Blast cabinet

[SCOTTRODS]

If it were me, I'd use 80 grit aluminum oxide for your described projects. Especially since you're cutting rust often. Glass bead takes forever, and anything else I have used is a huge dust issue.

[fusername]

I was worreid about dust since its a cheap cabinet i figured it would leak pretty bad, and more about it removing metal when I am working on aluminum parts. Am I being overly catious? I have never used anything but glass bead.

[Ol'fogasaurus]

http://www.kramerindustriesonline.com/f ... -chart.htm

I’ve posted this table before but it gives some ideas for the proper media to use for different occasions.

I don’t use AL oxide for several reasons.

1) It is hard on the HF nozzles.
2) The HF stuff jams from what I have been told; I think I was told that their media was too large.
3) It is very aggressive and you can cut through things quickly if the material is soft.

On the other media, sand, as a media, compacts the metal making it brittle and rust faster. They learned this before I was interested in cars in the 50s.

Glass beads leave a residue and should be cleaned off. It also makes things rust faster if a protection is not put on it after cleaning the dust off.

Soda, as I understand it, does not etch glass but you should protect things anyway just to make sure. It is messy and makes a lot of dust but it does work. I have watched it being used on an older Mustang II and it was impressive and cheap. Luckily the guy lived a couple of blocks away from a Costco so baking soda was close, cheap and could be had in build. As I drove up to where the car was being blasted it looked like someone was burning leaves with all the white dust/smoke rising from the garage; and they had a plastic sheet over the garage door too.

Lee

[SCOTTRODS]

Good link, Lee.

One of the first things I recommend as an upgrade to the HF cabinet, is to get a better grade gun. The 30 dollar guns at northern tools are a decent gun for the money. You can do better, but you WILL spend a lot more money as well. Along with the northern tools gun, buy a tungsten carbide nozzle for the gun..... It'll last generally about 10 times as long as any nozzle from HF. There are more expensive ones, and bigger, better guns and more.... But this is a good combination for the bucks. The tungsten carbide nozzle ain't cheap, but you can buy them on eBay for a very fair price as well. I blast a lot at home, using the siphon gun from northern.... in the HF cabinet. I mean I blast A LOT...... no better deal for the money.

As far as the media to use, the link from Lee is a great link. There are probably a hundred others with the same info..... Nothing I can add to it, except a couple of personal experience pieces.... Again, I blast A LOT..... The BEST All around media is and probably always will be aluminum oxide. The grit size is available in many sizes, to give whatever profile needed for finishing. Most media can be had in a number of grit sizes.... The AO is not the cheapest, by any stretch up of the imagination.... Bt bang for the buck..... Another one I have a hard time beating in the long haul. It is long lasting, thus outweighing most cheaper alternatives in value. This advice is all related to siphon gun applications..... Things change when we go into pressure blasters......

I my experience with pretty much all media, is there is always some sort of residue left over. With Glass bead, the best way to clean off the residue, is to blast with clean dry air while scrubbing with a clean dry stiff bristle brush. This is a very good approach for a lot of media, however the biggest pain media is the soda. Soda has to be washed away with soap and water typically, in order to ready something for paint..... Although it is sold as a wonderful thing, I can't see the benefit in anything I blast, being blasted with soda. The equipment needs to be dedicated to soda, as it will contaminate other media and embed in the surface, when introduced along with sharper media..... Making it even more difficult to clean from the surface..... As you can see, I'm not a fan of soda. It is non abrasive to glass and chrome and stainless trim as well..... Doesn't even etch the steel you're cleaning off. The best soda blasting equipment is also very expensive, where the stuff from Eastwood and other similar models, are less than adequate in my opinion, though they do work. Soda is also sacrificial and is said to be cheap, but once you figure in the very fact that it is designed to obliterate on impact, the cost goes up significantly when compared to reusable media.

Start by using the gun that comes with the cabinet. It actually does work, but has design issues (most notably, the inlet angle of the media suction hose, at the gun....), and will wear nozzles out very quickly.... Again, do not introduce soda to your blast cabinet. It just complicates things. Get ready to upgrade/update the entirety of the gun system..... Make certain also, that you supply the driest air you can for blasting. If you don't, you will likely find issues with your process.

Keep in mind, my advice is all based on my personal experiences, and not all, but almost all, directed toward putting a powder coated finish on parts. A comparison should be made here, as powder coating requires almost exactly the same kind of surface prep as paint, aside from the surface profile (roughness) needs to be 1-1.5 mils.... Where paint needs under 1 mil in almost every case. The cleanliness, and care is exactly the same. Grease free, oil free, smooth consistent substrate.

