Jump to content
Sign in to follow this  

Any abrasive blasting experience here?

Recommended Posts

Hi all-

Can anyone give me a general primer on bead blasting, soda blasting, etc, for an occasional use home mechanic?

I want to remove rust, grime, goo, corrosion, etc from auto and motorcycle parts at home. I see these portable units at Harbor Freight, but I don't know enough to know what to avoid and what the better routes to go is.

Glass bead vs walnut shell media? Soda pros and cons? Can I use roadside sand in any of them?

Space is at a premium, and the ability to move a unit around is preferred, as opposed to cabinets.

Enlighten me, please!

Share this post


Link to post
Share on other sites

Glass bead blasting would probably work good for what your needs are. Glass beads are aggressive enough to remove heavy rust but still leave a smooth surface finish. Glass beads also work fairly well on soft metals and sheet metal if you you keep the gun a little farther away.

Walnut shell and soda blasting is better suited where you are removine light corrosion and paint and where you want to keep surface disturbance to a minimum.

You can use silica sand (playbox sand) but silica is verry aggressive and will remove a lot of underlying material too. Silica dust is a health hazard and causes the lung disease Silicosis. Something you may want to keep in mind.

Share this post


Link to post
Share on other sites

A media blaster is a pretty basic machine, there are a few basic parts to it. The biggest problems most people run into are keeping the media dry and having an air compressor that is large enough to keep up. From what I have seen, the harbor freight blasters are fine for the home mechanic.

As for the different types of media, that depends on what you are trying to do. You cannot use normal sand in one of these because sand contains silica, of which the dust can cause all sorts of health problems. It has actually been made illegal in most places to blast with normal sand containing silica. The "sand" used for "sand blasting" is most commonly aluminum oxide. This is available in a variety of grits, the courser the grit the more aggressive the blasting will be. Aluminum oxide is very abrasive and will damage the base metal, leaving a very rough surface finish (which is fine in some applications).

Glass bead tends to be less abrasive than aluminum oxide, but takes much longer to remove paint and rust. It can still damage aluminum, but is less likely to, and typically leaves a much nicer finish than aluminum oxide. I have seen glass bead used on cylinder heads with success, but you have to be careful when doing it and mask off areas that you do not want damaged.

Plastic media and walnut shells are even less aggressive yet, but again, take even longer to remove rust and paint (you may actually have trouble removing paint with these in some cases).

Soda blasting uses baking soda, and is one of the least abrasive methods of blasting. This is often used on cylinder heads as it will not damage valve seats, valve guides, or the aluminum around them. This will typically not remove paint or rust very well, but works well on carbon build-ups and grime. The other reason why this is commonly used on engine parts is that baking soda dissolves in water, so rinsing the parts eliminates any left over media that may be trapped in or on the parts.

Share this post


Link to post
Share on other sites
Hi all-

Can anyone give me a general primer on bead blasting, soda blasting, etc, for an occasional use home mechanic?

I want to remove rust, grime, goo, corrosion, etc from auto and motorcycle parts at home. I see these portable units at Harbor Freight, but I don't know enough to know what to avoid and what the better routes to go is.

Glass bead vs walnut shell media? Soda pros and cons? Can I use roadside sand in any of them?

Space is at a premium, and the ability to move a unit around is preferred, as opposed to cabinets.

Enlighten me, please!

Wow! That sucks! I had a bunch typed out, and the darned laptop messed up, doesn't look like it posted!

I blast quite a bit. Instead of typing it all back out on this computer (spacebar needsa sledge hammer)... I'll just ask if your planning on blasting any aluminum. If your not going to blast aluminum, I'll try to re-create the post that I lost ;-) If your going to be blasting aluminum, then my post is just a bunch of wasted space :smirk:

Share this post


Link to post
Share on other sites

My plan so far is completely unplanned.

I just find myself using a wire brush on car and bike parts, including aluminum outside parts of cylinders, etc, to clean off baked on grime, and I wish I had a better system for cleaning and getting into tight areas where a brush won't reach.

Glass bead sounds appropriate. I doubt I would use this machine even once a month, but when I need it, it would be awesome.

The portable machines would be awesome, but it sounds like you go through a lot of material, since it can't capture the media like an enclosed blasting cabinet.

Share this post


Link to post
Share on other sites

Need a big compressor or you will be futzn around the media and air feed constantly. Those cheap tank harbor f units eat tips and gate valves up quick.

Share this post


Link to post
Share on other sites
My plan so far is completely unplanned.

I just find myself using a wire brush on car and bike parts, including aluminum outside parts of cylinders, etc, to clean off baked on grime, and I wish I had a better system for cleaning and getting into tight areas where a brush won't reach.

Glass bead sounds appropriate. I doubt I would use this machine even once a month, but when I need it, it would be awesome.

The portable machines would be awesome, but it sounds like you go through a lot of material, since it can't capture the media like an enclosed blasting cabinet.

I do a lot of blasting with coal slag aka black diamond... I've never used glass beads. But your probably better off with a cabinet, and trying to work out the space issue. Your going to make a heckuva mess with a portable one.

