Badger 360-cup backpressure and erratic output issues

Sounds like, as you mentioned, tip dry.

I use Pollyscale, and I had fits with it until I got some help from Triarius. Some of this may help with MM Acryl.

I used to shoot it straight like you mentioned- you gotta thin the paint. The rule of thumb is to the consistency of 2% milk. It's hard to declare a strict ratio- it'll vary by bottle and even how much paint is left in the bottle. A way to see what 2% consistency is to pour some 2% milk in a mixing cup and see what it looks like. Sounds simplistic but it worked for me.

Also- add some acrylic retarder to your thinner. This can help. And Ithink the MM Acryl thinner is alchohol based (though I am not sure). That would make it dry fast, so maybe an alternative thinner? Not sure if water, like for Pollyscale, would work? Maybe Windex?

Another thing that really helped for me was to lower the air pressure. I normally shoot at about 8-10 psi froma gravity fed brush.

Try adding some needle lube to the needle.

Keep something handy to clean the needle in while you are working. I take a cotton ball, stick it in a soda cap, and soak it with Windex. If I do get some tip drying, I stick the end of the AB in that.

As for the cup bubbling- that could be a by-product of the tip dry, since you said it happens only at higher pressures, but I'm not real sure what to advise there.

Hope some of this helps you out. I know how frustrating it can be. I almost gave up on Pollyscale until Triarius came to the rescue.

As Jon has suggested above, it sounds as if your paint isn't thinned enough.

I have, on occasion, had similar problems airbrushing Tamiya metallics when insufficiently thinned. (Metallics typically have fairly coarse metallic particles which can settle quickly in your airbrush cup and clog the innards in no time at all.)

When your paint flow stops, if you release the trigger (closing the needle) and you get a very short burst of irregular paint spatter, it usually means the nozzle is clogged and the needle returning to the "closed" position is squeezing a little of the paint in the nozzle out into the airflow. 

I'm going to take it a step further and suggest that you give your tip/nozzle a thorough cleaning. You may have compacted dried paint inside the nozzle further restricting the paint flow. Remove the tip/nozzle and soak it in lacquer thinner for a couple of hours.

Take a really, really close look at the tip.

I had problems almost identical to yours and tried everything that you have tried and nothing worked. I soaked the tip and the nozzle in thinner over night. Nada. I tried everything I could think of as well as suggestions found here. Then one day I took the tip off of my 155 and swapped them out and everything worked fine after that.

Turns out that there was a very fine crack in the 360's tip. I haven't had any problems (besides operator error) Since I did this.

Hope this helps.

Jeff 

sounds like tip dry is the issue. work at the lowest pressure possible depending if you're using it as a bottom feed or gravity gun at the time (the higher the pressure the faster the paint dries), also may want to try some needle juice to stop the paint from clinging to the needle.  the previously mentioned retarder or exetender is also helpful, especially if you're in a low humidity environment where paint also dries faster.  If nothing else works - Badger has the best CS in the airbrush biz - you can always conatct them for help.

koz out