Oxy-acetylene welding will be quite okay. None of the welds needed on the MechMate are critical - all of the welds are fairly low stress.

Selecting a good arc weld electrode for the Mechmate

6013 for the Y-Car
7018 for the table

A good read in spanish and read in english.

The 7018 (iron powder coated) sticks need quite a high Amperage and you seldom see them used by a DIY guy with a small welding machine.

If Gas welding is acceptable then brazing is strong enough. Alot of race car, racing karts, and racing bicycles have been brazed with good success. Brazing has a higher tensile strength than steel, 120000 - 130000 psi. The joints need to be fitted nearly perfect, as it does have strength in gap filling properties

Maybe its time for a new welder... With one of these babys everyone can weld like pro :)

Have it ever cross you mind that hiring a professional welder (person not machine) for a day? This would clear one hurdle of your build.

Sorry, Ken, I don't see your point.... ;)

You don't have to weld it yourself if you know you are not up to it. Hiring or ask a favor from someone who can weld better the me when its call for goes a long way for me.

My scenario.
I only have stick welder (borrowed). I know my welding skill is not up to par. BUT sufficient for horizontal welds & enough to keep the metal sticking together, (ugly but that still get the job done :o). I also know I can fit fairly well & I don't trust contractors to pay as much attention to fitting as I wish. So, I build the table top side down to eliminate overhead welding, Fit the gantry & Y-car as best as I could then did all the spot weld & haul the lot to a welding shop with MIG facility to finish off the full welds under my own supervision (make sure the welding sequence is followed) this cost me peanuts when consider the outlay for a MIG welder & hiring CO2 just for this job not forgetting that the weld quality is guaranteed.

In fact my total outlay for the welding
~US10 welding rods, with 75% left over
~US20 welding fee (for a familiar face :) )for 1/2 hour job.
~ 1 big favor to a friend who borrow his truck for sending the Gantry to the welding shop.

Compare to ~USD600 (this is cheapest local price for MIG) US30 hiring+deposit of CO2 cylinder, +XX for consumable...

BUT you can also hire a pro welding person or get a friend to do the welding with your equipment.

Acquiring new skill would be nice, but it depends on if it is your objective.

Michel, you will get used to welding after just a few inches. It`s not that hard, just a little bit of training.

Ken, I think you wrote this in another thread: " ...You only need that "can-do" attitude...":)
and like Gerals said: ...Welds don't have to be beautyful, they have to be strong...
I used only stick welding on my MM, and allthough I`m not a welder, everything went smooth and now I can weld.:)

can not agree more. :)

Not forgetting, there are more then one way to skin the cat. :)

I sell weldings alloys for a living, we have rods you can use without hoovering over the piece, you press the rod at the piece and it opens the arc, you keep pushing the rod at 45deg to the juncture and it keeps welding and the welds are pro-like.

The rods I sell are expensive, but what I learned from this technique is that you can do the same with brand name 6013 rods, these are cheap, just put 10A more than usual to the machine and try it on some scrap metal

Pablo, are those the rods with iron in the flux? (we call them "iron powder" rods)
That type of rod, and most others, need to be "fresh", or baked dry, before using them.

I also used the 6013. I also read this welding guide which was posted in some other thread. It helped a lot finding a good technique.

Gerald, that sounds like a pain for the DIY guy who will have rods sitting around in the garage for while before he needs them. What will happen if you use the rods after they have sat in the garage for a while without baking them? This is one of the reasons I went for a MIG welder initially.

I have a metal box that I keep my rods in... Inside is a 40 wat light bulb that burns 100% of the time. It keeps the moisture out and the rods baked and ready. I have both a mig and a stick welder... Different jobs need different equipment...

6013 is general electrode I use. It is the most common electrode used here. They are almost impossible to go wrong when welding structural or mild steel. Some times we also use them for pressurized vessels/pipes.
Even I can weld with these :)
Moist electrode... Its best to store them in sealed boxes or containers if you know you are going to stow them away for a long period, I personally like common plastic food containers. I've seen ppl storing theirs in large coffee cans.
But if you have a pack of damped electrodes, 2 ways, 1st the pro method, use drying oven, 2nd layman method, stick the electrode to ground for a few second until you see the electrode stats to glow... but there a limit to this recovory, if they are wet, I suggest to discard them.
I know this because I do need to supervise steel fabrication from time to time, I know how things are done & what should happen but don't have to do the muscle work... Yes, I'm that PITA guy who only know how to point his fingers :D

No, they aren't, and most of the product line repels moisture so they can be stored without much care. Brand name is Magna (www.magnagroup.com or my site www.peu.net) These are specialty rods for maintenance, not the usual alloys used in the industry, for example we have an electrode that can weld almost all steels, yeah, that include inox, low-med-high carbon steel, manganese steels, spring steel, etc etc, you have to see it to believe it.

