Review By Dean Bielanowski  GMC Website - http://www.gmcompany.com


GMC MOC6L Oil-less 6L Portable Compressor

Review
By Dean Bielanowski

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Please note: Since this review was published, Global Machinery Company (GMC) has gone into receivership and is no longer operating. As such, spare parts or technical support cannot be obtained directly through them. Their website at www.gmcompany.com appears to still be available online and offers some product information and manuals but contacting them will receive no reply. Note that OnlineToolReviews.com does not work for GMC, nor do we offer any support or spare parts for their products.

When it comes to woodworking, DIY or even just home ownership, there is no more versatile tool than an air compressor. It delivers the air power needed to inflate car tires, soccer balls, paint just about anything, drive nail guns, riveters, sanders, shears, blow guns, sand blasters, and the list goes on. No home owner or DIYer should be without one in my opinion.

GMC (Global Machinery Company) have recently made available a portable oil-less 6L air compressor, and for those large compressor owners, you will realize how handy a smaller unit can be at times. So let's take a closer look and see what it has to offer.

The MOC6L Air Compressor
One of the first things you will notice with this unit is that it is oil-less. Well, you may not notice it right away, but the packaging certainly tells you it is. Is an oil-less compressor a good thing though? Well, yes and no. Oil-less compressors usually cost a little less and are smaller in size than comparable oil-use compressors, plus you don't have to worry about the cost and effort in replacing the compressor oil on regular occasions; so those are the main advantages. The disadvantages with oil-less units is that they are generally noisier than oil-use models and can have less of a lifespan. So there are tradeoffs to consider when purchasing oil vs oil-less units, and determining your exact or expected use/needs first will help decide which type to buy.

Back to the MOC6L specifically now. The compressor is portable, having a fold up/down arm which allows you to roll the unit around on the ground, thanks to a set of wheels on the underside of the unit. The wheels have rubber tires that make for very smooth rolling. I only wish my local shopping center had trolleys that rolled this well. The arm is plastic and it does bend and flex a little. I would have liked to have seen perhaps an aluminium one for extra strength but the plastic does keep the weight down and I find I usually carry the unit more than rolling it around anyway. At the front are rubber feet to stop the compressor rolling away. Additionally, the rubber wheels/feet act as anti-vibration and stability devices to stop the compressor moving around when it is working (something my old compressor is prone to do!). Up top is a fixed foam covered carry handle to lift and carry the compressor off the ground. This is situated so the compressor is balanced front and back to make it easier to carry around. Weighing in at just 13kg, this is a compressor you can comfortably carry around with one hand.

The compressor has a six litre air storage tank. You can't really see this because it is enclosed within the plastic shell housing on the outside. This housing is also useful as it protects the user from touching hot metal parts of the tool, and those compressor cooling fins and pipes can get very hot as the compressor operates. The unit is about the size of a small suitcase and its rectangular shape takes up less room in the back of the van, ute, or in the workshop for storage. It measures 525mm (L) x 285mm (W) x 455mm (H).

The compressor motor assembly is also wrapped in this shell and it is a direct drive, fan-cooled unit, as opposed to a belt-driven model. Direct drive are also generally a little louder in operation. It is rated at 1.5Hp or 1100W. Generally the motor rating is paired to the size of the storage tank. The larger the tank, the larger the motor to keep it filled adequately and up to pressure. The 100W motor is more than adequate for this size tank. It has a pump displacement of 5.2 CFM (cubic feet per minute) but the continuous air supply is rated at 2.5 CFM. This figure is quite important because it will determine what type of air tools can be used satisfactorily with the compressor. For example, some air tools, like air sanders or die grinders use a continuous supply of air as they are operated. For these tools a larger CFM rating is needed, otherwise the air supply in the tank and that delivered by the pump cannot match that consumed by the air tool, and so the tank drains quickly and the pump cannot keep up, allowing the tank pressure to fall to levels not suitable for the correct tool operation. On the other hand, air tools like pop riveters and nail guns use air in short bursts, and as a result, the compressor has time to catch up when tank pressure/air capacity falls. There are also air tools like airbrushes, which do use a continuous flow of air, but because the volume of air is much lower than larger spray guns, smaller compressors will happily keep up with their air requirements. Remember too that it is possible to use a small compressor to power a spray gun or a sander or air grinder. You just can't expect to use that air tool continuously and must use it in short bursts with pauses in between to allow the compressor to catch up. You will find most high volume air tool users will have a large compressor because running high demand air tools on small compressors can get frustrating rather quickly.

