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| Spraying issues http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=55244 |
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| Author: | Ken Mitchell [ Tue Sep 06, 2022 7:49 pm ] |
| Post subject: | Spraying issues |
Hi guys, Apologies if this could be in another forum, but I have a technical question about spraying that perhaps someone can solve. The pressure on my gun drops immediately when I start a pass, and I can hardly go for even a couple of seconds before it's at zero. The pressure builds back after a few seconds, but then it's a repeat, repeat, inefficient and inaccurate spraying situation. I've changed out so many things to try to find the culprit, namely isolated this line (put a disconnect to my car garage line), changed guns, changed the pressure regulator, tried bumping up the pressure in the tank (a large 80-gallon Craftsman), and at the regulator, and tried various adjustments at the gun. What on earth could be causing the pressure to drop over just one or two seconds, then build back up just as fast? Thanks for any ideas you can offer, Ken |
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| Author: | bluescreek [ Tue Sep 06, 2022 7:53 pm ] |
| Post subject: | Re: Spraying issues |
first off what kind of gun and brand do you have a regulator on the gun? all my guns have a regulator on the gun and I set them to the makers suggested settings Usually about 20lb The large tank should be set about 160 psi Do you have a water oil separator on the compressor if not get one If you have a harbor freight gun get a real one I never had great results with them So answer these questions and we can start your path in the right direction |
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| Author: | Ken Mitchell [ Tue Sep 06, 2022 8:02 pm ] |
| Post subject: | Re: Spraying issues |
Thanks for the list, John. what kind of gun and brand one small Wood River, one cheap Harbor Freight unit do you have a regulator on the gun? NO regulator on the gun, just a wall-mounted one all my guns have a regulator on the gun and I set them to the makers suggested settings Usually about 20lb The large tank should be set about 160 psi OK, maybe I need to bump that up; I thought 90-100# would be enough Do you have a water oil separator on the compressor if not get one YES, built into the regulator If you have a harbor freight gun get a real one I never had great results with them OK, good advice! OK, from John's initial questions, it looks like maybe I should try bumping up the tank pressure. If that works, next I should get a 'real' spray gun! |
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| Author: | bobgramann [ Tue Sep 06, 2022 8:45 pm ] |
| Post subject: | Re: Spraying issues |
Set the regulator at the gun (and at the tank) with the trigger open. Make sure that your hose to the gun isn’t one of those thin plastic coiled hoses—they won’t pass enough volume. If those two things aren’t the issue, then it sounds like you have a kink or blockage somewhere between the tank and the gun. A small orifice somewhere will let the pressure build with no volume but won’t pass enough air to maintain the pressure when volume is needed. If the pressure drop is shown on the gauge at the tank, then the obstruction is between the gauge and the tank. If it all worked before and not now, then some crud got into it and blocked it somewhere. What fun! |
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| Author: | Clay S. [ Wed Sep 07, 2022 6:35 am ] |
| Post subject: | Re: Spraying issues |
The length and size of the hose can also affect the pressure significantly, but it does sound like you have some sort of restriction between the gun and compressor. If you have an old compressor/ tank be careful if raising the pressure to 160psi. Moisture generated by compressing the air can rust and weaken the tank and the additional pressure can cause it to fail. 125psi is enough to run most air tools (many are made to work well at 90 psi). If you have an air blower nozzle or other air tools do they behave the same way - a few seconds of hi pressure then quickly dropping off? What is the pressure you are setting the wall regulator to? If you are not regulating the pressure at the gun how do you compensate for the pressure loss in the hose? I use a cheap $5 HF regulator at the gun and don't even worry about what the dial indicates, I just adjust it where the gun sprays properly. |
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| Author: | Ken Mitchell [ Wed Sep 07, 2022 8:27 am ] |
| Post subject: | Re: Spraying issues |
I think I may have found the main culprit. The output valve on the main tank had somehow gotten turned to a barely-open position. It's quite loose, and I've probably bumped it inadvertently a few times reaching around to the shut-off valve. I'm going to try again this afternoon. As with many things, a small issue can cause major problems! And yes, Clay, I don't usually go over 120# on the old tank (20 years of use). I'll report back... fingers crossed. |
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| Author: | doncaparker [ Wed Sep 07, 2022 8:49 am ] |
| Post subject: | Re: Spraying issues |
Wouldn’t it hiss loudly all the time if that were the problem? Just curious. Hope that’s all it is. |
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| Author: | dzsmith [ Wed Sep 07, 2022 9:01 am ] |
| Post subject: | Re: Spraying issues |
If you add a regulator at the gun, make sure it’s a regulator rather than a simple valve with a gauge. The valve will drop pressure and also drop air volume. |
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| Author: | bluescreek [ Wed Sep 07, 2022 10:44 am ] |
| Post subject: | Re: Spraying issues |
yes get one with a gauge and set it up with the trigger pulled don't just dial in 20 lb there is a you tube channel you may want to sign up on call FINISH SOCIETY |
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| Author: | Clay S. [ Wed Sep 07, 2022 5:05 pm ] |
| Post subject: | Re: Spraying issues |