There are things I don't understand from Lee in his post above..... I don't know how glass bead can have any effect on how fast metals rust.... But I suppose it really has more to do with how things are handled, and the relative humidity, and possible other factors, such as fumes from a stripper or acid in the air ( a battery in the room can cause rust on metals that are completely bare as well, as an example).

Sand, as scribed above..... It is a great abrasive, and is cheap and easily acquired (even Home Depot sells play sand), but it has a bigger drawback than the mentioned metal effects... It can cause a deadly respiratory disease, called silicosis. What happens is the silicon in the sand gets in your lungs, and instead of you being able to cough and expell the dust, it sticks to your lungs and will not cough up like all other media dust ( I think there is another that is dangerous as well. It's likely to be the silicon carbide for the same reasons....) you CAN USE THE SAND but the only way to use it safely is with supplied fresh air systems.

Keep on readin' .... Between me and Lee, we'll get you hooked up well soon.

[fusername]

I have seen how fast parts rust comeing out of a glass bead tank, but I always blamed it on the fact they were VERY well degreased from the parts tank prior to blasitng, and now have a fresh exposed surface ready to rot. that is some really good info you posted, I will probably experiment with some AO when my glass gets old.

[Ol'fogasaurus]

Until tonight my garage was pretty dry (our water heater started leaking) but after the warning about the rust problem associated with glass beads (a machine shop) I started taking a brown rotary Scotch-brite disc to the parts and got the shiny metal back... if that helps any.

Lee

[fusername]

I always just used ot get em we w/ something. most parts were engine parts, so from the blast cabinet they got tossed back in the parts tank to rinse down, then everything in the building had a film of oil on it and that went a long way to preserve stuff.

[fusername]

Lee you might be safe, a 220 compressor just turned up on CL, the guy wants to trade for a 110. If he gets back to me w/ the CFM I might do it, but it doesn't look all that meaty, only 2hp motor...

well, I take it back, some online reading shows that a good single stage piston compressor will give ya ~4 CFM per HP, with 3 being more realistic. No rush, i figure I'll find a nice 220 or dual stage unit w/ a rotted tank in the next year or two fora good deal somewhere.

[Ol'fogasaurus]

I just went out and looked, I have a 6.5 HP DeVilbiss, 60 gallon compressor which is not the biggest or best but it works. It runs a lot and has trouble keeping up with the blast cabinet and/or air tools. The style of compressor itself makes a big difference. Knowing what I know now, I would go with 80 gallons and not get the type of compressor that mine has.

Lee

[fusername]

found a 3 hp single stage taht is in my price range, http://worcester.craigslist.org/tls/3352450388.html
i think I will need to stick w/ putting two cheaper compressors together for now and runnning at a low pressure, I can't afford what I really need, and don't wanna buy half of what I need. Although I do have some 110 motors lying around, maybe I should just buy a dual stage pump, piggy back the motors and add the hp. kidding, unless I find a screaming deal on a pump.

[hugging corners]

ive had troubles finding riongs for it (same pump),
....but ater rebuild i realy like my hotrod
viewtopic.php?f=49&t=135987

[fusername]

the cabinet wants 9 cfm, so I am thinking if I buy a new comp, its gotta be 12-13 CFM min, do you blast w/ urs?

[Ol'fogasaurus]

The schticker on the tank says 15.2 cfm. I never thought about it before but I use one of the larger opening nozzles; I wonder just how much of a difference that makes.

Lee

[SCOTTRODS]

My compressor runs 10.4 cfm @ 90 Psi..... I use a 3/16" nozzle and get fair work from it. I don't have huge expectations. I do have lots of patience and don't try and over work my compressor. I figure I'm actually getting around 12-13 cfm at 60 psi..... That's about as much nozzle as you should use for that, and truly it's more nozzle than I should be using. I used to use a 1/4" nozzle, but my compressor couldn't get anywhere near keeping up. At least at the smaller nozzle size and lower PSI, I can keep rolliing for long times with no rest.... It's still pushing the compressor a bit hard, but it does fine.

The one thing I have found, is that once you reach 5 hp and up, the prices seem to be exponentially higher per HP, for decent compressors. My favorite ones are still Eaton Polar Air compressors, for the money and the quality.

The link I am pasting here is a HUGE amount of info that will spin your head for blasting stuff.... about 5-6 pages in, there's a section that will give CFM requirements for Blast Nozzle sizes and Pressures and such.... and more.... but it does give something more concrete to help make nozzle type and size selection for sure.

[fusername]

I will def be using smaller nozzles, even w/ two comps put together, i only have 9 cfm between them.