Welding equipment & techniques

[smreish]

This thread started from this post (http://www.mechmate.com/forums/showthread.php?p=7954&postcount=5) on another thread,

Mig is easy and will do all of the work necessary....but you could get by with a stick welder if your careful.
The welding requirements really are minimal!

[Doug_Ford]

I used both stick and MIG. Stick on the table and MIG on the gantry and car. If your welder is large enough, you could MIG the entire thing.

[Gerald D]

The idea is that you could use any type of welding. There is no critical welding.

[Greg J]

Craig,

I used a wire feed MIG welder. Very inexpensive and easy to use. Not easy to get good looking welds :) Allot of "splatter", so extra time required to remove splatter marks.

[Robert M]

Greg,

I will say I’m the last one to pretend knowing how to make a nice weld cord/joint. Actually, I’ll debate with many on & about wood & woodworking since it’s my trade, but never the less I have/do my share of some welding with a nice little LINCOLN Power MIG 140 (http://www.lincolnelectric.com/products/intros/powermig_140_180.asp ) welder enough to understand some basics, not all of them, but some.
One of them is a little about splatter. Many reasons why it occurs, but top of my head for now is that you are welding to “cold”. Feed rate not good, wire size wrong, wrong gas, impurities from corrosion or protective oil on steel…. and the list goes on & on.
But I’ll stand on one thing as far as I’ve experience ( not that much after all, just hobbyist welder ) with various type of steel combination I’ve weld together, if splatter occurs it is defiantly not because of the machine type ( MIG for this discussion ) it is most likely a code 18 !!! :confused: ( most likely the real cause is 18’’ from the cause ) !!
Again… Please this is not in any form some type of personal attack here, au contraire, just exposing my experience and from what I was guided by some reel pro’s, witch defiantly for my part of the experience may be questioned since remember, I make a living as a studio furniture maker, but on the other side, defiantly not just an average tree hugger guy !!:rolleyes:

One thing I’ll say, the Power MIG 140 will do for most of the needs for the big blue beast, it Can weld up to ¼’’ no problemo, but 5/16’’ is pushing it !! ) but if you can afford it, go for the 180, just a tab more powerful for less than +/- 175$ more. !!
With any of those, lots of fun waiting with out major splatter, if any !! ;)


Amicalement, Robert :)

[J.R. Hatcher]

I was using my mig welder with flux core wire and getting the same results as you. I talked to the instructor at the local community college and he told me to invest in a bottle of gas, switch to solid wire and it would make all the difference in the world .... and it did.

[Gerald D]

Investigate some anti-spatter sprays or paints before welding. The good ones really do help a lot. The bad ones don't help at all, plus they contain silicon which makes subsequent painting nearly impossible.

In my shop;
- all anti-spatter spray is totally non-silicon.
- grinding off spatter is forbidden. It must be chiseled or scraped off. If spatter is so severe that a chisel doesn't break the blob off cleanly, then the job goes to the scrap and the welder goes for re-training.

[revved_up]

I see I have much to learn and alot of practice ahead of me. I will try to keep all my future questions in the appropriate threads. I look forward to the challange.

as a side note: Sean I sent you a pm about the laser cut parts.

[Greg J]

Robert,

I agree totally. As usual, I didn't give enough detail. Like J.R., I am using flux core. People have told me to use gas and solid wire and the issues would go away. Another advantage is the welding is easier to make nice beads. My next MM will be much cleaner.

[Doug_Ford]

I have a small Lincoln welder too. Gas and solid wire eliminates the splatter but, at least on my welder, you are limited to welding thinner metal. Flux core allows you to weld the thicker stuff. However, I'm betting the larger (250 amp) welders can weld thicker material with gas and solid wire.

[Gerald D]

MIG vs. Flux-Cored: Which Welding Process Is Right for You? (http://www.mig-welders.com/mig_welders.htm)

[firebrick43]

I would like to make a few comments on welding.

Now as Gerald put it there is no critical welding on this machine so some of the following is moot. Most of the following is just therory and does not neccessarly apply to the mechmate.

