Benzo
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| posted on 15/1/12 at 11:40 AM |
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Painting Primer & Spray Gun setup.
Hi guys,
Im at stage now with my rally car build that im starting to want to prime some spots after sandblasting & welding.
I have inherited a Devilbiss GTi spray gun which i am told is a good'en but i aint got a clue out to use it!
I cannot get any sort of decent even flow to come from the gun..
Can anyone point me to a crash guide here on how to -
A) What Paint i should be using (what to ask for/ buy)
B) What way it be mixed to put into the gun (does it need mixed with thinners/ hardener)
C) Tell me what pressure i should have the regulator set to for spraying?
D) Tell me what the 2x screws on the back of the gun do because at the moment i cant get them to do anything 
Putting so much effort into all this sandblasting to get a nice end result and everything i paint feels rough and like sandpaper once it has dried,
getting ALOT of splatter (technical term im sure  ) out of the gun
Iain
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ashg
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| posted on 15/1/12 at 12:17 PM |
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A) What Paint i should be using (what to ask for/ buy) if its an older gun it will have 2k seals in it so it will work fine with 1k and 2k paint. it
may need a new seal kit to do water base.
B) What way it be mixed to put into the gun (does it need mixed with thinners/ hardener) most paints are normally mixed with 50% thinners to spray
them. it will have guidance on the paint/in the paint shop
C) Tell me what pressure i should have the regulator set to for spraying? if its a hvlp gravity fed gun you will need around 30-40psi you will also
need large bore air hoses and couplings
D) Tell me what the 2x screws on the back of the gun do because at the moment i cant get them to do anything one controls the needle for paint flow
the other controls the fan (spray pattern) practice on a piece of wood aim for a cigar shape. if you travel at about 1/2 foot per second you be
getting a nice even coverage without runs when you overlap.
the biggest thing with a devilbiss gti is that you need loads and loads of air but at low pressure if your compressor is anything less than 100L your
going to struggle painting a car as you will run out of air before you finish a side and the paint will flash off while your waiting for the
compressor to catch up. also if you work the compressor too hard it will get red hot and you will end up with water and oil getting into the air
lines which will get into the gun and ruin the paint finish.
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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ashg
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| posted on 15/1/12 at 12:23 PM |
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also forgot to mention. a gti is usually for base and finish. for primers you really want a pri. what needle and air cap are on the gti? usually it
will be something like a 110 if it is you may have to thin your primer down even more to get it to spray. consistency of the paint should be almost
like water. it should stir somewhere between the resistance of a cup of tea and a cup of hot chocolate.
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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Benzo
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| posted on 15/1/12 at 12:49 PM |
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quote:
Originally posted by ashg
also forgot to mention. a gti is usually for base and finish. for primers you really want a pri. what needle and air cap are on the gti? usually it
will be something like a 110 if it is you may have to thin your primer down even more to get it to spray. consistency of the paint should be almost
like water. it should stir somewhere between the resistance of a cup of tea and a cup of hot chocolate.
Thanks Ash, Some great info there..
unfortunately im not with the gun now so i dont know what kind of Cap it has, it will be what ever came on the gun, it was a gravity feed. Is it worth
my while looking into a pri gun?
It is an Older gun and was used for 2k previously so im guessing it should do my job.
My compressor is 300L with 2 x watertraps and a regulator so that should be spot on.
I think the serious problem than i am having is the thinkness of the paint, last but i painted i mixed about 25% thinners /75% Paint and i couldnt get
any paint out of the gun so i was screwing at the needle settings trying to get some out and then when it came out is was splattering.
So next attempt..
Compressor set to 40psi
Paint 50/50
& abit of practise 1st to get the shape right 
Can you advise me on the paint front? i have just been using grey primer i had on the shelf, but now i need more so wondering what i should be getting
/ asking for!
Thanks mate!
[Edited on 15/1/12 by Benzo]
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Peteff
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| posted on 15/1/12 at 01:54 PM |
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Is there a knob by the air inlet in the base of the handle? This controls the incoming air pressure on most gravity guns. The air is controlled at the
cap by adjusting how far the trigger can be pulled. Mix your paint till it runs like milk and don't hang about when you are putting it on.
[Edited on 15/1/12 by Peteff]
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Benzo
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| posted on 15/1/12 at 02:22 PM |
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Thanks guys,
Great help.. trying to get the boot, engine bay, floor and inside prepped and primed over the next few weeks
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