How To A Master Welding Thread

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Feb 19, 2019
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There has been a lot of interest in welding and purchasing welders lately. I asked @Stacy E. Apelt - Bladesmith if we can add a master welding thread to the stickies and he said that we could. I have been involved in welding for around 20 or so years. I was a welder with certs in GMAW, SMAW, FCAW AND GTAW or MIG, Stick, Flux Core and TIG. I welded aluminum for years and then got into field welding stick steel and then tig steel and a little bit of inconel. I became a welding inspector and taught welding at Bellingham Tech in Washington state. It was a good school and I wished that I could have kept with it because I have never learned more than when I was teaching and I enjoyed it. Hopefully I have gained enough knowledge through that that something will be useful and I am going to save several slots to fill out different categories. I am going to post a second thread for questions so that we can leave this thread clean enough to find what we are looking for. I know a lot if other guys here have some very good experience and hopefully they can fill in my knowledge gaps. I want to keep this to a clean outline so I am asking that 1. Please title your post about the subject that you are sharing and 2. Please be able to backup your post with research or professional standards. I don't want to be stuffy about this and if you just have a great tip for fitting or something else that could be useful feel free to post but if it is a random opinion from some old timer that you talked to and you can't explain why it works please don't post it. If it is a good tip but you don't know why it works or helps then post it on the questions thread and we will try to figure it out and then add it. I have a TIG/ Stick unit and will try any experiments that I can for you and maybe others can help. I have access to most welding codes and can give you the code answer if you think that helps. I know we have guys here who have welded just about everything and they should be able to fill in what they know. Perhaps @Larrin could help us with material science and anything else that he is willing. As knife makers there can be a need to weld martensitic steels or titanium and I don't have that experience so I'm hoping that others can help with that. If we do a nice job with this we can have a nice welding manual for knife makers. Only for the reason that I'm hoping that this can last, things such as questions or questionable answers may be moved to the questions thread at least until we can find a answer or prove them. Thanks for understanding and thanks in advance for all of your help. I will try to add to this every day or so. I'm sure that I will be the one who learns more than anyone else so thank you for that.

I also want to add that I will do my best to tie in articles from industrial trade journals books or publications but I'm sure it won't be perfect and I am not a writer so take everything you hear from a welder with at least a shaker of salt.

I'm going to try to organize this the best as possible so I will start with a overview of a subject and as I have time and as questions come up I will add to the subject. Please be patient with me welding is a passion but I can't say that writing is. I may move some info around so as to make it as easy as possible to reference. Please reply to the questions thread if you guys would like things broke down by category of subject or if you would like each processes broken down from start to finish including what type of power sources are need and techniques, technology, code and technical items even if they repeat in other areas.

I would love to have volunteers for information that I do not have personal experience with. If anyone want to do that you can reply to the question thread or call or text me at 360.305.6225. Here are the current list of subjects that I have not had personal experience with. There are probably more and I will add them.

1. Forge welding
2. Welding martensitic steels
3. Welding copper alloys.
4. Welding Titanium
5. Brazing and soldering ( I have some experience)
6. Welding nickel alloys ( I have some experience)
 
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1. Welding overview and processes most common to knife making.

Welding is the mixing of materials usually metals so that they become one piece and are mixed at the atomic level. If the materials are not mixed but rely on another mechanism it is something else such as brazing or soldering. The difference between those is usually considered to simply be that soldering is below 800 degrees F and brazing is over.

Welding requires a energy source and for knife making it will normally require a heat source. Oxy-Fuel welding is not as common as it used to be so we will look at arc welding first. Because we are bringing the materials up to the point where they will begin to react to oxygen we also need a shielding gas to prevent damage to the materials. All of the processes will require then a heat source and a shielding gas and this can be done in many different ways. A weld does not require that we add extra material but in many cases we will want to do that in order to add extra strength to the weld since other than forge welding or very thin material it is difficult to heat and fuse a large area at the same time. While we are at it let's break down the difference between the terms of fusion and penitration. All welds require fusion. Penitration is simply the depth that our heat source penitrates. Forge welding has almost no penitration but needs to have full fusion.

Processes.
SMAW: One of the first many people will incounter is SMAW (Shielded Metal Arc Welding) or more commonly Stick welding. This is one of the oldest and most common arc welding techniques. It requires a CC (Concistant Current) power source and is most commonly used with DC+ polarity. This involves a electrode that has a covering that will produce a gas cloud at the arc and often flux and a slag former. Some of the oldest types of electrodes were simply a wire covered with paper. The paper would burn off at the arc and consume the oxygen and then produce a small gas cloud that would keep additional oxygen away from the weld puddle. SIDE NOTE: The difference between a Rod and electrode is that a rod is added to the puddle vs a electrode has power running through it. A electrode in AWS(American Welding Association) Standard is marked with a E (example E7018 or E6010) a rod is marked with a R and if it can be used either way it is marked with both (example ER70-S6). I will do a breakdown of what the AWS codes mean at a later date. There can be other additives in the coating as well such as arc stabilizers, iron powder, alloying elements, Flux and slag formers.

