Help with SandBlaster
 

I have a sandblaster cabinet. It is a harbor freight unit, and it just does not seem to work that well. It will start working ok in the beginning and then slowly it just stops working and it is hard to tell why. The media is not dirty. I'm wondering if it is my compressor. I'm hoping not because going out to get a new one just really is not an option. And mine is basically brand new. The cabinet seems to be in really good shape. I was originally using the harbor freight gun and it was not working so well so I got the eastwood upgrade kit with the foot pedal and new gun. But it did not seem to help and I was thinking that the nozzle was too big and the eastwood gun did not offer different sizes so I went back to the harbor freight gun. And I'm using a 4 mm nozzle.

I am a little low on the grit, does the hopper need to be filled to the max or is it ok if it is low? It is not empty and the intake tube is covered with media but just on the low end.

What about a regulator, should I be using one?

What about high flow fittings?

Below are some pics and specs on my compressor. Any suggestions?


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Make sure you have a way to dry the air. Moisture is a problem and builds-up as you blast. A harbor freight drier would likely suffice.

I think it is just the way they are, have not used one in quite a while but do remember when I had used them in the past they just seem to clog, would usually just block the end of the nozzle with a glove and give a pull of the trigger and blow the media back and start again, usually worked to free things up.

There are a bunch of sandblasting cabinet videos on youtube, including modifications.

Several common themes I've seen with the sandblasting cabinets videos / threads are to put a whole bunch of air dryers in line to keep the air as dry as possible (like three or four in a row). Also, a lot of cabinet users remake the intake/air metering/mixing valve to get better mixing.
You could certainly experiment with media levels, but you've got a clogging issue. It might be better to sort that out first. Adding more sand just makes a bigger mess to go through while sorting things out.

Also, pay attention to media. Make sure you aren't using playground sand. It collects moisture, has uneven grit size, and will clog. Invest in good media.

Also, you are on the low end of cfm rates. This is a factor (at least with the external sandblasting tanks- I have no experience with the cabinets). The HF freight units will list a range (such as 12-16 cfm), but that doesnt mean it works well at 12. With the regular sandblasting units, it might barely work, and might be a pia. Your compressor might provide the minimum at 90 psi for a couple of seconds (it won't work well @11.3 cfm), but will quickly drop to sub 90 psi, which will promote clogging (won't work at all). I would recommend sistering another compressor to get the cfm/pressure up.

From what I have read (others who have had frustrations like you describe), you kind of need to address all of these to get a consistent result.

Good luck

As I recall there is a problem with the HF pickup tube. Mods in the video below, starting at 8 minutes.

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I did not do the mod, I used the HF cabinet, but replaced all the guts including the pickup tube with the kit from TP tools when I built it.

https://www.tptools.com/Build-Your-Own-Cabinet-and-Trim-Kits.html

You need to eliminate the pickup tube and gun both are crap, also helps to have at least 20cfm compressor.

They all do this. You need to back flow it periodically when you are using it.

There are 2 ways to do this. Hold the nozzle HARD agains the cabinet (not the glass) and step on the pedal. The other way is to hold your hand over the nozzle (with the glove on) to block the nozzle.

This blasts air the other way through the hose and sand hopper to clear out any debris or blockages. I have to do this every 2-5 minutes depending on what I am blasting and the media.

I bought a replacement gun and pick up pipe from Tractor supply, and it works really well now . It was basically useless before that .

I had an HF unit and went to a Barrel Blaster unit which was much better, actually worked perfectly.

That said one thing I found w/ both units is you have to do what @unclebilly said above. Drain out the media and then hold your gloved hand over the nozzle and pull the trigger. This will backflow out any paint chips or blockages out of the pickup and nozzle hose that are reducing flow.

Also keep a good nozzle tip on it. Change it often w/ new. Ceramic ones last longer (not sure what HF has), and the more course your media the faster they wear out.

Suction cabinets suck, and that's all. Find one that recirculates the medium in a hopper behind the unit. Use glass bead, don't overfill, and a moisture trap is manditory.

When it stops working, burp it. Put your (gloved) hand over the nozzle to plug it, and pull the trigger briefly. This reorganizes the incoming sand supply.

Yes, this usually fixes the problem.

I said to cover the nozzle with a glove, something I used to do but probably better to use the side of the unit itself or have something in there to use for this, and not use your hand, if there was a tear in the glove that could be a real problem.

thank you everyone for your replies. Thank you for the suggestion about plugging the gun with your glove. I have already been doing that.

I went into the garage and found that there was some debris in the nozzle, so I was hoping that might fix it alone, but since I was already there I decided to remove the siphon pipe as in the video above, thanks dad911. I screened the media and started her up. Same results! It still is barely doing anything.

I know as Leakyseals951 said above I am at the low end of the cfm requirement. But there still seems to be a ton of pressure. I did find a leak at the gun inlet so I fixed that.

Another question is how often should I change out the media, is it possible that it is worn out? I'm using the media Black Silicon stuff from Harbor freight. I'm thinking I should just go buy a new bag as well.

What do you guys think?

Any input on what nozzle I should be using?

What about higher flow fittings and / or a regulator?

Thanks,

Rodney

You could certainly go to a 3/8 fitting from your current 1/4, but also check your hoses for constrictions as well. For example- a lot of cheaper 3/8 hose will have internal 1/4 choke points. Also look for any swivel connectors in your line, and ditch them. Make sure you don't have any 1/4 cutoff valves in the line. I would even avoid the 3/8 cutoff valves, although you probably wouldn't notice a difference with that.

I would remove any regulator or regulator/moisture collector combo.

I did a lot of measurements of air flow over the summer on my HF sandblaster, and all of the above made a difference in airflow. For example, I would let the compressor build to full pressure, then open the hose, timing how long it took lose pressure. Things like regulators significantly lengthened the time to completely lose air, even if fully opened. The straight water collectors didn't make a big difference. Neither did long hoses, which kind of surprised me. These things come more into play when you get higher cfms, but even at 10cfm, you can probably use every advantage you can get.

I think if you went through the hoses on the cabinet, you might find those are restricted as well, and would potentially "undo" any benefit from 3/8 couplers, and need upgrading. This is important- make sure the internal constrictions in the HF aren't already limited to 1/4.


On my own sandblaster, I did all these tricks and it helped a little, but i still ended up on CL buying a used second (and third) compressor to take me from approximately 6cfm to 11cfm to 23cfms. No replacement for displacement.

-another advantage of getting a second (cheaper/smaller/ used) CL compressor- It will get you up to 15 or so cfm, can run off 120v (since your 240v is already spoken for) and you can turn around and sell it when you are done. No need to go buy another 60 gallon compressor.

Did you mod the sipon/pickup?

If the media's not clumping or dirty, it should be ok.

Years ago, when I was young and stupid, we'd sandblast in a garage, sweep it and screen it, and do it again......