My sandblasting actually started out with one of those small Harbor Freight style units, what are they, 100? 150lbs? My current unit holds 2,000 lbs... We use somewhere around 8 ton a week of coal slag. That dead man shut off on those small ones doesn't last very long. He's right, those little nozzles don't last very long, but... with the small stuff your doing, I don't think it'd really be a problem.

Unless you want to spend some good money, I'd stay away from Soda blasting. A 3/16 nozzle (smallest I use) takes somewhere in the neighborhood of 50-60 cfm to run. For Soda blasting, you'll want a compressor capable of twice that so it doesn't get too warm, and then you'll have to throw in a pretty spendy air dryer.

If your using Silica Sand or Coal Slag, you can get a compressor a little closer to the real cfm you need, but the bigger the better... you'll still have moisture problems, but its a lot easier to get away with just having a few water traps on your lines.

The sandblaster itself is the easy part, the compressor is the part that'll make you pull your hair out or not. If your compressor is too small, it'll run continous, get hot, put out hotter air, and give you more moisture problems...

What do you have for a compressor?

Share this post


Link to post
Share on other sites

I have a tall 60 gallon Craftsman 220 volt compressor. It's overkill for most home use, and will keep up with a D/A sander, which is always my measuring benchmark.

I would be using a blaster in 5 minute bursts. Would I go through a bunch of material every time, like emptying a $25 bag?

Thanks for all of the replies!

Share this post


Link to post
Share on other sites

I used a walnut shell blaster on my 1949 Harley Davidson aluminum heads, cylinders and crankcases. For aluminum you want to use media that is not aggressive, something like walnut shells or glass beads. We happened to have a cabinet walnut shell blaster at the foundry that I worked at at the time so it was free for me.

Blasting with sand or other aggressive media is done specifically for roughing up the surface and is usually used on steel to remove paint and rust. The sandblaster guy that I used did my Harley frame to prep it for molding with bondo and paint primer.

Share this post


Link to post
Share on other sites

just get a cheap blaster...or make your own!

use sand, yes it is abbrasive, so run less PSI...problem solved.

if its just to clean up some almuminum...use soda at a high PSI

Share this post


Link to post
Share on other sites
I have a tall 60 gallon Craftsman 220 volt compressor. It's overkill for most home use, and will keep up with a D/A sander, which is always my measuring benchmark.

I would be using a blaster in 5 minute bursts. Would I go through a bunch of material every time, like emptying a $25 bag?

Thanks for all of the replies!

I don't use D/A sanders too often, but a quick search tells me they use 15 to 25 cfm. You'll potentially be using somewhere close to 50 cfm. Your compressor should have a cfm rating on it... Thats the important one. I have a couple of 60 gallon 220 volt compressors. If I remember right, one is 17.5 cfm, and the other is 20 cfm, neither will work well blasting.

Someone else can do the math, ( I should be on the road right now!) but if you have a 60 gallon compressor... and run the pressure up as high as you can (thats bad because the air will get hotter, something to cool the air would be nice, with water traps in your line) I'd guess you can set your compressor to 160 psi? So, how long it takes to drain a 60 gallon tank from 160 psi to about 70 psi? at 50 cfm.

Really hard to say how long a bag will last you. It all depends on how big of a hurry your in. You can set the abrasive flow really slow, to make "every hit count". It'll take a lot longer, but you'll use much less. Turn the flow up so you can do a speedy job, and you "waste" a lot more... not all of the particles are hitting the surface, they are bouncing off of themselves.

(((Shouldn't really be saying this part... Its very dependant on how you run it. But to give you a really REALLY big ball park kind of a guess... Trying to ride the line between speed and efficiency... I, at one time, used 50 lbs in 10 minutes. You'll have it slowed down quite a bit from that I would guess, so 50 lbs would go longer for you)))

Like I said before though... all of my experience is with silica sand or coal slag. If your using walnuts or something like that, I don't have a clue, except to assume that moisture is a much bigger problem, like it is with soda.

$25 bag? Not sure what your looking at... You can get a 50 lbs bag of "Black Blast" from menards for $6.98

:smirk:

Share this post


Link to post
Share on other sites
I have a tall 60 gallon Craftsman 220 volt compressor. It's overkill for most home use, and will keep up with a D/A sander, which is always my measuring benchmark.

I would be using a blaster in 5 minute bursts. Would I go through a bunch of material every time, like emptying a $25 bag?

Thanks for all of the replies!

What is the SCFM rating on your compressor? A blasting cabinet will definately burn up the air. You will need something in the range of 10-15 SCFM @90psi to operate a small blaster for more than 30 seconds at a time.

Share this post


Link to post
Share on other sites

Mine is rated at 9 SCFM@90. Right on the edge of that spec.

The cheapo Harbor Freight units talk about 2-3 CFM@50. They must be really weak compared to a decent machine.

Share this post


Link to post
Share on other sites

i wouldnt be trying to blast anything with any less then 10-15CFM@90 psi

would nto be worth your time or your money.

Share this post


Link to post
Share on other sites
Mine is rated at 9 SCFM@90. Right on the edge of that spec.

The cheapo Harbor Freight units talk about 2-3 CFM@50. They must be really weak compared to a decent machine.

2-3 cfm?? woah... you talking about a small hand held one with the abrasive container riding on the gun like a paint gun?? talking about completely different things here...

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×