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DICKEYBIRD
04-18-2018, 08:55 AM
The time to weld the diagonal braces onto the vertical segments of my CNC bridge-mill project is approaching & some advice from you experienced welder/fabricators would be greatly appreciated.

It's really nothing fancy, just a 3" square tube (1/4" wall) welded to a 3" square tube (.290" wall). The welds will be made with the parts flat on a table and then the 2 assemblies aligned & bolted to the base. I'm hoping the bolt together plan will allow it be assembled without having to have them stress relieved.

I have a 200 amp, AC-DC stick welder that has worked well for me so far but never anything this big. I have a few typical rod sizes & types on hand but am happy to pick up what is best for this job.

Any suggestions as to amperage & rod sizes? Also, to minimize distortion, I won't be welding it solid all the way around. I'm thinking a series of short welds will be plenty strong enough with a cool-off period after each weld. How many, how long, where & what order should the welds be made to keep the warping to a minimum? Any other tips are welcomed.

http://i57.photobucket.com/albums/g227/DBAviation/DiagWeld_zpssgwi49kj.jpg (http://s57.photobucket.com/user/DBAviation/media/DiagWeld_zpssgwi49kj.jpg.html)

3 Phase Lightbulb
04-18-2018, 09:05 AM
Welding is an art so the best advice I could give you is get plenty of extra 3" 1/4" wall square tubing for practice welding. Keep practice welding on your spare tubing until you feel you're ready.

SLK001
04-18-2018, 09:21 AM
Start by grinding a bevel on the piece that is cut. A 1/8" deep will do just fine. Start with a 1/8" 6013 stick at 90 amps. Weld a substantial tack at the upper end of the mate, then quickly flip it over and make the same tack at the lower end of the mate. Let cool and examine for alignment. If okay, repeat the tacks at the other ends of the previous tacks. Keep laying down these tacks in pairs, keeping the pairs at exact opposite of each other to keep distortion at check. Keep an eye on the straight piece, as a lot of heat can pull it into a curve.

JoeLee
04-18-2018, 09:23 AM
It's hard to say exactly. I always make a few practice runs on scrap before I proceed to the actual work.
Some manuals like from Lincoln Electric may give you more information on where to start as far as rod selection and amperage, but in the end you have to fine tune.
I always run a few test passes on scrap before I do anything.

JL................

wdtom44
04-18-2018, 09:33 AM
Welding flat on the table, no problem. Try a 1/8" 6013 for a nice looking bead, or 6011, at around 140 amps, you are welding fairly thick steel. Adjust your speed so the weld forms nice and smooth. Too slow and it will build up and be convex. Too fast and you will leave gaps. You want it to be slightly concave or flat making a 45 deg angle between the two pieces. Hold the rod at about 45 degrees to everything. The thin edge of the diagonal piece may require less amps. To minimize distortion tack it all together with short say 1/4" long tacks then weld on opposite sides a little at a time. You probably want 3/4 to 1" long welds. Possibly you could weld only the 45 deg. cut sides too.

Captain K
04-18-2018, 09:41 AM
I would suggest that you bevel the cut piece all around, and grind all the rust and mill scale of mating piece. 6013 is a poor choice in my opinion, very minimal penetration. If you choose to go with short tacks, each one should be ground before adding the next. Not really a technique for 1/4" material and a stick welder, more for sheet metal/mig. I would use 1/8" 7018 100 amps or so, on DC. Leave a gap, maybe 1/8" or a little less between pieces, line up, clamp everything down. Make 2 tacks on wide angle, check for alignment both ways then tack 2 corners on narrow side. Clean up tacks, then weld an inch from the corner out both ways. That's how I would do it, but I'm not a pro welder so YMMV.
Good luck.
Be Safe.

Black Forest
04-18-2018, 10:26 AM
Post a picture of the whole piece to be welded and I will tell you where to start and in which direction to weld. Use some NEW 1/8 " 7018 rod o at least a newly opened box. Or bake the rod a couple of hours at 300 degrees. 90 amps maybe 95 will be just about right.

loose nut
04-18-2018, 11:00 AM
I would suggest that you bevel the cut piece all around, and grind all the rust and mill scale of mating piece.

6013 is a poor choice in my opinion, very minimal penetration.

If you choose to go with short tacks, each one should be ground before adding the next. Not really a technique for 1/4" material and a stick welder, more for sheet metal/mig.

I would use 1/8" 7018 100 amps or so, on DC. Leave a gap, maybe 1/8" or a little less between pieces
.

Captain K has it right.

Slight bevel, you must grind it clean, 7018 is the proper rod, size is up to you but I would go with 1/8, you could go smaller if you are not confident it is easier to run, 100 amps DC approx. but every machine is different so it could be more or less to get the right heat. Trial and error. If you are welding on the flat then you can go hotter (125 maybe) for a second pass.