I have welded tig, mig, arc, and gas(oxy/fuel). I have certifications in several different types. I see people all the time pushing mig welding to beginners and it makes me cringe. You can teach a monkey to make nice looking mig welds in a matter of an hour or two and that is the problem. Mig welds can look absolutely beautiful and have no penetration or have porosity and you wouldn't even know it unless you cut the weld in to sample strip and bend it for analysis. I don't know how many times when I was working on certs and the weld would not pass inspection even though the instructor though it looked great. They would fail dye penetration test or show porosity when ground and bent in a test rig. Ended up being the machine that was giving the fits but it showed no outward appearances. With arc, tig, and gas welding, if the weld looks pretty with no outward defects, 99 percent of the time the weld is a sound one.

I am of the personal opinion that a beginner would be better off buy a nice DC stick welder and learning to use 7018 for most work. The skills take a little more time to pick up but rarely does it take some one more than 8 hours to learn the skill. Heck I was 7 or 8 when I learned and was doing a decent job. Plus a stick can do very heavy work and very light as well (I prefer gas or tig for light work however)

I don't have the aversion to grinding welds as Gerald does, although I agree with him on using a chisel to cleaning spatter and a grinder should not be used as a crutch for poor welding. In thick heavy pieces, a good penetration weld should be preformed first(6011), one side built up(7018), and the Root ground mostly ground out from the oppisite side and 7018 bead put in its place.

In the production eviroment, the mig has earned its place because of its speed and therefore reduced labor cost. A nice DC (or AC/DC) arc welder will cost about the same as a small mig(I won't include the no name harbor freight and similar jobies) and will have much more capacity/power.

[Gerald D]

Even with our production MIG welders, we revert to stick arc when a weld gets critical. Yes, a beginner should be using stick.

Jay, I have no experience with flux-core mig - does that give any more penetration than the typically poor penetration from gas-shield mig? Do beginners have better strength with the flux core mig? If this is the case, then it might be a serious thing to watch for the guys who are aiming for cleaner welds and want to switch from flux core to gas shield. (The only good thing I can say about spatter is that it indicates better penetration :))

[firebrick43]

Yes and no Gerald on the flux core migs. It has been my observation that it is an increasing trend that heavy industry is actually going to flux core wire welders. These welders are very large, computer controlled, with inverters and a lot of other technology built in(also expensive). With advances in the flux in the wire they are a lot better in controlling contamination than gas shielded mig and amazingly leave little to no spatter but you do have to chip of the slag(it comes of very easily). The smaller mig (<250 amps)welders just don't cut it and while I am not certain, I belive part of it is due to wire size(ie amount of flux that is in the center of the wire). Also remember that one of the reasons that mig is hard to get good welds is that it is very hard to see the puddle straight on because of the large diameter of the gun. Other welding process, especially stick does not limit your view of the puddle. This is one reason that most critical pipe applications (Gas, oil, chemicals, ect) are not certified to use mig and are typically welded with tig on the root pass and 7018DC on the following passes. MIG welders are starting to be used in these applications but it is normally again the very large, computer controlled and modulated models, some even are automatic or robot welded.

For beginners wanting good looking welds, a 7018 ***DC*** rod used in a good ***DC*** welder will do a beautiful job. A little anti splatter spray will keep it from sticking. A 225 amp dc stick welder will cost about the same as a 125-140 mig welder when you consider the gas. And those little 140 amp migs are marginal for any thing bigger than sheet metal.

[Greg J]

Jay,

Excellent points. I'm already thinking about the next MM and a stick welder will be in the plans.

Not so much for the MM (not as critical) , but when I welded up (using flux core MIG) my gantry crane, all welds were in the flat, horizontal position. No vertical or overhead welds. Not that I could weld them anyways. :)

I was very concerned about penetration (strength of weld) and went overboard on length of welds. More length equals more area equals more penetration. I also make up for my poor welding skill thru design. The gantry structure is rated for 3,000 lbs [1,360.7 kg] but I only attached a 2,000 lbs [907.1 kg] chain hoist. Raises the factor of safety from the original 3 to 4.5.

[Doug_Ford]

This is the inside cover of my Lincoln 135 MIG welder. It shows the settings that are required depending on whether you are using gas and solid core wire or flux core. As you can see, the solid wire and gas is limited to thinner material. I've had excellent results with it and the flux core splatter scrapes off fairly easily with a chisel.

[GregA]

I just considered another angle here.

If you are a total noob to welding, like me for instance... Going to a fabrication shop to have the mechmate welded and painted, will only cost a few hundred dollars more than purchasing everything you need to weld the mechmate.

