Siphon gun and Pressure pot blaster?????

[jamie392]

This is a weird question but I got a discount 10 Gal pressure pot sandblaster on clearence. The blaster didn't come with a gun or nozzle... The guy in the clearence part just added in a siphon gun kit. I'm not sure if he knew what if it would work, and it seems kind of strange to me. I guess I can hook up the sand mixed air hose from the pressure pot to the input on the siphon and just not connect air to the gun, and it should work.. But do you think it would work half as close to the real nozzle/gun that usually comes on the pressure pot blasters?

I don't want to be fighting with it or struggling with it. I want it to work properly but if I can get away with this set up I will stick to it as I'm short on money.

Thanks a lot
Jamie

[Phil V]

It will probably work for a short while but the pressurized sand will eat a hole in the shiphon gun. Not only that but how are you going to control the sand and the air going into the siphon gun. Most pressurized blasters have a ball valve right near the ceramic nozzle to the shut off the sand when needed.

[AlexeiVT]

I'd just check around and see if you can purchase a replacement "proper" end for a pressure blaster, from any one of numerous discount places (Harbor Freight comes to mind).

I think the Ball Valve type works better than the cheap dead-man valve setup...but in either case, you'll at least need to start w/ one or the other, because the improtant part is the piece that threads to the ball valve (or deadman) and retains the nozzle in place.

As I recall, the dead-man type (the cheap one, mind you) was probably only $10...but, it failed soon after, since the sand ate away at the guts inside pretty quick.

The ball-valve, on the other hand, holds up pretty well (if you get a case-hardened steel one)...but even if you have to replace it, in a pinch a standard brass ball-valve would work (sure, it'd get chewed up faster...but they are cheap enough, readily available, and fairly universal).

It'd probably be better to at least get something closer to what was originally supposed to be on there...because there's nothing quite like the feel of 100 lbs of air pressure, mixed in with sand, whipping around unpredictably when you least expect it...plus, the ball valve setup will accomodate a significantly larger diameter hose, to allow for more material flow and less clogging.

Keep your sand dry and well sifted, and your incoming air filtered...and even when using the "right" components, this can still be a challenge to maintain...when you constrict it even more at the output, chances are only higher that you'll just get more problems in maintaining the flow...but nothing is impossible, just working against you more.

[AlexeiVT]

Also, keeping in mind the way the sand flows between the two.

On a siphon blaster, it comes in a basically 90 degrees to the head...now this is OK, and holds up for a while w/ siphon blasting, which is inherently less efficient and lower actual pressure (as I recall, it's when my first head, and replacement head, on my siphon setup wore out, that I switched to pressure blasting).

The pressure blasting nozzle, is basically setup to run in-line w/ the material flow. Sand still does take its course on the material finish over time, but just figure how much more accelerated the process would be if the sand was hitting at right angles to the gun...it'd blow a hole through the top of the siphon feed gun pretty quickly...after all, it is just blasting straight up, w/ all that pressure, against what generally are zinc or potmetal parts.

[Ron H]

Jamie, I have a hf 110lb unit, I think it is 20 gal. I don't see how the syphon feed gun would work. The blasters work on two interely different principles. I have only used the ball valve set up that came with my unit. It works great. I would recommend only running 45lbs of pressure and open the sand feed valve only half way, the valve is located on the bottom of my tank. I would recommend waiting until you can afford one of the correct gun/valve setups before starting. If you decide to try the other gun plug the unused hole. Ron

[Ron H]

Dead man nozzle in hf mailer received today for $9.95.

[AlexeiVT]

I'd avoid that Harbor Freight deadman valve (that was the type I referenced in my earlier post).

When you go w/ the ball valve setup, it's a simple and durable, and reliable design.

The HF "dead-man" valve, is not actually a true dead-man valve setup. I tried one, and it didn't hold up very well, didn't last long, and only worked properly a few times...whereas the ball valve setup has seen quite a few bags gone through it w/ not much wear.

The HF dead-man, had a pretty weak internal design...I took mine apart to see if it could easily be repaired, since it always leaked air. It works by having a spring pressure in the lever, atually pinch down on a flexible internal rubber tube. That rubber tube has all the sand going through it at full force. Mind you, that tube is a hole lot more flexible, has a much thinner wall section, and is a much smaller diameter than the proper sandblast hose that comes out of the tank...all meaning that there is a lot of material running through that, and it wears out pretty quick in a short while, and you have sand spraying out of the top of the valve.

A true dead-man valve, has a rubber block that closes over the front of the nozzle. The real deal costs considerably more than any HF alternatives, and then you have to also factor in the much higher cost for the associated nozzles.

Your best bet, is going w/ a ball valve setup, not only for the sake of durability, but also for ease of use...you just basically open the ball valve up all the way and start moving, adjusting your sand/air ratio...w/ the cheapo dead-man, your hand gets tired pretty quick, just because you have to keep on squeezing to keep it open.

When you blast, you want the actual hand held portion to be either fully open, or fully closed...anywhere in between and you're just wearing out the surfaces that chewed up by the sand, at a faster rate than normal, and you'll soon develop leaks, meaning the compressor will cycle and needlessly push air through a setup that isn't closing all the way.

[AlexeiVT]

Hmmm...l took a look at the new HF dead-man valve, and it's a different setup than they were offering before. The one they have now, actually does seal off the flow w/ a rubber block vs. what they had before that actually just pinched and internal hose. So who is to say whether the new is any better than the old...I'm still opting for the ball-valve setup.

