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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.
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