Posts
Comments

MachinistBlog.com

Plans, projects and how-to's for home machinists

I’m learning how to TIG weld

The stringer beads on the left were TIG welded by my instructor. The ones on the right were the made by me after about an hour of practice.

I started taking a 10-night, 30-hour TIG welding course this week at a welding supply company.  I enrolled partly because I enjoy learning new skills and partly because TIG welding is especially useful in a machine shop.  You can use it to weld almost any kind of metal and it can make very small, precise and neat looking welds with very little heat distortion.  It’s also a very clean welding process that you could do in your living room without getting yelled at too much because it doesn’t produce any spatter or sparks and it creates little or no fumes.

Machinists will frequently use TIG to add a new layer of metal to parts that are worn and then they’ll re-machine them.  Mistakes, such as a hole that was drilled in the wrong place, can be repaired in the same way and you probably won’t be able tell they ever existed.

TIG uses electricity to create heat with an electrical arc, which makes it similar to MIG and “stick” welding.  But in those two processes the electrode (a wire or rod) gets melted and deposited in the weld.  But a TIG electrode doesn’t get “consumed.”  It just creates heat and a filler rod is used to add material to the weld puddle if it’s needed.  So it’s very much like oxygen-acetylene gas welding but with some huge advantages.

  • You can almost instantly turn the heat (arc) on or off.
  • You can very easily and precisely control the amount of heat using a foot pedal.  Sometimes a thumb wheel on the welding torch is used instead.
  • It’s much easier to see and control the weld puddle.
  • You can weld almost any kind of metal.
  • It’s safer. Oxygen and acetylene can be very dangerous.  TIG welding is almost always done with argon gas which can’t burn or explode.  You also only have to deal with one tank of compressed gas instead of two.

TIG welding does have some disadvantages

  • TIG welding requires more skill than MIG or stick welding.
  • TIG welding is a slow process.  TIG is to MIG what walking is to running.
  • TIG welding equipment costs more.  If you’re going to buy a TIG welder make certain it can produce AC (alternating current) because you’ll need it if you want to weld aluminum.  Many of the inexpensive/cheap imported TIG welders you see for sale on eBay and the Internet are DC (direct current) only machines.  So beware.

Being able to weld aluminum is one of the best reasons for buying a TIG welder.  You can weld aluminum with a MIG welder but you’ll need to invest in a spool gun and a tank of argon gas.  And you still won’t be to make welds that are as precise and as neat as those made by a TIG welder.

By the way, most TIG welders can be used to do stick welding.  You just replace the torch with a “stinger” to hold a welding rod and go to it.

That’s my real quick overview of TIG welding.  If you want learn more this Wikipedia article is a good place to start.  You can also leave a comment if you would like to hear more details from me.

I didn’t get to spend much time in my workshop this week

I was in my welding class two nights and I worked late (until 8 PM) on two other nights and all day today (Saturday).  Monday night was spent cutting our grass and doing other household chores.  And I went to bed at 8 PM last night because I’ve caught a cold (my first in 2 or 3 years) and I was exhausted.  So I haven’t gotten any work done on my CNC router this week yet, although I am hoping to spend a good part of tomorrow working on it

I did get some work done on my “winter” workshop.  Some of my wall space was taken up by large plastic storage bins that I’d filled and stacked to the ceiling with things that we don’t use very often.  I got rid of some by ruthlessly throwing out (or donating) things we’ll probably never use again. The room also has a really nice big computer desk that’s kind of the modern equivalent of a roll-top desk because all the storage compartments and cubby holes it has.  I was going to keep it but I’ve decided not to so I can have a longer workbench and more room for tools.  So I’m going to have to throw out or find other places for the things that are in it.  I think it’s going to be a tedious chore and some of the storage bins I just emptied will get filled back up.  But it has to be done.

Inexpensive Plasma Cutters

I think you’ll find this short video interesting if you’ve never seen a plasma cutter in operation.  I found it while helping a friend look for a plasma cutter he can afford.  Of course, now I want one, which is not surprising considering my new son-in-law is a welder and we’d both like to have a well-equipped metal fabrication shop.  I’m also currently taking a MIG welding class and I’m obviously interested in machining and metalworking.  But I’m not sure if I can afford one right now.  My wife probably thinks a LCD TV would be a better use of our money and so would a new snow blower.  Hell is also freezing over soon and I’m going to have to buy my brother a wedding present.

Here are the machines I’ve researched so far and what I think of them.

Harbor Freight 240v plasma cutter with digital display

This unit is frequently on sale for about $700.  It gets good reviews but some say it eats up consumables (cups, rings, tips, electrodes) pretty quickly and they’re expensive to buy.  It also runs on 220/240-volts and I’d prefer to get a dual-voltage machine that can also run on 110-volts.  It also has a fairly short (10-foot) hose and ground cable.  It comes with a 1-year warranty and you can also get an inexpensive 2-year extended warranty for it, which would eliminate most concerns about its durability.  Harbor Freight has a very good reputation for replacing products that break under warranty.

