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  #41 (permalink)  
Old 09-29-2009, 09:23 PM
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Default Re: Waterborne

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Originally Posted by RONWEN View Post
Dan/Eiji,
What isn't clear to me is Eiji's pressure pot system -- if the regulator is set at 5psi at the pot why is the setting at the gun ~30psi?
Also, Eiji I (like Dan) am wondering if a better choice (for me at least) would be a gun mounted cup? Is there a lot of messing around cleaning out the pressure pot and also the feed hose?
I also need to sort out for my purpose (occasional spray finishing my projects) the choice between the gravity feed and bottom pots?
The pot pressure only needs to be enough to get the paint out of the pot and up to the gun. The pot usually sits on the floor nearby and only requires a few PSI. The gun pressure is the amount needed to make the whole paint gun function properly.

The pot can hold more paint than a gun mounted cup, making it ideal for bigger projects.
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  #42 (permalink)  
Old 09-29-2009, 10:19 PM
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Default Re: Waterborne

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Originally Posted by Qwas View Post
The pot pressure only needs to be enough to get the paint out of the pot and up to the gun. The pot usually sits on the floor nearby and only requires a few PSI. The gun pressure is the amount needed to make the whole paint gun function properly.

The pot can hold more paint than a gun mounted cup, making it ideal for bigger projects.
That makes sense. I'm guessing then the ~30psi at the gun (gauge) is reduced to ~10psi at the fluid tip hence HVLP (low overspray).
I still wonder if the detached pot is the best choice for smaller projects i.e. spraying a table not an entire set of kitchen cabinets.
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  #43 (permalink)  
Old 09-30-2009, 12:11 AM
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Default Re: Waterborne

I've got a pressure pot and it's not messy at all. I typically put my finish in some type of container that I set in the pot, that way there's no messy clean up process. I simply take the container out of the pot when I'm finished and flush the system out. Since I almost exclusively use wb products I typically only flush everything out with warm water, blow out the lines and I'm done.
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Last edited by rnt80; 09-30-2009 at 03:28 AM.
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  #44 (permalink)  
Old 09-30-2009, 12:46 AM
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Default Re: Waterborne

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Originally Posted by rnt80 View Post
I've got a pressure pot and it's not messy at all. I typically put my finish in some type of container that I set in the pot, that way there's not messy clean up process. I simply take the container out of the pot when finish and flush the system out. Since I almost exclusively use wb products I typically only flush everything out with warm water, blow out the lines and I'm done.
That sounds pretty good. Doing it that way, the detached pressure pot is probably even easier to clean up after than the cup attached to the gun setup. -- No matter how much (or how little) spraying there is to be done.
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  #45 (permalink)  
Old 09-30-2009, 01:14 AM
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Default Re: Waterborne

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Originally Posted by DanClark View Post
Ron,

Sorting out all of this finishing information and comparing it to my needs has been a major headache for me too. Generally, I've found two kinds of users - finishing noobs like me searching for good, basic information and old hands who have years of finishing experience. While having the experienced finishers provide information is great, many of them have been using the same tools for years and some of their tools info is a bit out of date.

With Eiji, we have a rare opportunity - a seriously fine woodworking craftsman who is working through the process of finding the right finishing tools and who is willing to share his experiences. Like you, I much appreciate Eiji sharing his knowledge and experience in the finishing arts and his learning process.

