Paint gun not working well

[rockdogz]

I just shot some primer today for the first time in a while, and was reminded how poorly my paint gun was working. I have a DeVilibiss Finishline III, and I don't think it has been adjusted correctly from the start.

When I paint, it comes out splotchy and the gun seems to pulsate instead of flowing smoothly. The paint dries with a pebbly texture and not smooth. I have a gauge/regulator on the gun, and it seems to be useless because no matter where it is adjusted, it shows 100psi while not spraying, and 0 while spraying.

My guesses on what is wrong vary from a gun that is not adjusted correctly to air supply issues ( I have a relatively cheap 4.5HP 21 gal compressor) to a problem with the gun itself. Does this sound like too dry of a paint mixture coming out?

[ProdigyCustoms]

Sounds to thick amoung other things, you probably need more reducer. You are going to struggle if you don't get a regulator that reads properly. Consistant pressure is very important.

[68protouring454]

also you want at least a 1.6 if not a 1.8 for primer, also the finish line you want about 23 at the regualtor on the gun, you do have one right??
the finish line is easy to set up, the fan adjustment is simple, its fine to use it fanned all the way out, then have the trigger so it opens all the way then crank stop in one turn or so, some pics maybe??
jake

[rockdogz]

I have 2 different tips, but I didn't see any markings on them. How do you tell what size they are? I'll try to take some pics, or maybe even some video would be better...

[Happyfunballs]

Most Finishline's come with a 1.5 fluid tip and needle. Just reduce it another 10%(you want the viscosity of 2% milk) and you'll be good to go.

[68protouring454]

seems alittle thin for urethane primer, anyway, is it a finishline or a craftsmen which is also a devilbiss finishline, on second tip the box should be marked, also on barrel of plastic tip it should have size, if not most all autobody stores will have these tips, go get a 1.8 for priming, you can also get a 1.3 or 1.4 for base clear, they are like 15 bucks
jake

[Happyfunballs]

My suggestion for viscosity is a typical rule of thumb for most spray guns. There isn't anything wrong with over-reducing primer. It's perfectly normal procedure to reduce orange peel during the last few coats. And it also works well to get it through a gun if you don't have the IDEAL equipment. It was a suggestion to adapt his material to fit his process, rather than spending additional money on equipment. May want to ease-up on the criticism, remember, we're trying to help them.

[68protouring454]

i did not mean it for that i was laughing at the comparison, not making fun, sorry i did not state it a different way, no prob here
jake

[JoshStratton]

This is the best forum out there for painting tips. Unreal the amount of knowledge you can find there:

http://www.leopardsystems.com/paintucationforum/

[Happyfunballs]

:smoke:

[rockdogz]

Ok, so I stripped off all the epoxy primer I shot last weekend that was mixed with reducer instead of catalyst :doh:

Then, i mixed up a big batch of primer with catalyst, and decided to test on some cardboard. Well, it's really not working now at all. The spray coming out was not giving any coverage at all, and while I was trying to adjust the spreader adjustment valve to vary the mix, the primer just started dripping out the front of the gun.

https://static1.pt-content.com/images/noimg.gif

I think something's got to be really wrong here - do I have all the pieces to the gun?? I had a feeling that months ago when I was cleaning out the gun, I used compressed air and blew a necessary piece out and lost it - maybe a seal? Here's what I have:

https://static1.pt-content.com/images/noimg.gif

Are these all the pieces?? After I was cleaning up I noticed that the fluid tip seal was mushed - on the left is the mushed one and on the right is a new one. Could this be the problem and letting the primer out?


https://static1.pt-content.com/images/noimg.gif

Finally, here is a short video capture (I took more of me spraying but it's a little far away to see much) that shows the regulator valve go from 80psi when not spraying to about 20psi when pulling the trigger. I did find out that I'm using a 1.6mm tip, spraying DP40LF with DP402LF, 2:1 not over reduced (can you over reduce with catalyst, and do I need to with a 1.6mm tip?)

