Grex Genesis XBi Review

7/2012

There are many reviews of the Grex Tritium with the pistol grip handle, but not so many for the Genesis line, especially the XB and XBi siphon models. The folks at Grex have kindly sent me an XBi for review.

It came in a nice foam lined plastic case.

Included were a barbed hose adapter, a siphon bottle, a spare bottle, a wrench for the nozzle, and two needle caps. The XBi has a 0.50mm nozzle and needle, while the XB has 0.30mm parts. Grex airbrushes are made in Taiwan. The bottle adapter is the fanciest I've ever come across. it's heavy chrome plated metal, and the bottle itself is glass. The spout is standard size and other brands of bottles and cups will fit. The XBi weighs 103g with no bottle or cup attached. The manual is for all Genesis models and is very complete, with clear instructions for use and care.

First Impressions

If you had a bucket of mixed airbrushes, it would be easy to pick out the Grex. The green handle is a Grex trademark.

The first thing I noticed about the XBi was the long nose. Here it is next to my trusty Badger 155. It puts the nozzle way out in front of you. But still, it balances nicely at the trigger. Grex says the reason is to accommodate larger bottles and hands. But, it is also longer from siphon to nozzle.

The finish is perfect, and it looks like quality. The trigger pull, like almost all airbrushes, felt a little stiff for me, and had a slight amount of roughness. The hose connection is the standard 1/8 inch size.

Breaking it down

Here it is disassembled. Notice the special wrench to fit the nozzle.

I removed the needle seal adjuster with a small screwdriver, and the Teflon seal stayed inside. I couldn't figure an easy way to get it out, so I left it in place. It sits far inside the body, almost to the paint intake. So, there is a very short path from the seal to the paint chamber.

The only o-rings are in the air valve assembly, and there is no reason for them to ever come in contact with solvents.

The first time I removed the handle I was surprised that I couldn't see the needle. It turns out they have extended the needle chuck so that it sticks out the rear of the handle and completely encloses the rear of the needle. This is the Quick Pull feature that partly differentiates the XBi from the plain XB.

In effect, it functions just like a cutout in some airbrush handles. Grex says the advantage over a cutout is that the internal parts remain covered. It allows you to grab the needle and pull it back without removing the handle or moving the trigger. As I have mentioned in other reviews, I personally see no advantage over just pulling back on the trigger. A negative factor here is that you have to completely remove the chuck to pull the needle for cleaning. On most airbrushes, you can just loosen the chuck. And, usually a chuck will have an entry taper to help guide the needle during insertion. Here, you must hit the tiny hole in the needle tube, so you have to be extra careful.

If you pull back the needle with this or the trigger and then release it so that it slams forward, you run the risk of flaring or cracking the nozzle. I would avoid doing this.

At the rear of the handle is a needle limiter. The regular XB also has this, but a different part number.

There is a mysterious gap in the threads that doesn't seem to have any function. Grex says there used to be an o-ring here, but they found it wasn't necessary. The red ring is plastic, and gives a smooth feel. There was some heavy grease in the threads that made it hard to turn. I cleaned them with mineral spirits and an old toothbrush, and it feels better to me.

The trigger assembly looks like the Harder & Steenbeck Evolution, with the hex shaped needle tube. And, like the Evolution, there is no adjustment for tension. I even found that, like the Evolution, the rear section, which Grex calls a spring housing, was tricky to get started without cross threading. The threads on the Evolution spring housing are identical.

Since the rocker is separate from the trigger, assembly is a little more difficult than the Evolution.

The top of the trigger is angled and has ridges that give good traction.

The trigger sits on a small pin or anvil inside the body. The anvil passes through a seal in the air valve. There is some sort of lube on the seal. The tension on the air valve is adjustable from the bottom with a pair of tweezers. I tweaked it for a light feel.

The needle has a very slight double taper that's difficult to see, and comes to a really sharp point. Grex says the design of their double taper allows better control for fine lines. There are 5 grooves in the rear end that identify it as the 0.50mm needle. The shaft diameter measured 0.055 inches.

The nozzle is the small threaded type, but big enough to grip easily with your fingers. Still, be careful not to over tighten it. The XBi comes with two needle caps. They are held in place magnetically, so they and the head are obviously not brass.

You just get them close, and they pop on. And, it's just as easy to pop them off. If you want a fully exposed needle, the brush will spray without either of them. The XB model appears to have a standard threaded cap.

Trying it out

I installed a lighter spring for the trigger pull and did my doodle with food coloring on a paper towel. I tried to use the needle limiter, but I couldn't adjust it far enough. Most limiters will allow you to completely stop any needle movement. But, even with the limiter all the way in, there was still too much travel in the trigger to do the fine lines I wanted. So, I didn't use it.

I contacted Raymond at Grex, and he helped me figure it out. I just needed to use a little more muscle to tighten the limiter the first time. It turns out it barely has the range to fully stop trigger travel. I suggest you retract the needle the first time you do this. On the right is another doodle using the limiter. The brush will do really fine lines. Trigger control is very good.

Maximum coverage for painting models is about 3/4 inch.

After flushing well, I removed the nozzle and swabbed the body out with my dental brush and there was still some green inside.

Conclusion

As I pointed out above, the Quick Pull feature is something I wouldn't use. It's something extra to fool with every time you want to pull the needle. This, the nozzle size, and the magnetic caps are the differences between the XBi and XB.

I think the magnetic needle caps are a gimmick. They would be easy to knock off and lose. I doubt whether many people change caps often enough to justify them.

I'm not fond of the long nose because I like to be close to my work. But, I could get used to it, and it's not a big deal.

It's a nice airbrush, and it's certainly well built. It sprays fine with a good range of coverage. If you need even finer detail, the 0.3mm parts of the regular XB would fit. They would have to include the needle, nozzle, nozzle cap, and needle cap.

My sincere thanks to Grex for the sample, and Raymond for his help.

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