gun question

[davew]

Could anyone tell me if a siphon feed gun can be converted to a pressure feed by just connecting the feed line to the bottom of the gun in place of the siphon tube?

Thanks in advance for any help!:confused:

Dave

[Phil V]

Yes it can, BUT the problem is the fluid tip and air cap need to be changed from siphon feed to pressure feed setup. Without the right fluid tip and air cap it will do a crappy job of atomizing the paint etc.

[Warren]

I converted all of my old suction guns to pressure 15 years ago. How they work will depend on the cup and how it fastens and also the gun itself and how you dial it all in.

The old sharpe 775's will leak with over 3 lbs pressure in them cause the tips were never lapped to the nozzle, still I sprayed a ton of NC lacquer with those and low pressure and way way oversized nozzles turned down and got absolute glass smooth finishes. Yes they were prone to leaking and so I had to watch out.

Got Devilbiss 510's which are 502's do not leak with up to 15-20 lbs pressure.
Never used the Sharpes again. The Devilbiss worked just wonderful run pressure even though it is considered a suction gun it goes both ways.

In each case a suction cup is not meant to be pressurized however if you reef on cup hard so it is really tight they will work and not leak and I have used those things 1000's of times. I can tell you for sure it works and it works well. The last custom furniture job I had to run 6 guns two of them were pressurized suction Dev 510's.

I removed the curly metal tubes in all my cups and plugged them. Then I drilled and tapped the top portion and put a fitting that screws in and allows you to push fit a 1/4 air line. Sharpe makes a gauge that allows the air to go through the gun at the set pressure and you run a line off that gauge to the cup, usually 3-5 pounds will make a big difference. On of the best improvements was pressurzing my contact cement gun. 3 pounds pressure and 30 at the cap delivers more fluid than 60 pounds of air could do.

Usually I run pressure with a pots and a 25 foot hoses and that is by far the best for me. I stick two battery warmers on each pressure pot and monitor them with a digital heat gauge.

Usually the angle of the needle and the nozzle are different in pressure guns as a small change in the fluid screw makes more of a difference as the material is under pressure. I have also run Sata gravity guns removing the cup and running fluid lines run to them.

Too much pressure with too thin materials can cause problems but when it is dialed in you can get excellent finishes with less overspray cause you are now getting the material to the cap by pressure rather than suction. You can use what air you need to break up the material and most of the time I get away with using less or sometimes alot less than what the gun is supposed to run at.

I first saw the pressurized cup on an Accuspray Series 10 I bought maybe 20 years ago or a bit less but I hated the gun and never even gave it a chance

I primered a few cars with pressurized cup guns and they came out glass smooth. Aways filter the material and maybe even twice cause if you you let off on the trigger of a pressurized gun and there is a speck of dirt in there the needle may not seat and it will leak.

Pressure is wonderful when you have used it for a bit and are used to it.

Warren

[Warren]

Years ago I took a Sharpe Primer suction gun and took the cup off.

Turned it upside down and put a gravity feed cup on it. Then pressurzed the gravity feed cup and used the gun to spray polyester primer. It worked great as well though at first holding it upside down was stange but it wasn't too bad either.

Warren