Iwata HP-C seal damaged ?

[Chris g]

Ready to paint, filled the cup pulled the trigger back and nothing happened, the needle was stuck solid. I guessed the needle was gummed up with paint so emptied the cup and put some airbrush cleaner in the cup and left it to soak overnight. Next day, gently turned the needle and eventually it came free, so I stripped the airbruh down and cleaned it. (there was quite a bit or dried paint on the needle).

Put it all back together and everything was ok for about half an hour, then the neeedle stuck again so I did the same as before, not so much paint on the needle this time.

When I put the needle back in I noticed some black bits in the cup, thought at first it was dried paint but when I dabbed it with cleaner nothing happened so I'm wondering if I've destroyed a seal.

I can't see a seal at the needle inlet hole to the cup but don't remember if I ever could.

Back of needle to show size of the bits in the cup.



Does this look like part of the needle packing ?

Any help appreciated.

 

[haasje dutchairbrush]

It could be part of the seal though it looks more like dried paint to me. If paint doesn't flow back than the seal should be ok. I tend to have this "sticky" needle effect also but only when using urothane paints (or used thinner to thouroughly clean)

To be sure you have to check it. I can't show it with a HP-C but i think the assembly will e more or less the same as a cm-c.

The seal is located just after the trigger (A). If you disassemble the back you can get a small screwdriver in and get it out.

B and C are pics of the needle seal (couldn't get any sharp pics). On C you can vaguely make out the black o-ring that is the seal.

 

[basepaint]

If its paint it will rip apart easy,If it's part of the seal (o-ring) it will not. I'm with Haasje as i would say it's dryed paint

 

[Chris g]

Haasje,

I think I've found the screw, if I'm right it looks like a brass ring with a slot cut in it, but when I shone a light down the body to find the screw I saw some more black specs so I removed the nozzle and cleaned the body out using the back of the needle.

I think you and basepaint are right, the stuff I got out this time definitely looked like dried paint. I thought I'd leave the screw and see if cleaning the dried paint out had fixed the problem.

After using the airbrush for about an hour with no problems, I took the needle out to have a look. I found wet paint on the needle back towards the the air valve. When I put the cleaned needle back in it didn't seem as tight so I think the seal might need tightening, and I guess some lube wouldn't harm.

Thanks for the help

 

[Chris g]

OK finally got a screwdriver to fit, (also been a bit distracted by the good weather !!!) so having taken the needle seal out I found loads of dried paint around the thread, (seal is white teflon and looks OK)

In the second pic you can see the slot, the brass screw is 3.8mm diameter) so you need a screwdriver with a blade about 3.5 mm.

The third pic is another view of the needle seal, showing the seal itself



cont.

 

[AndreZA]

You can remove the seal from the brass nut and give it a good clean. I also like to cover the threads of that nut with some chapstick when I re-install it. It just help with a better seal.

 

[jord001]

Remember when you fit it back together and insert the needle, there should be some resistance but not too much, it should not easily push through. But be careful tightening it and only do a fraction of a turn at a time once you're there or there about.

lee

 

[Chris g]

I didn't think the last two pics had posted, anyway in the second pic you can see the slot. you need to get a screwdriver to fit (the brass screw is 3.8mm diameter).

Another view of the needle seal

You can remove the seal from the brass nut and give it a good clean. I also like to cover the threads of that nut with some chapstick when I re-install it. It just help with a better seal.

Thanks, good tip