A couple months ago I bought a small sand blasting cabinet to save time cleaning up the smaller parts of my T. It worked okay for a stretch but now it doesn't seem to want to pick up any sand. If I made any changes to it between working and not working they were unintentional so I have no idea what I may have changed.
I don't know a whole lot about the standard construction of these things but mine is little more than a steel box with a media sump in the bottom, a pick-up hose going down there and an air gun which picks up the media through a venturi effect. The pick up hose is about half an inch in diameter and ends in around ten inches of steel pipe. The relatively large diameter doesn't seem to clog and my sand has always been dry. That steel pipe on the end of the hose just sits down in the sump. My compressor is a little smaller than I should probably be using but it's good for up to 125 PSI for a little bit so I doubt that's the problem.
What I think is happening is that when the pick up hose is totally buried in the sand it has no way to also pick up air to help push sand through the line. When it is near the surface of the sand in the sump it doesn't seem to pick up anything BUT air.
So what do you guys think? Since the air in my garage doesn't seem abrasive enough to strip away old paint and corrosion, how can I get this thing picking up sand?
Did you recently replace the gun nozzle? On mine, if I push the new nozzle in too far, it blocks off the passage for the sand to come in.
Does your cabinet have a fitting and filter on the side to hook up a shop vac? Mine does, and if I don't have the shop vac running, I can't see a thing inside the cabinet because of all the media and dust swirling around.
Mine just has a filter on the side but I'm not opposed to modifying it. When it was working well I also couldn't see a whole lot through the sandstorm inside. I'll have to take a good look at the nozzle to see if it's blocking the pickup tube.
How does yours handle drawing sand into the hose, is it just a totally submerged pipe?
A couple of problems I've had: moisture in the air making sand clog the nozzle; sand too big. Yes, really. It was labeled "Fine", but I had to screen it before blasting because there were enough bigger grains to gather in the nozzle and clog it.
Yes, mine works by suction and the venturi effect just like yours.
Moisture in the air line will also play havoc with blasting, but that usually results in a slow degredation of sand pickup.
I don't use sand in my cabinet, I use aluminum oxide media that I order from the Eastwood company. Others will likely have recommendations for a cheaper source for blasting media.
Most times you can clear the gun by putting your finger over the end of the nozzle. This will blow the obstruction back out of the gun and pickup tube. Only problem is, now what was blocking the gun will be back in the sand. Every so often sift your blasting media through a screen.
Air compressors get hot when running steady and the air dose not cool fast enough before going into the moisture trap. What I did in my body shop was to run 50 feet of air hose thru a 5 gallon pail of water before the moisture trap to cool the air.
I'll try a wider nozzle tonight too, then and see if that helps. Being the cheapest rig available it has no moisture trap.
An easy way to dry out damp blast media in your cabinet is to place a trouble light down on top of the abrasives and leave it for a few hours. This heats up the cabinet above dew point and drives off the moisture.
From time to time, do what I call burping my gun. Hold my finger over the nozzle and pull the trigger.
I've tried burping the gun numerous times with no results. I've also tried just stopping and inspecting the whole works but I have never found any sort of jam in the plumbing.
Next places I'm looking are the nozzle itself and I'm going to try running the pickup a little shallower in the sump. I'm wondering if my media just isn't fluid enough to sink down to replace what's being drawn up, which I guess could also be a moisture problem.
If it turns out to be moisture then I'll be amazed by how dry it can feel while still presenting a problem.
Look for a hole in the suction line to the media.
I would take the gun out of the cabinet and take it apart and inspect. I have two instances were debris was sucked into the gun and was very hard to see until I A) took the feed hose off the gun, and B)took the nozzle off and inspected and cleaned well.
If that does not work, try clearing the pickup tube and hose with a wire rod---do not poke through the hose.
Is your cabinet like a bench top model? Or more like a standing floor model? I have the later, but borrowed a bench top version before I bought mine. Unfortunately, I think most of us overwork our compressors trying to use things like this.
