Much to my surprise, Gary Glass, the president of Iwata Medea, sent me a Smart Jet compressor. Maybe he saw the kloodgy setup on my Gimme Air page and took pity on me. At any rate, I was sure happy to receive it.
Here's the box.
The Smart Jet doesn't have a tank. Instead, they have supplied a long coiled plastic hose to go between the compressor and moisture separator. The hose does two things. It holds enough air to smooth out pulsations from the compressor, and it cools the air to make the moisture separator more effective. It's actually pretty clever.
There was a hose to fit Iwata airbrushes and several other brands, plus adapters for Paasche, Aztek, and Badger. Aztek is spelled wrong, but it works.
The Smart Jet is an oil-less piston compressor. The box says it was made in Taiwan. It has a 1/8 hp motor, and weighs just a little less than 8 1/2 lbs. A label on the bottom says maximum pressure is 80psi and flow is 0.71 cubic feet per minute.
Here is the assembly drawing from the manual.
DeVilbiss Patent, that shows how this type works. I believe this is pretty standard in small oil-less piston compressors. There is a flexible seal that wipes the inside of the cylinder as the piston wobbles back and forth. There is no wrist pin or separate piston as in an oiled compressor. This reduces cost and insures that there will be no oil in the output. If you would like to know more about them, there is a good article here.
Iwata warranties the Smart Jet for one year parts and labor. How long will it last? That depends not only on the quality of the parts, but also how many hours it runs. A hobbyist might just run it a couple hours a month, while an artist might use it for several hours every day. My guess is that Iwata considered the worst case when they came up with the one year limit.
There are no part numbers, so I don't know how repairable it is. But, I have heard of a couple of cases where the pressure switch failed, and Iwata was able to supply replacements.
Power is controlled by a switch on the top of the motor as shown on the left. The thing that makes it smart is the black pressure switch in the picture on the right. It starts the motor at pressures below 30psi, and stops it when pressure reaches 50psi. It is not adjustable.
The Smart Jet doesn't have a regulator, but it does have a moisture separator. You can see it in the picture above, behind the pressure switch. On the left below is a top view. The attached pressure gauge goes to 100psi. Next to it is an airbrush holder that clips on the metal mounting plate. In the picture on the right, is the rubber O-ring that secures the moisture separator to the mounting plate from the bottom.
Gary says that the holder will work for a siphon fed airbrush if you insert it handle first. I never would have thought of that, and it works unless you have a fat bodied brush like the Paasche H or Badger 175
Trying it out
Noise -- The Smart Jet is advertised as a quiet compressor, and this is an important feature for many users. I am not a good judge of this because I have a significant hearing loss, and without my aids, I can't really hear it unless I put my ear close. From three feet away, I can't tell if it's running. I don't have any way of measuring sound intensity, so I asked my son what he thought. He said it was moderately noisy, but quiet enough that you wouldn't notice it in the next room. I suspect it might bother some people if it were right next to them on the bench. It's kind of a knocking sound. I think you could carry on a normal conversation or listen to the radio over it with no problem. It is significantly quieter than my little diaphragm compressor, and I don't believe you will do much better without going to the expensive refrigerator type. The soft plastic feet do a good job of isolating it from the bench. They also keep it from dancing around. It stays where you put it.
Regulation -- I guess to keep cost down, Iwata didn't include a regulator. So, the only way to adjust pressure is to open the bleeder valve on the moisture separator. The knob is marked with + and - signs. Turning the knob in the plus direction closes the bleeder and increases pressure. The minus direction opens it and lowers pressure. Of course, by doing this the compressor never reaches the 50psi shut-off and it runs continuously.
The instructions in the manual say to hold the trigger down when setting pressure. The adjustment is nice and smooth, and setting is easy. Regulation is not too great. With a Neo CN and a setting of 20psi, the pressure rises to about 24psi when you release the trigger. With a setting of 30psi, it rises to about 36psi. But, with the Iwata HP-CR, which uses more air, a setting of 20psi trigger down results in 29psi trigger up. And, a setting of 30psi will go all the way up to 46psi. So, it depends on the airbrush.
If you leave the bleed shut, the pressure will cycle from 30 to 50psi as you airbrush. The frequency of this cycle will vary depending upon how much air your brush uses. An airbrush like the Neo CN that sips air will cycle about every 2 1/2 seconds, whereas a Paasche H #3 will stay at about 30psi and never reach the 50psi cutoff until you release the trigger. It takes less than one second for the H to drop the pressure to 30psi. The good news here is that the H works fine with 30psi. The Iwata HP-CR stabilizes at about 35psi.
The 100psi gauge means that readings in the normal airbrush range will be kind of course. But, I guess since the compressor is capable of 80psi, this is a precaution against possible gauge damage.
Heat -- It does get hot. I connected an airbrush and set the bleeder for 30psi. Then I let it run for 10 minutes. At the end of that time I measured the head temperature with a digital thermometer, and it was 140 degrees F. That's way short of boiling, but you couldn't hold your hand against it. I've never done this with any other compressor, so this may be typical. At any rate, you don't want to put this in a box or do anything to restrict air flow.
The Smart Jet appears to be a well built little compressor. Its noise level is probably comparable to other compressors of the same type and really not bad. It would have been better with a real regulator, but it is useable. The bleeder method, however, kind of defeats the purpose of the pressure switch, and the continuous running will make the compressor run hot. The lower cost Sprint Jet looks like the same compressor minus the pressure switch and coiled hose. So, if you are going to use the bleeder to regulate, it might be something to consider. The more expensive Smart Jet Pro does have a regulator plus a sheet metal cover that might reduce the noise level.
For most purposes, the Smart Jet will do fine. But, if you are a T shirt artist who needs continuous pressure of 40psi, it isn't going to hack it. And, if you do really fine stuff where pressure control is critical, you should look for something with a tank and a regulator.
How I use it
A little moisture collects in the first separator, but the second one stays dry. I allow the compressor to run with the bleeder wide open for a couple of minutes after each use to clear moisture out of the compressor and separator.
The tank has a shutoff valve, and I made a wooden handle for it that you can see on the left. I leave the tank charged to 50psi so I don't have to wait for it to re-charge.
I'm a happy camper. Many, many thanks to Gary for sending me the sample.
My tank is a little over 5 gallons. There are people on the internet who will assure you that connecting a small compressor like the SmartJet to a tank as large as mine will burn it up. I sincerely doubt whether any of them have actually tried it. I can only say that my setup charges the tank from zero to 50psi in slightly more than 7 minutes. The compressor gets warm, but certainly not hot. After that, it only runs to refill from 30psi, and barely gets warm. I leave the tank charged, so it never needs to be completely refilled.
On the other hand, a smaller tank would work just as well. In fact, I can shut off the valve to the tank while airbrushing, and the only effect I notice is that regulation is not quite as good and the compressor runs a lot more often. The hose between the compressor and regulator acts like a small tank.