
David Duffield

[gsxrken]

Ditto on the filtered dust mask and caulking of the box. I find that less air pressure is better, around 60 psi or so. Higher than that and you're just vaporizing the glass bead on contact with your part. This gets very dusty, and diltues your glass bead pile into something more like powder, which is not as abrasive. In any case, the beads do have a limited lifespan, so keep it fresh. I've thrown in a handful of "black beauty" sandblasting powder to speed things up in some cases and have had no ill-effect.

[RallyJon]

Thanks for the advice, guys. Doing some reading it looks like both Eastwood and tptools recommend plastic beads for paint stripping. I guess glass beads are more for rust removal.

[fuelie600]

Jon,

It's probably just the paint.

Try shooting the beads at different angles. Also, check the hole in the blasting nozzle often. It will errode. Once the hole gets too big, the efficiency will drop off.

It's boring, boring work. zzzzz.....

Good luck!

[RickM]

I've found that "hard" paint is the easiest to remove with blasting. Paints that are softer absorb the impact of the media and you get nowhere quick.
IMO, you're problem is most likely the size of your compressor. You need adequate pressure AND Volume. The less volume the less media. Also, if your compressor is constantly trying to keep up pace with your blasting then you're going to get alot of moisture in the line which will crap things up.....prevent/slow media flow or clog, media clump etc.

I've done calipers with plain ole sanitized play sand, but at a distance and was carefull not to create waves in the metal. One technique to play with is to blast the surface at an angle and not straight on (Perpendicular). Paint will come off much faster this way.

BTW, what are the requirements of your blaster and the capabilities of your compressor?

(If the compressor is adeqaute then the abovementioned tip size suggestion is my next guess)

[jpnovak]

yes, play sand is cheap and agressive. Works great for calipers, engine tins and fuchs paint. I sometimes use it on really rusty stuff. I keep two buckets, one of sand and one of fine beads.

Dry air is key. Also check for clogs and casting problems on your siphon gun. I found a few burrs in mine at the pickup and was getting clogs in the gun. I spent 10 minutes with the dremmel and smoothed out the ports. Worked wonders. Constantly moving the pickup in the box helps too.

I mounted my cabinet to a rolling shelf unit. Makes it easy to store and roll outside for blasting. Fresh air is good!

[DonDavis]

Jon,

Lets see the cabinet. I was at Harbor Frieght and almost bought the grey one with 2 doors. I have a Coleman 5hp 27 gallon compressor and thought it would handle my projects ok. What are you running?

[Joeaksa]

I have one of the two door HF cabinets and it works well. Does leak but have a vacuum cleaner on the puppy and that helps. Used the glass media for a while then started mixing it with a bit of sand and it works better.

Volumn on the air compressor helps more than pressure. A bigger tank and compressor is the key.

JoeA

[ChrisBennet]

For data points I've used 3 bead blasting setups: A shops, and 2 friends home setups with BIG compressors. They all gave me the "wow, this is going to take forever" impression.
I just had 4 964 valve covers bead blasted professionally by a restoration place after trying to strip myself them with aircraft stripper.
They took 1 3/4 hours to strip them.
Conclusion, it takes a lot of time.
-Chris

[toolman]

You need a big a$$ compressor, like 18 to 20 CFM at 100 lbs to run a blast cabinet. If it is going slow, pick a coarser media.

[RallyJon]

It's sort of like this one, but a bit bigger and with just one door:



I'm using a 6HP, 30 gallon Craftsman compressor, which is good for 6.4CFM at 90psi. 20CFM would be nice, but I'd need to put an addition on my house to have a place to put it.

[DonDavis]

That's the one I am considering. Is yours the red one, 1 door and a touch bigger?

[RallyJon]

Yes. Red, one door, slightly bigger.

[Matt77Euro27]

Get the Red one from HF. I have used both and I definitely like the red one better. Make sure you seal the corners with silicone before you put in the media. These are definitely cheap cabinets. If cheap stuff bothers you at all, don't get either one of them. I use the red one exclusively with glass beads on mostly aluminum parts and it works great.

If you are on a budget, definitely spend the money on the compressor not the cabinet. I have a 6 CFM unit, but would prefer more.

Matt