TheSamba.com :: View topic - Harbor Freight pressure media blaster problem

Wed Aug 20, 2008 9:09 pm

A buddy and I just got one of the 40-gallon units from Harbor Freight and I'm having problems getting the media to feed.

I'm using walnut media and wanted to see how much it would use. So I only put about 2 cups in. The media only feeds for a second or so unless I keep shaking the thing with one hand. Should I just load it up?

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=34202

Max

Thu Aug 21, 2008 3:20 am

I'll tell you the part THEY don't tell you, because thats the same blaster sold by Clarke and Eastwood.
Maximum grit size of ANY media is 80 grit. If you can't picture what 80 grit looks like, find a piece of 80 sandpaper and look at the grain size on it. Pretty small isn't it. I use coal slag (Black Diamond, Black Beauty etc.) and while it comes in bags marked 60/80, I still have to sift it through screen wire to get the 60 grit particles out. If i don't, it WILL jam.

Thu Aug 21, 2008 8:32 am

I've got a 20 gallon unit from Harbor Freight. The Home Depot sand plugged up bad, but the #30 industrial quartz sand from Unimin Corp. I found at a local home store works fine!

Thu Aug 21, 2008 8:37 am

Mike Fisher wrote: I've got a 20 gallon unit from Harbor Freight. The Home Depot sand plugged up bad, but the #30 industrial quartz sand from Unimin Corp. I found at a local home store works fine!

Home Depot sells blasting media? :?

Thu Aug 21, 2008 8:39 am

Same thing happened with mine,tried walnut shells first, used the biggest ceramic tip, still plugged. Used smaller media, flowed better(not plugging) but still intermittent. Swapped from 4 HP 25 gallon compressor to the 7HP 60 gallon compressor intermittent flow problem went away. Now I fill it all the way up with aluminum oxide emptys pretty fast = big mess :) Lloyd

Thu Aug 21, 2008 8:45 am

Icy wrote: Mike Fisher wrote: I've got a 20 gallon unit from Harbor Freight. The Home Depot sand plugged up bad, but the #30 industrial quartz sand from Unimin Corp. I found at a local home store works fine!

Home Depot sells blasting media? :? It's called a "sand blaster". I'm not worrying about walnut shells/aluminum oxide or ANY fancy "blasting media" :lol:

Thu Aug 21, 2008 11:02 am

Two reasons I went for walnut media, First is that I intend to use it on body work and I'm worried about warping the metal. Second, I'll be using this outside and wanted something bio-degradable.

It doesn't seem to be clogging at the nozzle, but perhaps it is at the bottom of the tank. I can usually get some momentary flow just by shaking the tank.

I am pretty new at this. For bodywork, is there another media that would work better? Or perhaps just two cups of walnut isn't flowing to the hole in the bottom of the tank?

Max

Thu Aug 21, 2008 11:45 am

Mike Fisher wrote: Icy wrote: Mike Fisher wrote: I've got a 20 gallon unit from Harbor Freight. The Home Depot sand plugged up bad, but the #30 industrial quartz sand from Unimin Corp. I found at a local home store works fine!

Home Depot sells blasting media? :? It's called a "sand blaster". I'm not worrying about walnut shells/aluminum oxide or ANY fancy "blasting media" :lol:

I don't know if you're joking or not, but the instructions for the unit should clearly state that playground sand is NOT a suitable media.

It's people like you who are the reason warning labels are put on hair dryers, warning the consumer not to use it in the shower.

