Thread: spray guns?- small compressor

Graeme,

I ordered the PSH-1 and at the same time ordered the 2.2mm tip for an extra US$31, regretably haven't had the opportunity to use it yet though. All up with freight was still a reasonable deal.

Cheers Brett. Let us know how it works out.

I picked up a brand new 2.0mm nozzle for my PSH1 on ebay for US$15.95 including postage recently, but like BrettC haven't had the chance to try it yet.

The Iwata is a good make - but I'm not sure what its air requirements are for this one. If they say it is only good for small objects might be OK with your compressor - though I wonder, is the W77 a touch-up gun. If it is a regular gun, it would be OK for spraying most anything - but - could be it needs 10cfm free air if it is. Otherwise the compressor will run continuously (ish) and get very hot, or you got to stop frequently and let it catch up. Best thing is to check the free air requirements for the gun before you buy. Also, quite a bit of stuff here if you do a search. Good luck. If this doesn't make sense, PM me.

Jaspr- (US) $16 odd is a brilliant price for the 2.0mm PSH1 nozzle delivered to Oz. When I looked at them, they seemed to all be around the (US) $31 mark before postage.

Murray- the Iwata W77 is a suction feed gun rated at 8.8 cfm @ 50psi for one type of 2mm nozzle and 12 cfm@ 50psi for another 2mm nozzle. Are these ratings free air delivery? I assumed they were but am not certain.

Would this gun consume too much air to give me a decent spray job? Would I even finish a 1200mm by 700mm coffee table top before it ran out of air? It isn't a touch up gun.

The Porter Cable PSH1 is rated at 8.5 SCFM @ 40psi for the 1.5mm nozzle with a recommended operating pressure of 45psi.

My head is spinning

When you buy a spray gun the actual code for the spray gun eg: W77 only tells you the model of the gun. In the case of the Awata W77 its a medium sized body which would fit most normal sized persons hand and fitted with a 1 litre pot would be suitable to use as a general spray gun.

There is a list of sizes for each gun which is termed the "set up" which consists of the air cap, the nozzle and the needle for the nozzle. Most companies make various combinations to suit a wide range of customers who may have different sized compressors or wish to use it in a particular way. You need to check the brand of guns chart (usually enclosed in the box the gun body comes in) this will give you the codes which tell you the sizes of the "set up". Most good brands also give you a guide as to what paint its suited for.

The smaller the CFM rating the smaller the fan width and amount of area you can cover with the gun in a minute, but you can spray continuously. If you have a bigger air capacity you can purchase a "set up" which needs more air and you can therefore spray a job faster.

With lacquer it dries so fast that most of the solvent is lost in the transfer from the gun to the job, so you need to have lots of thinner but more of the paint coming out of the gun. If you buy a gun with a smaller nozzle (such as the 1.5 mm) the paint will be out of balance and the amount of air drying out the paint during travel to the job will be to great for the smaller amount of paint able to get out of the gun. The end result will be a dry sandy or orange peely surface. Normally when you check the paint specification it will stipulate the size of the nozzle for the gun along with its viscosity (how thin it is)

Use a 2mm gun with enamel type paint and you will get runs and sags. If you use different paints which are different in their characteristics you need to have different "set ups" for each one to get optimum results.

You could take an average (a general purpose gun) and it would spray most paints sort of OK but none of them anywhere as well as is possible with the right gun "set up."

Originally Posted by bookend

Jaspr- (US) ....Murray- the Iwata W77 is a suction feed gun rated at 8.8 cfm @ 50psi for one type of 2mm nozzle and 12 cfm@ 50psi for another 2mm nozzle. Are these ratings free air delivery? I assumed they were but am not certain.

Would this gun consume too much air to give me a decent spray job? Would I even finish a 1200mm by 700mm coffee table top before it ran out of air? It isn't a touch up gun.......

My head is spinning

Yes, those ratings are free air requirements.

I think you will get away with it - just. The compressor will run most of the time on a large surface. For a coffee table top, I'd guess you might make, say 5 - 6 passes left to right, lengthwise, stopping the flow at the end of each pass, overlapping as you come back - OK, maybe 7 - 8 passes - depends on the dimensions. The compressor will kick in pretty soon after you start but when you finish the top, you'll have to stop and reposition the table to get at the rest- compressor will catch up and cut out... ready for the next onslaught.... so, I'd not be concerned for this sort of work.

If you are spraying a (biggish) bookcase, say, you'll probably want to go longer before taking a break - and then the compressor will probably run continuously for a minute or two. It'll get hot, and it might not catch up, in which case you'll notice the flow isn't quite as enthusiastic as it was when you started so you stop and let it come back up to pressure. You won't see the gauge when you are spraying because it is on the regulator generally, and too far away, but you'll "know" if you haven't got enough pressure .... I can't recall what material you are spraying (product). If it is "watery" you might want to try starting lower (on a test board) than 50psi -maybe 30 - 40 otherwise it'll run. Increase the pressure till you are happy with what's occurring. I'm not an expert - just a trial & error (sadder but wiser school) graduate.

A couple of things havn't been mentioned here which are important for you to spray with your compressor and gun.

