Spray equipment ?

I have a GMC 40l compressor, and have finished spraying a fence, using a cheap spraygun. I set the pressure to about 100, and managed to spray for about 1 minute, before the compressor kicks in due to low pressure. I then had to wait about 1 - 2 minutes until the pressure built up again. PITA, as it was a trellis fence of about 30 metres long by 3 metres high. :(
I am not (although this would solve the problem) about to buy a bigger compressor, but I thought that maybe a gravity fed gun using lower pressure (according to the packaging) may eliminate some of the waiting, should I need to repeat such a job.

Any comments would be appreciated :confused:

Why are you using such high pressure?
40psi at most even with a cheap gun!
The time it takes for the comp to cut in is more relavent to the size of its tank and the pressure your running 100psi is way to much, its OK for the comp to run conituosly so long as it keeps up enough flow to run the gun properly.

Unfortunately, at less than 80 odd psi, the gun would just spit out little blotches of paint - sort of pulsating :confused: .
I am VERY green when it comes to spraying, and as the compressor is at best an 8cfm unit, and I believe the gun requires between 6 - 8 cfm to operate, I was hoping that by switching to a gravity fed gun, which according to the box, only requires about 2 - 3 cfm to operate, I would be able to learn to also spray finish on furniture projects as well as the odd repainting of fences :o

You'll find on cheap guns what the box say's and what really is are two very different things, probably written by the sales dept!

Possibly you have some sort of a leak in the gun causing the plusing, thread tape all the joins from the pot to the gun(the path the paint leads ...), also with cheap guns the nozzle doesnt sit in its seat very well(poor machine work or corrosion because of cheap materials)causing the venturi action to break(pluse).
To counter act this an increase in pressure is needed...

What I have done before is to spin the nozzle in a drill and use a fine file on it to get a nice flat seating area.

The nozzle lives under the aircap(the bit with the wings!)

Your 8cfm comp should run your gun, if not theres something wrong with it. If you were to paint a car where a conituous flow is critical too the finish quality the minimum is considered 10-12cfm.

I can only imagine how much overspray your genarating with 100psi!

Overspray :o
The 'stuff' I was spraying was Bunnings Walpamur Fence Finish, which in hindsight was probably not the right viscosity (ie too thick).

The gun I have is (again from Bunnings) a Tradeair Model TAR-SSG and the enclosed brochure and stamps on the side of the gun says S770. It supposedly has a 2mm fluid nozzle and has a material output of 345cc. Requires 50psi with an air consumption of 8.8 cfm.

I believe that an HVLP gravity fed gun requires only about 2 - 3 cfm and thus my question.

Will my current gun be any good for applying finishes to woodworking projects, taking into account the use of a GMC compressor ? :confused:

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Originally Posted by Soren

Overspray :o
The 'stuff' I was spraying was Bunnings Walpamur Fence Finish, which in hindsight was probably not the right viscosity (ie too thick).

The gun I have is (again from Bunnings) a Tradeair Model TAR-SSG and the enclosed brochure and stamps on the side of the gun says S770. It supposedly has a 2mm fluid nozzle and has a material output of 345cc. Requires 50psi with an air consumption of 8.8 cfm.

I believe that an HVLP gravity fed gun requires only about 2 - 3 cfm and thus my question.

Will my current gun be any good for applying finishes to woodworking projects, taking into account the use of a GMC compressor ? :confused:

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Hi ya,

S770 would be a Star gun & a 2mm fluid nozzel would be correct for a S770.
I've used a S770 for more than 5 years & it's fine for spraying lacquer.
Does it have a air adjustment knob at the base of the handle? If so this would confirm it as a Star gun.

I hope the S-770 works ok because i bought one as a backup the other day.
I believe the S770 is quite a good model (for the price anyway).

It should work fine with spray finishes on woodworking projects. I have mine running of a 24L 2HP compressor. It's ok for brief passes at 40-50 psi :)

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Originally Posted by MajorPanic

Hi ya,

Does it have a air adjustment knob at the base of the handle? If so this would confirm it as a Star gun.