These are the regulators I use at the gun. The price has increased since I last bought them but they are still pretty cheap. They work as a regulator not as something that just restricts the size of the air passage. I don't know how accurate they are with the gauge reading, but they do adjust the pressure fairly well. I adjust them to wherever the gun will spray properly and don't pay attention to the reading ( they may read fine - I just don't think about it) https://www.harborfreight.com/125-psi-a ... 62695.html |
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| Author: | dzsmith [ Wed Sep 07, 2022 6:04 pm ] |
| Post subject: | Re: Spraying issues |
Clay S. wrote: These are the regulators I use at the gun. The price has increased since I last bought them but they are still pretty cheap. They work as a regulator not as something that just restricts the size of the air passage. I don't know how accurate they are with the gauge reading, but they do adjust the pressure fairly well. I adjust them to wherever the gun will spray properly and don't pay attention to the reading ( they may read fine - I just don't think about it) https://www.harborfreight.com/125-psi-a ... 62695.html I don’t think that is a regulator. It looks like a simple flow valve with a gauge. |
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| Author: | bcombs510 [ Wed Sep 07, 2022 6:19 pm ] |
| Post subject: | Re: Spraying issues |
dzsmith wrote: I don’t think that is a regulator. It looks like a simple flow valve with a gauge. I’m have this one which I *think* is a proper regulator. https://www.amazon.com/DeVilbiss-HARG55 ... 75&sr=8-14 That being said, I’m going to try regulating the pressure at the source. I’m using a California Air Tools compressor and can set the output. Dan, I think you shared a while back this was a big improvement for you? I’m going to try the same thing next time I’m spraying. Thanks for the tip! Sent from my iPhone using Tapatalk Pro |
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| Author: | Barry Daniels [ Wed Sep 07, 2022 7:57 pm ] |
| Post subject: | Re: Spraying issues |
I've shown this here before. It is the regulator I use on my gun. It is USA made and is a real regulator at an affordable price. https://www.amazon.com/gp/product/B0073NVA2Y/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 The reason you want a regulator on the gun is that it cancels out the pressure drop that is created in your air hose. A regulator on the air compressor will not give you accurate control of pressure at your gun. |
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| Author: | bluescreek [ Wed Sep 07, 2022 8:08 pm ] |
| Post subject: | Re: Spraying issues |
https://www.amazon.com/dp/B07BW9BX6D?pd ... cefbda6bf0 this is one I use |
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| Author: | Barry Daniels [ Wed Sep 07, 2022 8:28 pm ] |
| Post subject: | Re: Spraying issues |
Like the one before, that LE LEMATEC is not a diaphragm type regulator but an orifice valve that restricts flow. So it does not hold a true limit on pressure. |
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| Author: | Ken Mitchell [ Fri Sep 16, 2022 7:11 pm ] |
| Post subject: | Re: Spraying issues |
Thanks to everyone for your input. It turns out that the main problem WAS indeed that the output valve on the tank had inadvertently gotten turned to where the pressure was almost completely turned off. As I sprayed, the pressure would quickly go down, then build back up in a couple of seconds. But... issue solved. This HAS gotten me thinking about getting a better spray guy, though. I spray with WATER based finishes, and only spray 2-3 instruments per year, so I don't need the Cadillac or Ferrari spray guns. But I WOULD appreciate any recommendations on a mid-level, medium-sized spray gun, if people have favorite brands or types. Thanks again for the help, and for any spray gun recommendations you may have! Ken |
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| Author: | bobgramann [ Fri Sep 16, 2022 7:52 pm ] |
| Post subject: | Re: Spraying issues |
Some years ago when I could no longer get repair parts for my Asturo gun (whick I liked a lot), I called Jeff Jewitt at Homestead finishing and asked him for his recommendation. He sold me a Qualspray AM-5008P gun. I’m using the 1.3 mm tip. I spray EM6000 with it. It works very well. I am able to dial in a good spray pattern with it and lay down an even wet coat. I believe the gun is called an LVLP. It requires only 6 cfm. When I called Jeff, I thought I was going to upgrade to the top of the line Fuji turbine system. He recommended that I stick with the compressor and get that gun. It was a good recommendation. And, it was a lot less expensive than what I thought I wanted to buy. |
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| Author: | Ken Mitchell [ Fri Sep 16, 2022 8:59 pm ] |
| Post subject: | Re: Spraying issues |
Bob, thanks for this info. The reviews for the Qualspray AM-5008P are great, and Jeff's name is everywhere as well. I'm going to look seriously at that set-up! |
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| Author: | Clay S. [ Fri Sep 16, 2022 11:03 pm ] |
| Post subject: | Re: Spraying issues |
Barry Daniels wrote: Like the one before, that LE LEMATEC is not a diaphragm type regulator but an orifice valve that restricts flow. So it does not hold a true limit on pressure. You may not think this regulator and the HF cheapie are air regulators, but they regulate the pressure at the gun just fine and can be set to hold the pressure unlike simple restricting valves. Try one you might like it. |
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| Author: | doncaparker [ Fri Sep 16, 2022 11:21 pm ] |
| Post subject: | Re: Spraying issues |
Another Jeff Jewitt spray gun to consider: QS-125WB. Very nice package, and works fine with small compressors. |
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| Author: | James Orr [ Sun Sep 18, 2022 1:26 pm ] |
| Post subject: | Re: Spraying issues |
Another vote for the QualSpray guns. I sold an Iwatta and grabbed the AM-8008/5008 kit. The Iwatta was great, but the QualSprays work better with my small California Air Tools compressor (which is a dream come true compared to my old 1000 decibel compressor) Between the two guns, I've used the larger of the two exclusively so far. I believe it's the 8008. |
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