What size hose is ideal for painting???
10-29-2012, 11:46 AM
#1
What size hose is ideal for painting??? I have a 3/8" plastic hose and a 1/2" rubber hose. I believe both have 3/8" fittings and are 50ft. Which hose would be better suited for painting a car, and why?
I prefer to use the rubber hose since I don't have to worry about it coiling up and jumping around. The rubber hose will always stay flat on the ground.
BTW...I'm using the Harbor Freight HVLP pro kit with a 1.4 tip. I've already used it on the jambs and on a few test panels...not bad for a $40 gun.
I prefer to use the rubber hose since I don't have to worry about it coiling up and jumping around. The rubber hose will always stay flat on the ground.
BTW...I'm using the Harbor Freight HVLP pro kit with a 1.4 tip. I've already used it on the jambs and on a few test panels...not bad for a $40 gun.
10-30-2012, 01:15 PM
#4
I don't mind using the 1/2" hose. It's not really that bulky. i just figured the 3/8" hose would keep up the volocity of the air, making it better. If both will shell out equal performance then I rather use the 1/2 hose since I know it won't coil up on my like my 3/8" plastic hose and end up hitting a freshly painted panel.
5/16" is pretty small. I didn't think something that small would work.
5/16" is pretty small. I didn't think something that small would work.
10-30-2012, 01:42 PM
#5
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Are you using a conventional or HVLP system?
A HVLP system requires something like 10-13cfm @ 25psi.
That 5/16 spec is per the MFG; but they say the main restriction in most systems are the 1/4 air fittings, which are too small; you need to switch them out to 3/8" fittings if you don't already have them.
A HVLP system requires something like 10-13cfm @ 25psi.
That 5/16 spec is per the MFG; but they say the main restriction in most systems are the 1/4 air fittings, which are too small; you need to switch them out to 3/8" fittings if you don't already have them.
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11-01-2012, 10:44 AM
#8
Will do. Thanks for your help guys.
BTW, I've noticed that the longer I hold the trigger on the HVLP, the more the pressure will drop. I mean, I have the gun set at around 90psi and when I pull the trigger the PSI drops to 35 right away. If I continue to hold the trigger for 5 seconds or more it will drop 5 psi every second. When I paint the entire side of the car I will be making several passes from front to rear, which each pass will take about 10 sec +/-. I'm just worried that as the pressure drops the color will lay out differently.
Oh and my compressor is a older 40gal Craftsman and the specs are 8.6scfm @ 40psi and 6.4scfm @ 90psi. 130psi max pressure
BTW, I've noticed that the longer I hold the trigger on the HVLP, the more the pressure will drop. I mean, I have the gun set at around 90psi and when I pull the trigger the PSI drops to 35 right away. If I continue to hold the trigger for 5 seconds or more it will drop 5 psi every second. When I paint the entire side of the car I will be making several passes from front to rear, which each pass will take about 10 sec +/-. I'm just worried that as the pressure drops the color will lay out differently.
Oh and my compressor is a older 40gal Craftsman and the specs are 8.6scfm @ 40psi and 6.4scfm @ 90psi. 130psi max pressure
11-01-2012, 11:47 AM
#9
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90psi at the gun?!?!?!?
Most HVLP guns need it regulated down to about 25-35psi at the inlet of the gun! I use a miniature regulator/gauge hooked between the gun and hose.
From those specs on the compressor, it's undersized.
http://www.autorefinishdevilbiss.com...lId=0&TabId=86
Pressure drop will effect paint spray patterns.
What dryer/filter do you have on the air system? I recommend a desiccant type filter for painting; even if it's just the cheap inline ones.
Most HVLP guns need it regulated down to about 25-35psi at the inlet of the gun! I use a miniature regulator/gauge hooked between the gun and hose.
From those specs on the compressor, it's undersized.
http://www.autorefinishdevilbiss.com...lId=0&TabId=86
Pressure drop will effect paint spray patterns.
What dryer/filter do you have on the air system? I recommend a desiccant type filter for painting; even if it's just the cheap inline ones.
11-01-2012, 02:58 PM
#10
I have a small regulator on my gun...http://www.harborfreight.com/150-psi...uge-68223.html. The reason why I have it at 90PSI is because when I pull the trigger it drops too far down. Am I suppose to set the pressure with the trigger pulled or left alone?
I think I'm going to shoot a quick video of what i'm talking about so you guys can see.
I'm using two filters. I use this filter on the line as soon as it leaves the tank...http://www.harborfreight.com/inline-...ter-68215.html
Then I use this one right under the regulator, as a last line of defense...http://www.harborfreight.com/disposa...ter-68224.html
I've never had any issues with getting water in the system. I always drain the tank before I paint and every other cycle.
I think I'm going to shoot a quick video of what i'm talking about so you guys can see.
I'm using two filters. I use this filter on the line as soon as it leaves the tank...http://www.harborfreight.com/inline-...ter-68215.html
Then I use this one right under the regulator, as a last line of defense...http://www.harborfreight.com/disposa...ter-68224.html
I've never had any issues with getting water in the system. I always drain the tank before I paint and every other cycle.
11-01-2012, 03:03 PM
#11
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The reason you're having pressure issues is because the compressor is too small for a HVLP setup. The pressure shouldn't drop much if any at the gun when the trigger is pulled if the compressor is large enough (maybe 1-5 psi).
I set the pressure without the trigger pulled, then on/off/on/off the trigger to see how the gauge/regulator/pressure respond, mine stays steady within the few psi as above.