Regarding keeping the electrodes moisture free, I also use the method described above, a wooden box with a 40w lamp inside does wonders to keep them in usable conditions for a looong time.
Unless you live in a place with high moisture all year round, 6013 is very forgiving, but there are others, for example aluminum rods, that degrade pretty fast due to moisture.
Also 6013 is cheap enough to discard if it looks degraded, but as I said, they are forgiving, keeping them in the box they came closed should keep them usable for a long time.

Then there is the issue of the welding machine you use, most common type is the AC transformer, a bit more difficult to the novice, but not that difficult either. The next type is the inverter, little machines that weight nothing compared to a transformer and have many advantages over them, for example, they stop current flow when your rod sticks, preventing overheating, the current flow is smoother and most of them also can be used as TIG welders (TIG is almost the same technique as MIG) and did I mention they are light? for example I have an ESAB Caddy, a 150A machine that can weld at 100A with 100% duty cycle and it weights less than 3kg (7lbs)

quote "(TIG is almost the same technique as MIG)"

This is a very misleading statement, especially since there are beginner welders here that might be confused.

guys guys, not trying to confuse anyone, I said almost!, both methods use Inert Gas to protect the area to be welded, both methods are electric, one has a wire feeder and the other is feed by the welding person, even can be used without consumables.
For the novice, ARC is the method of choice, you can do some nice welds without spending months to learn the technique.

Pablo, As a welder I understood what you where getting at, I think you should of used the word "process" instead of "technique". Technique infers physical manipulation in some way.

The TIG process is similar to Oxy/Fuel in technique. Novice/hobbiest tend to think more in the technique frame of mind instead of the process mindset.

I am just trying to keep the novices on the straight and narrow as there is a lot of confusing and conflicting information out there.

Thanks for the clarification, now I know a new technical term in english, as you noted, I used the wrong word

Probably the best thing a beginning welder should do (besides practice) is get the "Miller Student Package".

http://www.millerwelds.com/resources...dex.html#books ( at the bottom of the page)

You get 11 welding books, three slide calculators and a poster, for $25 and that includes the shipping.

A few of the books sell for $25 by themselves if you were not a student.

Good find. :)

I purchased long time ago the John Deere book on welding (http://www.deere.com/en_US/compinfo/.../complete.html) its an excelent resource for a welding newbie, it covers oxy-acetylene and welding rods only, so if you are looking for tig or mig its not the book.


Pablo

And just to clarify, you don't have to be an actual welding "student". No one asks for any references when you order.

Allot of discussion here about feeds, speeds, and cleanliness to eliminate spatter and improve the weld appearance. I agree, but another consideration is the choice of gas. For most MIG mild steel applications use a 75/25 or 80/20 argon mix. Another thing to consider is to shield the weld area from wind, make sure your shop fan is not blowing across the weld or you have defeated the purpose of the shielding gas and will experience porosity in the weld (looks bad and is structurally compromised).

Scott

Thanks for the suggestion! My order arrived here in 3 business days.

Extra bonus for Canadians -- it shipped UPS, but there were no taxes, duty or brokerage on the package :D.

Michel

Michel,
So what is your impression of the books and the value of the information in them? Give us a review!

Here is a pix of what is in the box (the poster was too big, and your get a Velcro box to keep it all in). You get a 2010 Miller catalog too (of course Miller has to get some advertising in - can't blame them for that!).

There is a lot of info. Stuff you might never dream of (like spot welding different metals together). The TIG and MIG books are really detailed; they take you from total beginner (how to roll a gas cylinder around) to filler metals for all the different grades of stainless. The TIG book is maybe 100 pages and the MIG book is 150 pages.

The slide rules are great, and come with a zip lock vinyl pouch to keep them clean.

Best $25 a person who welds could spend.

If I had to describe the package in one word, it's "comprehensive". There's a LOT of detailed information -- much more than I've seen in some other "introduction to welding" books.

I browsed through the GMAW book, as that's most applicable to my welder. I'm impressed at the technical detail, and the fact that it reads like a textbook, not like a sales brochure. They cover all the relevant concepts without getting into specific model numbers and part numbers (which are, of course, irrelevant to the actual activity of welding).

Highly recommended!

Michel