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Mine does at least. As long as it performs like a star :D :D
I'm thinking of maybe buying one of those $35 touch up guns too with the small capacity container for the occassional bowl finishing spray. Just seems to right size for this task.

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Originally Posted by MajorPanic

Hi ya,

.............. Does it have a air adjustment knob at the base of the handle? If so this would confirm it as a Star gun.

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I believe it does, refer attached image

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Originally Posted by Soren

I believe it does, refer attached image

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I do beleive it is an early version of the S770 :D
So there should be no problems ;)

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Originally Posted by MajorPanic

Hi ya,

Does it have a air adjustment knob at the base of the handle? If so this would confirm it as a Star gun.

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Hmmm I have two different model IWATA guns that have the air adjustment knob at the base of the handle.....Or am I only dreaming...will have to check on that tommorrow

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Originally Posted by Dean

I hope the S-770 works ok because i bought one as a backup the other day.
I believe the S770 is quite a good model (for the price anyway).

It should work fine with spray finishes on woodworking projects. I have mine running of a 24L 2HP compressor. It's ok for brief passes at 40-50 psi :)

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Hey Dean!

I set my regulator to 41PSI for the HVLP nug & the only time I change it is if I use the touch-up nug (6PSI).
For the 770 I wind the air adjustment all the way CLOSED & then pull the trigger while turning the air adjustment knob open. When the nug picks up the lacquer & gives a full spray patten I stop adjustment.
The air adjustment knob is only ⅓ open, if that. I reckon I'm spraying at about 15-18 PSI or so.

"It supposedly has a 2mm fluid nozzle"
With that size you should be able to spray thick honey!

MP so the S-770 2mm will spray lacquer OK, I need a cheapy to tie me over until I replace my samson(RIP!)dam cant seem too find the parts to repair it yet.
Might even splashout and grab a binks or devilbiss one day.

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Originally Posted by Shane Watson

Hmmm I have two different model IWATA guns that have the air adjustment knob at the base of the handle.....Or am I only dreaming...will have to check on that tommorrow

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But Shaneus,

Is S770 stamped on the handle of your nugs?

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Originally Posted by MajorPanic

I do beleive it is an early version of the S770 :D
So there should be no problems ;)

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MajorPanic

What do you mean, the spraygun was only purchased 9 days ago ? :confused:

Nope they havn't..

http://www.anestiwata.com/PROD_IMAGES/W100-P.jpg

http://www.anestiwata.com/PROD_IMAGES/W400.jpg

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Originally Posted by Harry72

MP so the S-770 2mm will spray lacquer OK, I need a cheapy to tie me over until I replace my samson(RIP!)dam cant seem too find the parts to repair it yet.
Might even splashout and grab a binks or devilbiss one day.

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Hi ya Harry,

I've used the S770 for years & it was fine for me.;)

Ask Shane about IWATA guns, they have a VERY GOOD reputation, if you want to go up-market. ;) :D

"Hmmm I have two different model IWATA guns that have the air adjustment knob at the base of the handle.....Or am I only dreaming...will have to check on that tommorrow"
Most have an air adjustment on the lower part of the handle, even my samson has.

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Originally Posted by Soren

MajorPanic

What do you mean, the spraygun was only purchased 9 days ago ? :confused:

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Sorry Soren,

Where did 'purchased 9 days ago' come from? :confused:

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Originally Posted by Harry72

Most have an air adjustment on the lower part of the handle, even my samson has.

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Yeah well, my workhorse IWATA (VX707) dosn't but my finish coat IWATA'S do

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Originally Posted by MajorPanic

Hi ya Harry,

I've used the S770 for years & it was fine for me.;)

Ask Shane about IWATA guns, they have a VERY GOOD reputation, if you want to go up-market. ;) :D

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Yep I've use a iwata before nice guns, 2pac like a mirror no buff!

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Originally Posted by Shane Watson

Nope they havn't..

http://www.anestiwata.com/PROD_IMAGES/W100-P.jpg

http://www.anestiwata.com/PROD_IMAGES/W400.jpg

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Thanks Shane!