Like most things, part of the problem is not finding the right answers, it's putting it all together. Here's a summary mind-dump of what I've picked up in the last several months of reading and researching finishing and finishing tools:
  • Spray finishing tools have changed in the last few years. This means that some of the old "wisdom" no longer applies. Some changes:
    • Old technology - what was available:
      • Gravity, unpressurized cups above a conventional (non-HVLP) spray gun.
      • Siphon feed, unpressurized cups under a conventional spray guns.
      • Off-gun pressure pots with conventional spray gun.
      • Large, conventional (15+ CFM) compressors were used for the conventional spray guns.
      • HVLP turbine systems.
    • Newer technology - new technology added to the old technology:
      • Pressurized, above-the-gun cups.
      • Pressurized, below-the-gun cups.
      • Smaller compressors can power conversion guns
      • HVLP available for any style of gun/system.
      • Liner systems like PPS available from 3M, Asturo, and Devillbis give you the ability to spray in any position and provide easy, fast cleanup.
  • A lot of spray finishing info is aimed at folks who refinish automobiles (and similar) and not woodworkers. And much of the time it's difficult to determine which market a spraying tool is aimed at.
  • Almost all automobile finishers prefer gravity cups, while woodworkers prefer pressurized spraying because it lays down the finish faster.
  • Automobile finishers spray for long periods of time in one stretch, while woodworkers spray in more random, short runs. This impacts which is the best spray gun, cup, and compressors for your needs.
What this means to me is that some old wisdom may no longer apply. For example, "A gravity gun gives you a better finish." Or, "A gravity cup (implying above-the-gun) cup won't let you spray upside down." So, based on this information, and especially from Eiji's comments and your comments, my current conclusions are:
  • With a good HVLP conversion gun, you can get finish quality that is equal or superior to a good HVLP turbine gun.
  • You can get traditional HVLP turbine gun benefits - like less overspray and reduced material usage - from a good HVLP conversion gun.
  • Currently, the primary benefit of turbine HVLP is ultimate portability for work-site use. For shop use, where you have a compressor, there are limited or no benefits of a turbine HVLP.
  • Given that we are finishing wood, it is feasible to use a smaller compressor (maybe 4+ CFM) and still get decent productivity. (Not high-volume productivity maybe, but at still decent.)
  • You can add another tank to your current small compressor for spray finishing. (This looks like a good option to me.)
  • You can connect two small compressors in parallel to improve CFM. (Don't ask me for details on how to do this.)
  • Using a sealed liner system like PPS, DeKups, Asturo, etc., you can spray from any position (upside down, sideways,etc.) with a pressurized or unpressurized above-the-gun, below-the-gun, or off the gun cup or pot.
One subtlety of this is that, while I believe the above is true, it's not necessarily true all the time, for all people, or in all conditions. For example, Asturo makes a liner system: Asturo Liner. BUT, it looks like it only works for above the gun gravity cups and NOT pressurized cups (above or below the gun).

I hope this information is useful. And that it doesn't sound too confusing, because this has been a confusing journey for me. I think I'm pretty close to the end of my search, but hey... There's still tomorrow. I might change my mind again.

Regards,

Dan.
Dan,

Don't forget that turbines don't require water extraction. Just a small note, but not to be forgotten. Apollo and I suspect others have guns that can be "converted" to use either their turbine or a compressor. The best of both worlds for those of us that have changing situations and only want to own one gun.
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  #46 (permalink)  
Old 09-30-2009, 04:08 AM
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Default Re: Waterborne

TTB,

Yes, good points - there are definitely benefits to turbines. But I'm finding that my original impression of them was somewhat skewed. Now I think it's more balanced.

Regarding dual purpose guns, I think you're probably right. But...

An issue to watch for with dual purpose guns is the CFM required. Turbines put out a lot of CFMs at low pressure. I think you could use a dual purpose gun IF your compressor pumped out the CFMs.

For example, I believe Fuji turbines pump out something like 100 CFM at 3 - 8 psi. I think the best my ST200 can put out is about 6.5 CFM. I'd be very surprised to find a gun that could handle both environments.

One nice thing about the 6008 conversion guns like Eiji's is that they can be used with a PPS cup, a traditional on-gun pressure pot, or an off gun pressure pot.

Regards,

Dan.
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  #47 (permalink)  
Old 09-30-2009, 03:40 PM
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Default Re: Waterborne

This turned into a very informative thread, thanks guys.
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  #48 (permalink)  
Old 09-30-2009, 04:29 PM
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Default Re: Waterborne

Quote:
Originally Posted by rnt80 View Post
I've got a pressure pot and it's not messy at all. I typically put my finish in some type of container that I set in the pot, that way there's no messy clean up process. I simply take the container out of the pot when I'm finished and flush the system out. Since I almost exclusively use wb products I typically only flush everything out with warm water, blow out the lines and I'm done.
The 3M Paint Preparation System is is very clean and convenient. It allows you to store unused material without transferring to another container and since it is available for both siphon and gravity feed guns it only requires you to clean the gun after use. No pressure pot hose to clean. Not that that's difficult with WB finishes but less is less.
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  #49 (permalink)  
Old 10-01-2009, 07:39 AM
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Default Re: Waterborne

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Originally Posted by MichaelKellough View Post
The 3M Paint Preparation System is is very clean and convenient. It allows you to store unused material without transferring to another container and since it is available for both siphon and gravity feed guns it only requires you to clean the gun after use. No pressure pot hose to clean. Not that that's difficult with WB finishes but less is less.
This looks similar to the 3 mini cups that are included with the system I purchased. Also, the smaller cups allow easier access in tighter areas.
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  #50 (permalink)  
Old 10-04-2009, 04:31 AM
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Default Re: Waterborne

the 5psi at the pot is to pressurize the pot so the fluid gets to the gun and out the nozzle (a higher viscosity product will need a higher pressure).

The 25 -30 psi at the gun is the air needed to properly atomize the finish with the wide fan setting. less air is needed to atomize at narrower fan settings.
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