For example, I am looking at $1500 fabrication and painting cost beyond materials. Looking around at welding kit I think it would be easy to spend that if you were a total welding noob...

[Greg J]

GregA,

Another aspect that's an advantage. Purchasing the equipment and learning to weld is self reliance. There are so many "small" items on this project that need welding. It would be a time savings to do it yourself, rather than wait on a shop.

I don't think one needs to be an "expert" welder for this project. The design is very forgiving.

[domino11]

Greg and Greg,
I also like the opportunity to buy a new tool and learn a new skill. I bought a mig welder about 5 years ago and find all kinds of stuff to do with it. I wonder how I got by without one for so many years berfore!:):eek: Now it will help me build my Mechmate!

[DMS]

Gentlemen,

I have also got Ac Stick Welder (150 A) and learning Welding process. This Manual helps me.
If anyone interested here it is -

[m_leblanc]

I just considered another angle here.

If you are a total noob to welding, like me for instance... Going to a fabrication shop to have the mechmate welded and painted, will only cost a few hundred dollars more than purchasing everything you need to weld the mechmate.

For example, I am looking at $1500 fabrication and painting cost beyond materials. Looking around at welding kit I think it would be easy to spend that if you were a total welding noob...

Do yourself a favor or more likely a gift, buy a welding machine and learn how to use it, that's what I did not so long ago and I am asking myself how I made to do without one before, always have the odd thing to weld. Best of all you will have it the way you want and when

[IN-WondeR]

I'm using a 250 Amp Co2 welder for my welds, and I'm no pro at this either, but I seem to be getting better at adjusting Power and feed of the wire so I get much nicer welds than I startet out with...
It's all int setting up, so try on some scrap bpieces of metal and just try to weld it together and get a smooth weld then you slowly learn both how much wire to feed and how much power to pull.

It should sound something lilke frying bacon on a pan when you weld... So just think FOOD....:D

[domino11]

Kim,
Have you ever tried using argon/CO2 mix instead of straight CO2? I find it makes better welds on clean steel. CO2 I believe will give a little better penetration but not as nice a weld and a little more splatter. Gerald do you have any comments cause I am not the expert here, just some personal observations over the years in hobby welding. :)

[cobra427mnsi]

Another question re: welding, for the guys with experience. Do you clean off that bluish/grey scale coating on new steel before you weld or does it matter if it is left on? It seems to me that there is a little more splatter from a flux core mig welder if I don't remove the scale, but removing the scale is a PITA for each weld.

Paul

[domino11]

Paul,
I generally clean any surface I am going to weld. This included NEW steel as well. If it is new steel, I generally use just a grinder with a knotted wire wheel and get the metal nice and shiny. If it is rusted I use a grinder and then clean it with the wire wheel well too. I have found that it takes less time to properly prepare my surfaces than to grind out bad welds due to surface impurities and then clean and re weld. With really clean surfaces, my welds go easier and I know they will hold. :) I have done a lot of welding on old rusty cars and every time I cut corners on the grinding I regretted it later. :(

[Gerald D]

Mixed gas (CO2 plus Argon and some others) cost more, but people pay for it because it makes for better welds. Mixed gas helps the under-powered welders to get better results.

A powerful welder will burn through the "scale" and make a good weld. If your welder is not that powerful, best is to clean the scale off first.

In volume production, we don't clean the scale, nor use mixed gas because our 300-400 amp welders have a lot of punch.

[cobra427mnsi]

Thanks for the info

Paul

[Gerald D]

Correction to my last post; after checking with my welders, we are using a mixed gas (http://www.afrox.co.za/templ-files/product/361_Argoshield_Universal.pdf) for production. Havn't personally held a mig torch for many years and my memory is going rusty.

[IN-WondeR]

I bought my welder used, with a full bottle of gas, so right now it's straight forward Co2, but when I'm going to have it replaced, then I'm going for the mixed version.... I have also heard the splatter would improve. And as for thread, I'm getting full rolls from work, so this is high grade mig thread...:D

[ekdenton]

I have been a welder for 35yrs now. Done pretty much all kinds. I haven't got my gantry parts yet but the table has some pretty hefty metal to be joined.
The strongest most reliable welds will be with a stick welder using 7018 or comperable tinsel strength rod.

