Talk:Welder

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Main > Digital Fabrication > RepLab Tools > MIG Welder

From John McGinnis

I saw you have a target for development for a open source welder. If you really want to cut your design time to virtually nil you probably ought to look here -- http://diy-welder.com/index.shtml.

Substitute an appropriately sized hydraulic motor as the driver source for the alternator powered by the power cube. Probably the only thing you would need to validate is his position in open sourcing the board design and BOM.

Stick, mig, tig. What's not to like?

Best Wishes

John McGinnis

Question

Regarding your comment on a 'datalogging constant current/constant voltage AC/DC MIG+TIG+Plasma cutter with HF starting, controllable pulse duty water cooled open source welding machine' - do you understand the basic conceptual power electronics design so you can start us on the process? Furthermore, if we can write down a proposal, we could get it crowd funded. If you can help us on this, or point us to other experts interested in helping, that would be great.

Answer

From Jean-Francois -

well I'm no expert on the subject, I started playing with arduinos a few months back and I got some background from the course I got taking my ham radio exam however I was recently laid off so I might not have much time for now to contribute, I have two welders on hand but they are MIG which is simpler, one is a full "magnetically coupled" design that uses adjustable transfomers only to control the power, there's also my friend new weller MIG, it's a compact solid state design I always thought doing a combo MIG and TIG power supply would the best because more the circuit can be dual purpose saving on manufacturing costs of but a MIG and a separate TIG you also want a TIG because it's more much versatile than MIG (mostly welding aluminium, special alloys like inconel and exotic metal like titanium) also I think MIG can be improved by TIG features like pulsing (either voltage or feed rate, maybe controlled by a proportionnal switch on the MIG whip) having a TIG power supply also allows to connect a "replacement" plasma cutter whip (both TIG and plasma cutting use a constant current power supply, as opposed to MIG's constant voltage)

I think the first thing to do would be to take appart a few modern TIG and MIG of different manufacturer, figure out the circuits and each particular "good ideas" the engineers added

then build a low power prototype proof of concept or a plain featureless solid state MIG and TIG (separate) power supply

then try to re-use parts of the two circuits to design a new TIG+MIG PS

then scale up the power by using bigger IGBTs (if they are fast enough, if not use power MOSFET)

using an arduino for the brains will attact lost of attention for the rest of the maker community, especially electronics-oriented, arduino-oriented and welding-oriented communities

because giving the operator of the welder full control through an open source controller is something no other welder manufacturer has ever done

the only mechanical challenge IMHO is designing a good cheap simple electrically adjustable wire-feeder for the MIG part (hey .. what about wire-feeding TIG ?!)

I have not yet taken my MIG machine but I suspect that the power section is built similar to a PC power supply on a bigger scale something like a power factor compentation block at the mains power input, then a big step-up toroidal transformer then the rest is a switch-mode power supply controlled by a microcontroller (or an ASIC (application-specific integrated circuit) since weller is a big company maybe they had one made), in fact modern welder have an automatic feedrate setting and I bet it's that same controller regulation that !

there are cheap, 300$ to 500$ TIG and plasma cutter combo kits on ebay, they are probably the cheapest source of information on TIG power supplys (and the circuit design will reveal the cheapest way to do it)

the datalogging, in my opinion would be the most novel thing about it

maybe a 1.8" OLED on the welding whip could give feedback to the operator about the weld he just did maybe offer advice for obvious problems or information about weld quality or energy/gas/wire consumption

maybe an entire welding session could be recorded both on camera and through the datalogging power supply and then an instructor/student or an auto-didactic person could review the information and learn how to improve their techniques

about HF starting, I would bet it's not just high-frequency but also high-voltage, to cause the air to breakdown and arc from a larger distance between workpiece and TIG anode


Online welding communities (well.. forums really): (some are neutral, some are manufacturer specific, sometimes manufacturer-hosted, I think only the neutral ones will be favorable to DIY talk (both DIY welding machine making and DIY welding itself, since forum members are making their livings off of welding they may not be favorable to competition ?))

  • http://weldingweb.com/ - 25,048 members , over 500 active on a monday evening, manufacturer neutral, probably DIY friendly but not sure
  • and there's the welding subforum on cnczone, the biggest DIY and pro friendly forum about everything fabrication-related.

oh the subforum got it's own separate website, it's kinda small but growing. 16,586 members, 166 active.

  • Cnczone itself is 160,821 members, unknown actives.

There are much bigger forums out there but these smaller ones are usually more friendly to newbies and full of knowledgeable people.

There are quite a few DIY MIG welder designs, but most I have seen yet and magnetically coupled hard to control and keep stable types that use lots of expensive copper and weigh way too much, and they're not energy efficient. I hope this puts you on the right track.

-shodan

Build a Welder from old Microwave parts (Instructabliss How To)

SMAW instead of GMAW

Perhaps I'm missing something, but it seems to me it would be far more productive to focus on the SMAW process rather than GMAW. In this developmental effort the advantages of GMAW are overshadowed by it's complexity. SMAW welding requires nothing but a transformer and flux coated electrodes, which can be made from coarse wire and common minerals. GMAW requires relatively fine wire of precise composition and, more significantly, shielding gas which must be either be compressed and stored or produced on demand. Furthermore, the welding process in GMAW is partially controlled by the machine, which will require electronics, while in SMAW all the control hardware/software comes with the person holding the stinger. SMAW welders are so easy they can be made in a village, and they are, literally.

For sheet metal welding a spot welder would complement SMAW very well and is also mostly a transformer and rectifier (which can be made from copper oxide). Spot welding is also very complimentary to robotic welding.

I've looked around the site to try and find out more information as to why GMAW was chosen over SMAW, but I've come up empty. I think the global village construction set is an absolutely wonderful idea and I'd like to see it succeed. I'd like to help out how I can and I'm hoping I can get some more info on this. sinarcsin (talk) 18:33, 26 January 2013 (CET)

I tend to agree with the above. The number of variables with GMAW welding rises hugely. The constant voltage power supply of a GMAW welder is more complicated even without factoring in the amount of tuning and control you need for the correct burnback, feedrates, inductance for short-arc etc etc. I'm presuming TIG is out of the question due to the availability of argon, but this also limits GMAW to CO2, which is only good for ferrous metals. I guess FCAW is an option, but accurately making flux-cored wire would be quite difficult I imagine. SMAW power supplies are so easy to design and extremely robust I think if electrodes are as easy to make as stated above, it would be better to start with a stick welder.Llama (talk) 01:43, 26 June 2013 (CEST)

As to my knowledge there are many open source designs for welding power sources, so a good next step would be to develop an open source flux coating and production method. I think a good first goal would be to emulate the E6010 and E6011 welding rods. Exact electrode composition tends to be somewhat guarded information, but these were among the first SMAW electrodes to be developed so the patents covering them will have expired before many of us were born. They also predominantly use easy-to-aquire ingredients, such as cellulose, sodium silicate, talc, titanium dioxide, manganese powder, sodium fluoride and others. We may not even need to develop exact analogues since there's very little chance anyone producing these rods will ever get them certified for structural or pressure use. Just something usable that produces a weld as strong as the parent metal that is not prone to cracking. There are specific tests (that involve welding and bending plates) using relatively simple equipment that can be used to evaluate these properties. sinarcsin (talk) 20:47, 28 July 2013 (CEST)
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