Now kiddies these are BMW class spray nugs!;)
What we are talking about (S770) is a good Commodore quality nug! :D

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Originally Posted by MajorPanic

I do beleive it is an early version of the S770 :D
So there should be no problems ;)

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This is where the comment comes in, ie only purchased 9 days ago from B.....gs :confused:
I hope the gun will be OK for finish applications, with the 'less than perfect' compressor :o

Hi Soren,
I believe your issue is not the compressor nor the spray gun as being any problem. The pressure you mention is way to high firstly for most guns. The viscosity of the material your trying to spray is way too thick and therefore your trying to move thick material into a air borne mist that is spray painting.

You need to determine the composition of what your spraying in particular the solvent that dillutes the spray medium. For example if your usig auto acryl lac then thinners for that particular paint is required. If your using house paint that is water based then use water to thin the paint etc. Oil paint would have to be thinned using turps etc.

Your trying to transfer material that is wrongly thinned for spraying and this is the "poor" transfer and spattering of paint. This is where your going to burn your compressor out for it has to work like a "dog" moving liquid lead from the pot.

Always check if a particular paint in fact is recommended for spray applications.

Have fun! You have a reasonable set up but a very thick medium laboring your compressor.

http://www.ganet.org/dnr/p2ad/pblcations/paintbas.html

:o

Nah Id say more like a Hyundai excel, the samson is more like the commy/falc range.
They all still get you from A to B!

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Originally Posted by violincrafter

Hi Soren,
I believe your issue is not the compressor nor the spray gun as being any problem. The pressure you mention is way to high firstly for most guns. The viscosity of the material your trying to spray is way too thick and therefore your trying to move thick material into a air borne mist that is spray painting.............

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I was hoping that was the case, and I now have a 'viscosity' cup which "should" enable me in thinning the paint appropriately.
My main question is still outstanding however, in that: "is an HVLP gravity gun better for the compressor I have (8cfm GMC) ?"

I really appreciate all the responses received so far :o :o

Dont bother with them unless you just intend to paint stuff where a nice finish isnt needed.
Still it wont hurt to have both types...

Is this the fastest growing thread or what!!!

viscosity' cup, I use a stick!

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Originally Posted by Harry72

viscosity' cup, I use a stick!

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ROFLMAO

How do you time your stick ? :D

The diff between the guns are in the hands of the operator and like all things its a matter of personal preference. I like suction feed guns and also gravity HVLP types. Each has its benefits and probs. They arnt that pricey either depending on brand names. The suction types leave a little paint in the pot and this is to leave any particles there. But then again if paint is filtered there should be no particles there in the first place but then again<<<what if? A gravity gun will clog right away if there is poor shop practice or other reasons. Gravity also poses a problem with poor seals after time. As with all things liquid via gravity likes to find its way into many places it can escape. To answer your question try both and see which you like the best without any spills.

Your compressor should handle both and of course the gravity feed HVLP will be easier on the unit but technique will play an important role as will the seals be and hopefully no paint consolidation settles at the bottom or should I say at the top to require a clean of this type of gun and cause dreadfull splattering and clogging early in the work :( . Gravity wants things to settle and find points of exit.

A gravity gun seems like a waste of money for fence painting as is a good arnold suction gun! :eek:

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Originally Posted by MajorPanic

The air adjustment knob is only ⅓ open, if that. I reckon I'm spraying at about 15-18 PSI or so.

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WOW :eek:
Maybe that is the trick to "Major-quality" finishes.
I'll give it a try :D

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Originally Posted by violincrafter

..........Your compressor should handle both and of course the gravity feed HVLP will be easier on the unit but technique will play an important role as will the seals be ..............

A gravity gun seems like a waste of money for fence painting as is a good arnold suction gun! :eek:

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I just checked the IWATA site, and that suggests that the HVLP is actually requiring minimum of 9 cfm, whereas the suction gun only requires 5-10 cfm ?

When I was at Supercheap at Ringwood the other day, they had an "HVLP" gun for $99 which supposedly only needed between 3 - 4 CFM to run !! is that worth it, to 'save' the compressor ?
:confused:

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Originally Posted by Harry72

"MP so the S-770 2mm will spray lacquer OK, I need a cheapy to tie me over until I replace my samson(RIP!)dam cant seem too find the parts to repair it yet.