Problem is unless you want to invest $$ in a good welder, the smaller "crackerbox" type welders have what is termed "drooping voltage". Which causes the arc to drop out just after you strike an arc. For a beginner this can make learning to weld very frustrating. A larger welder that does not do this is not really a hobby type welder it is one that you would use for business. Kinda like the difference in a MechMate and a hobbie cnc:)

If you decide to use a mig, you will need a 220v size mig perferably using the 75/25 co2 argon mix with bare wire. Which will give you the most heat and therefore penetration. This will be the smoothest combination also. Straight Co2 works but is not near as smooth and makes a colder weld at the same settings. If you have everything set correctly there will be very little splatter to clean and it should scrape of easily, however I don't see anything wrong with using a grinder or flap disk for cleaning, as long as you don't get real aggressive and gouge into the base materials. Small scratches will be covered with the heavy equipment enamel type paint.

Note: if you use mig you do not drag like stick welding, the weld puddle will actually be behind the cup and you will need to get used to just seeing the front and sides of the puddle. You have to get used to knowing how wide the puddle needs to be and adjust your travel speed to maintain the same puddle width. Dragging a mig will give little penetration, and ugly welds IMO

The blue bark on the channel iron and angle iron I normally leave without any cleaning or grinding the flux or gas in the case of mig welding will flow the impurites out of the weld. The only time I seriously clean and degrease is for tests.

[ryancromwell]

i work in a weld shop i have acces to lasers brakepress welders
i have been welding since 1998 i got a new welder it is a miller it does pulse mig and mig and accupules and accu speed .we have 3 lasers 2 of them are 5000watts the other is 2500 watts .i would like to make a table top cnc engraver mill . make one like accucarve.

[ryancromwell]

co2 is a colder weld more ar is a hotter weld at same setting

[ekdenton]

Argon will give hotter weld and thus better penetration, but is normaly not cost effective to run straight argon for mig welding (at least here in USA) alot of folks use a mixture of 75% co2 and 25% argon. This is a less expensive mix of gas that give very smooth welding and better penetration than straight co2. But the cheapest way to go is still straight co2 and bump up the amps for more penetration.

I think the norm is:
MIG
flux core wire okay
co2 100% better
c02 75% argon 25% best

TIG
argon 100%

[Jaladel]

I have about 2-500 hours operating a mig welder using argon shield gas. I was always happy with the quality. I believe it was a lincoln 210 or equivalent. 220 volt, 30% duty cycle, .035 - .045 wire.

Anyways, I didn't see it listed in this thread, so:

You have to switch polarity of the welder when you switch from Flux core to Shield gas. And if your polarity is wrong for the process you are using, you'll get splatter and ugly welds.

If this was already covered, my apologies. I am currently getting prepared to build a CNC router, probably out of wood, possibly from steel.

Thanks

[cobra427mnsi]

Jaladel
Please explain the changing of the polarity some more. If I am using flux core, what should the polarity be? eg the torch is pos. or neg. etc. I have a Hobart Handler. I bought it used and it has a provision for gas but I am not using gas. I don't know if it was set up for gas (polarity) before I got it. I suppose I could switch polarity and see if there is less splatter.

Thanks,
Paul

[Doug_Ford]

Paul,

Have you tried to download the manual for it from the Hobart site? I bet it is available and will probably show you how to reverse the polarity. The manual for my small Lincoln mig welder has instructions for accomplishing the process. It simply involves switching leads inside the welder. A simple 2 minute operation.

[domino11]

Guys,
I believe that with gas and bare wire the torch should be positive and with flux core wire the torch should be negative. Duh, oh yeah, check Dougs photo of his welders cheat sheet, they list the two modes and the correct polarity. This will be the same for all welders.

[cobra427mnsi]

Thanks guys for the info. I will check out the welder tomorrow.

Paul

[Gerald D]

Flux-core vs gas-shield........

You can use flux-core when it is windy - used outdoors, on construction sites. Gas-shield should not be used under windy conditons (it blows the shield away), normally used indoors only.

[TheDave]

I think this thread is getting pretty silly - we're really splitting hairs about the best welding setup.

Let's back up a minute and remember what most people on this forum want to know:

I'm going to buy a welder to build my MechMate - and probably not use it too much ever again. What should I buy?

The best answer is really a MIG welder with flux core wire.