HVLPs use a LOT of CFM but at a low pressure. Per the link I posted, a normal sized HVLP gun requires a MINIMUM of 13cfm at 30psi; you're running about 9, maybe 10 (with the 8.3cfm@40psi rating.)
I set the pressure without the trigger pulled, then on/off/on/off the trigger to see how the gauge/regulator/pressure respond, mine stays steady within the few psi as above.
HVLPs use a LOT of CFM but at a low pressure. Per the link I posted, a normal sized HVLP gun requires a MINIMUM of 13cfm at 30psi; you're running about 9, maybe 10 (with the 8.3cfm@40psi rating.)
11-01-2012, 04:55 PM
#12
You may have a point there but when I use my brothers Sharpe which has a 1.3 tip the pressure does drop as much. If I set the pressure at 40psi it will drop to around 35psi+/-. My brother said that these harbor freight gun suck up a $hit load of air, more than other HVLP guns. I was thinking of swapping regulators with his and see what happens.
The only reason why I didn't buy a bigger compressor is because (a) I didn't have that much money and (b) more importantly, all the compressors I ran across were all 220V. I only have 110.
Any ideas on what might give me an edge?
The only reason why I didn't buy a bigger compressor is because (a) I didn't have that much money and (b) more importantly, all the compressors I ran across were all 220V. I only have 110.
Any ideas on what might give me an edge?
11-01-2012, 05:52 PM
#13
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you can paint the car in sections. maybe do one side one day the other side the next. then hood and so on. you really dont wanna be in the middle of the hood and loose pressure. orange pill will be horrible not to mention your color not laying right. pressure will change the color of a metallic.
as far as pressure at your gun, im not sure about HF guns but iwatas only require 10 at the cap which would be around 16 19 at your regulator.
as far as pressure at your gun, im not sure about HF guns but iwatas only require 10 at the cap which would be around 16 19 at your regulator.
11-02-2012, 11:02 AM
#14
I really want to try and avoid painting the car in sections. I've heard that a car has to be completely assembled when shooting metallic colors due to the way metallics lay out. They say there's a high chance it will come out different.
My original plan was to paint the 1/4 panels, trunk and doors on the car all at once. Then I was going to paint the fenders and hood the next day followed by the bumpers the day after that. But then I was told that would not be a good idea and it would be better to paint the car all at once with all the panels bolted on.
What if I paint it in sections like the way I originally planned, but after the 3rd base coat flashes I lay an additional mist coat to try and even things out? I can also shoot one coat vertical and the next horizontal to try and even things out even further.
My original plan was to paint the 1/4 panels, trunk and doors on the car all at once. Then I was going to paint the fenders and hood the next day followed by the bumpers the day after that. But then I was told that would not be a good idea and it would be better to paint the car all at once with all the panels bolted on.
What if I paint it in sections like the way I originally planned, but after the 3rd base coat flashes I lay an additional mist coat to try and even things out? I can also shoot one coat vertical and the next horizontal to try and even things out even further.
11-04-2012, 08:55 AM
#15
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i paint cars in sections all the time. i hate seeing tape lines. you just have to make sure you use the same sealer same air pressure and same number of coats. i would stay away from the mist coat with a solvent. that will cause the metallics to stand up and also make it harder to match. what color are you going with?
11-05-2012, 07:29 AM
#17
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When you paint in sections be sure the part you are painting is in the same position that it will be on the car. You don't want to paint a door laying on a stand and then hang it on the car next to a qtr. that was painted verticle. The metalics will "settle" and lay flat on the horizontal panels and could end up darker.
Don't use a regulator at the gun, you will get the pressure drop that you described. You need a good diaphragm regulator/filter on the wall that your hose plugs into. Preferably 20 foot from the compressor.
Don't use a regulator at the gun, you will get the pressure drop that you described. You need a good diaphragm regulator/filter on the wall that your hose plugs into. Preferably 20 foot from the compressor.
11-05-2012, 08:13 AM
#18
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When you paint in sections be sure the part you are painting is in the same position that it will be on the car. You don't want to paint a door laying on a stand and then hang it on the car next to a qtr. that was painted verticle. The metalics will "settle" and lay flat on the horizontal panels and could end up darker.
Don't use a regulator at the gun, you will get the pressure drop that you described. You need a good diaphragm regulator/filter on the wall that your hose plugs into. Preferably 20 foot from the compressor.
Don't use a regulator at the gun, you will get the pressure drop that you described. You need a good diaphragm regulator/filter on the wall that your hose plugs into. Preferably 20 foot from the compressor.
That's contradictory to just about everything I've seen in professional shops, read online, and read in the instructions of HVLP guns!
11-05-2012, 10:08 AM
#19
When you paint in sections be sure the part you are painting is in the same position that it will be on the car. You don't want to paint a door laying on a stand and then hang it on the car next to a qtr. that was painted verticle. The metalics will "settle" and lay flat on the horizontal panels and could end up darker.
Don't use a regulator at the gun, you will get the pressure drop that you described. You need a good diaphragm regulator/filter on the wall that your hose plugs into. Preferably 20 foot from the compressor.
Don't use a regulator at the gun, you will get the pressure drop that you described. You need a good diaphragm regulator/filter on the wall that your hose plugs into. Preferably 20 foot from the compressor.
Won't using a regulator at the gun be more accurate? I'm not a pro, as you can see, but I would figure the PSI will change from the beginning of the hose to the end of the hose.
11-05-2012, 10:10 AM
#20
I just finished painting the inside of the doors and hinges. The 1/4 panels are done so all I have to do is finish the trunk and I'll be set to paint most of the exterior panels. 
I think I can finally see the light at the end of the tunnel
I think I can finally see the light at the end of the tunnel