My experiences with affordable import TIG..
A few months back, I got a little red 160 amp TIG unit that is likely from the same factory in China as the 130 amp at HF. Great value and fun units. With practice, you will learn to control the heat and bead and will do some nice work. Except for some silver soldering, this has been my first experience welding.
After a few small practice projects around the house, I am almost done rebuilding a milled Yugo AK with 4130 side plates. From the pictures of other people's similar MIG projects, TIG is the way to go with neat, precice controllable welds and no splatter. You could TIG weld in your church clothes and not get dirty!
One disadvantage of these affordable import units is that there is no foot control to add amps for starting and to control heat once the arc is lit. To solve this, I bought a $3 rheostat and some wire at Radio Shack. Then, re-wired the amp control to a remote box and knob that sits right by my left hand. This made making precice voltage changes with a lit arc and mask on much easier. When I get around to it, I will rig it up to a home made foot pedal that will give a 80 amp range of current. Having a foot controllable 0-80 amp range would be ideal for the 1/4" 4130 steel I am working with now.
For shielding gas, I use pure Argon for the carbon steel. I made a mistake and bought a new 20 CF (cubic foot) tank at Harbour freight (I think $70?). At a local welding gas place, this tank cost $26 with tax to fill. You would think with the regulator set at less than 15 CF per minute this tank would last a good long time like over an hour right? - WRONG! I don't know if it is becuase the machine sends argon to flush the line every time you power on or start the arc but this little tank needed filling after what seemed like very little work. After quickly using up three tanks worth ($78) and asking the wife to get refils three times during the gas place's limited business hours, I needed another plan.
It turns out that most places charge almost the same to fill a giant sized tank as they do for my weenie little 20 CF tank. I have abandoned my little tank and ended up renting a giant tank from a local welding supply store. The economics are much better. Tank deposit was $200 which I will get back. Monthly rental is $5.50 or $50 per year (I did the year plan). The rented tank is huge about 5' tall (220 CF I think about 11x bigger then the weenie tank). It only costs $30 to fill and I can exchange this cylinder for another one with one trip. So learn from my mistake - Don't buy a weenie tank, buy or rent a big tank. little argon tanks are a money pit if you want to do any amount of welding without interuption.
To buy and fill the the small 20CF tank (3x) with 60 CF of gas was $148 out of pocket and took three trips to get it refilled.
For the big 220CF tank annual rental and one fill (less deposit) I am out of pocket $80 but now have argon that would have cost me $286 to buy with the smaller tank - plus saved the wife 11 trips to get it refilled!
Other TIG advice from my experience:
- Practice and know what to expect from the current level before you work on something you care about. When I bought my 160 Amp unit I had visions of raw power being required to make metal stick. I found most of the time I actually operate using much less than 50-70 amps for a lot of work
- If you do not clean the work pieces completely and then degrease with something like acetone, you may get weld contamination and pops and splatters as tiny bits of grease and foreign matter explode in the arc. With TIG clean is king!
- While starting the arc is easir with more amps, try to use the least amount of power to get penetration. Even though you may be tempted to crank it up, it is easy to burn through thin stuff and as the work piece heats up, less power is needed/desired.
- Even though the knob is not as easy as a foot petal to control, learn to adjust the current with a live arc to get better heat control when things get too hot.
- I have not had need to buy any collets or cups. What was useful was buying a bunch of spare electrodes, you will touch the molten puddle, stick to the work when starting and otherwise have to stop very often an regrind contamination off the electrode and keep shape on the tip when you are learining.
- Clean and degrease your filler rod with acetone before use
- Use the right sized filler rod for the job and current
- Learn and practice managing that molten puddle you dip the rod into. The rod should melt in the puddle, not in the arc
- Patience - it's not the fastest way to weld but the resuults are worth it if you are take the time
- Use very bright lights to illuminate your work, it helps a lot to cleraly see your work from under the mask before the arc is lit.
- Keep an eye on the electrode tip, shape, contamination and size. Regrind properly and replace when it it gets out of spec as your weld quality and precicion will suffer.
- Buying a big thick copper plate for backing stuff was a good investment since melted steel won't stick to it, leaves a smooth finish and acts as heat sink to disperse heat and prevent warping.
- A good comfortable work table to steady your arms and elbows or sit is a plus.
I am sure professional welders will have more to say but I just wanted to share what I learned as a self-taught back-yard TIG noobie.