I've read up on questions on this forum for frames, but I have not really seen any information on grits and my apologies if it has already been brought up. Never really thought of this question before buying. I got 50 pounds of coal slag for $10 very cheap. It says it's 20/40 Black Beauty. Not sure what grit I should be looking out for, I am willing to purchase any nozzle size needed. I want a really smooth surface like gl***, but don't want it to be too weak to take off rust.
I used coal slag once because it was free. I normally use play sand but a friend just did a '32 frame for me and likes using gl*** beads. He's in the business and has access and the equipment, don't know if that would work for you????
be careful on sheet metal blasting can cause more damage I have used black beauty, the course stuff on frames but it sometimes struggles to get inside the pits. it is supposed to be safer health wise (lack of silicone) blasting dust is bad so take care of the lungs I may blast with a mid grade sand, then go back over with a finer sand this seems to keep the warping issue chances down for sheetmetal and works on frames I then DA/hand sand sand with 80 and apply epoxy I like removing the 'fuzzies' before priming and a big tarp from HF will let you reuse a lot of the sand we have a couple of local machine shops that will sand blast stuff I like to use them for the frames but do not trust them on sheet metal they have some heavy duty blasting equipment that knocks them out quick
As HRP said, fine or extra fine. 20/40 grit is neither. 80 grit is fine. I'm sure the 20/40 will work but you'll need a 3/16" or 1/4" nozzle, which means you'll need a good size compressor to deliver the CFM to push the media out at the proper pressure. I'm ***uming you have a REAL sandblaster and a worthy compressor. Also, blasting is not going to give you a 'gl*** smooth' surface. It will be a roughed up surface, perfect for epoxy primer adhesion. I just blasted my roadster frame and a couple of panels. I pour 80 grit Black Diamond into my Texas Blaster and use a 5hp I/R compressor with 18 CFM. Does a fine job!
Just found the Black Beauty spec sheet. Yeah, I'll be renting a compressor for this job. First time ever doing this, will be eventually blasting the entire car but right now only doing inner fenders. Thanks for the tips! 12/20 Co**** gradation is appropriate to use when a rough profile is required, such as for heavy rust, thick coatings, mastics, tank linings, ships, barges, and concrete blasting operations. A heavy 3.0-4.8 Mil Profile is achievable with this grit size. Minimum Nozzle Size: 1/4" Medium 20/40 is best used for new construction, mil scale, paint and rust removal, and maintenance applications requiring a moderate mil profile of 2.0-3.8. Min Nozzle Size: 3/16" Fine 30/60 is often used to create a smooth surface, high pressure water blasting systems, or brush off blast. This grade can provide a 1.0-2.6 mil profile. Minimum Nozzle Size: 1/8"
think about what a rented compressor does....and think about nozzle size...and air flow... and what it takes to warp sheet metal. The trick to not screwing up body panels, is to use a small nozzle, and fine grit sand. Take your time. If you rent a 100 cfm compressor with a 1/4" nozzle, it will be putting a LOT of energy into the air, and that energy in turn is used to propel the sand at the metal at a very high speed and volume. The energy has to go somewhere...it turns to heat as the sand hits the metal. I've never had any issues with using 60 grit, a 1/8" nozzle, a "real" 5 hp compressor, and some time. I've heard horror stories about metal getting destroyed by someone using a big *** compressor, and getting the job done in 15 minutes.
I've got four inner fenders to do, but they're very rusted and pitted. May have to plug weld some holes but my blaster should take care of that.
It's somewhat odd though. On their website Black Beauty 20/40 is called fine, and 30/60 is called very fine. It also says their 20/40 is closer to 80-100 grit.
Just found an ALC Keysco Model F-100DM 40002. Very nice made in the USA blaster, with a dead man's valve only used once. Came with a 1/8 nozzle.
IMHO the ALC blaster is just a glorified HF blaster with some upgrades however, it'll probably be fine for your 2 inner fender panels. If your planning to blast an entire car...….I'd rethink the ALC purchase. With that said, I saw a pic of someone on the HAMB who blasted his whole car with one of those. I bet he had a monster compressor and it took a long time. One of the biggest downfalls is with a 1/2" hose and fittings and the blasting tip being ceramic (they wear out fast), the machine WILL clog...…...a lot. Especially with you running 20/40 grit through an 1/8" nozzle. In addition, your hand is gonna get tired quickly holding down the deadman handle. I modded a similar HF 90lb blaster a few years back and it worked but it still clogged every few minutes then I'd spend 10 minutes clearing the clog. Just not worth it! https://www.garagejournal.com/forum/showthread.php?t=207210 I finally upgraded to the Texas Blaster. It's a real blaster with true 3/4" ID fittings and hose and a real carbide tip. Took me a couple of hours to do the roadster frame and panels. The blaster clogged twice. Unclogging it takes all of 30 seconds! Oh yeah, it cost $50 more than a new ALC 40002.
Be careful blasting body panels . Unless you like working with warped panels. I made that mistake years ago on a 69 Camaro. I have great success with Dustless blasting.
Always tried to find an angle, which the nozzle would clean the rust, w/out overheating the panel. Pressure, grit size, standoff distance and rate-of-sweep movement all contribute.
I figured it would be a little better than those Harbor Freights. I read the reviews on those, people complaining they received broken parts ect. That one over there, somebody was selling on Craigslist for a real good deal. My budget so far has been under $150 category, so have been looking out for a vintage or at least a modern blaster that is made in the USA. Good advice, the tip and hose are interchangeable. I could change to a larger hose, change out nozzle, and different handle on the unit by the time I need to use it for heavy work. I eventually want to sandblast two cars in my driveway before the winter. I had planned on blasting @ 75PSI at an angle, and using coal slag or crushed gl***.
Has anyone used fine grit garnet instead of coal slag with any success? Both are silica free so can work in my garage, worth the extra price?
Watch the sheet metal,I worked at a body shop that did sand blasting. Newbie on the hose warped a VW barn door bus. Like they said distance,speed,grit.
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