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How many stages in turbine hvlp is enough?

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Forum topic by Carloz posted 10-28-2016 10:04 PM 1316 views 0 times favorited 9 replies Add to Favorites Watch
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Carloz

956 posts in 425 days


10-28-2016 10:04 PM

I understand the more the better as you can always tune down but not up. However the price quickly goes up with each stage.

So let’s say we have Fuji:

2 stages : 5 psi pressure.
3 stages: 6.5 ps
4 stages: 8.5 psi
5 stages: 9.5 psi

Realistically what do you loose with lower power turbine:

a. Not being able to spray some finishes at all. Which ones ?
b. Necessity to thin more.
c. Loosing quality.
d. Loosing speed.


9 replies so far

View SuperCubber's profile

SuperCubber

1009 posts in 2118 days


#1 posted 10-28-2016 11:39 PM

This should answer your questions: https://youtu.be/IfGzCjRO_ZY

He actually uses Fuji in his discussion.

-- Joe | Spartanburg, SC | "To give anything less than your best is to sacrafice the gift." - Steve Prefontaine

View Fred Hargis's profile

Fred Hargis

4756 posts in 2327 days


#2 posted 10-29-2016 10:49 AM

You do loose A&B, but not necessarily C&D. For me the sweet spot was a 4 stage (Fuji) but a lot of guys use a 2 stage and get very good results. It just depends on what you intend to spray. Maybe oversimplified, but it’s the viscosity that makes more stages better, the thicker the finish the more “oomph” it takes.

-- Our village hasn't lost it's idiot, he was elected to congress.

View rwyoung's profile

rwyoung

409 posts in 3306 days


#3 posted 10-31-2016 03:20 PM

What Fred said. Make a list of the types of finishes you expect to realistically use. For example, you may want to re-do some painted trim in the house so add latex enamel. But you probably don’t need to spray creosote or glue (or maybe you do!). Or if you only ever expect to spray stain/shellac/poly the list is short, easy and probably points at a 2-stage.

Then, look for the various manuals and see what the N/N set recommendations are AND the viscosity ratings for when that particular N/N set is used on the gun. You may find that even with a 1.8mm or 2.0mm N/N and matching air-cap the viscosity rating (if just given as seconds, it usually means a #4 Ford cup at 77F or 75F—temperature I forget) is 40 seconds, you may find that the particular latex enamel you want to use is more like 180 seconds. So now you need to thin. Overthinning alters the color & adhesion properties of the paint. How much is over thinning? Good luck getting a manufacturer to tell you anything more specific than 10% by volume.

Anyway, make you lists, compare the numbers using products you expect to use (most have viscosity ratings available in their spec sheets from the manufacturer’s web sites). If you score high (maybe 80% match) on the 2 stage then personally I’d pick that. If for a few extra bucks you score significantly higher on 3 or 4 stage, I’d figure out how to scratch up the extra $$$.

One other thing, price out the accessories. Is the hose included (usually)? Longer hose or flex extention? Cost of filters, gaskets, backflow preventers? Gun type? Needle/nozzle/air cap set costs? Shipping & sales tax?

-- Don't sweat the petty things and don't pet the sweaty things.

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Carloz

956 posts in 425 days


#4 posted 10-31-2016 03:43 PM

Unfortunately nobody can predict the future. Right now I plan only use it for polyurethane and dyes. I am looking at few pieces of furniture that I made and see quite noticeable finish defects in places I tried to manually stain with water based dye, where it went wrong in corners and crevices. Nobody around notices it but it bugs me.
So a two stage would work. However someone wants me to spray paint his bicycle, which I understand requires 4-5 stage. Then textured stucco on the small fence in front of the door cracked and needs to be taken care of. I will probably have to fill the crack and repaint the fence with outdoor latex paint….. Sure for the price of 4 stage I could buy a two stage unit plus a good airless sprayer but having two things in the garage that only see occasional use is not for me.
So thanks for the input. I decided to go with the a 4 stage unit even though it is twice expensive than a 2 stage.
I never was sorry that I overbought a tool but often time had to pay twice encountering a limitation of a cheaper tool.

View rwyoung's profile

rwyoung

409 posts in 3306 days


#5 posted 10-31-2016 07:22 PM

Pushing heavy body exterior latex for a large job, rent an airless for a single project.

A 4 stage should be able to do it but unless you also have the capability to use a paint-pot, it gets to be a real drag refilling that 1qt cup on a large exterior job. You can get 2qt cups for some guns as either a remote cup or as one that hangs off the gun. In that case, the gun starts to weigh in at 5 lbs filled. A paint pot of any volume will require a pressure assist from a compressor to push the material up the hose to the gun.

Solvent borne enamel paints one might use to paint metal can be thinned to a greater extent than water-borne and so can be pushed through with a “lower end” system. The 4 stage can definitely do it without significant thinning. But so could a 2 or 3 stage. Know of one guy that paints cars for a living using a 2-stage (>10 year old) rig and works just fine.

And yes, you can predict the future. Happens all the time. Just not with 100% accuracy.

-- Don't sweat the petty things and don't pet the sweaty things.

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Carloz

956 posts in 425 days


#6 posted 10-31-2016 09:33 PM

I have zero experience with using sprayers, even missed my opportunity to tag the neighborhood with graffiti when I was young. But I would not try to thin automotive paint, unless specifically instructed by the manual. That stuff should be far more critical than wood paint. And unless you want your bicycle fully scratched the moment you ride off you would not use solvent borne enamels. You need urethane paints that are far more durable and tougher ( and expensive too).
As for the exterior latex, the keyword is “small” the fence I have in mind will probably take one capful of paint.
Thank your for the comments.

View rwyoung's profile

rwyoung

409 posts in 3306 days


#7 posted 11-01-2016 02:50 PM

OK, then find the data sheet for the polyurethane paint you plan to use and check what the viscosity is when mixed.

Looking at some Eastwood, PPG and SW paints, all which use a 3:1 mix ratio, they give the viscosity for a Zahn #2 cup.

Most turbine HVLP manuals list recommended setups based on the Ford #4 cup. Conversion charts exist and are easily found with Google.

Zahn #2 16-24sec == Ford #4 14-32sec. A 2 stage HVLP can push this no problem with a tip in the neighborhood of 1.5mm. A 3 or 4 stage could obviously do this too.

So for a bike frame (assuming you mean bicycle), I’d be more interested in how the gun itself performs. I’d want to be able to control the fan pattern very precisely. A cheaper gun may not be able to do this to your satisfaction.

The tech data sheets give very specific instructions on the use of reducer (I said thinner which is not exactly the same, so poor use of terms on my part). Same as with latex paint, reducers are used to control flow-out but do have a minor thinning effect if used properly.

Should also have mentioned in the accessory list, proper PPE. A respirator with good VOC and particulate filters is a must.

-- Don't sweat the petty things and don't pet the sweaty things.

View Drew's profile

Drew

329 posts in 2934 days


#8 posted 11-01-2016 04:07 PM

Nobody has ever wished they bought fewer stages!
Buy the best unit you can afford. I’m a big fan the Fuji units. The T70/75 is my favorite gun, hands down.

-- TruCraftFurniture.com

View Carloz's profile

Carloz

956 posts in 425 days


#9 posted 11-02-2016 09:28 PM


Nobody has ever wished they bought fewer stages!
- Drew

...Only their wives.

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