Fixing a Sputtering HVLP Gun

      A part replacement does the trick. January 27, 2007

My SATA Minijet 4 has a problem with sputtering (sounds like the air flow). It has never done this until recently (the last month). I am careful to clean it well after each spray. Everything is well kept. I've looked on the SATA website and all they can offer is that it could be many things. All of which I think I have done correctly. The one thing it says is that if the air-flow distribution ring is damaged, it will sputter. How do I know if it is damaged or not? It looks okay to me, but I'm not that experienced in this area. What could be the problem? I'm spraying the ML Campbell Krystal Clear. Also, even though it sputters, it still lays on relatively smooth/level.

Forum Responses
(Finishing Forum)
From contributor G:
I can't figure out what the air-flow distribution ring is. If the packing where the needle goes into the gun is damaged or loose, it will sputter. Tighten the packing nut a bit and put a bit of Vaseline on the needle where it contacts the packing.

From contributor J:
Contributor G is right. A loose packing nut will cause sputtering. Another cause is a loose fluid nozzle. To properly tighten your needle packing, trigger the needle (with gun off line of course) and tighten the packing nut until the needle won't seat into the fluid nozzle when released. Then loosen the nut until the needle snaps forward.

From the original questioner:
I have been reading through documents about this gun and found that the airflow distribution ring is probably the reason it isn't working. Well, I followed the directions on removing the ring and the plastic positioning pin on the back snapped off. It looked dried up and there were particles of old lacquer stuck back behind it. So, I just ordered a few more rings and did a really thorough cleaning of the gun. I took apart the (packing nut? - the thing that the needle sticks through with the spring/plastic gasket). There was a lot of old lacquer stuck in there as well. We cleaned it up so it looks like new, so hopefully one of those things will have fixed the fluttering problem. The new rings will be here Monday.

From the original questioner:
The part finally came in. We replaced the part in the gun and the gun works like new! I am very pleased with the finish we are getting now. Next, we need to order a gallon of gloss Krystal and try it out! So, the air distribution ring was the problem after all.

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