If you are unsure of what size compressor to buy, let the CFM requirement of your tools be your guide, ensuring you check the CFM of the air tool which will use the most air. Most air tools will have listed a recommended CFM figure for best use. Match your compressor's CFM output to this maximum CFM figure to determine what size unit to buy. And remember to look for the "Free Air Delivery" CFM figure, and not the pump displacement, because as you can see from the figures on this compressor reviewed here, there is a large difference between the numbers!

So, with this unit having a Free Air Delivery of 2.5 CFM, there are definitely going to be some limitations on its use. It will happily power virtually any size air nailer with no problem. It will cycle the motor more often but it will keep up in almost all nailing applications. It will happily run air inflation devices like tire or ball inflators. There is more than enough capacity and air flow there. Airbrushes are no problem either, and I have run die grinders and an air sander on it just fine, but in shorter bursts with pauses in between. High volume air spray guns can be a bit of a problem because you usually need to spray fairly continuously to do the job properly. I have sprayed nitro-cellulose finishes using this compressor and a touch up gun just fine on smaller woodworking projects though. So it's not going to be perfect for every task, but its certainly capable for most DIY or small scale woodworking/metalworking or workshop cleanup tasks, and that is the market it is aimed at, and priced at too

Back to the features... The main ON/OFF button is located just forward of the handle to turn the motor ON or OFF. The compressor will automatically switch on when the tank pressure is below 85 PSI (pounds per square inch) and automatically cut out at 115 PSI. The upper limit is a safety cutout feature to ensure tank pressure does not exceed the tank's rating. The lower 85 PSI cut-in pressure ensures the tank retains a pressure of between 85 PSI and the 115 PSI cutout pressure. There is a tank pressure gauge on the left side of the main control panel of the compressor.

You will find that most air tools will have a functional pressure range of between 80 and 120 PSI. For air tools that have a maximum 100 PSI rating, the air supply from the compressor will need to be regulated down to 100 PSI. This can be done via use of the onboard regulator knob (large yellow knob, center on control panel) and regulated air pressure gauge (right side of control panel). You can set virtually any pressure air supply needed, even if the tank pressure is 115 PSI. The regulator knob adjusts the pressure downstream of the actual regulator, and hence can have a different pressure than the tank pressure. To regulate the air pressure, there needs to be air flowing for this to be achieved. You can simply hook up an air blower or other device (except nail guns or intermittent use air tools) and allow the air to flow. While the air is flowing from the tool, turn the regulator knob either way to raise or lower the pressure to the air tool. Once this is done you should have a consistent flow of air at the regulated pressure you have set. Note that if you set a max pressure of, say, 90 PSI, the Tank pressure must be above that figure to guarantee supply. The tank pressure can never be lower than the regulated air pressure at any given time. Simple logic there and this is the same with any air compressor. It is a good idea, when setting a specific regulated air pressure, to start by opening the flow of air to the tool, then reduce the regulated pressure down to 0 PSI. Then slowly raise the pressure to your desired setting indicated on the regulated air pressure gauge (right side of the control panel). This way the downstream air pressure setting is more stable and consistent. You can find that if regulating in an opposite manner, from high pressure down to low pressure, that the regulated pressure does not maintain its setting consistently, or rises again to match tank pressure. So be sure to lower output pressure to 0 first then slowly raise it via the regulator knob to the max pressure desired.

The compressor has the safety cutout valve also located on the control panel. This operates automatically but should be checked occasionally to ensure it hasn't become stuck. You can check it by pulling on the ring outwards to make sure it isn't sticking. A stuck valve can mean the compressor's pressure can exceed maximum safety limits. Thankfully this rarely happens but a regular check of the valve's function will ensure safe ongoing use.

The remaining outlet on the control panel is the actual air outlet. This is a 1/4" Nitto style outlet for hooking up your air hose to transport the compressed air to your air tool.

On the underside of the unit is the tank drain valve. This is used to drain moisture from the tank that forms and accumulates as air is compressed and stored. The more humid or warm the outside air, the more water is created in the process. The drain valve should be released, ideally,  after the end of each day's use. You might only remember to drain the tank once a week, and that is probably ok, but I wouldn't let water sit in the tank for any longer. It can rust the insides of the tank and cause problems later. This seems a hotly debated topic. Some compressor owners rarely empty their tanks and have reported no problems with corrosion, but why risk it? Empty it as often as you remember. Make it a part of your routine when you shut off the compressor after each use. Soon it will become habit! Because this drain is attached directly to the compressed air tank, if the tank is full of air, when you release the drain (by screwing the nut inwards toward the tank), compressed air will be released. As a safety precaution, you should drain excess amounts of air from the tank before releasing the drain screw. It is probably not a bad idea to leave maybe 20-30 PSI of air in the tank when you release the screw because the remaining air rushing to escape the tank via the drain will help move moisture toward the drain hole. Just remember that when you go to use the compressor again that the drain valve is re-engaged, by screwing it outward from the tank until it seats, otherwise your tank will never fill completely and your motor will be working overtime, and probably overheat. Thankfully the sound of escaping air is a good identifier that you have forgotten to close the drain!

