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Procon Boy PS-267 vs PS-270


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After fighting it for a long time I am ready to jump into the wonderful world of airbrushing. I received an Iwata Revolution CR .5mm for Christmas (thanks Santa) which I am planning on using as my general purpose airbrush (and might convert to .3mm when I get some experience under my belt). Thanks to my OCD (and having yet to fire my Revolution in anger) I am already shopping for a detail brush with a .2mm, e.g. Procon Boy PS-267, PS-270, Tamiya HG III SF, or Grex XGI2-ES which you can pick up for a reasonable price all in the neighborhood of $95-$115. H&S prices are no bueno in comparison. I had a couple questions for those that are knowledgeable about the Procons:

 

1) The PS-267 is approx $20 cheaper than the PS-270, are the only differences the MAC valve and the angled connector, or does it go deeper than that?

2) Being a newbie I don't think I need the added complication of a MAC valve but if someone could illustrate the practical advantages of having it that would help.

3) I mainly build 1/48 WW2 aircraft, does the .2mm/.5mm lineup make sense?

 

Any feedback is greatly appreciated.

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All of the mentioned airbrushes with 0.2mm nozzle are good if you are on a budget.  You don't need the MAC valve; it's just one more thing to worry about.  Unfortunately, all of them require the use of a small wrench to remove the nozzle for cleaning.  Chances are you will strip the threads on the nozzle even if you are careful.

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I have both the 267 and the 270.  For some reason my 270 atomizes finer - not really sure why as they seem to have the same specs and design.   I don't use the mac valve all that much as the airflow is hard to control.   I heard the Iwata external mac valve is better.

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Interesting - I have the P270 and I'm loving the mac valve - it can be finely adjusted compared to what can be bought separately, and I've never touched again the pressure control of the compressor since I started using it.

The P270 even relegated my H&S Infinity 2-in-1 to the back seat...

As for cleaning, I have never removed the nozzle over the past 2 years (since I bought it in fact) - I simply spray several cups of cleaner until it comes clear; I also remove the needle to make sure it has no residue left that may impair its movement (true that I'm diluting the paint often 70% thinner / 30% paint)

Edited by Hamster Volant
Gave a precision re: thinning ration.
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Hmm..  I was planning to buy an external mac valve but now that you mention the built-in one is better I should practice using it.    I do the same for cleaning now.   I used to follow the backflushing method mentioned in the instructions by loosening the nozzle 1mm -- until one day I bent the needle  : (    

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In order to better understand how the mac valve worked, I closed it fully and then experimented by opening it a bit at a time, spraying and checking the result.

Combining that with the back-travel limiter (to adjust the paint flow) I have been able to spray very fine lines and luftwaffe-style mottles as well as covering large surfaces (mac valve fully opened).

For reference I'm building in 72nd scale.

Edited by Hamster Volant
added a precision
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Im not to sure how a built in MAC valve adds a complication...
Maybe in the cleaning of it when stripped down but if you use it as intended then I cant say Ive ever had a problem with any of mine.

 

A MAC valve is there to adjust the speed of the air rather than lower the pressure.

It does lower the pressure in a similar way to a regulator but when you lower the pressure at the regulator the speed drops too, while a MAC valve will drop the pressure and increase the speed because it creates a restriction in the air flow.

 

MAC valves are just about thee most misunderstood functions of an airbrush. Its not a regulator.

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Imagine you have a garden hose.
The pressure is to low to allow you to spray the water as far as you want to.
You have two options, turn the tap to increase the pressure to make the water go further or leave the tap how it is and put your finger over the end of the hose pipe.
The constriction will make the water squirt further even thought the pressure at the tap is the same.

 

In that example your finger is equal to the MAC valve on an airbrush...

 

When you think of it like that you can do many more things than you thought you could with relatively low pressure coming out of your compressor.

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Thanks for the helpful analogy : )  Just what I needed.  I normally spray MRP which is very fine and there are times I want a very tight spray pattern to create very fine lines/mottling.   I would try to tweak the MAC valve to lower the pressure by tightening it  : )      Just gave up eventually and went back to adjusting the pressure on the compressor.    Can't wait to try it out again.   Get the 270 if you can, FritzNYC : )

Edited by crackerjazz
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Way ahead of you, the order is in. Thanks for all the info, the garden hose comparison by ElectroSoldier is a great analogy. I would never have guessed that the pressure coming out of the airbrush could be greater than that coming out of the compressor.

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On 1/11/2022 at 3:21 PM, FritzNYC said:

Way ahead of you, the order is in. Thanks for all the info, the garden hose comparison by ElectroSoldier is a great analogy. I would never have guessed that the pressure coming out of the airbrush could be greater than that coming out of the compressor.

No thats wrong.

The speed increases after the constriction, not the pressure. The pressure does drop. But the drop in pressure isnt why you should be using a MAC valve, thats what the regulator is for...

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Agree, a restriction in a line can’t increase pressure above the output of the pressure source (your regulator setting). 
 

A better analogy is to compare your airbrush setup to an electrical setup. Your line pressure equates to voltage, your air+paint (mass) flow rate equates to current (amps) and your needle setting and MAC valve equate to resistors. You can model a simple DC circuit to understand how each affects the others.   In this case, you can’t get more voltage (pressure) out of your battery (compressor) by simply changing an inline resistor (valve/restriction). 

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