First you will need to have a air transformer which is a filter and pressure regulator combined. You can get by just with a regulator but a proper transformer makes it a lot easier to connect and to operate from.

A gun usually requires about 40 -50 psi to work correctly, your compressor will be pressureized to about 100-120 psi far too much air to spray with. The stored air will be let out at say 40psi by the compressor and the tank will have a reserve of air, you have to hold the trigger for one minute continuously for say 8cfm to be extracted from the compressor as murrayD99 says you only spray as you move along and you stop at the end of each pass. If you painted a house door it would take about 30-40 seconds depending on the fan width and your gun settings.

The compressor would kick in about 90psi but you will have lots of air to use as you only have the pressure set at 40psi. The compressor will keep pace or beat you by the time you finish spraying. It could take you a few minutes spraying before the pressure drops below the 40psi you need to have from the tank of air. The tank storage capacity helps you extend the air available so if you add pipe or extra tanks you can store more air and spray longer before the compressor needs to kick in. I see Bunnings have available air tanks you can buy you could set one up for the compressor to fill also in line with the compressors tank. Some people who have a permenant compressor set up in their shops use large diameter pipe to act as a storage tank, your small compressor would take a while to fill extra capacity up but you would be able to spray larger objects.

What you also need to do is connect the air transformer about 5 mitres from the compressor with a air line. The air is heated up when its compressed and this allows the air to cool down enough for the air transformer to catch the water in the air. If you don't cool the air down it will exit the gun and along with the air as steam and end up on and in your paint causing more problems.


If you are using a 8cfm gun you would be able to happily spray a car with it. I would have no hesitation using a 12cfm gun with a 8cfm compresssor as you normally only spray for short bursts. It would take you longer than a bigger gun but if your gun is too big you have to wait around for the paint to dry before you can apply the next coat so waiting for the air to build up is really no different.

Finally, the beauty of spraying lacquer is you can easily stop at any time even in the middle of a big panel and start again even if the first lot of paint has dried, you just melt the two coats together with thinner and you won't see the join.

Thanks Murray and Durwood.

The practical advice you've both given is invaluable and to the best of my knowledge hasn't been discussed anywhere on the net.

I'm a lot more confident that the small compressor can do what I want it to without taking the shut my eyes, give it a go and hope for luck approach.

Cheers!

Kompressor Fax.

Kompressors are MADE to wrun.

Getting hot is goode, cause it drives the condensation out of the oil.

And people who go "Ohh the great Satan has arisen - the compressa is getting hot" - I dunno, the notion is just way off the mark......

Getting hot is just part of the deal, and they are designed to remove / radiate / soak up the heat of some of the compressed air.

The issue of excessive heat, is only an issue, if the comprtessor is wrapped thicky in wood dust, blankets or is operating in a very small unventilated enclosed space.

Then "overheating" starts to become an issue because of material breakdown of the lubricant etc., from excessive heat.


And the notion of "Oooo the compressor is not keeping up" simply because it's operating most of the time, - is crap too....

The idea is that if your optimum spraying settings for a particular gonne, spraying your laquer (or what ever), thinners, and all... is say 40 psi, and the air supply can keep your gonne fed with air at this pressure, no matter whether your sprayink for 30 seconds or non stop, then it does the job.

If however you need to be spraying non stoppe, like 20 minutes continiously, and within 30 seconds (or what ever) and you need say 40 PSI at the gonne, and it's dropping to 35psi, then you have an insufficiently rated compressor.

But a compressor that is completely inadequate for continious running can and usualy is, with a goodly sized reservour, completely up to the job of spraying for short and intermittent periods.

It's like my sand blasting outfit... it will give me 100psi for about 30 - 40 seconds and then slowly drop down to about 80psi.... when continiously running.

So for the 30 seconds - it cleans really well.. and after that.. not so good.

But if I am only doing short jobs.. or intermittent bursts - it's great...


Same with the spraying.....


As I dislike NASTY smelly and kind of toxic gear oil, and my compressor also feeds my respirator, I run my compressor on OLIVE OIL.....

The air gets fed through an oil fume filter, a condensate seperator, and what I am breathing gets fed through an activated charcoal cannister.

Works really well.

And I do oil changes every ~50 hours of running time, or 6 months what ever comes soonest.


But my dear little compressor, is working nearly non stop, while it's feeding me air and my gonne.

I get to breath, the gonne gets it's 40psi and all is well.

2shane... "hot" is relative. I meant hot hot hot... and the compressor I had ran continuously and couldn't keep up. I think it was rated at 10cfm and delivered about 7. The gun needs 10cfm. Solution: sell it and upgrade to a 3cyl machine that delivers 12cfm. End of problem.

Not wanting to hijack - but sandblasting? What are you using? PM me perhaps?

2shane,
a "hot" compressor will carry more water vapour in it's air supply which will condense as the gas expands and cools when it leaves the spray gun. Therefore, from what I understand the hotter a compressor runs the greater the water vapour problem. With regards to the olive oil, I think you may be causing more problems than with normal oil. Olive oil is quite acidic and the mixture of the acidic olive oil and water vapour in the system may be causing corrosion. I'm famimliar with the positive pressure air supply you are using and the fact it has active charcoal filters etc, however it may pay to speak to an oil company rep to see if they have specicfic reccomendations for hookah compressors. They may use a silicone oil, I'm pretty sure that compressors used to fill dive tanks do.

