Iwata HP-M1 Review

4/2016

My friend Patrick Stack bought an Iwata HP-M1, and he was kind enough to loan it to me for a review. Here is the handsome box it comes in.

And here's what you see when you remove the cover. Patrick has installed a Badger air hose adapter on his.

I asked Patrick if there was anything else under the airbrush, and he said it was just foam all the way down. I guess there must be marketing reasons for doing this. Here is the quick start guide that came with it.

On the reverse side is the same thing in Japanese. It's so minimal as to be pretty much useless. The guide does refer to their site for more in-depth instruction.

First impression

The HP-M1 and HP-M2 are single action gravity fed airbrushes. Both are part of the Iwata Revolution series. The standard Revolution nozzles and air caps will fit, but obviously the needle of the M is much shorter. The M1 has a .3mm nozzle and the M2 has a slightly larger .4mm nozzle. It appears that you can interchange parts. The needle seal is the same for both versions, so the needle should be no problem.

The cup of the M1 is just 1.5ml. That's pretty small, but you don't use this airbrush for broad coverage. The M2 has a larger 7ml cup.

As you might expect from Iwata, fit and finish are beautiful. The lack of a longer handle feels strange, but we'll see how that works out. The trigger is purely up and down and has a good smooth action. And, the needle adjust on the rear is super smooth. The cap needs a firm push to get it to stay on.

Disassembly

Here is a how it looks taken apart.

I didn't remove the needle from the adjustment knob, and I didn't remove the needle seal. And, I didn't remove the internal parts of the air valve, because it is spared as a complete assembly. I went on the internet looking for spare parts. My old standby Coast Airbrush doesn't show them.

Here is a closeup of the trigger.

Here is something I don't understand. The shaft is perfectly round. This means it can sit in the airbrush body in any orientation, even sideways. That could be really bad when you go to install the delicate needle. Notice the little round dimple near the top. That's an indicator of how the shaft is oriented when installed. Nowhere in the instructions does it point this out.

And, even when the trigger is oriented correctly, it is still very easy to damage the needle. Most airbrushes have some sort of guide to align the needle with the trigger hole and needle seal. The body of the M doesn't. There is nothing but feel to determine alignment. That's not good when the needle is as fine as the one in this airbrush.

Here is a closeup of the needle and adjuster.

There are two set screws. The rear one secures the needle in the adjuster. In front of that is a movable ring with numbers. It has a set screw that allows it to be calibrated. There is a mark on the body that acts as a cursor. A jeweler's screwdriver is needed for the screws, but is not included. I suspect Iwata figures most people aren't going to mess with them. I don't intend to. The rear end of the needle of Patrick's airbrush is recessed about 1/4 inch inside the adjuster. It wouldn't have hurt if they had made the needle a little bit longer so that it was flush or protruded a little.

If you remove the needle from the adjuster, here is one way to re-install it without splitting the nozzle.

1. Very carefully install the needle by itself in the body. Push it forward gently until it barely closes the tip of the nozzle.

2.With the rear setscrew very loose, slip the adjuster over the rear of the needle and turn it in all the way.

3. In this position, tighten the setscrew. This will assure that you can never over tighten the adjuster and split the tiny fragile nozzle.

There may be other methods to accomplish the same thing, such as installing the needle from the front or installing the adjuster first and using it to guide the needle. I don't want to experiment with Patrick's airbrush.

I assume it comes from the factory already set up this way. The numbered collar can be set any way you like.

Trying it out

I sprayed some blue food coloring through it at 20psi to do the sample below. It had a nice fine pattern. Opened wide it will cover about one half inch. I found the grip strange and not very comfortable. It's like trying to write with a stubby pencil. Of course, that's strictly a personal thing. Patrick likes it, but he finds it more convenient to use his thumb on the air valve. Some people remove the handle of their conventional airbrushes, so they might like this one.

To clean, I flushed generously with water using an eyedropper to pump water in and out of the front and rear openings in the cup. When I pulled the needle, there was still some blue on it, so I think this is a necessary part of cleaning.

Conclusion

I guess you can tell that I'm not crazy about the design. It amazes me that they would make the trigger free to rotate. Even the cheap Chinese airbrushes have keyed triggers. And, requiring a jeweler's screwdriver to release the needle? The Paasche H has a set screw, but at least it is a standard allen head type. And, why make the needle so short that when fully in place it is recessed 1/4 inch inside the adjuster? If it stuck out enough to grab, it would make changing the needle a lot easier and safer. Better yet, put a little knob on the end.

Does it spray well? Of course. Any Iwata is going to spray well. But, Iwata also offers a Revolution SAR single action with a standard handle for less than $85. It's siphon fed and has a .5mm nozzle, but you can get a .35mm conversion kit that should spray just as fine as the M1. And, if you are willing to go with something a little less flashy, the Badger 200G is also a gravity fed single action. It has a .25mm nozzle, sells for less than $50, and in my opinion and Patrick's sprays just as well as the M1.

So, unless you really want a stubby airbrush, I don't see the point of it. And, unless you are a very experienced and careful airbrusher like my friend Patrick, I would not recommend it.

My sincere thanks to Patrick for loaning it to me.

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