Hobart “Airforce” plasma cutters

Plasma cutters need compressed air to operate.  Hobart sells a line of plasma cutters with built-in air compressors, which I think is a really nice feature.  The 250ci, which runs on 115-volts, sells for about $800 and their dual-voltage (115/230v) model 500ci goes for about $1300.  The 115-volt machine can cut up to 1/4-inch thick steel.  That’s probably more than enough for most home shops, but I’d like to have the dual-voltage machine’s ability to cut steel up to 5/8-inch thick.  Unfortunately, the Hobart 500ci is way out of my price range.

Hobart is a trusted name in welding.  So getting service, parts and supplies is not going to be a problem.  Their plasma cutters come with a 1-year warranty but I’m a little concerned about the cost of getting one of these machines fixed if it breaks after the warranty expires.

I’d like to consider buying a new Miller, Lincoln or ESAB cutter but they’re even further out of my price range.  I often buy used equipment and I wouldn’t hesitate to buy a good used plasma cutter if  I knew that they were generally reliable and durable.  But I don’t know if they are.  I don’t want to buy a used machine without a warranty and then have it stop working a few months later and find out it will cost me hundreds to get it fixed.

Plasma cutters manufactured by the Wenzhou Chiry company in China

The Cut 50 that you see in the video was made by Chiry.  Their plasma cutters are imported and sold under various names like Simadre, Longevity, Parker, Ramsond and many others.  They make two machines I’m interested in.  One is a dual-voltage (110/220v) plasma cutter that you can buy for as little as $370 (and maybe less) with free shipping on eBay.  They also have a dual-voltage 3-in-1 machine that is a plasma cutter, TIG welder and arc welder for $580 on eBay with free shipping and a free foot pedal control.  The other companies charge more, although not that much, but they often have better service and support and longer warranties.

I’ve read a lot of reviews and they’re pretty good, and many of them are very good.  But there seems to be a significant number of buyers who have received machines that were dead on arrival.  I find that a bit worrisome.  Also, if the machine breaks while under warranty you’re going to have to ship it back to the seller and hope that they’re still in business and will honor their promises.  By the way, most sellers offer a 1-year warranty and some offer a 3- or 5-year warranty.

There’s definitely some risk involved in buying one of these machines, especially if you buy one on eBay.  Even so, I’ve been very tempted the last few days to just roll the dice and order one, which is very unusual for me.

Here are some more reasons why I’m considering one of these machines:

  • I’d really like to have a dual-voltage machine and I can’t afford the one Hobart sells.  One reason is that I don’t have a 220-volt outlet in my garage yet, although that will probably change soon.  I’d also like to be able to take it and use it at a friend or relative’s house.  These plasma cutters are small and light (~20 pounds) and a 110-volt 20-amp outlet will provide enough power to cut most things.The Chiry machines will automatically adjust themselves to the voltage they’re plugged into, just like the Hobart will.  They don’t come with a power plug installed because they leave it up to you to install one for either a 110 or 220v outlet.  I’d put a 220v plug on it and then make up an adapter so it can be plugged into a 110v outlet.  That’s how I think Hobart does it.
  • The 3-in-1 machine doesn’t cost much more than just the plasma cutter.  I don’t care that it can arc weld, but I’d love to be able to do TIG welding.  One advantage of TIG is that it can weld more kinds of metals than the other welding processes.  However, the less expensive Chiry 3-in-1 machines can not weld aluminum because they’re DC only machines, not AC/DC.   Which I think is a good reason to get a better TIG welder instead. TIG can also create very small, clean and neat looking welds.  It also doesn’t produce any sparks, spatter, slag, smoke or fumes.  It’s also slower, requires more skill and you’ll also have to buy or rent a tank because it uses argon gas.

We obviously don’t have a lot of experience with plasma cutters.  So my friend and I would appreciate it if you would leave a comment if you have some advice or other suggestions for us.

Addendum

I’ve learned that there are two ways to start a plasma flame.  The least expensive torches use “high-frequency” or “contact” start that can interfere with computer or electrical equipment (CNC!).  They require you to touch the torch to bare metal to start the plasma flame.  More expensive torches usually use a pilot arc to start the flame, which will allow you to begin cutting before you come into contact with the metal.

Everlast sells a pilot arc plasma cutter (SuperCut 51P) for $680 (September 2016) and Longevity sells a similar unit (ForceCut LP-50D).

Random Quote

You pile up enough tomorrows and you’ll be left with nothing but a bunch of empty yesterdays. I don’t know about you, but I’d like to make today worth remembering.

— Harold Hill in “The Music Man”