Welding equipment & techniques - Page 2

ryancromwell · #31 Thu 01 May 2008, 21:40

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 · #32 Thu 01 May 2008, 21:47

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

ekdenton · #33 Fri 02 May 2008, 11:13

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 · #34 Fri 02 May 2008, 11:43

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 · #35 Fri 02 May 2008, 12:26

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 · #36 Fri 02 May 2008, 14:46

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 · #37 Fri 02 May 2008, 14:58

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 · #38 Fri 02 May 2008, 22:17

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

Paul

Gerald D · #39 Fri 02 May 2008, 23:10

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 · #40 Fri 09 May 2008, 11:03

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 · #41 Fri 09 May 2008, 13:40

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 · #42 Sat 10 May 2008, 08:52

Quote:

Originally Posted by 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.

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/Cat...t.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 · #43 Sat 10 May 2008, 09:36

Ed,

Very well said!

WTI · #44 Sat 10 May 2008, 16:59

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 · #45 Thu 22 January 2009, 20:23

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 · #46 Thu 22 January 2009, 22:22

now for my 2 cents those of you that are new to welding i have one thing to say

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 · #47 Fri 15 May 2009, 16:17

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 · #48 Fri 15 May 2009, 18:29

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 · #49 Fri 15 May 2009, 20:47

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 · #50 Fri 15 May 2009, 23:31

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 · #51 Sat 16 May 2009, 04:36

For a stick welder, 140 Amp will manage.

domino11 · #52 Sat 16 May 2009, 09:17

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 · #53 Sat 16 May 2009, 09:43

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 · #54 Sun 17 May 2009, 06:08

That 140 amp Mig will be fine. I have a 135 Miller and have built great projects with it. http://www.cnczone.com/forums/showpo...&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 · #55 Sun 17 May 2009, 19:21

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 · #56 Sun 17 May 2009, 20:59

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 · #57 Mon 18 May 2009, 00:00

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:

DougC · #58 Sat 07 November 2009, 02:49

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 · #59 Sat 07 November 2009, 07:06

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 · #60 Sun 08 November 2009, 10:37

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.