Gravity Feed vs. Bottom Feed

[Parrish Woodworks]

Looking to upgrade spray finishers from and Earlex 5500 to a Fuji Spray System. Trying to decide on the spray gun itself. What are your opinions on a gravity feed gun vs. a bottom feed gun? Pro's vs. cons? 

Thanks...

[jteneyck]

Looking to upgrade spray finishers from and Earlex 5500 to a Fuji Spray System. Trying to decide on the spray gun itself. What are your opinions on a gravity feed gun vs. a bottom feed gun? Pro's vs. cons? 

Thanks...

Gravity feed guns just run out of finish when the cup empties.  Bottom, suction feed cups spit and sputter as the finish gets down to the dip tube or you tilt the gun too much.  If you want to upgrade I would do more than just buy a better quality gun, I'd put the 3M PPS cup system on it, too.  That will allow you to spray at any angle, even upside down, without sputtering, right down to the just about the last drop of finish in the cup.  I'd also get a pressure feed gun which will allow you to spray a much wider range of products using the PPS H/O cups than a gravity or suction feed gun.  Having helped a couple of folks sort out problems with their Fuji guns there's no way I'd get one with their bottom cup on it.  The seals and check valve are high failure items.  That alone makes the PPS cup system a good move.  

John

[Parrish Woodworks]

Gravity feed guns just run out of finish when the cup empties.  Bottom, suction feed cups spit and sputter as the finish gets down to the dip tube or you tilt the gun too much.  If you want to upgrade I would do more than just buy a better quality gun, I'd put the 3M PPS cup system on it, too.  That will allow you to spray at any angle, even upside down, without sputtering, right down to the just about the last drop of finish in the cup.  I'd also get a pressure feed gun which will allow you to spray a much wider range of products using the PPS H/O cups than a gravity or suction feed gun.  Having helped a couple of folks sort out problems with their Fuji guns there's no way I'd get one with their bottom cup on it.  The seals and check valve are high failure items.  That alone makes the PPS cup system a good move.  

John

Thank you John. I will look into the 3M PPS cup system...

[Snipe Hunter]

John is correct. I prefer gravity feed. I'm paying about $20 an ounce for my paint. Leaving $20 dollars in the bottom of a cup bothers me. I've also found gravity feed guns lay out clear top coats much better than gravity feed guns. Not sure I'd invest in PPS if I was just a hobbyist though. I do use them but only because it's faster clean-up. Time is money in the painting business. If I can spend a dollar for the cup and filter-cap and save 10 minutes cleaning, it's a money maker for me.

[jteneyck]

John is correct. I prefer gravity feed. I'm paying about $20 an ounce for my paint. Leaving $20 dollars in the bottom of a cup bothers me. I've also found gravity feed guns lay out clear top coats much better than gravity feed guns. Not sure I'd invest in PPS if I was just a hobbyist though. I do use them but only because it's faster clean-up. Time is money in the painting business. If I can spend a dollar for the cup and filter-cap and save 10 minutes cleaning, it's a money maker for me.

I'm mostly a hobbiest, and I'm cheap, so I clean the PPS liners and lids.  They often last several years before the liner frays, so there really is almost cost for consumables.  In your case, I'd throw them after a single use, too, and I sometimes do if I'm using a solvent based finish where clean up would be too much hassle.  

A major advantage of the PPS system is being able to spray at any angle. That alone makes it worth the price.  I can spray inside of cabinets and drawers now w/o having to flip the piece upside down, etc.  It's almost like having a pressure pot gun, w/o all the associated hassle.  

John

[Alan S]

Has anyone tried attaching a plastic bag full of finish to the feed tube inside the cup of a bottom fed gun?  That might make it behave more like a 3M PPS system.  I don't know how strong the bag would need to be to resist breakage upon emptying, but as a cheapskate hobbyist was thinking of giving it a try with my ancient Accuspray 23i-T.

I figured I could fill the bag with finish, close it with a rubber band, squeeze out the air, then slide it on the tube and screw on the pot.

[Rob Young]

Has anyone tried attaching a plastic bag full of finish to the feed tube inside the cup of a bottom fed gun?  That might make it behave more like a 3M PPS system.  I don't know how strong the bag would need to be to resist breakage upon emptying, but as a cheapskate hobbyist was thinking of giving it a try with my ancient Accuspray 23i-T.

I figured I could fill the bag with finish, close it with a rubber band, squeeze out the air, then slide it on the tube and screw on the pot.

Not exactly the same thing but I normally use a pressurized bottom cup gun. I put in the little poly bags you can get from Harbor Freight as cup liners. Mostly to make cleanup easier. But on a couple of occasions when I had multiple things to spray with different coatings, I could remove coating A's bag and close it with rubber band. Shoot some solvent. Insert new bag, shoot coating 2. Remove, clean, back to 1.  On the whole, would have been easier with two guns. 

But still find the cup MUCH easier to clean when using the liners. Less time and less solvent. Really only need to clean the dip tube.

Could probably use zip-lock bags for the same purpose but these are reasonably shaped to fit the average 1 qt spray cup.

https://www.harborfreight.com/hvlp-spray...94631.html

[Snipe Hunter]

Not exactly the same thing but I normally use a pressurized bottom cup gun. I put in the little poly bags you can get from Harbor Freight as cup liners. Mostly to make cleanup easier. But on a couple of occasions when I had multiple things to spray with different coatings, I could remove coating A's bag and close it with rubber band. Shoot some solvent. Insert new bag, shoot coating 2. Remove, clean, back to 1.  On the whole, would have been easier with two guns. 

But still find the cup MUCH easier to clean when using the liners. Less time and less solvent. Really only need to clean the dip tube.

Could probably use zip-lock bags for the same purpose but these are reasonably shaped to fit the average 1 qt spray cup.

https://www.harborfreight.com/hvlp-spray...94631.html

I used to work with a guy who used baby bottle liners in his 8 oz siphon feed cups. They actually work about as well as PPS cups for siphon feed guns assuming you strain your finish first (you should anyway). These were AccuSpray HVLP/Turbine siphon feed guns. I still use those guns too but with PPS cups. Still, imho the best turbine guns ever made. The only downside is the siphon feed but all the upside qualities are worth it imho. I do use an Apollo gravity feed for clear coat. It has been very, very problematic but it lays out a nice top-coat.... when working correctly. I've used other guns: QualSpray, Fuji and a couple others and wasn't impressed.

[Mr Eddie]

Gravity feed guns just run out of finish when the cup empties.  Bottom, suction feed cups spit and sputter as the finish gets down to the dip tube or you tilt the gun too much.  If you want to upgrade I would do more than just buy a better quality gun, I'd put the 3M PPS cup system on it, too.  That will allow you to spray at any angle, even upside down, without sputtering, right down to the just about the last drop of finish in the cup.  I'd also get a pressure feed gun which will allow you to spray a much wider range of products using the PPS H/O cups than a gravity or suction feed gun.  Having helped a couple of folks sort out problems with their Fuji guns there's no way I'd get one with their bottom cup on it.  The seals and check valve are high failure items.  That alone makes the PPS cup system a good move.  

John

+1
The PPS cups are the way to go. (And not really expensive.)  Being able to spray from any angle without thinking about it is a very helpful feature.

Lonnie