WELDING PART 2
In part two of his welding magnum opus, our Jim explains what kit he went for, post course.
Jim Lindsay on what kit to buy
Last month we looked at the different welding processes within reach of the amateur and talked about my experience when I joined the evening welding course at my local place of learning, Peterborough Regional College.
I chose to learn the TIG (Tungsten Inert Gas) process. Some other people on the course chose TIG, but the majority opted for MIG (Metal Inert Gas). After 36 hours of tuition and practice I finished the course being able to produce acceptable welds in mild steel, stainless steel and, to a lesser extent, in aluminium.
Welding, like any skill, needs plenty of practice if you are going to be even moderately good. Hands-on courses, Youtube and books will only get so far. You need your own kit and plenty of scrap steel to practise on! Let’s assume then that you’ve learnt the basics and decided to invest in some kit. What should you get?
MIG
For most people MIG is the best bet, so we will look at that first.
There are two types available, gassed or gasless. In this set up, more correctly known as self-shielding, the welding wire is coated with flux, much like a stick welding rod. The flux melts as the arc is struck and provides the gas shield necessary to prevent the weld from oxidising. At first sight, gasless may seem like a good idea, but it produces a fiercer arc, which is not suitable for welding thin material and it also makes a lot of unpleasant smoke!
In practice, you will get better results with a machine using a separate gas supply.
You can spend as little as £50 and get a brand new MIG machine, but it won’t be very good. ebay is full of unknown Chinese makes at throwaway prices. They are
mostly rubbish and what you’ll get for your money is frustration. Buy the best you can afford. If you are on a tight budget, the Clarke MIG welders sold by Machine Mart are a good bet. Something like the Clarke MIG160TM, costing just under £400, will do most of what you need. If you’ve got a bit more cash to commit, look at brands like ESAB, Parweld or R-tech. All these have warranties that will be honoured and spare parts will be readily available.
Although they supply industry as well as DIY users, R-tech are a good bet for the amateur. They provide good support for customers and their website offers how-to video tutorials using their own machines. Another good source of machines and advice is the professional welding suppliers in your area. Don’t be put off by your lack of knowledge. They want to sell kit and they are usually happy to help.
Ben, who was the star of our welding course, found a second-hand Kemppi MIG machine on ebay for £500, complete with gas regulator and hoses. It was in top working order and a stinging good deal. Kemppi supply to the professional market and their MIG machines new start at over £1000. If you are confident enough and know what you are looking for, great machines can be found second-hand, usually from hobbyists who buy them full of enthusiasm and good intentions, only to let them gather dust in the corner of the garage. Bike journalist John Millbank, who is pictured in this story, got an excellent deal on a new MIG machine that was for sale in the reduced section of our local Machine Mart store. It was an ex-display model with a few scratches and a small dent, but in perfect working order.
Gas
As well as the welder, you will also need gas. For MIG you use a mixture of Argon and CO2. For as little as £10, the world’s favourite auction site has plenty of offers on disposable Argon/co2 cannisters. However, these cylinders do not last long and it can be difficult to accurately regulate the pressure supplied to the welding torch.
BOC is the best known supplier of industrial gas in the UK. They will rent you a cylinder for a monthly fee, which varies depending on the size. They will charge you for the gas separately, and you can take it back and exchange it for a full bottle when needed. They also offer mini cylinders with annual, rather than monthly rental. Most big towns have a BOC depot.
You probably won’t use much gas so go for a small cylinder to start with. You can always trade up to a larger bottle if you find that you need it.
There are other outfits which will supply gas for a one-off cylinder deposit plus the cost of the gas itself. This can work out cheaper than renting from BOC. Instead of
renting the cylinder on a monthly basis, you pay a one-off deposit.
There is plenty of choice out there and with some research you will be able to decide what suits you best.
You will also need a regulator. which screws into the top of the gas cylinder. This shows how much gas you have left and allows you to set the flow rate at which the gas is delivered to the welder. If in doubt, ask your gas suppliers for advice. They usually have regulators for sale. as well as the necessary hoses to connect the cylinder to your welder.
TIG
The same rules apply when buying a TIG machine. Buy the best you can afford. The electronics in a TIG machine are more complex than in a MIG machine so they tend to be more expensive, but not by much.
Your first decision is whether to go for just DC (Direct Current) or to choose an AC/ DC machine. A machine that offers AC (Alternating Current) allows you to weld aluminium. In the positive part of the current cycle the weld metal is cleaned, while in the negative part it is heated.
All other metals are welded using DC (Direct Current).
The next decision is whether you go for a Lift TIG only machine or one which offers both Lift TIG and High Frequency (HF) starting methods. With Lift TIG, you bring the tungsten very lightly into contact with the metal, then draw it away to start the arc. HF start allows you to generate an arc between the tungsten electrode and the work without making physical contact between the two. Machines with HF are more expensive, but it is worth paying the extra. It is easier to start the arc in HF.
Whether you are buying new or secondhand, go for a recognised make. You will also need a means of sharpening the tungsten electrodes. When you start you will spend a lot of time doing this because you will repeatedly dip the tungsten into the weld pool and ruin the tip. This is known as ‘dipping the tungsten’. You can buy dedicated sharpeners, but they are expensive. With practice you can do a good job on a bench grinder. You need a fine wheel and you should not use it for grinding anything else as it will contaminate the tungsten, which in turn will affect your welds.
You use pure Argon gas for TIG welding, but apart from that, the information concerning gas purchase already given applies to TIG as well.
What I bought
I decided straight away to go for an AC/DC machine with both Lift and HF start options. I looked first at buying new, and in this case, the ones I favoured all involved an outlay of over £2000, which was beyond my budget.
Turning to ebay I came across a used GYS machine with a starting bid of £750 and located 50 miles away. I’d considered a new one of these already, but ruled it out as too expensive. It’s a French-made device with a good reputation. I won the auction for £821. The seller was a bike fan, so we found plenty to talk about. He also had three different Argon gauges, a brand new foot pedal (this allows you to control the input current remotely so you can vary it mid-weld as necessary), loads of torch spares and some stainless steel welding rods that he was willing to let me have, all for an extra £100. As the foot pedal on its
own o sells for £360, it was an irresistible offer. o I loaded up the car and drove home happy. h I’d already organised the gas so I was w ready to hook everything up and make a start. With the welder up and running, I spent s some time making test pieces before starting s on my first project.
Get welding
The longer the gap between learning and making m a start, the harder it will be. Once you’ve y done your course and bought your welder, w get on with it straight away.
Spend some time joining pieces of scrap. You Y can pick up plenty of usable bits of steel s from a fabricator.
They’ll usually let you have the pick of their scrap bin for a few quid. Once you are confident enough in the quality of your welds, choose a straightforward project and get stuck in. A simple welding table is a good place to start.
As I have limited space in my garage and everything needs to be portable, I chose to make a portable welding trolley. It took about three times as long as I thought it would, but I was moderately pleased with the result.
Unless you are particularly gifted, you won’t match the work of people who weld every day but also, you don’t know what you are capable of until you try. Learning is rarely wasted.