[jamie392]

Thanks for all the advice! I actually just built one myself for 15 dollars. I'll post pictures later but it works awesome probably better then most of the ones you can buy. I got one of the huge cone tips... probably about 4 inchs long by 1 inch at the base, and got a dead man valve, some pipe a coupler and some hose and put it all together. It works perfectly!

Now I just have to figure out the settings, it seems I either have to much sand pooring out or to little. What settings do you guys usually use? half on the sand, half on the air?

Thanks
Jamie

[AlexeiVT]

I usually blast w/ 100 lbs of air or less, and regulate it down to that PSI at the tank or inline w/ the air supply.

At the pressure blaster, I run w/ the air valve wide open.

When I start fresh, I generally start w/ the ball valve on the bottom of the tank, nearly or fully closed. Then I'll open up the handheld nozzle and valve assembly fully, once that's open, I'll play w/ and tweak the sand control valve...giving things just a moment to equalize.

Having clean dry sand that isn't too powdery yet, is essential to things moving through easily. When it gets broken down and reused, it tends to settle in much more densly, w/ little air space between grains (it'll still cut, if you can see through the cloud...but it's nearing time to change to fresh media when you get to that point).

The HF blaster that I use, has comparatively smaller (and cheaper) replacement ceramic nozzles, and the ID of them is about 1/8" or so (they vary of course, due to media, so a worn one could throretically be used w/ coarse media).

Not sure what the specs are on the handset you fabricated, but you'll know soon enough if it's working ok...too large an opening and you wouldn't get the high pressure and high flow at the nozzle...but so long as the orifice is similarly small, all should be ok.

[AlexeiVT]

Also, I forgot to mention...don't fill the hopper tank all the way to the top...at about 3/4 full or so, you've got the air pressure working on your side w/ just enough puch inside the tank to help things go/

I try to get the most out of my sand (before putting it in the compost heap over the groundhog's nest) which inevitably leads to a clog. Having a coat hanger on hand, to prod up inside the bottom of the hopper w/ the sand regulating valve removed, has saved an otherwise less than productive blasting session.

Better units, actually have a threaded tubular post, w/ holes cut into it, that extend up into the hopper, thereby reducing the problems associated w/ compaction of nearly toltally spent media.

For my blast setup, I eventually fabricated a cheap booth from leftover wod I had laying around, covered w/ thick mil plastic (which the roof only seems to last a year after the UV rays get to it)...but, so long as the item your blasting is set out on a crate above a tarp, and you have a semicircle of tarps to capture the bulk of heavy media that isn't broken up, you'll end up w/ enough useable media to blast quite a large surface area.

Picklex is great too, if you later intend to topcoat w/ epoxy...you can blast and wipe it down and store it inside, and the metal surface will keep indefinately w/ a rust free finish so long as it's kept from the elements.

[Ron H]

Jamie, try setting your air at 45lbs initially, and the bottom valve halfway open. You can easily warp your panels with too much sand and air. You are only removing paint, it doesn't take much. I use my sand usually three times. Sounds like your tip may be larger than what I use, although it is the inside diameter that counts. I would start with the jams or other contoured surface when starting so you con't have to worry about warping a "flat" panel. Hold your nozzle at an angle to the surface. I can barely see the sand coming from the nozzle when I use mine. I have a date this weekend with 200 lbs of black beauty (sand not a woman) myself. I also try to hit rusted areas with newer sand, as the new sand is 'sharper' and cuts the rust better. If you don't use tarps to catch the sand you will think you have moved to the beach. Also remember to use a good respirator and a hood with safety glasses, and a pair of leather gloves and long sleeves. Ron

[AlexeiVT]

Keeping the nozzle moving is the key (and I guess I take it for granted myself)...I've seen plenty of warning about cautioning against blasting for fear of warping panels, but I myself have never experienced any problems.

I've blasted full size hood skins w/out the reenforcement bracing, doors, fenders, and quarters, and have never had an issue w/ warping.

I suppose it's like anything else...if you have heavy duty equipment, and are dead set on holding the nozzle in a single place until it's destructive, well, maybe then you'll have problems (they do make sandblast equipment to clean long span bridges...and obviously, that's not what you want to use on your car, even tuned down)...but seeing as you have what's the norm for this, I think you'd actually have to go out of your way to create problems. Bigger equipment is only more effecient when you know how to use it...a smaller DIY setup may take you longer to accomplish the job, but you do so w/ much less risk of distorting the panel...some pro blast shops don't differentiate between setting the pressure and material flow rate up at it's highest, to get the job done quickest (if you're talking frame rails or 16 gauge steel, not much to worry about...but when you go to 18-20 gauge sheetmetal, being patient during the blasting, pays off big-time when it comes time to prime).

No need to clean everything off on the first pass...rather keep things moving all the time (if you get a crusty corner, then maybe you can work it in place till it cleans it off).

I set mine at 100 PSI, which means that shortly thereafter, and from that point on, I'm loosing pressure...get too low, and it's enough to keep any effective sand flow.

Rather than wear heavy gloves, I just wear a pair of nitrile gloves (much less bulk, and does the job needed)...When sandblasting, and the amount of air flying around, coupled w/ the drying out effect of the sand, I find that simple gloves keep the moisture in the hands, so they don't dry out and crack. Of course, I make it a point not to blast directly at my hands or near them w/ anything I hold, so haven't felt the need for heavier hotter gloves.