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Thread: siphon type sandblaster
05-20-2007, 03:17 AM #1
I have a Cyclone brand sandblaster; the siphon type, not the pressure pot type.
It is absolutely pathetic.
I'm running a Gardner Denver 80 gallon 5HP compressor with refrigerant air dryer, and a second filter-regulator in the line to get dry air.
I'm using (or trying to anyway) fine glass beads to prep aluminum surgical instrument handles for clear anodizing.
I'm having a helluva time getting the siphon to suck up any glass beads...it comes out of the nozzle in occasional little spits and pathetic little dribbles.
I seem to be mostly blowing air.
I'm running at 100 PSI.
I've tried burying the pickup tube in the glass beads...no joy.
I've tried laying the pickup tube just above the surface of the glass beads...a bit better, but I constantly have to adjust the position of the pickup tube to keep it close enough to suck up the glass beads.
The suction at the end of the pickup tube is pretty weak, but there is some.
It seems to me, that the glass beads are plugging up the end of the pickup tube when it's fully immersed in glass beads, but I can't think of a design for the pickup tube end that will not clog with the beads almost immediately.
Can anyone recommend a pickup tube design for fine glass beads?
Failing that, can anyone recommend a quality brand of siphon type gun and pickup that I can buy and fit to the cabinet?
Thanks in advance.
05-20-2007, 03:38 AM #2
I bought a siphon type at Sears many years ago. While it kind of worked, when I went to a pressure type, that worked much better and seemed to use less air with small nozzels. It definately put out more sand.
05-20-2007, 04:37 AM #3
Does your pick-up tube have a bleed hole in it so that you get a mixture of air and beads? Sounds like it doesn't or it is the wrong size and that is why it sorta works when you lay the tube on top of the beads.
05-20-2007, 07:00 AM #4
05-20-2007, 10:25 AM #5
I have used the siphon type and while it does work, it does not work nearly as fast as the pressure type. If you want to go 3 to 4 times faster than the best a siphon type can offer then get a pressure type.
05-20-2007, 11:40 AM #6
I was disappointed with the performance of my siphon blast system. It used a lot of air and worked about the way you describe. I switched to a pressure pot. It has a few new bugs (mainly associated with moisture), but works a lot better than the siphon system. The siphon parts are in my recycle bin. WWQ
05-20-2007, 12:26 PM #7
I to have move from the siphon to a pressure system. Would never think of using a siphon again. Pick mine up HF and for the little that I do it is OK. And that is speaking as a painting contrator. Only good for small jobs. Remember the PSI= the amout of work it can do. In fact I tie my little compressor in to my larger one just for the higher psi out put. It will pay you to more on in time blast med and air from the siphon.
05-20-2007, 06:26 PM #8
My cabinet type bead blaster has a siphon type pickup. It has a piece of steel tubing that runs from the left rear of the cabinet, down thru the abrasive, and back up at the right pront corner where its attached to the abrasive hose going from there to the gun. The tube itself has some small holes down beneath the abrasive level, and the end was originally plugged with a stopper with a hole thru it to act as a restrictor for how much air it could suck in.
I put a ball valve on the end of the tube so I could adjust the air for various grit, and that helped a lot in smoothing out the abrasive flow. If I close the valve completely, which simulates the pickup just buried in the abrasive, then it spends about 5% of the time blowing out excessive globs of abrasive and 95% of the time just blowing air. With the valve wide open, it just blows air since there's never enough suction to pull and significant amount of abrasive thru the holes and into the tube. The setting where it works best is much closer to fully closed than to fully open. In addition to the nozzle, the other wear item in the gun is the abrasive nozzle which is not typically visible. If either one is worn past its useful life, you'll have problems with excessive air use and uneven abrasive delivery, or both. I run DuPont Starblast in my blaster most all the time, and the nozzles are good for roughly 100hrs of blast time before they start showing signs of wear that causes poor operation. Both are carbide, and IMO its a waste of time to fool with ceramic versions of either part because they wear so fast. Borazon nozzles would last near about forever, but their cost would be hard to justify on a bead blaster.