The only notable feature on the rear of the unit, apart from the cooling air fins in the housing are power cord storage "rings" to wrap the power cord around.

Included with the compressor is a starter air tool kit. The smaller parts are found in a clear plastic case which slots into a tray on top of the unit. The standard accessories supplied include:

  • Nitto Fitted Air Hose Coil
  • Blow Gun
  • Blow Gun Adaptor
  • Tapered Inflation Fitting
  • Tire Chuck
  • Inflation Needle
  • 1/4" Male Nitto Plugs/Adaptors (x2)
  • Roll of Teflon Tape

A printed user manual should see you through any required setup (although its pretty much ready to go out of the box) and any troubleshooting, should you need to do any... we haven't had to yet, touch wood!

The MOC6L Compressor is also covered by a 2-Year Home Use repair or replacement warranty, and GMC are known for honoring warranties in all genuine warranty cases too.

In Use
Since I have a larger compressor in my shop already, this smaller unit finds use wherever I need to undertake smaller scale work around the home (when portability becomes important). I use it mostly for all my trim installation work along with my brad nailer and finish nailer, and for these it works very well and the portability makes it rather user friendly. It happily runs my large framing nailer too and will keep up without a problem (although I am not driving nails constantly every second or two). Nonetheless it does perform my frame nailing tasks with zero problems. It powers my model airbrush for painting scale models (my other hobby) and neatly slots under my hobby desk out of the way. Because of its operating noise when the motor is underway filling the tank, I can't really operate it in the middle of the night with the young ones asleep upstairs however. But as long as I fill the tank before the sun goes down and have the regulated pressure set, I usually have enough air to last an airbrush painting session.

As mentioned above, it's probably not ideal for continuous air-use tools like sanders or grinders. The capacity and CFM rating of this unit limits to how long you can run these tools. This is not a fault of the compressor itself, just a symptom of its smaller size. These units as with most DIY standard compressors will not run high consumption air tools like sanders and grinders which are very air thirsty. Always refer to the air tools spec on the carton when selecting suitable air tools. These units are ideal for Car tire, toy and camping inflation, air brushing, basic paint spraying (via suitable regulation), air blowing and most air fixing guns.

In terms of sound output of the unit while underway, there is no listed sound level in the manual or on the compressor itself that I could find, and I don't have a sound level meter on hand to check it myself. I would guesstimate that when the motor is underway filling the tank, the sound level would have to be close to 80-90 decibels. Like most direct-drive compressors they are quite noisy and its a good idea to use ear protection if you are near or working in the immediate vicinity of the compressor. I wouldn't say the noise level is excessive in comparison to other similar-sized direct drive units I have used before.

In terms of durability and reliability over time, I cannot comment yet. I haven't had this unit long enough. It has done quite a bit of work already and so far so good. I have another GMC compressor that is also still going fine. However, you will at least get two years service at a minimum thanks to the warranty offered (home use) and I would expect it to last longer than that with proper maintenance and regular cleaning ensuring safe and efficient operation.

What I like most is the shape and design of this compressor. It is neatly packaged into a streamlined case and light enough to take anywhere without breaking your back. Plus there are no components sticking out just waiting to catch power cords, walls or anything else that is easily damaged.

The MOC6L is quite competitively priced at AUD$129. Sure you can get a 2HP compressor these days with a larger tank for a little less, but the MOC6L is definitely more portable and user-friendly for small scale tasks. But as mentioned above, work out your air requirements first before you go shopping and if the MOC6L fits the bill, it is worth checking out.

 

Available to Order through these Companies...
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In Australia
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GMC MOC6L Photos
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The GMC MOC6L Portable Compressor.


Folding handle allows compressor to move along flat surfaces.


Top carry handle is located for true weight balance.


ON/OFF button and circuit reset switch.


Pressure gauges with tank pressure on left and regulated air pressure gauge on right.


Safety valve (left), regulator adjustment knob (center) and Nitto style regulated air outlet (right).


Fan cooled motor housing and cord wrap supports at rear.


Car tire inflation is just one task ideally suited to this unit.


Air cleaning is a quick and easy method of cleaning a shed, workshop, or to get dust from hard to reach places.

 

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