video, about 300k (http://www.camarorestoration.com/videos/paint.wmv)

Here's how I feel after today after wasting at least $25 worth of primer: :banghead:

[68protouring454]

tom, no you cannot over reduce with catalyst, BUT you can over catalyze it, the catalyst is the hardner and you should not mess with less or more of it, mix exately how it says too, buy some mixing cups at paint store, they are like 30 cents each and use them always.
tom the pressure before pulling trigger is fine, thats how much pressure you have coming into spray gun, that is normal, it is a hvlp gun, you want it to be around 20-25 psi for spraying no more or less, 1.6 will be fine for epoxy. are you sure everything is clean?? clean where paint goes from cup to gun and in that area very well, let soak over night in lacquer thinner, then clean with small brushes. also there shoulod be clicks in trigger one for just air, the other will let fluid come out.
now, the two knobs onthe gun the top one is the fan or pattern, the bottom is fluid and adjusts how far needle is pulled back(meaning the further the needle is pulled back the more paint/primer will come out) i have a finish line for priming, adjust top knob all the way out for full fan, then turn in 1/2-1 turn, then bottom knob turn out until trigger is opened so much it hits handle before it stops, then turn the bottom knob in until you feel it move trigger, once moves goes 1/2-1 turn, this will be perfect.
now when cleaning, go dump leftover paint out, fill gun 3/4 with lacquer thinner, shake it for 20 seconds, then spray some thru gun while shaking, then still while doing this turn top knob until it has no more fan , it is all coming out of tip with no fan, now go dump gun out, wipe cup with cloth, then put some more thinner in gun, shake alittle then spray some, now go back to waste paint cup/bucket etc and drain some thinner into waste and watch to see if thinner is still dirty coming out, wash out until thinner is clean, and then take just tip off gun and let it sit in thinner in cup until next use, have cup about 1/3 full with thinner at all times, also gun should work without tthat one white gasket that goes behind fluid tip (the 1.6 tip)
also that regulator does not look adjustable is it?? if not go over to compressor and adjust pressure there until you get 22-25 psi at gun regulator WHEN SPRAYING, on top of that with nothing in gun pull trigger and hold it, have 22-25 psi on regulator when spraying, an see how long it can go without losing pressure, i bet this is an issue too as you have a small compressor and these hvlp's use 10-12 cfm at 90 psi
jake

[rockdogz]

Thanks a lot for your help Jake -
I have had the gun apart with parts soaking in thinner since Saturday. I will try shooting some thinner through it. Some paint stuck in the gun makes sense, as it sure used to perform better than it does now. I think my compressor only provides 4CFM at 90psi. Do you think that it is definitely too small to power this gun at all then? I will test it out, but can probably go 45-60 seconds full-out without the compressor cycling on . The guage/regulator that came with the gun is adjustable - I will re-check to make sure it is 22-25psi when spraying.

[68protouring454]

yeah it is too small but it wil work for however long it will maintain 20-25 psi while spraying, get a spray gun cleaning kit with the small brushes, also they make gun cleaning kit that coms in a gallon can, has a metal strainer basket and is alot more potent then thinner, it works nice, but if you have any nylon small brushes use it with thinner and get in whre the paint comes from the cup into the gun, blow it out real good and look in there, get it clean, let me know
jake
feel free to email me, its in my profile

[68protouring454]

when the gun loses pressure, it will clog up as it wil not atomize the paint/primer, so watch regualtor and stop sprayiing when it gets down to 16-18 psi, it will clog up the air cap not the gun itself, also make sure tip, the tiny holes on side of center fluid whole, make sure those are clean and you can see thru them
jake

[vanzuuk1]

I am not a body guy but when I do spray I always shoot a little thinner first.If the gun sprays the thinner ok then does anything strange shooting paint the paints not reduced or strained enough.

[68protouring454]

straining only takes dirt/chunks out when putting paint into gun, epoxy primer is 2-1 and i have never ever had a problem with it
jake