Teh blast nozzle itself should have a venturi cross section for the most even abrasive dispersion but that's something you'll hardly ever find in a typical cabinet blaster. A cylindrical nozzle tends to blow air thru the center and abrasive around the periphery whereas a venturi nozzle gives an even mix of air and abrasive across the pattern. The difference shows up in stark contrast on a bigger blaster. We've got a larger Clemco pressure pot type blaster, and found the difference in blasting speed and results was pretty amazing when we replaced the cylindrical carbide nozzle with a Borazon full venturi nozzle. Only problem is, that nozzle alone cost about as much as a fair sized complete cabinet blaster sells for.
If you do a lot of this type blasting (texturing of aluminum), you might want to keep an eye out for a vapor blaster. They give results that are hard to match with a dry blaster IMO. However, you'd have to dedicate the blaster strictly to aluminum, since blasting any sort of ferrous stuff in it will cause discoloration and staining of aluminum that's blasted afterward.
05-23-2007, 01:51 AM #9
Thanks for all the responses and information.
I was all ready to deep six the Cyclone sandblaster and buy a new pressure pot style, when I decided to try making a new siphon tube with a couple of small side holes in the inner tube and a larger outer tube to promote better airflow and slow down the ingress of the glass beads.
It works...like a hot damn!!!
I blasted all my 200 parts in a couple of hours...they look gorgeous, and I don't have to drop 1500 bucks for a new sandblaster. (never mind the hassle getting rid of the old one would have caused).
So my faith in siphon type blasters is somewhat restored.
All it took was a bit of jiggering.
05-23-2007, 07:46 AM #10
metalmunchr speaks the word on siphone types
esp. the gun parts
[ 05-23-2007, 10:28 AM: Message edited by: wippin' boy ]
05-23-2007, 11:14 AM #11
My siphon sand blaster's pickup tube is a bit different and works REALLY well.
It's a smaller (sized to fit air hose, 3/8?) tube INSIDE a larger (5/8 ish?) tube. I crimped the assembly in the middle so they stay together (a through bolt or some pop rivets would work). They are flush on the bottom, the inner tube is a bit longer so it's easy to hook u the air hose.
I leave the tube loose and if it jams, I just pull it out of the sand, hold my hand over the end of the gun and squeeze the trigger. The offending jam just blows out the end of the pickup tube and I'm back in business.
This setup allows for surface level pressure, down inside the sand burm. When I'm low on sand, I keep moving the pickup to keep it buried.
This setup seems to work a bit better than the hole right above the sand level.
05-23-2007, 11:17 AM #12
I was going to add what Tools said, I just hold it tight against the inside of the cabinet and pull the trigger...kind of a powered backflush if you will.
05-23-2007, 01:05 PM #13
Here is a tip -- If you are recycling media, make sure you are somehow screening out rust flakes and such which will plug up a siphon pickup. I put a window screen below the expanded metal floor on my homemade blast cabinet to serve this purpose.
05-23-2007, 01:42 PM #14
I have the large H.F. bead blasting cabinet with siphon feed. It works great! The design of the siphon tube is the key to getting good performance. Apparently a small hole is needed about halfway up the tube to provide some bleed air to get things started. I've run various grades of glass bead, walnut shell and soda at varous times to good results.
I also use a vintage Cyclone Brand Vacuum dust collector unit mounted on a 55 gallon drum wih a large bag to collect dust and keep the field of vision clear. It is powered by a 2 HP 3,750 rpm Baldor. You could suck a bowling ball into it if you wanted to. [img]smile.gif[/img]
The original H.F.gun was terrible with the ceramic tips so I purchased a Snap-On gun which has a carbide tip and center orifice. It's been runing all grades of beads for more than ten years ever since and the tip and inner orifice still look like new with NO WEAR.
The only thing I do when I start using the machine is to briefly prime the system by putting my finger over the tip while pressing the air lever. This clears the tube and it will work fine while you use it. This is not absolutely necessary but it helps.
I power it with an 80 gallon verticle twin stage air compressor that does 18 CFM at 100 psi. It cycles nicely while I'm using it. If I had a compressor with much less volume it would probably run all of the time.
05-23-2007, 01:52 PM #15
Years ago I had a small gun, Grainer, probably. The only way I got ANY decent performance was to modify the sand hose to a much larger diameter, and built a gravity feed hopper out of a refrigerant tank, and even then had to "stir" the media frequently to avoid plugs. It did work much better than the siphon setup.
05-23-2007, 02:17 PM #16
I gave them all away, pressure pot included.
Pathetic is a perfect word.
That was with 5HP two stage compressor.
But then I was trying to do big stuff.
Like using a pencil eraser.