trouble with my sand blaster

I recently purchased a pressure sand blaster from Northern Tool. Trouble is, I simply cannot get a flow of sand out of it. It pressures up quickly, doesn't leak, etc, but will only spit air minus the sand out of the nozzle. If I remove the nozzle it will shoot a 1/4" stream of sand across the street, but put the nozzle back on and it spits and sputters. I've checked all of the valves, the hose, etc but no go on getting a usable flow of sand out of it. Anybody got an idea what I'm doing wrong. PS - my compressor is a 90 PSI upright model that runs all of my power tools, etc, and I've used it in the past with a syphon blaster with no trouble, so I don't think its an air flow issue.

 

sounds like maybe your sand is too wet or too course. What are you using?

 

i dont think the sand is wet, same thing was happening to me.
my problem was that i had to filter the sand because i had large peices that would get stuck in the ceramic nozzle peice.

what i did was took a bucket with a window screen over it, and poured the sand over it, large peices wouldnt fit in the lil holes of the window screen, so thats what i filter out.

so try filtering your sand, worked great for me.

 

It should have a valve to limit the amount of sand. On mine it has to be almost closed. You want the sand coming out of the nozzle to be just barely visible

 

What grit is the sand? I find anything coarser than 40 grit doesnt flow well at all, if you have 24 grit that could be the problem?

 

If your Northern store is like the ones up here, and you got your sand there, the sand is likely too course. I bought a pressure pot and went to Northern for the media. I went around and around with the manager about how course the media was but he refused to accept that it was. When he got enough complaints he would switch media brands but always bought the course stuff. I found that my local Menards has a good cutting media made from coal slag that runs through the blaster really good. Sometimes I think the media is a little too fine because it looses its cutting edge after reusing it a couple of times, but I guess I would have someting that is too fine than something that just plugs it up.

 

Air needs to be dry also.

 

certain grits need the right size ceramic tip. Ive used lots of media and youd be amazed what you find even in new clean sand. sometimes i swear black beauty is just what they can sweep off a machine shop floor. also start off with a full flow of air then SLOWLY release the sand valve. I also used to hold an icepick in my other hand to break up any crap that gets stuck in the tip. good luck

 

Does it have a mixing valve on the bottom of the tank and a choke valve? I have an old TiP and the mixing valve at the bottom needs to be balanced to adjust the flow of sand. You can close the choke valve and open the mixing valve wide open to blow out any obstruction in the bottom of the tank. Hope this helps.

 

First off would be to check the nozzle for any blockage, also check the nozzle size to see if it's to small for the size media you are using. I have always used a # 60 for the small nozzles, a 3/32 to 1/16 should be good for a fine grit sand. But you should always sift the sand prior to putting it in the hopper - start with the air valve wide open and the sand valve closed, slowly open the sand valve till you see the sand coming out, no more than 1/4 open. Remember that a industrial blaster runs on alot more air and has a larger dia. nozzle.

 

Are you using playsand?

 

I'll second tinbender's comment. You need to keep the bottom valve almost shut or the bottom fitting seems to get overwhelmed with sand and clog up. I also don't try to use mine on very humid days because the sand gets sticky, even with an inline moisture trap.

 

a picture of your setup would be good to post, does your pot have a valve at the bottom?, here's what i would try, shut the bottom valve off, then take the nozzle off and let all the sand shoot out till there is only air coming out, then put your nozzle back on and turn the air on, then open the bottom valve slowly till the sand starts coming out, it should come out ok then, and before you stop blasting turn the bottom valve off before you turn the air off,

 

I'm just throwing out suggestions,,,did you drain your compressor?,,,do you have a in line moisture trap?,, sand has to be dry and don't use play sand,,,HRP

 

Thanks for all of the suggestions - I did buy the sand at Northern also, and it is somewhat coarse. I think I may be opening the sand flow valve too much (based on the comments here) I was opening it all the way and wasn't getting any sand to flow. I'll try again tomorrow, and if I can't get it to work I'm going to take it back to Northern and they can prove to me it works or give me another one. I think my old syphon blaster was easier than this!

 

If I remove the nozzle it will shoot a 1/4" stream of sand across the street,

sounds like you got some problems with the nozzle to me. they get blocked pretty easy. seems like when I did my OT car I spent more time dicking with clogs and refilling the pot and straining sand than I did actually blasting

 

I just went through the same headaches with Northern s/blast "sand"..The store here only stocked a brown looking media that had lots of large ,pebble sized pieces in the bag.I spent most of my time unclogging the nozzle ,etc...Bear in mind that it's been in the 90+ degrees here in NC and the hood,mask,goggles,overalls made the job a real chore ...When I ran out of media ,I found that the local Tractor Supply stocked Black Diamond brand blast media in a fine grade & a coarse grade.($7.99/50 lbs) My system will only tolerate the fine grade,but it's all the agressiveness I need . The media says on the bag "graded & washed" .I have had no more trouble with clogging caused by the media size,however, with the humidity like it is ,moisture is a problem..I just drain my compressor ,line filters daily..

 

FILTER THE SAND.
I went round and round with my Harbor Frigt POS.
To get it to work I changed all the valves, filter the sand , dry the air.
Now it almost works passably.

 

I had the same problem with my sand blaster. Its most likely the sand size thats restricting the air flow.

 

I buy silica sand from a gravel/aggregate supplier. $7 bucks for a 100lb bag. Usually flows really good. Like budd says, slowly introduce sand with the bottom valve and turn it off before shutting the air valve. Also, reach over and give the whole unit a good 5 second shake every so often as you use it. Keeps things loosened up. I was really frustrated with my blaster at first but, just like a lot of things in this hobby, you have to learn the little quirks. After that it becomes a valuable tool. Always wear your respirator under you blasting hood. Silica/rust dust is not good for you.

 

Thats what I had to do, an old window screen worked great.

 

My experience with blasting has produced the same issues you mention. All of the replies here are the same I found, nozzle clogged with a few pieces of too large grain, also, damp sand, or moisture getting in thru the air. You have to check all of your bases.

 

Do not blast with sand without a respirator IT WILL KILL YOU

 

OK, Here's what works for me. turn OFF the valve at the bottom of the sand container. Turn ON the air so it is shooting out the nozzle. OPEN the sand valve SLOWLY and only PARTIALLY. You dont need the sand valve fully open. Good luck!

 

SIFT THE SAND! 70 psi for body panels shooting at a 45 degree angle not straight at the panel.Drain the compressor & the filter.SIFT the SAND!I have a HF 40 lb POS and my comp& filter never produce moisture. I use play sandWear a hood & respirator.Then epoxy prime bare metal.Oh & SIFT THE SAND