I have a 5.5 HP, 30 gallon and it is really too small, but it gets me by if the compressor is in tip top shape which I try to do.
These are really simple devices, it is just finding the restriction.
It's just a little bench top model with my 3hp/11gal compressor trying to keep up. I don't think I'll kill the compressor any time soon but when it cycles so often it must be getting pretty hot. I try to do one part at a time, then go paint it while the blasting rig cools.
My next compressor will be much bigger.
I run 2- five horse compressors,and I made my own cabinet.It is five ft wide and three foot high and deep. I made my shoot a little to deep,so feeding the gun was a problem,untill I added an air lift. It is basically a small nozzle with 3-5 lbs of air regulated to it off the main line@125psi. I feed media out a 1/2 inch pipe tee at bottom and this small nozzle boosts the media up to the gun.Currently am using Black Beauty as a media. It is a lot easier on the gun and all the hoses .It also doesn't seem to be as subject to moisture/humidity.
Good news, anyone who said "clogged nozzle" was right. Turns out there was a flake of something wedged in there sideways that was impossible to see until the tip was removed and held up to a light. Five seconds and a coat hangar later and I was back in business, seemingly working better than ever. The weird thing about this flake was it didn't restrict airflow at all, it just messed up the Venturi flow enough to prevent any draw on the sand. Fixed now and as usual I can see I was wildly overthinking it. Thanks to all the forum members for pointing me to the easy answer first.
Jack, I'm also using Black Beauty media and it's a relief to see I'm not the only one. I got it because I asked a guy at work where to buy media and he just happened to have a mostly full bag free for the taking. I was unaware it was gentler on the equipment as the grains feel pretty sharp compared to the silica bead I was brought up on (for blasting aluminum aircraft parts).
I also went to the ceramic tips,and they out last all the others I have tried. I have over the years,worn out 6-7 guns. You learn that once the system quits,you have to first, find the problem,fix it, and get back to work.
The suction hose can be buried in the blast media. I agree with the other comments - you either have a blockage or an air leak on the suction side. Look for a cracked weld or a hole in the plastic tubing.
Glad to hear that you found the problem.
Try to rig up a way to attach a shop vac to the side of your cabinet to help give you a clearer view inside while you're blasting. The shop vac also helps lower the pressure in the cabinet, which helps to keep the media storm from leaking out around the door seals.
If your cabinet doesn't have one, putting a light inside the cabinet and turning off any room lights while you are blasting will also help with visibility.
Easy and quick help - probably not a total fix - is to make a little screen to cover the inlet. I made mine from brass screen wire (brass mesh) that has holes slightly larger than the media. It stops those little flakes from coming up and blocking the media flow to the gun. None of them are perfect. I'm on my 4th or 5th cabinet and have gone through probably a dozen guns. The best I have found for the money is a cheap Chinese one off ebay for $20 including shipping. Comes with 3 ceramic nozzles of different sizes. I've gone through a couple of these and just bought one for my brother. http://www.ebay.com/itm/Sandblaster-Air-Siphon-Feed-Blast-Gun-Nozzle-Ceramic-Tip s-Abrasive-Sand-Blasting/151699607156?_trksid=p2047675.c100011.m1850&_trkparms=a id%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D31192%26meid%3De328003e2667405e951 5ceac99598a98%26pid%3D100011%26rk%3D1%26rkt%3D4%26sd%3D181732825575
I just bought a bigger cabinet, have been going to make a new one for years but never have time so bought a used Atlas at an auction. I think it's the same one Grizzly sells for about $1400. Works fine for bigger stuff. I just did the seat frames out of my CJ2A, room to get them in and work on them.
I use glass bead, 70-100 grit. I haven't tried Black Beauty but this cabinet came with something black in it, I drained it out. Far too aggressive for brass.