Mick

Originally Posted by journeyman Mick

2shane,
a "hot" compressor will carry more water vapour in it's air supply which will condense as the gas expands and cools when it leaves the spray gun. Therefore, from what I understand the hotter a compressor runs the greater the water vapour problem. With regards to the olive oil, I think you may be causing more problems than with normal oil. Olive oil is quite acidic and the mixture of the acidic olive oil and water vapour in the system may be causing corrosion. I'm famimliar with the positive pressure air supply you are using and the fact it has active charcoal filters etc, however it may pay to speak to an oil company rep to see if they have specicfic reccomendations for hookah compressors. They may use a silicone oil, I'm pretty sure that compressors used to fill dive tanks do.

Mick

Ohhh Mickles.... Hmmmmmmmm poor fellow... replies:

a) If air has a relative humidity... say 15%, and it's compressed into 10% of it's original volume, the latent HEAT concentrates.... so it's impossibly to squeeze AIR into a smaller space without it heating up...

b) The compressor only absorbed heat from the air, through radiation and convection.

c) The parameters are FIXED... the relative humidity of the air, the degree of compression, and the degree of cooling, both after compression and during expansion, the environmental heat, and the amount of expansion - determines the condensation or dew point of the air.

So therefore, the temperature of the compressor, and it's oil has NO bearing upon the moisture that condenses out of the air that it compresses.

However a NICE HOT compressor (good running temperature) through it's heating of it's lubricant - drives the blow by moisture out of the oil that can and usually does incrementally creep into the lubricant from frequent COLD and SHORT delivery cycles. (short and infrequent running times).

d) I use a vapor filter, for the oil fumes, and I use a condensate seperator, so condensation in the compressed air is not an issue for me.

e) Olive Oil - see without going into ALL the history of lubricants..... Well vegetable oils only went into decline as lubricants, when the mineral oils became both cheap enough and reliable enough to compete.

f) Olive oil is not particularly acidic nor corrosive... in fact it's an excellent lubricant and it's NON toxic.

g) The corrosion in the tanks, is caused by the tanks never being drained, nor getting hot enough to drive the moisture out of the tank and through the lines to the condensate seperator. It's the water, oil and bacterial and metal combination that sets a really good electrolytic reactions and cells....

The carbon in the steel, the iron in the steel, the acidic by products of bacterial decomposition / digestion of the oil, the ION rich and very conductive acidic soup that is created...

Olive oil really isn't an issue for corrosion of anything in the compressed air delivery system.. it's the ?????? maintainance and the people who fail to perform it, that creates it.

Silicon oil is not used in compressed air systems, on the basis of toxicity, it's used because mineral oils decompose / and oxidise rapidly at the higher pressures within the cylinders of the compressor.

I designed and built my own breathable air supply system.

I was so bloody indignant at the prices these thieves charge for such a system, as in $1500... that I went and designed my own and built it on a material only cost of about $50 - which was mostly the price of the fittings and half a days work.

And I picked the brains of LOTS of compressor engineers and sales people.. and well they were not much help....

IMEO..... most of them seemed to be of the mindset that if it's not out of a packet... then it can't possibly exist.

But you can buy their product in 200 liter drums for only $965...

(and Oooo it's special extra heavy duty compressor oil made for Australian conditions....- and since most of the planet has the same "reasonable" conditions as Australia, me thinks they are full of marketing hype and ????????)

Simple.

Olive oil is used as the break in oil for some of Honda's car engines.

It would make an excellent stand alone lubricant for most engines, with consideration that it has no endurance modifiers (detergents, anti oxidants, viscocity etc), and hence would probably need to be changed 3 or 4 times as often...

More regular oil changes = more running costs... and olive oil, for the time being, is not exactly cheap.

It's an excellent all round lubricant... I use WD 40 on my lath bedways and I use olive oil as my cutting tool coolant and lubricant - applied by brush...

Olive oil works well on my bike chain...

Though there is a little off set, in that because it has NO anti-oxidant additives etc., it will oxidise slowly over time... but the compensation for it, is that it is NON toxic, it washes off and out of everything with soap and water and it's an excellent lubricant - like other lubricants, within it's limitations.

I have been using it in my compressor/s for years and I have never ever had any failures due to lubrication.

I just change it a bit more regularly than I would the stinky horrible and chlorinated / sulphurised toxic gear oils..

Simple.


Time for beddes

2Shane.



This is a good enough sites to fill in many of the gaps.


http://www.ecompressedair.com/librar...rsystems.shtml

http://www.hse.gov.uk/research/rrhtm/rr427.htm

http://www.hankisonintl.com/Air/answer1.htm

http://www.plantservices.com/articles/2006/182.html

http://www.geo4va.vt.edu/A3/A3.htm

http://www.synlube.com/oilv.htm

http://www.worldlube.com/glossary.html

Some interesting info there Shane