Sandblast cabinets

[wbleeker]

Hi Guys
I have a problem with my sandblast cabinet, it is new and I can't seem to get it to suck the grit through the gun. I am using Garnet grit that I got with it, it is dry so that is not the problem. I tried putting a baffle plate in above the pickup to eliminate any tendency of the grit to pack tight in the bottom of the hopper, no difference. I emptied the hopper and checked for blockages etc, nothing? I put my finger over the end of the suction tube and pulled the trigger and couldn't feel any suction so I am thinking perhaps it a gun related problem? Any ideas?
Will

[comerrm]

Does air come out the end of the nozzle? If it does try holding your hand (with a glove on) over the nozzle, it will backfire the air through the suction hose and possibly unclog whatevers blocking it. It doesnt take much to block it.
-rob comer

[japcas]

Try putting one finger over the tip of the gun, with the glove on of course, and pull the trigger a couple of quick time, not holding it long. This forces air through the gun and back down the suction line. If there is anything clogged up in there that will usually dislodge it. Be sure to use a small shop vac to pull out the dust before opening the door after blasting. It's not supposed to be good for you to breath. Let us know what you find.

[rockrat]

2 good replies so far.

I have to take my gun apart every few hours of use and make sure it is clear.

As the tip erodes, the performance will drop. That will seem like sand is not passing (when it is passing) but the pattern is lousy and no cutting action happens.

You might also double check that your air is as dry as you can get it. Any moisture and you will get little hard sand balls that gum up the works.

The old place I used to work had a vibrating gizmo on the botom of the box to keep the sand from creating a dune effect where the pickup tube is sudenly at the bottom of a dune and there is no sand around for it to pickup.

Take the gun apart and shake it out. That should fix the problem.
rock-

[pcarpenter]

Rockrat-- that may help explain the poor performance I have gotten from mine since I got it. I started out with the largest tip which may behave like a well-worn tip. I would say, however, that it did better when I was using glass beads instead of Al oxide. It makes sense that it would flow better. It makes sense because while it will flow more air and media, the velocity is reduced, allowing the heavier media to fall out of the stream.

I can take no credit for this tip since someone else posted it here months ago when this topic came up the last time: The tip is to grind the chrome off the end of the dip tube and braze a washer with a smaller diameter hole over the opening. I think the smaller opening prevents "packing" of the media at the end of the tube. I have not done it yet as I have not had the opportunity to be frustrated with the blast cabinet since, but I have it on my list of little shop projects.

Paul

[Scishopguy]

2 good replies so far.
You might also double check that your air is as dry as you can get it. Any moisture and you will get little hard sand balls that gum up the works.

The old place I used to work had a vibrating gizmo on the botom of the box to keep the sand from creating a dune effect where the pickup tube is sudenly at the bottom of a dune and there is no sand around for it to pickup.

Take the gun apart and shake it out. That should fix the problem.
rock-

Rock,

We had a Trinco Dryblast Cabinet where I worked and had problems with moisture, even with glass bead. We ordered a moisture seperator and installed it where the air came into the unit and that solved the problem. The moisture here in Florida is the root of all problems.

We also had problems with the sand hanging on the sides of the recovery cone. I guess the static electricity built up in the box and caused the media to clump as it slid down the sides. We would have to kick the box once in a while as we were blasting. That vibratory gizmo sounds like it would be the ticket.

[ProGunOne]

Be sure to use a small shop vac to pull out the dust before opening the door after blasting. It's not supposed to be good for you to breath.

I'm sure most probably already know but a repirator must also be worn to prevent:

Silicosis

Silicosis, one of the oldest occupational diseases, still kills thousands of people every year, everywhere in the world. It is an incurable lung disease caused by inhalation of dust containing free crystalline silica. It is irreversible and, moreover, the disease progresses even when exposure stops. Extremely high exposures are associated with much shorter latency and more rapid disease progression.

Silica dust is released during operations in which rocks, sand, concrete and some ores are crushed or broken. Work in mines, quarries, foundries, and construction sites, in the manufacture of glass, ceramics, and abrasive powders, and in masonry workshops is particularly risky.
Sandblasting is one of the high-risk operations for silicosis. Any abrasive blasting, even if the abrasive does not contain silica, may pose a silicosis hazard when it is used to remove materials that contain silica, such as remains of sand moulds from metal castings.

Some operations, like dry sweeping, the clearing of sand or concrete, or the cleaning of masonry with pressurized air can generate large dust clouds. Thus even in open air these activities can be hazardous.

[gundog]

I don't know what kind of cabinet and blaster you have but I have a cheap Campbell Hausfeld Hopper I use with a cheap HF type cabinet. The fitting going into the bottom of the hopper has some holes in it and if you push the hose on all the way and cover the holes it won't feed the media. After I am done using it I push the hose on all of the way to cover the holes so the media does not leak out the holes, and the fitting needs to be adjusted to have the holes pointed up.
GD

[speedsport]

The nozzle on your blasting gun has to be sized to the CFM output of your compressor and to the media you are using. Another thing is the pickup tube needs a flexible piece of tubing with holes in each side in the part that is surrounded by the media and open end out of the media to maintain constant airflow.

[wbleeker]

I got to have a play with it today, I took the gun off and made sure it and the lines were clear and actually got it to work slightly but I am not impressed with the results, I think that the abrasive seems too fine and am going to get some coarser stuff to try. An old engineer friend of mine told me that sometimes jobs are specified to be blasted with new abrasive and to not reuse the abrasive and that the used abrasive gets sold to people like us. It sounds logical so I will go and get some new abrasive and try it. Thanks for the help fellas I will let you know how it works.
Will