Why? Because it is much easier to learn and is probably the most forgiving. As Gerald pointed out, there are no critical welds on this project, so it doesn't matter if this won't provide the best possible weld. If we were striving for that, then we'd have to take into account many more things - the welding environment, exact steel composition, how the steel is cleaned, what it is cleaned with, what kind of residue is left, what kind of finish will we be applying, etc., etc.,

When taking all things into account, the trade-off for weld quality vs. ease of use is a good one to make here. We're not sacrificing that much quality for significant gains in how easy it is for a novice to do the welding himself.

The goal of the project is to have a working CNC router. Although it's important to build things with care and quality, the argument of using flux core wire vs. solid core and shielding gas is pretty moot.


Just my 2 cents - and I don't mean to derail the discussions here. It's important to have your polarity set correctly no matter what you're using, and I'm sure everyone will be glad to help people get the welder set up correctly. But let's not worry too much about what welder we're using.:)

[Jaladel]

I checked the Lincoln manual online and found that flux core wire feeders requires that the electrode be negative so..

Flux Core Welding
Electrode - Negative
Ground clamp - Positive.

Good luck.

This agrees with Domino11's info as well...

[ekdenton]

I think this thread is getting pretty silly - we're really splitting hairs about the best welding setup.

Let's back up a minute and remember what most people on this forum want to know:

I'm going to buy a welder to build my MechMate - and probably not use it too much ever again. What should I buy?

The best answer is really a MIG welder with flux core wire.


Why? Because it is much easier to learn and is probably the most forgiving. As Gerald pointed out, there are no critical welds on this project, so it doesn't matter if this won't provide the best possible weld.

Possibly silly to some, but also there are those that really enjoy the construction part of the mechmate and I see from the threads that there are some that build more than one or plan to make more than one. IMHO if it is just one build why even purchase a welder in the first place? Just have it welded by someone who has the proper equipment?

Flux core is definately not the easiest to learn, but would be okay for the base table channel welds, if you were using the flux core in a larger size such as a 250amp. ;) (kiss)

I think when most were talking about the flux cored mig welder though, they were probably looking at a typical welder like this:
http://www.mylincolnelectric.com/Catalog/equipmentdatasheet.aspx?p=59618
Which is what they sell at Home Depot and Lowe's.

Although the output range is 30-140 amps, take a look at the welder specifications near the bottom of the page,
it is 20% duty cycle,19.5volts,90amps. Okay.......that is not enough, 7" channel is 1/2" thick in the corners. You will have what looks kindof like a weld on the surface but the base metal will not get hot enough for even a minimal passing weld. Also at 20% duty cycle that is 1 minute of weld and 4 minutes of rest for the machine. (when I welded my table I used a 250amp Mig welder set at 25.5v and 260ipm wire feed rate) That is about 30% more than the max. capacity of the above listed welder.

I only chimmed in on this thread hoping to give back some knowledge, because I really apreciate all the shared knowledge here, hope I didn't offend anyone.:):)
To me a tool like a welder, air compressor, drill press, ect. ect. should be purchased with a mindset that it is an investment. I was taught by my father and always have firmly believed that with tools don't skimp......you get what you pay for. Why else would we be building the best cnc router?????:):)

[Marc Shlaes]

Ed,

Very well said!

[WTI]

Those who have access to Craigslist:

http://www.craigslist.org/about/sites.html

Have an endless supply of used welders in the tools section. You can buy a used Miller, use it at your leisure, then sell it and get your money back.

But I bet you will keep it after seeing how handy it is.

[skippy]

When I was searching the internet I came across this MIG DIY Guide that maybe of some use for other people.

http://www.mig-welding.co.uk/

[dragonbreath]

now for my 2 cents those of you that are new to welding i have one thing to say :D Practice you will have scrap metal fron cutting your parts so throw it up on the binch and practiece change the settings on the welder which ever you use and run flat beads until you get an acceptable weld then put 2 pieces together and weld them put them in the vice and try to break the weld if it is a good bead with good penitration it will bread the metal next to the bead then cool your weld down a little your making the metal brittle but above all practice practice practice

[cvriv.charles]

Wow. So my LincolnElectric 140amp MIG isn't going to cut it?!?! If thats the case my girlfriend is going to be pissed seeing that she bought that for me for xmas. I havent even got to use it yet.

I saw that DC stick welders 200amp+ cost in the thousands! Is this correct or am I not looking at the right welders? Can anyone reccomend a good stick welder for a decent price? I need to be able to weld atleast 1/4" steel.