Thu Aug 21, 2008 3:14 pm

In addition to the Black Diamond I mentioned, I have a conversion nozzle for soda. I use it for flash rust, paint milder surfaces. Alot of folks here have had problems but I use Armex Flow Control which is coated to repel moisture. It sits in 50 lb bags in Virginia humidity and flows fine. Other common problems are the blaster uses too much. That comes down to experience with the throttling valve and media valve. I've got a 2 stage 80 gal. compressor keeping the blaster tank pressure right at 100 psi, I run the throttle about 3/4 open and the media valve on the bottom about 1/2 open. This gives me a fair amount of media coming out at VERY high speed and works well. I can run soda for 1 hour straight, non-stop and only use about 40 lbs.
The Armex is an industry standard, made by a branch of Arm and Hammer. Runs about 60 cents per pound. If you search for it by name on Google or on Thomasnet (an industrial supply search engine) you'll find a distributor. Might also look for distributors of Natrium. I believe that is the product name not material name. (like Chevy is a product name, car is a material). Hope you have better luck, more time spent with it will improve your results and media usage.

Thu Aug 21, 2008 4:45 pm

Like Redneckjoe said, It comes down to throttling the supply valve at the bottom of the tank. 1/3 to 1/2 open worked best. I used 20 grit plastic media in my HF 110 lb model with good success so it isn't necessarily limited to 80 grit as Redneckjoe has suggested.

One thing that really makes these units come alive is to shitcan the whimpy 1/4" air inlet and step up to 3/8". Use good 3/8' or 1/2" supply hose as well. These units are constricted on the inlet side. They need more CFM to work well. Like bumping the vents from 37's to 42's in a set of IDA's... these things gotta breath.

Thu Aug 21, 2008 5:59 pm

Good point Hophead, I didn't even think of mentioning that. Moving up to the 3/6 can help alot of tools work better. :)

Thu Aug 21, 2008 6:17 pm

It is crappy the the manufacturers of most tools don't mention the larger size inlets are really needed to get the required CFM to make their products work as advertised. I learned about it reading a book on auto painting. You can't get a HVLP gun to work well without 3/8" fittings and larger air supply lines.

I run 1/2" hose With 3/8" automove style fittings. I made a 3/8" male to 1/4" female adapter so I can run all my pneumatic tools regardless of the inlet size.

Dual action sanders really need 3/8" fittings to work well. It is all about getting the CFM to the tool so it will work as it was designed

Fri Aug 22, 2008 6:05 pm

When it comes to sandblasters it`s all about CFM. If you have a small compressure you`ll Kill it for sure. It will also pump more water then you can drink in a day and sandblasters don`t like wet sand. If you just have a small compressure get a hand held unit and hit the hard to get rust spot. My compressor 5hp single stage as rated 12.5 CFM at 100 psi. only give me 75 psi when running my blaster with a new tip. One thing that you have to remember the bigger the grit your blasting the bigger the nozzle you need and the more CFM your compressure need`s to give.

I also just picked up a small refigerated dryer this thing kicks ass.

My compressure in the back ground.

New and old nozzles. I use the new ones for the store bought grit $ and then use the old ones for the playsand.

Fri Aug 22, 2008 6:20 pm

Well, I went ahead and put the rest of the 25 lb bag of walnut in and gave it another shot.

Much better. :D

I think with only a little media in the tank the shape of the bottom doesn't present enough of a slope near the hole. It was just spitting out enough to uncover the hole and the rest wasn't filling in.

Now I can start working on technique.

Max

Tue Aug 26, 2008 11:42 pm

Years ago, I bought the same type of Chinese sandblaster at a tool store. I bought sandblasting sand (more uniform grains) at Meeks Lumber and had good luck with it but the sucker would, occasionally, plug up at the bottom of the tank. I had to stop what I was doing, let the pressure out of the tank, and remove the hose from the connection at the top of the tank so I could unscrew the outlet at the base of the tank. Once I cleaned it out and reinstalled it, the unit worked fine.
I wish that I had bought an American made pressurized sandblaster, with the removable lid on top of the tank, but it would have cost over $400.

Tue Sep 02, 2008 11:59 am

there is restrictive areas in the harbor freight blaster. i pulled the t's where the hose meets the fitting on the bottom of the tank. take them apart and look into the pieces. you will notice that the treads are to long and need to be grounded down. the spot where the guage hooks up and t's off to the water seperator. that also needs to be grounded down. check all the areas that where metal treads into metal.