The advantages of SMAW are that it is simple and probably the most portable welding type. It is good in adverse weather and less than perfect conditions or materials and can give very good welds even with inexpensive equipment and can weld most steel as well as some other alloys and can weld in very restricted areas.

The disadvantages are that it tends to be slow with a lot of waste. It also cannot weld all materials because it requires the Flux coating and this can contaminate some welds as well as the gas cloud consisting of mostly Carbon Monoxide and this is not inert and can react with the base materials.
 
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5.
Power Sources

Power sources are the heart of arc welding. And for knife makers they tend to be one of the items that I see the most questions about. The reason is pretty simple. This is the thing we need to go out and buy and we want to make sure that it will do what we need.

(I will be doing this one in parts and will try to start with what will be most helpful first and then build around it.)

There are two basic types. Transformer based and inverters. I will give this article to explain the difference and the pros and cons in depth. https://www.thefabricator.com/thewe...ng/the-great-debate-transformers-or-inverters . The quick overview is that transformers were the first successful industrial welders. They are rugged and last forever and can be repaired. Inverters needed modern shielded electronics to be successful but have the advantage of being far cheaper for the same output and allow much more control of the power and can come with some very advanced features that make them very desirable. The downside is that if anything goes wrong they will often require computerized part swaps and may not be worth repairing. Since these are the least expensive and offer the most options they are the ones most of us will get so I will start there but first I will go through some basic electrical theory of what they do.

Most welding is done with direct current (DC) and even when it is not DC is still giving us the effects that we want but ideally we are reversing the polarity intentionally for a reason but some simpler welders are just lowering the voltage and raising the amperage from the line power. Electrical energy is described in two ways, voltage and amperage. The difference between the two is often compared to how a pipe carries water. Both measurements are a way to carry energy and the total energy measurement is called Watts and that is calculated by multiplying the amps by the volts. A similar measurement is Joules. Joules are Watts over time for a total of energy that is transferred.

Voltage can be compared to higher pressure because it is more resistant to friction losses and can carry the same amount of energy through a smaller conductor but it is also harder to keep it inside the conductor and if we think of insulation as the pipe walls it needs more insulation to keep it where we want it. And don't forget that air is one of the most common insulators. For this reason some TIG welders have high frequency start to help the spark jump the gap so that the electrode does not have to touch the work. Other than that it is not desirable to have high voltage as can be attested to by any welder who has welded in the summer time with sweaty gloves. It is also the most dangerous of the two since our bodies use voltage for muscle contraction and it is both more easy to get shocked by and it can affect our hearts and usually not for the better. When electricians are in a situation where something could be live they take care to make sure that the electrical path does not go across their hearts by keeping one hand away from any type of ground. High voltage can be carried over longer distance with lower friction losses. (I do realize that this is not the same thing as what we think of as friction but I'm a welder and have to make things as simple as possible to be able to understand them.) A machine that holds the voltage constant is called a CONSTANT VOLTAGE/CV machine. Wire feeding machines are CV. With this the machine adjust the amperage for you so that the voltage is consistent so if you move the tip closer it will burn off wire faster and if you pull away it burns off the wire slower so that you do not pull the wire out of the puddle or break the arc. This means it is hotter when you have it closer and colder when it is further away.

Amperage is often compared to the water volume where a larger pipe must be used to carry more if the pressure is not raised. It creates heat when used in a conductor that is to small and that heat increases the restriction and that makes more heat and so on. Electricians carefully monitor the load that can be put on a item so this cascade effect does not affect your home wiring. My dad is a electrician and me being a rebel made sure to pick a trade where I could do what he tried so hard to avoid. Another name for amperage is current. A machine that holds amperage concistant is a CONSTANT CURRENT/CC machine. Machines for TIG and Stick are CC machines. CC machines decrease the volts as the electrode is moved closer to the work and turned up when it is pulled away so as to not break the arc off. This means that more heat is added if the arc length is increased. Thus can be useful for some things such as when the weld is tied into a thicker area. It is one of the most common problems with newer welders doing vertical welds that when they see the puddle starting to get hot to subconsciously pull away and without thinking make the weld even hotter. Because of difficulty this causes it is normally best to set the machine hot enough so that a very short and predictable arc is maintained. To add to this problem a long arc is hard to get good gas coverage on and if O2 hits it some of the metal will begin to burn in the plasma stream raising the temp even higher.

If it can do both it is a CC/CV machine.

To be continued....
 
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