Pulsating Spraymaster Airbrush

[GWMark]

I've just been on a air brushing workshop, which was very good, and gave me a chance to try out an airbrush that I had been given for my birthday, a dual action Spraymaster. This looks to be a copy of the Badger dual action (150 I think). All went reasonably OK on the first day, but on the second day I had nothing but problems with the airbrush and nobody was able to make the thing perform.

 

The problem I had was that the brush would pulse rather than give a steady stream, the air supply was not the cause, as it had a large reservoir and other airbrushes ran from it with no problem. Despite successive stripping down and cleaning we could not stop this thing from pulsing, the longer you used it, the faster the pulse rate became.

 

Does anybody have any ideas what I should do with the airbrush? Or should I just give up and get a recognised make? I suspect it was a fairly cheap copy in the first place. Does anybody else have one of these airbrushes?

 

I ended up using a borrowed Iwata airbrush, so was probably rather spoiled by the way this one performed, but then it did cost 10 times what I believe my cheap copy cost!

 

Thanks

Mark

[JeremyC]

Mark,

 

I'm not familiar with the airbrush you have, but I had a similar problem with a cheap airbrush from Machine Mart. Cause turned out to be a damaged seal between the body and nozzle. In the Clarke brush [and also my Badger] this is a white plastic washer, which can be found by unscrewing the tip. Possibly in cleaning the brush you've lost this.

 

Jeremy

[M Graff]

Yes, I agree with the above. It´s most likely an air-leak between the paint nozzle and the housing. Some makes of Airbrushes use an O-ring and some a nylon/teflon washer.

[landscapes]

Hi Guys

 

I also purchased a Clarke CAB 2P dual control Airbrush from Machine Mart at the end of last year as a Christmas present.

 

I still have not felt confident in using it yet, also I have no reasonable area at the present time in my house in which to spray models either.

 

My question to Jeremy is which Clark air brush did you buy, have you used it and what sort of results have you got from it.

 

I only intend to use it for weathering OO scale locomotives when I finally get around to it.

 

Regards

[Captain Kernow]

My old Badger 200 did this after a few years, and the only cost-effective option then was replacement.

[bertiedog]

Don't panic too much, it's an internal air leak causing the pulsing, the internal washer around the main needle shaft has split, or is not seated correctly. It can be replaced with a home washer, made from rubber sheet, or tiny rubber O rings, or if the design suits, cotton thread can be bound around the shaft, and packed in like a miniature packed gasket under the retaining nut.

 

My Aerograph spraygun is 70 years old and relies on packed cotton thread to make the seals, but works 100%.

 

Yes, an Iwata or Aerograph or Badger will be better than the cheaper copies, but within the limitations of how well it is assembled the cheaper copies do work. ....you just have to take apart, and carefully inspect all the bits and assemble correctly, some thing the Chinese copy makers do not do.

 

Stephen.

[cromptonnut]

I still have not felt confident in using it yet, also I have no reasonable area at the present time in my house in which to spray models either.

 

When I first started practising with my airbrush, I just used water in the little bottle, which I sprayed onto sheets of paper, to practise getting an even spray. No problems with smell or overspray or any other difficulties associated with paint

 

That might be a good practise option - and if you get hot when you're doing it, you can give yourself a little misting to cool down!

[M Graff]

Don't panic too much, it's an internal air leak causing the pulsing, the internal washer around the main needle shaft has split, or is not seated correctly. It can be replaced with a home washer, made from rubber sheet, or tiny rubber O rings, or if the design suits, cotton thread can be bound around the shaft, and packed in like a miniature packed gasket under the retaining nut.

 

My Aerograph spraygun is 70 years old and relies on packed cotton thread to make the seals, but works 100%.

 

Yes, an Iwata or Aerograph or Badger will be better than the cheaper copies, but within the limitations of how well it is assembled the cheaper copies do work. ....you just have to take apart, and carefully inspect all the bits and assemble correctly, some thing the Chinese copy makers do not do.

 

Stephen.

 

A split / unseated rear needle gasket can´t cause pulsing in the spray!

There is no air-pressure on that side of the airbrush. It is only where there is a pressure difference, that you can experience the problems described.

Otherwise I have 40+ airbrushes here that I have serviced all wrong.....

BTW, if you are to replace the gasket. Use a material that withstands thinners (don´t ask me how I know...).

I have used Flax strands (I think that´s it´s name? it is what plummers use) to seal the rear needle bearing.

[bertiedog]

The pressure comes from the high air pressure around the tip, where it's rapid speed outwards causes a pressure drop around the needle tip, drawing the paint through from the paint reserve.

 

However if the seal around the needle has gone, where the needle enters the paint chamber, the negative pressure that is sucking the paint can suck air from normal atmospheric pressure outside the gun into the paint stream, around the stem of the needle, where it mixes in short bursts as it bubbles into the paint stream.

 

Most airbrushes, and the Aerograph spraygun, share the same design, the needle passes through a small O ring or Teflon washer etc. The Paashe design is different, it has external mixing, the needle does not move, and they do not spurt or pulse.

 

Cotton thread will resist all thinners if used as a washer around the needle.

 

THE PICTURE IS SIMPLIFIED BUT SHOWS THE POSITION IN MOST TYPES OF THE SEAL THAT IS LEAKING.

[bertiedog]

The picture shows the Paashe airbrush method for reference, the needle is hollow and fixed, and as long as correctly seated, no air can cause spurts. The paint is mixed with air outside the cone, where the air is passed over at an angle, but still causing a pressure drop that sucks the ink or paint.

[M Graff]

[GWMark]

Thanks for all the responses, I suspect you may be right about a split or leaking seal. I dismantled it last night and found that there was some paint residue in an area that I would not expect paint to be, the part I have shaded yellow in this diagram of the airbrush

 

 

The front O-ring, numbered 5 in this diagram, was slightly out of shape, but refitting this and trying again did not resolve the issue, I suspect it is the packing, numbered 7, that I need to look at next. I did not get the brush enough apart to get to the packing however. In fact I'm not sure how to get to this at the moment, but I never removed the retaining screw and the inner assembly that hold the plunger arrangement in (No. 12). I suspect I need to find an uninterrupted evening to sit down and really strip the thing completely.

 

Thanks again for all your help

 

Mark