Tip Clogging in Air-Assisted Airless Guns

      The low pressure and low flow can lead to a lot of clogging at the tip. Here's some discussion about filtering and cleaning.December 6, 2011

Question
I recently purchased a cat AAA set up and am having problems keeping the tip from becoming clogged. I知 using the 411 tip in the bobcat gun and am spraying MLC Krystal and Krystal sealer.

I知 leaving lacquer thinner in the lines and hopper when the gun isn't in use and I soak the tip and retention ring in thinner as soon as I知 done spraying. I just started running thinner through the tip as I知 flushing the lines (previously, I just took the tip off before flushing the lines and put it in thinner). Is there a better procedure? I still probably push/spit clogs out when finishing and have had the gun clog almost every time I use it. This might be part of the problem as I知 using it 5-7 days a month.

Forum Responses
(Finishing Forum)
From contributor J:
You probably need an in-line filter. I put mine on just before the gun. Filter your material wherever you can. I have two filters - one at the pump and one at the gun. Tip clogs are the most frustrating thing about airless.



From contributor P:
The CAT guns have an inline filter at the gun. Check and clean it often. It's amazing how much stuff accumulates there in spite of using a pickup tube filter.


From the original questioner:
How often do I clean the in-line filter? I cleaned it yesterday after it spit a bunch of stuff all over my work piece. I added a filter to the hopper and a lot of stuff still seems to get past.


From contributor P:
For now, I'd check it every time you clean up. If you don't see crap on the filter, your problem lies elsewhere. If you're catching a lot of stuff, it will be obvious, because it will be stuck to the outside of the filter. Are you seeing buildup on the outside of your tip, or does something clog the tip from the inside and stop up the gun completely? If it's buildup on the tip, keep a stiff toothbrush and a cup of solvent handy, and scrub the tip as needed.


From the original questioner:
Build-up is inside the tip and causes inconsistent spray patterns. Very annoying since it isn't easy to unclog the tip. The in-line filter has had a bunch of stuff in it when I致e cleaned it before.


From contributor G:
Also, if you add up the time spent wrestling with the clogs, you will find most of your day/night is clog time. I find that most our time was dealing with clogs even with fine finish Reversa tips, when doing lockers at night. A good design, the only one that works is strain the paint, fine gun filter, fine tip filter (essential), and Reversa-tip. Only problem is the stacked washer filter (way better than just filter boss alone) are hard to find. Most Reversa tips will not allow filter boss backing.


From contributor M:
I have the same CAT setup, except I use a 511 tip. I added a high pressure filter at the pump. So I filter at the dipstick, filter at the beginning of the fluid line with the high pressure filter, and filter at the gun with the little filter built in to the gun. When I am setting the gun down for any more than five minutes I pop the tip off and throw it in a jar of thinner. It lives in the thinner when not the gun. Every time the tip comes off, the gun gets wiped down with a thinner soaked rag, especially around the tip area.

When shutting down the pump, it gets flushed really well with thinner, then the thinner is left in the lines under pressure until the next use. I only spray CV. CV is nasty because it sticks to everything like peanut butter and once cured, nothing will eat it away. You have to be very diligent in your cleaning when you use CV. Another suggestion, get one of those ultrasonic jewelry cleaners and use it to clean your tip and aircap periodically. Also stay on top of cleaning/replacing your filters.



From the original questioner:
The hopper system didn't come with a filter in the hopper so I took off the mesh from a paper filter and installed it.It seems to help a lot. Contributor M - where did you get a high pressure filter?


From contributor M:
I got the filter as a recommendation from my finish supplier. Mine is not made by CAT although I do think they make one. Whoever your local spray equipment dealer is should have them for you as well. They are about 2.5" in diameter and about 6" tall and the get attached right at the pump. Disconnect the fluid line from the pump and put the filter right there. It helps even out the winking that can occur when the pump pulses.



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