I saw the Miller welders and they are like 2000 - 3000+. Thats crazy. Should I try and sell my 140amp and get a stick welder?!?!?

[smreish]

Your MIG should should be fine. Just use proper set up....If memory serves me right, that MIG is rated for upto 3/16" plate @ 20% duty cycle. You'll be fine. Just follow the directions.
Sean

[Gerald D]

I agree with ED in that a baby MIG welder is not going to be happy, particularly for welding onto the MM's main beams. The spec sheet for the baby Lincoln says: "MIG weld 24 gauge up to 10 gauge (.135") sheet metal in a single pass. Weld up to 5/16" steel using self-shielded Lincoln Innershield® wire (FCAW-S)."

[cvriv.charles]

So if I use the selfshielded I should be fine??? You know what im just goign to look for a used stick welder then. What amperage should I stay above to weld through 1/4" without problem. Im not about to halfa$$ this machine together.

[Gerald D]

For a stick welder, 140 Amp will manage.

[domino11]

Charles,
You could always weld together the leg sections and then bolt them to the main beam, therefore saving you the welding on that heavy channel. This has been done by many others for the sake of dismantling and transport possibilities. I think even some of Gerald's new tables are done this way from the pictures I have seen. :)

[Gerald D]

Our new tables have bolted cross-supports, but the legs and 2 other uprights are welded under the beam. The beam ends are also welded closed.

[MetalHead]

That 140 amp Mig will be fine. I have a 135 Miller and have built great projects with it. http://www.cnczone.com/forums/showpost.php?p=359053&postcount=239 (Yes ugly but strong) .

I also built several trailers with that unit that have been abused (Over Loaded) by their owners and they have held up to that abuse well.

So I think your GF did good and you should be able the build with that unit.

[Doug_Ford]

I too think you'll be fine with that MIG if you are using flux core wire. I have a 135 amp Lincoln and I weld 1/4" steel with it all the time. The duty cycle is low when you're at the highest amperage setting so you might have to let it cool every once in a while but that's okay. Plus, MIG welding is much easier to learn than stick welding.

[Gerald D]

It is simple enough to do a quick test on scrap to see if the welder will do it. Lay a 3/8" plate on the bench, stand a 1/4" vertically up, weld together, hammer the 1/4" till it bends over 90 dgrees without breaking off.

[cvriv.charles]

Will do:) But I am going to have to wait to do this though. The house in which my girlfriend and I are renting is not a good place for this kind of stuff. I would rather wait till I get my house with a garage.

We have actually been loking but have had ZERO luck. . . . . . .
Rest of this post copied to a new thread here (http://www.mechmate.com/forums/showthread.php?t=1752):

[DougC]

Greetings,

This site has got me planning/dreaming about building a MechMate here in the Pacific Northwest of Canada.

I have an oxy-acetylene welding system and was wondering if one could use this process to build a MechMate? I see no mention of anyone doing this or suggesting this earlier in this thread. While I am not an expert welder, I have some experience making fairly decent welds with material up to 1/4" thick mild steel. To join thinner materials to thicker heavier beams I have often found braze welding to be easier. Would braze welding be acceptable in this application?

Thanks,
Doug

[MetalHead]

I think Gas welding of the parts would be fine. Very Strong in fact. Done correctly gas welding makes better (prettier) welds anyway. This process is used to build aircraft.

Heat control is always an issue even im MIG or TIG.

I don't think Braze welding will be strong enough. You need fully welded joints to support the rack and torque this unit makes.

[Hillbillie]

Oxy-Acetyl Welding with a brass rod would not be strong enough for the table, but instead of using a brass rod, you can use a steel rod with flux and that will be stronger.

If price is an issue, usually ARC welders like the 225 Lincolns you can probable find a used one cheap. They can make a pretty weld with deep pentetration with some practice.

Mig welding, if it has enough amps can make a good strong weld with flux, Non flux welding makes the pretties weld, but has less strength. If I was using a mig then I would not use flux core wire, just solid wire with argon mix.

Just my thoughts.

[Gerald D]

I have an oxy-acetylene welding system and was wondering if one could use this process to build a MechMate? I see no mention of anyone doing this or suggesting this earlier in this thread. While I am not an expert welder, I have some experience making fairly decent welds with material up to 1/4" thick mild steel. To join thinner materials to thicker heavier beams I have often found braze welding to be easier. Would braze welding be acceptable in this application?

