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

GMC CEN Arc Welder
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.

Allow me to start by saying my metalworking skills are still somewhat in the journeyman stage. A few months back I had a need to fabricate some brackets for a make-shift storage system for the shed. I couldn't find what I needed locally but I could get the brackets elsewhere.

Naturally of course, I thought it was a good opportunity to grab an arc welder and learn the ropes myself rather than taking the easier option. You can never pass up an opportunity now can you? Or so they say!

Given my limited welding skills, I thought a small, basic arc welding unit would fit the bill. Much cheaper than a MIG unit and I could always upgrade later if my skills and needs progressed beyond the capability of this machine. I picked up the GMC CEN arc welder, which is their basic unit and retails for around AUD$98. An inexpensive machine for the occasional small metalworking projects that seem to pop up now and then.

GMC CEN Arc Welder
As mentioned above, this is an entry level machine for light-medium duty welding operations. It ships in a box mostly assembled. I only needed to attach the top handle and the work clamp to the welding leads. The basic kit includes a safety facemask, slag hammer/brush, and 10 consumable welding rods. Replacement rods are easily available from a number of manufacturers and can be found in most any good hardware store.

Specifications & Use
The CEN operates on a 240V circuit via a 10 amp plug, so you can use it from your common mains power points with no trouble at all (pertaining to Australian households). It can deliver a variable welding current from 40A right up to 140A depending on the type and diameter of welding rod you are using. This allows rods up to 3.2mm to be used for those medium duty tasks around the home or shop. The duty cycle of the CEN Arc Welder is rated 25% at 45A.

Welding current is adjusted via the large triangular knob on the front of the machine. It operated smoothly through the entire physical range. The only other control on this machine is the main ON/OFF switch to the upper left of the current adjustment knob. So as you can see, managing the unit itself is not rocket science. You basically set your welding current, switch on and give the unit a chance to 'warm up' before you begin welding. As an additional safety feature for the unit itself, the CEN welder has an automatic overheat shutoff feature to prevent damage to the machine should it get too hot. The machine will also reset itself after it cools down.

NOTE: It is important to note that the welding process itself generates a substantial amount of heat and sparks and as such, welding should not be carried out in the presence of flammable or combustible materials. It's not a good idea to use the welder in your workshop amongst the wood dust and debris that may be present on the ground, on the bench or nearby. A solid metal bench makes a good welding surface, or setting up outside on concrete can be ok if you have no other options. You can also buy dedicated welding benches in various shapes, sizes and forms.

The machine is extremely quiet. Being a transformer, when powered up, it resonates a quiet hum that makes a nice change from noisy woodworking machinery. It's aluminium core reduces overall machine weight making it very portable.

Personal Protection
Given that welders generate a large amount of heat and sparks and UV light, you need to protect yourself from physical injury. Always wear/use a properly rated welding mask/shield to protect your eyes from the UV light! In addition, a full length apron (preferably leather) or full length shirt and trousers should be worn, in addition to full cover footgear to protect yourself from any hot sparks that come flying toward you. A good quality set of welding gloves are also required to protect your hands and forearms. Thankfully, these safety items are all relatively cheap to buy. You can get fancy and purchase auto-darkening welding goggles/helmets, but if you are only going to use this machine occasionally, the standard welding masks are fine. Because of the fumes that can be generated from the welding process, ensure your work area is well ventilated.

A small magnetic welding holder device is also very handy when joining pieces of metal together at common angles. These are those gadgets that look like arrow heads with a hole in the middle and are really inexpensive to purchase.

Using the CEN Arc Welder
Given that the machine is a very basic unit and there is not much more to say about it feature-wise, let me quickly describe the basic welding procedure using the CEN to join two pieces of metal together. You might be joining at right angles for a bracket, butting up two lengths of metal to make a longer piece or perhaps joining one pre-constructed assembly to another.

We start by gathering the components (metal) to be welded and aligning these in the formation that you wish them to be welded. If these are painted, you will need to scrape off, or sand away the paint to expose the bare metal surface. This will allow a better and stronger join. Note that rusted metal does not make a good welding surface due to its decreased electrical conductivity. Choose an appropriately sized welding rod and set the machine to the appropriate amp rating for that specific rod diameter. On the GMC CEN machine, the amp setting window shows the appropriate settings for different diameter rods, so its easy to figure out what setting you should use.

Next attach the work clamp to the workpiece (which forms part of the electrical circuit) and start up the machine. Give it a chance to warm up before you begin and ensure you have all your safety gear on before starting the welding process. To begin welding, you need to "strike the arc" which is performed in a similar way to striking a match. This is the process of completing the electrical circuit allowing the electrical current to flow. Immediately after striking the arc, you need to keep your welding rod a few millimeters from the surface and slowly pass it over the intended join location. The process essentially heats the two metal parts melting them together. The welding rod also melts as you go and the aim is to form a small, but consistent weld bead during the process. It takes some practice to achieve a consistent weld, and your skill here can affect the strength of the welded joint.

Once your weld is complete, you can use the "slag hammer" to clean up the joint and remove any unwanted weld material. Allow the weld to cool fully before painting or using it in structural or weight bearing purposes.

Conclusion
The GMC CEN Arc Welder is a suitable unit for the beginner or occasional user. It offers a wide range of amp settings for various rod diameters, and its small size and low weight make it extremely portable for small offsite work. The unit is made in Italy, and so far I have not experienced any problems with the machine itself. At AUD$98, it makes a cost effective introductory welding machine.
 

GMC CEN Arc Welder Photos
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The "control panel" really only involves the on/off and amp adjustment control.


Amp is adjustable from 40-140 Amps for different diameter rods.


The small size and light weight make it very portable.


Heavy duty welding gloves and magnetic welding holder are essential equipment.


Work clamp and welding rod holder


Easy amp adjustment.


Despite the light show and shower of sparks, welding with an arc welder is relatively safe as long as you take the required safety precautions.


Closeup shot of a welded joint.
 

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