making a sandblaster
 

Wasn't sure where to put this... But can I make sandblaster using my regular 2 horse power compressor?

Why bother when they're so cheap?

$9.99 from Harbour Freight:
http://www.harborfreight.com/cpi/pho...6999/96972.gif

$10.99
http://www.harborfreight.com/cpi/pho...2899/92857.gif

Just make sure you strain the sand through a sieve beforehand. I've found larger chunks that tend to clog sandblasters.

If you're sandblasting a frame be sure to sneak up on the right pressure that removes the paint but not TOO fast. If it just whisks the paint away then it'll also be removing a fair amount of metal below the paint. A better bet is to use a less abrasive media than sand. Something like glass beads for example. Or if the paint is pretty tough then start with the sand but don't cut right through then finish with the glass beads.

Thanks guys. So I can just attache one of those things to a compressor and thats it?

Yeah, just plug the compressor hose to the fitting at the bottom of the handle, fill the bag/bottle with blasting media and that's it. Walnut shells do a good job at removing paint without damaging the metal underneath.

Yes.

No. First of all a blaster tends to use a lot of air, and usually your basic home compressor won't be capable of keeping up with the flow. You'll most likely end up having to wait for the tank to fill up and then working in bursts. Your compressor might not be too happy about such heavy cycling, so pay attention to it.

The blast gun in the first pic is a recirculating gun. You pour a cup of media in the cloth bag, press the rubber nozzle against the surface and pull the trigger. Good for spots, decidedly sucky at other stuff.
The one in the bottom pic works pretty much as a simple spray gun. Doing something like a frame would require quite a few refills.
I'd go for one with a longer pickup hose instead, so that you can use a bucket of media.
Another tip is to get a tarpaulin. Hang it like a photographer's back drop, step on to it and do your blasting against the backdrop. That'll make it easy to collect and reuse your media as work progresses.

You do realize that these tools need to be attached to a compressor (like the one the OP asks about) and that they are useless by themselves...

Don't you..?

No **** Sherlock

Work outside, stay upwind and wear a good dust mask and eye protection. Or make up a "blast cabinet" to contain the dust and work inside it. Ever hear of "Silicosis"? You don't want it.

Depends on how big your tank is.... the horsepower is kind of irrelevant.

And don't waste your money on the items previously mentioned. Those $10 blasters are worthless and I wager that none of those posting about walnut shells has actually BOUGHT a bag of walnut shells! Or actually used one of those blasters to strip a frame.

I'd add a picture, but I don't know how that's done yet. But if you look at picture #9 in this set...

http://www.flickr.com/photos/owhn/se...7608666766179/

You will see a "real" sandblaster, a pressureized unit that holds 90 lbs of sand. I use a fine sand, refered to as 60 mesh. It's about $8/per 100 lb bag, as opposed to $100 for a 50 lb bag of walnut shells.
It took well over 200 lbs of 60 mesh to clean the tandem. I don't think you want to spend that much time filling a 2 pound cup! :lol:
A pressure blaster is the best way to get a frame clean. The blaster in the picture was about $100 at Harbor Freight. Or, about as much as a 50 lb. bag of walnut shells. :rolleyes:

P.S. If the old finish is POWDERCOAT, start by using chemical stripper FIRST! Only use the blaster to clean when you're done with the chemical stuff. OTHERWISE, if you just try to blast off the powdercoat, you will get some holes in the PC, and then as you keep blasting, you ARE removing frame material from that spot where the PC came off first. Follow?
PC is made to resist abrasion, and sandblasting is a hi form of abrasion. USE JASCO FIRST! :D

As always, GOOD LUCK and don't hesitate to ask questions! :thumb:

I was hoping you would step in Dr. Deltron....
I built a frame for a guy and he had it powdercoated, but now wants me to paint it a different color. I tried chemical stripping it and that seemed to only soften up the paint, so I need to get the rest off before I paint his frame.

So after the advice on the board I went and bought what seems like a little bit higher quality blaster gun, it was like 50 bucks and has a hose rather than a bag. I have a 2 horsepower compressor.
I also bought a bag of play sand from home depot.... I'm guessing thats just not going to cut it. I can't afford the sand you use Dr. Del, anything that does an OKjob that is a bit cheaper?

Thanks

If you got one of those sucker type of blasters that has a hose dipping into a bucket of sand, it won't pick up very well with a long hose. Shorten the hose and it'll pick up sand a lot better. I've stripped and painted several cars using such a blaster. Typically a 2-3 gallon bucket lasts about 3-5 minutes. Then I moved it down about 5-ft and refill. Took about a week to fully strip a '29 Rolls down to bare metal. :)

BTW, sand from Home Depot sucks, they've got debris in there that'll clog any blaster. Make sure to pour it through a screen.

Coal slag(cheap,by-product of the steel industry) or Starblast(expensive,engineered media) will remove powdercoating like butter,but you'll have to use low pressure(suction type guns are not known for working well at low pressures) and you have to be VERY careful using Harbour Freight type blasters or you will etch the living cr*p out of the frame.

As been said,the safest(not cheapest) way for the home user with Harbour Freight type blasters, is to chemical strip the best you can,then finish with glass bead or plastic media.There is media that will leave a perfect "anchor" finish for painting but it's not cheap and you need more control than those small guns can provide.The cheapest would be coal slag(roughing)followed by sand(finish) as far as blasting goes.