7 1/2 HP Curtis compressor 17 CFM at 125 lbs, it's about ten or twelve years old, has run thousands of hours trouble free. Cost about $1200 then and has outlasted 5 of the cheap Chinese ones that seem to be what everybody sells.
I also have a 20 HP Gas compressor on a trailer and a Clemco sandblast pot and gun. Too much work for me anymore. Just took 5 Jeep wheels in to Les Schwab to have them sandblast and powder coat them. $30.75 each. I can't do it for that and don't want to. I have another gas engine compressor on a trailer with a 16 HP Wisconsin engine and a 12 CFM compressor. Both of the compressors are military surplus, got them for almost nothing years ago at government surplus auctions. The big one had never been run, I mounted it on a trailer, the smaller one was used, needed the carb cleaned.
Running your compressor out of air is frustrating. The thing to remember is that the amount of air is not as important as the flow of media and the air pressure. One of the things with the cheap bead blast set ups is that they flow too much media. If you have a lot of media coming out of your gun you will be trying to blast the media instead of the surface of the piece you are trying to clean. Make a restriction for the end of the pickup tube that is about the same size or slightly larger than the nozzle orifice. Use the smallest orifice you have for your gun. It will work far better, will give you steady air pressure and much longer blasting time. Try to have a stream of media coming out the gun that you can just see. Good pressure and it will clean just fine.
I'm off to the shop.
Tim, That "Black Beauty" blasting sand is supposed to be healthy to breath while sand inhaled is not good for your lungs. (cost is more than sand I believe)
Guys, check out www.idsblast.com and give one of my guys Jeff or John a call. They will be glad to answer any questions you have.
Here's another thing that helps if you have a good vacuum on the cabinet. Which ever hand you are holding the gun with -- take a look and find a spot where your glove is not tight against the gun. Cut a hole in that spot. The vac will pull air through the sleeve, keeping your arm and hand from sweating so bad inside the glove and sleeve and the air flow will pull the dust away from where you are blasting so you can see better. I punch the hole about where my knuckle is on my little finger. You might occasionally get a little bit of sand blowing back and hitting your hand. It's OK. If you don't want to punch a hole in those brand new Chinese gloves you could tape a piece of hose to your glove I guess but I have a hard enough time keeping track of two hoses.
I just came in from standing in front of mine for about an hour. Gets old after awhile.
Neat idea, Stan! Yes, blasting gets old, even using a cabinet. I have a tall stool that I can sit on while blasting, or I can stand. I also wear earplugs when using blasting to muffle the whine of my shop vac.
I have to stand in front of both of mine. I've tried sitting but can't see then. I ran the hose and cord from the vac outside through a hole in the garage wall and it really helped on the noise. The bigger one I just got really screams. I'm going to put a different type vac on it. Too loud, drive you crazier.
One thing that helps is to use a floor control instead of the sqeezy trigger. If you don't want to pop for the $50 or more for a step on one, just get a ball valve type with an arm type handle and clamp it down to a piece of plywood. (stick the plywood under one corner of the cabinet to hold it down solid) Run a bolt up though the handle and screw a golf ball (or old Ruckstell shift knob) on it and you will be amazed how quickly your foot will adapt to turning the air on and off. That's what I had on my first one for several years. In some ways I liked it better because you can turn the air on and leave it on, feather how much air is coming through; don't have to have your foot stepping on the pedal so you can't move around and you aren't pulling the trigger, getting a cramp in your hand and aren't restricted to one hand position. If you don't have to pull the trigger you can hold on the hose and wave it like a flag pole to blow off a piece you can't reach.
Coffee over, back to the shop.
I used the blower from an old clothes dryer and hooked it up to the overhead light.Turn light on and it is also evacuating cabinet. I ran the 4 1/2 inch vent line out side of shop,so all the dust goes with the wind. You don't need a lot of vacuum on cabinet,just enough to be able to see. Mine has been working for 25 years now.