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Tips
Tips

Got the blast cabinet set up, but not stripping

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tdskip

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Not stripping paint that is, not that anyone would want to see me strip, but that is totally different thread....

Anyway - I'm using walnut shells and it is taking FOREVER to strip old paint and rust off a brake drum exterior.

-the gun isn't clogged
-pressure from compressor should be adequate
-siphon gun is working properly and picking up material


Any trouble shooting ideas for me?
 
Walnut shell is a non agressive media. For work like that I usually use glass beads, and I may switch to something even more agressive. Some factory applied paint on my "vair for instance, can be tough to cut even with fresh glass beads. Walnut shells should do great on soft stuff like carb bodies and the like. This is just my 2 cents worth, but it is working for me so far.
 
To strip paint and rust from iron and steel, you should use aluminum oxide. Walnut shells are for polishing soft metals. Gun enthusiasts who do their own reloading polish brass cartridges with walnut shells.

Even with a large blast cabinet, it takes considerable time to clean up a rusty brake drum. The hobby cabinets (usually under $300) are convenient for small parts, such as brackets, nuts and bolts, etc. Unless you have a production blast cabinet, large parts such as a brake drum are a challenge.

The size of the air supply hose and fittings makes a difference. You get about 50% more stripping power using 3/8" fittings and hoses in the air supply. Standard automotive air hose couplings are 1/4" inside diameter. Hobby cabinets have 1/4" fittings.

I started with a 30" blast cabinet (Harbor Freight). It was OK but slow. It was definitely a hobby box. I next bought a 48" blast cabinet (also Harbor Freight but exactly the same as that sold by others for twice as much) which had a larger gun and 3/8" air fittings. It worked a lot faster.

For information on the various types of blast media and what they are used on, see https://www.kramerindustriesonline.com/blasting-media.htm. For more information on blast cabinets, look at https://www.mediablast.com/sand-cabinet-basics.asp (no affiliation with either company, just found them with Google).
 
Ah, so along with Jesse another vote for more aggressive media.

I do have a 1/4 hose on her now. If the aluminum oxide does work them I'll try stepping up to the 3/8 hose.

Thanks Rogers
 
For a rusty or painted brake drums, I would use Black Beauty (50-100lbs bags available at auto stores). It comes is several grits, just like sand paper. But brake drums outside, I would use coarse. Avoid the inside braking surface.

I used walnut shells on my ring and pinion and connecting rods, also a couple of brass lamps. It is soft, high dusting but will not harm softer metals.

Make sure that you have a moisture filter on the blast cabinet end of the hose to prevent clumping. Important that the filter is mounted on blaster-end away from the compressor for it to work properly.

For less agressive blasting on softer metals, turn down the pressure or you'll remove too much metal in the blasting process. For example, I use 40-60psi with glass bead on aluminum, but 80-100 with Black Beauty for heavy rust and scale.

Use a vacuum on the cabinet port to remove the airborn crud and always wear a mask while blasting.
 
I also use Black Beauty when an aggressive media is necessary. It lasts a good while. Make sure you have the vaccuum system working while using it and all medias.
 
You'll never remove paint effectively with walnut shells. This media should be reserved for very soft metals like aluminum and some non metals, even wood. You need a combination of the correct media and the correct pressure to do the job. Rust and corrosion require the most aggressive media and the highest pressure. Go to Eastwood Company's website where you can get some useful guidelines.
 
I've used a variety of products. My favorite so far has been 40-80 Red Garnet. It's hard to find, but pretty cheap. $22 for 50lbs in a tub from Tractor Supply Co. I use it in a Clarke Pressure Blaster, though, not in a cabinet. It removes paint well, doesn't clog, and leaves a very paintable finish. My second favorite is called JetMag, which I've only found at a company in Va. Beach. It's less aggressive than the Garnet, but leaves a slightly better finish. It's very cheap, around $8 for 55 lbs (25 kg). I believe it's an import from Canada.

In my Clarke Hobby cabinet, I've used glass beads (very slow, IMHO), and Black Diamond, a $7 per 50lbs coal slag available at Tractor Supply. It's very coarse, and is good for stripping paint from parts. It's considered a 1 time use product, but I've found that I get pretty good reuse rate in the cabinet with 60 PSI. I can blast for about 1 hour with 10-15 lbs. Both the beads and the coal slag are much slower than either product in the pressure blaster. Typically, each part I blasted with the cabinet took about 30 minutes (lower A-arms, spring plates, etc), while the pressure blaster blasted similar pieces in about 2-5 minutes.
 
I have been using a blast cabinet for about 10 years and sure agree with all of the above comments. One of the other variables is the air pressure. I use 80 psi and sometimes up to 100psi depending on the item and how bad it is. I would definatly go to 3/8" hose. I use sand, al oxide and glass beads, though I will buy black beauty when the sand wears out. I have used walnut hulls on aluminun but at a reduced pressure. Little buggers have sharp corners that can dimple the al surface. I buy my media mostly at Harbor Freight because it is expensive to ship. Comes in 50 lb boxes. Have not tried black beauty yet but suspect I should. I would not use anything other than fine because of the clogging issues and you should put a desicant dryer in line to get the moisture out. Frank mentioned The Eastwood Company and they have a lot of good info, also TIP products. Aggressive media will eat out your tips in a hurry so you have to keep a few of them on hand also.

Have fun with your bead blaster, beats wire wheels, et all!

Tinkerman
 
Not adding much, but I have used 40-60psi with walnut shells on Strombergs & SUs to get a finish that looks a tad better than when they left the factory, i.e not over restored. If I want a fancier finish, I tumble parts is a vibratory deburr machine.
 
Thanks for the help guys.

I'm using Aluminum Oxide now and that is working. Removing surface rust and paint just fine.

Tried the walnut shells on a carb body and intake runner and they started to polish up.

I think the next step is the 3/8 hose since while this is working, it is still taking a fairly long time.
 
Oddly, I've found that on my cabinet, the higher the presure, the slower the effect. I believe that's because I'm forcing more air and less media. When I crank it down to 50-60, I get better results.
 
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