Hey Dr.,that's Harbour Freights version of a "real" media blaster.Much better then suction types,but has nowhere near the control of a "real" media blaster.Real media blasters come with a cabinet/room and can seperate dust,broken media from good media so you can get a consistant finish without having to use new media.They have carbide nozzles with different spray patterns available,they have screens/vacuums in them to grade media before it returns to the hopper,on and on....it's a subject all to itself.

If you use sand,wear a good mask and try to keep the dust downwind.The skull and crossbones on the bag is no joke.

If the frame is butted or relatively modern lite weight frame, highly abrasive
media can easily remove several thousandths of an inch of metal in the hands
of a heavy handed user which could seriously damage the frame. Some of the
newer high zoot steel frames have mid tube thicknesses in the 10-20 thousandths
range. Older frames will be 30-40 thousandths in mid tube. Gas pipe frames
upwards of 100 thousandths. If the frame has any intrinsic value chemical
stripping is a better idea or sand and paint on top of the old paint.

Well I built the frame, it is .9mm thick and .6mm thick tubing. I don't want to blast through it or ill have to build my customer a new frame!

So, I tried out the sandblaster.
I used regular sand that I sifted through an ordinary screen, which got it pretty fine.
Used my 2 horsepower compressor.

I tried blasting the powdercoated frame, which I had already tried to chemically strip-- nothing. Didn't do a damn thing.

Then I tried blasting a steel Standard BMX frame from about 7 years ago, which I assume was also powdercoated because it was a pretty expensive frame. The paint came right off.

Then I tried blasting a frame that I built a year ago and rattlecanned. I used 2 coats of Krylon primer, let it dry 3 days, 2 coats of base, let it dry 3 days, and 2 coats of clear. This ended up being tougher than the BMX frame, but still came off if I put the blaster right up to it. I was surprised at how tough this was.

Then I tried blasting another frame I built a few months ago, and painted with a 2-part epoxy primer, acrylic enamel basecoat, and a 2 part clearcoat. This ended up being a bit stronger than the rattlecan, but not as strong as the powdercoat.

Maybe this information can be helpful to somebody. In then end, don't buy a cheap-o sandblast thing that you attach to your compressor. Just not going to cut it (literally), not powerfull enough. Unless I am missing something or doing something wrong. It seems that at least a 4 HP compressor that can get up to high pressure is neccessary.

Go get yourself some air craft paint stripper it will take the paint off.
Also general you don't want to sand blast paint off go ask a auto painter what they think of that idea.

What kind of prep did you do prior to the rattlecan? I'm getting ready to do the same thing myself on a frame and I'm interested in what a reasonable prep would be (the victim is a 1984 Schwinn World Sport).

[QUOTE=J
Also general you don't want to sand blast paint off go ask a auto painter what they think of that idea.[/QUOTE]

What are you talking about.

I didn't do any prep really, just whipped the bare metal down with a rag to make sure it was clean, then layed the primer.

I've found the Top Chemical - Paint Stripper Pro works really well on powder-coating. Was recommended to me by a local powder-coating outfit when I wanted to send them some intake-manifolds and turbo plumbing that had previously been powder-coated.

Those small compressors are made for nailguns and the like. To effectively sandblast or spraypaint you need to have 5+ horsepower (which usually means 220V motor). You can obviously get by with less, but it will take a lot longer.

Aircraft Remover will take off powdercoat easily. Just don't get it on your bare skin or it will burn like a MF!

http://www.autobodytoolmart.com/show...roductid=12816

Auto painters would love to be able to use sand blasters to strip paint off, if it wasnt for two things:
1) unless the blaster really knows what he's doing the repeated impact of the blast media can stretch and distort body panels. Not much point in having a great surface to paint on if it's twisted all out of shape.
Even a bike with very thin tubing would have much more surface rigidity than a door panel, so it's really not an issue for bikes.
2) the media gets everywhere. Unless you have someone who's a bit OCD in cleaning the car out there's always the risk of a hidden pocket of sand messing up the works at a later point.

It's not really about pressure as such, but more about pressure-at-flow. Pretty much any compressor can get the pressure up, question is if it can maintain it at a decent flow.
What you have in a simple set up is probably; compressor, tank and a pressure switch. The compressor runs until the pressure reaches its set value then it shuts off. The operator then gets a blast of steadily declining pressure until the compressor kicks in again.
If you're patient this is when you stand back until the comp goes off again, so you can get that initial blast of full pressure again.
If you're stubborn this is when you end up trying to run your tool on whatever it is that the comp can deliver continuously, which for your average garage appliance isn't much to brag about.

Over here a basic garage compressor would happily give a 10 Bar max pressure, but a comp suited to run a blaster might not do more than 6 Bar. Difference is, the shop comp will give you 6 Bars of continuous flow at "full throttle".

A kinda-sorta workaround for this is to run a small comp+big tank+reduction valve.
I've got a comp scrounged from an old A/C unit. It doesn't do too well WRT flow, but it sure can do pressure. So I run it against a big tank, and then I've got a reduction valve on the outlet. The tank goes high, then I have the red valve set to give me a nice 8 Bar feed for my tools, which gives me a few minutes of consistent pressure before the comp kicks in again.

Do note that compressed air equals a lot of stored energy. Be careful, think it through, and don't exceed recommended limits! If you're not entirely certain of what you're doing - don't!

+1 You really need a 5 HP or larger compressor.

For smaller item blasting, Harbor Freight makes several sizes of decent sandblast booths. Not big enough for a frame, but plenty big for parts. One advantage is that the sand is recycled in the booth. But probably not that practical for bicycles, as you can't fit a frame in one.