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Iwata HP-CS new nozzle/needle issue


Melonfish

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Hi All,

Rather than trawl a rando fb group I figured i'd ask those who use airbrushes regularly.
So i've had an Iwata HP-CS for a couple of years and i've had no major issues with it, I have bought an official nozzle and needle for it as replacement, however after fitting I get a lot of bubbling in the pot, if i fit the original needle/nozzle i'm fine.
This is likely user error, i'm probably doing something wrong somewhere but any ideas? I keep this thing clean like a zealot so I know it's generally fine but this has me a bit stumped.

both needle/nozzle sets are the 0.35 standards.

thank you
Pete

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Sorry if I'm covering the obvious, but check if the seals are the same - maybe try swapping the seal from the old nozzle onto the new one

 

Cheers

 

Colin

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suggests a leak around the nozzle to me (indeed some people backflush by loosening the nozzle assembly). It's the whole 'free sitting' nozzle you've replaced rather than just the screwed on tip? As Colin says, check the obvious stuff first; was the nozzle retaining screw done up properly and with a seal in place? 

 

Could it be something about the conical seating for the nozzle has become dirty and the old nozzle somehow seals against it by similarly dirty/pitted?

 

Andy

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7 minutes ago, Ngantek said:

suggests a leak around the nozzle to me (indeed some people backflush by loosening the nozzle assembly). It's the whole 'free sitting' nozzle you've replaced rather than just the screwed on tip? As Colin says, check the obvious stuff first; was the nozzle retaining screw done up properly and with a seal in place? 

 

Could it be something about the conical seating for the nozzle has become dirty and the old nozzle somehow seals against it by similarly dirty/pitted?

 

Andy

Hi,
It is the entire cone unit yes, the fitting is a consideration actually I do wonder, i'll give the fitting a good scrub and test again see how the cone sits in the recess.

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HP-CS bubbles in the cup? First place to look is to ensure the nose cap is screwed up firm against the o-ring seal on the airbrush body. Don't overtighten, I find hand tight is good enough.

 

Iwata_Cleaning_17

 

Before doing so, check the o-ring is in good condition. Was it replaced as part of the change over?

 

Iwata_Cleaning_16

 

It should not be needed, but a little beeswax on the thread will give you a quick check if this is where the problem is.

 

Ray

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1 hour ago, Ray_W said:

HP-CS bubbles in the cup? First place to look is to ensure the nose cap is screwed up firm against the o-ring seal on the airbrush body. Don't overtighten, I find hand tight is good enough.

 

Iwata_Cleaning_17

 

Before doing so, check the o-ring is in good condition. Was it replaced as part of the change over?

 

Iwata_Cleaning_16

 

It should not be needed, but a little beeswax on the thread will give you a quick check if this is where the problem is.

 

Ray

It was the O ring I think!
Took it off, give it a good lube and reseated, put lube on the threads (the iwata stuff) and the new nozzle/needle work perfectly. that's thrown me for a while that as the old set worked fine.

thank you.

 

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  • 2 months later...

I want to add I also had this exact issue about 3 weeks ago and the fix was something different.   (I also have experience exactly what you are experiencing as well though).

 

When I put the new needle and nozzle on my HP-CS...I would push just a little too hard on the needle as I was putting it in the airbrush.  So instead of just stopping when it stopped...I do an extra little light tap that seated it in even further.  This ended up being enough to cause the symptoms you are experiencing for me.

 

Now, when I seat the needle, I just stop when it encounters the first resistance of seating in the nozzle.

 

 

 

 

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6 minutes ago, Steve Arr said:

When I put the new needle and nozzle on my HP-CS...I would push just a little too hard on the needle as I was putting it in the airbrush.  So instead of just stopping when it stopped...I do an extra little light tap that seated it in even further.  This ended up being enough to cause the symptoms you are experiencing for me.

Pushing too hard can split the nozzle. I may or may not have had some experience with this issue. I do keep spare needles and nozzles on hand as they are fragile.

 

As mentioned above, bubbling in the cup often (always?) means an air leak. I too use a little beeswas on the body threads when I re-assemble after a compllete strip-down cleaning. I also apply some lube to the needle packing screw by putting lube on the blunt end of the needle and temporarily inserting it backwards into the needle packing.

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  • 3 weeks later...

I have a slight concern with the solution.

 

It is that the O-Ring is on the airbrush pictured so is common to both the old and new nozzles - but the new nozzle bubbles whereas the old one does not.  In my mind that suggests a problem with the new nozzle, maybe it is not machined quite right.

 

You say you have fixed the problem by lubing the O-Ring, my concern is that airbrush lube and wax can hide a multitude of sins - for example, I have a terrible eBay £15 knock-off Chinese clone which leaks like a sieve, but if I apply airbrush wax I can get stop the leaks - but I’m not fixing the fundamental problem, bad machining and O-Ring, I have simply bodged a workaround.

 

Possibly too late now, but had it been me, when I discovered that the old nozzle sealed but the new one leaked, I’d have returned it for replacement.  Only if the replacement nozzle also leaked would I have looked for other causes.

 

I don’t like using lube or wax to fix leaks because it might be fine now but when you next clean is it going to leak again and you have to disassemble to apply fresh lube wax - it isn’t a permanent solution.

 

Essentially, with a well made airbrush, the components should seal without the need for lube or wax - possibly I’d look at replacing that O-Ring to see if that makes a difference.

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57 minutes ago, nheather said:

I don’t like using lube or wax to fix leaks because it might be fine now but when you next clean is it going to leak again and you have to disassemble to apply fresh lube wax - it isn’t a permanent solution.

 

On 6/6/2023 at 11:12 PM, Ray_W said:

It should not be needed, but a little beeswax on the thread will give you a quick check if this is where the problem is.

 

With the HP-CS the O-ring should do the sealing. The HP-CS nozzle self-centres within the air cap by taking up on the tapered nozzle shoulder. It needs an O-ring to seal the air cap while providing a little variation, a little give, for variation taking up on the shoulder. I find hand tight is good enough. The beeswax on the thread (do not apply to the taper) will give you an indication if the problem does lie with the O-Ring. Possibly a temporary fix while you get a new O ring.

 

Iwata_Cleaning_9

 

Also, all air brushes are not the same. For example the HP-B Plus does not have the CS's self-centring. It has a nozzle rigidly screwed into the body of the airbrush. No taper and no requirement for an O-Ring as an air cap seal. It relies on a sealant on the aircap/main body thread. When you receive it new, Iwata provide a red sealant. This soon goes the first time you break the seal. Beeswax does a great job of providing a sealant. 

 

airbrush 3

 

 

It is worth noting that Iwata-Medea now offer beeswax as a thread sealant.

 

Airbrush Thread Seal

 

 

 

Ray

 

 

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