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the star gun will suffice for spraying lacquer mate , could even get away with putting a larger nozzle , cap and needle in for spraying sealers etc , or go the reverse and have a smaller setup for colouring up or toning etc.

either way it will do the job for the home handyman.


ps - what do u need for ol' smason , i might have a few spare bits and peices from a couple of junk pile guns at work.

let me know and i will have a look.

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Originally Posted by Soren

ROFLMAO

How do you time your stick ? :D

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I use a stick too, the flat one I use to stir the paint. Dip the stick into the paint, pull it out. Watch how far away from the end of the stick the paint breaks from a solid stream into droplets. The closer to the stick, the thinner the paint. Suprisingly sensitive.

regards,

John

I use a stick as well....Never use a viscosity cup & the quality of finish was never compromised. But once you've mixed several thousand litres you get to know.....

Yup stick yer paint!
Soren, dip the paint stick in and hold it out of the paint about 150mm, wait about 2 seconds then look how far the paint breaks into droplets(like Johnno said)
Depending how much paint your stick can hold on its surface is how much time you've got to judge it, ie use a stick with as much surface area as possible... a series of small holes drilled in you stick will increase the amount of time you can judge it for.

Denpending on what paint your using, with enamel and a 1.8mm nozzle 100mm is about right break distance, with poly and a 1.4mm nozzle go about 80mm or with 1.8-2.0mm nozzle you want about 100-120mm.
With the few goes I've had with pre-cat lac 1.4 nozzle 60-80mm, 1.8 nozzle 80-100mm
This is for a 10-20% thinning ratio.
See the pattern generating here... smaller the nozzle thinner you want the paint, if the paint needs to go on thick dont use a small nozzle(enamel/poly final coats).

Turbo, I need the outer sleave that the paint needle and spring assembley sits in, dunno what its called lost the parts# sheet years ago... and cant find one anywhere which is a bit funny, seeming you can still buy S90's new!

Thanks for that Harry72
I'll print it out and try my luck :D

harry

i know what your referring to , i will look in the spares tomorrow.

cheers

andrew

Hi Folks,

Anyway just wanted to drop a line on the subject of spray equipment. I have been using both the touch up gun and the HVLP Gravity gun and let me tell you the finish is SUPERB to say the least. Ive adjusted the HVLP for optimum performance and it really does reduce overspray and transfers more of the material to the work.

I have a 2.5hp 40ltr compressor that handles it quiet well without to many dramas. As a fact I tried a simple experiment to determine how if any strain is placed on the compressor. First I attached the touch up gun an let it "shoot" a test panel to see the amount of time when the compressor reaches the cut in point of 85 psi and working to 115 psi factory settings. The touch up sprayed for 28 seconds to reach 85 psi and the HVLP gun took 26 seconds of continual spraying. There was little difference between the two except the HVLP gravity had less overspray (in the air) than did the touch up gun.

I like both of them and thus far have given excellent results. The touch up has its advantages owing to work type and space as the gravity HVLP is slightly bigger and uses a pressure guage at its bottom making it longer with the hose attached.

Practice makes perfect and am very satisfied with the results.

Evenin' All, I am also new to spraying and have been learning by trial and error. I too have a little GMC compressor (only cost $100) and I think it is good for about 5cfm. And I bought the el cheapo spray outfit from Bunnings that include a spray gun (1.8mm), blower, degreaser gun, tire inflator etc all for about $35! I then proceeded to spray a sunburst lacquer finish onto an electric guitar and the results were great (much to my surprise). Being small item and using only short bursts so the comp had no problems keeping up.

I have since bought a much better although still inexpensive spray kit that includes two guns both gravity feed: a 1.4mm regular gun and a 1.0mm touch-up gun. So far only used the little fella and it is working well. I use 35 - 40 psi and am wondering if that is too much. I tend to turn the feed control right down and use a very narrow fan, almost no fan at all. Still I seem to get a lot of overspray and the spray booth (garage) fills with a lacquer cloud.

I would love to have a general reference on the ins and outs of spraying but I haven't found anything on the web. Can anyione direct me to a basic spray painting reference?
Asquared