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.

[isladelobos]

Selecting a good arc weld electrode for the Mechmate

6013 for the Y-Car
7018 for the table

A good read (http://www.thefabricator.com/ArcWelding/ArcWelding_Article.cfm?ID=1940) in spanish and read (http://www.thefabricator.com/ArcWelding/ArcWelding_Article.cfm?ID=1674) in english.

[Gerald D]

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.

[firebrick43]

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

[swatkins]

Maybe its time for a new welder... With one of these babys (http://www.millerwelds.com/products/mig/millermatic_211_autoset/) everyone can weld like pro :)

[KenC]

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.

[max.elliott]

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

[KenC]

The one bit that concerns me is the welding -- I know my welding skills aren't up to welding overhead. Heck, I'm still working on striking the arc, let alone attaching two pieces of steel! :D


Michel

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.

[Claudiu]

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.:)

[KenC]

can not agree more. :)

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

[PEU]

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

[Gerald D]

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.

[Claudiu]

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.

[domino11]

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.

[swatkins]

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...

[KenC]

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

[PEU]

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.

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)

[firebrick43]

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.

[PEU]

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.

[firebrick43]

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.

[PEU]

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

[WTI]

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

http://www.millerwelds.com/resources/tools/index.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.

[domino11]

Good find. :)

[PEU]

I purchased long time ago the John Deere book on welding (http://www.deere.com/en_US/compinfo/publications/john_deere_publishing/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

[WTI]

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

http://www.millerwelds.com/resources/tools/index.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.


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

[Scott Hightower]

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

[melissa]

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

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


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

[domino11]

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

[WTI]

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.

[melissa]

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

[Red_boards]

After reading this and spending some time trying to understand what I need, I see my best entry options as a newbie are a MIG welder 140 to 250 amps using flux core wire or a DC stick welder using 6013 rods.

What I haven't figured out about these options is whether the MIG option is gasless (or what gas is recommended) and what amps are needed for the stick welding.

I'd appreciate clarification

Thanks
Red

[J.R. Hatcher]

Flux core requires no gas...

[TheDave]

For amperage settings look on the box of electrodes. That will tell you the recommended amperage for that particular electrode.

It will probably list a sizable range, like 75 - 185 amps. Where you set it really is a personal preference. If you are a beginner start out in the middle of the range and experiment a little.

[Red_boards]

Thank you. Now I have an idea what I'm shopping for.
You have no idea how much these answers help me
- even if the questions seem too simplistic to you experienced people.

[Rascal]

The minimum recommended amperage for a mig welder for 3/16 material (7inch channel to 3 inch channel) is 160-170 amps using .035 wire. It would be better to have a 200 amp machine if you can afford it as this weld is more like welding 1/4 inch steel but I am confident it could be done satisfactorily in this application with 170 amps. You can use CO2 (cheaper) or 75/25 CO2 argon mix (more expensive but less spatter)for the gas. Flux core wire can be used but not so nice to work with. Polarity for the using wire that uses gas is DCEP and gasless flux core is usually DCEN. When purchasing a welder consideation of the duty cycle is of prime importance with more the better and 60% at full rated output for this type of machine would be excellent. Stick welding sucks (as does fluxcore) but if you use it 1/8 6013 electrode is run between 80-130 amps (7 inch channel to 3 inch channel) with 80 amps used for thinner material and 130 amps for heavier material. I would use 3/32 rod for the legs which is run between 40-90 amps. Good luck.

[chopper]

Polarity for the using wire that uses gas is DCEP and gasless flux core is usually DCEN.
DCEP means work is negative and wire is positive, Dcen means the opposite. you will need to check the welder to see which way it is set up, if it is reversed it will weld poorly ...
//chopper

[Red_boards]

Most of the people on this site have some idea what they are doing. As a complete novice in welding stuff I eventually took a low cost option, rather than have someone weld for me. I bought a 130W stick that can weld 3mm sticks, but only has a 10% duty cycle (so it can't do more than 1 full stick at full power). I'm sure many experienced hands scoff at this, but it got me going in welding and was enough to "stick" the bits of the table together. I just had to plan to cut/weld/cut/weld so that the machine got a breather between jobs. I know the welding is something that worries many coming into the MechMate world. I reiterate what Gerald has said. I've enjoyed picking up a new skill. Now many problems around the house look like welding solutions!