Forget welding with short tacks, it can lead to inferior welds unless you are really good. A pass down each side, grind the starts and stops then weld across both ends. Dont cheap out and try and run the rods down to the stub. Sometimes the flux fails near the end and you get porosity. After you run weld down the first side you will need to reset the gap on the other, let it cool first if you want.

Leaving a small gap 1/16" will help keep deformation (the contraction has somewhere to go so it help minimize the bending of the tubing) of the sections to a minimum but there will be some. The long piece that the brace is being welded to will pull towards the brace, nothing to do but try and minimize it. Post weld you can heat it red hot and then bend it back straight. Don't bend it cold. A welding engineer could calculate the amount of pre-bend, in the opposite direction, that should be used so that after welding the piece comes out straight but you don`t have that luxury. You could temp weld, at the ends of the tubing, a strong back (another piece of metal like an H beam that is less likely to bend then your tubing) on to the side opposite the brace with a piece of bar about one eight inch thick in between so that there is some pre-bend in the tube, this will help counteract the warping but is extra work and costs more.

Weld it all around so it will be strong enough, 2 passes if necessary. Fix the warping later you cant stop it anyway.

metalmagpie
04-18-2018, 11:58 AM
I suggest 1/8" 7014 rod. Do all the welds in the horizontal position.
No matter what you do unless you grossly overweld it you won't get a lot of distortion. 3x3x1/4" tube is mighty stout stuff.
How long you weld vs how long you wait is not determined by metallurgy, it is determined by the way your buzzbox is built. Read the manual and it will tell you a duty cycle. This is one spec not to be exceeded! Many small welders have their current capacity determined by marketing people. They get away with it by saying of course you hardly ever get to weld because it always has to be cooling down. A Miller Thunderbolt AC/DC, for example (I've owned 2) has a 20% duty cycle. Weld for two minutes, sit around for eight minutes.

Anyway, if you want zero distortion you will need to prestress the joint the opposite way from where it will bend. Which is complicated. You can minimize distortion by only welding on the sides, not top or bottom.

And finally, it looks like you might have designed a piece with fully enclosed dead spaces. If your part will ever be outside, you should put in weep holes before you weld. You don't want to see what happens when water slowly leaks in and fills a space and then freezes.

metalmagpie

Danl
04-18-2018, 12:18 PM
I would suggest that you bevel the cut piece all around, and grind all the rust and mill scale of mating piece. 6013 is a poor choice in my opinion, very minimal penetration. If you choose to go with short tacks, each one should be ground before adding the next. Not really a technique for 1/4" material and a stick welder, more for sheet metal/mig. I would use 1/8" 7018 100 amps or so, on DC. Leave a gap, maybe 1/8" or a little less between pieces, line up, clamp everything down. Make 2 tacks on wide angle, check for alignment both ways then tack 2 corners on narrow side. Clean up tacks, then weld an inch from the corner out both ways. That's how I would do it, but I'm not a pro welder so YMMV.
Good luck.
Be Safe.

My thoughts on rod selection exactly. I have never had good experiences with either 6011 or 6013 compared to 7018, with perhaps vertical and overhead being exceptions.

Dan L

Black Forest
04-18-2018, 12:30 PM
A lot of people think 6011, 6010 are a good general purpose rod. Not really. They are a fast freeze rod used mostly for gap welding on pipe joints to be followed by 7018 filler and cap passes. And they don't make nearly as pretty a weld as 7018!

Milton, you will get a lot of distortion on your geometry if you don't weld in a certain sequence. When welding a joint the joint first expands and then contracts to smaller than original. To test make two practice pieces with two 45's mated to make a 90 degree joint. Tack all four corners and then weld one along the joint from the inside to the outside corner. Do the other one from the outside point to the inside point. Do both sides and put a square on the two joints. You will see which way the pull. They will be off 90 by quite a bit. Try it and you will see. There are very specific steps to follow to keep things square.

garyhlucas
04-18-2018, 01:24 PM
If you have two of those frames to weld I would clamp the two straight pieces back to back with a strong clamp. Then after tacking, weld one side of the one diagonal, flip and weld the diagonally opposing joint on the other diagonal and repeat until you are done. Let it cool completely before unclamping. This way the two parts pull against one another and minimize the bend that occurs.

We used to weld long 1” stainless pipe booms with inlets all on one side. We welded up one sample and determined it would bend 1/8” per foot from welding. So we prebent them that amount in the other direction before welding and they came out nice and straight. We tried straightening after welding and the new bend was always away from the fitting and it was rippled.

Ian B
04-18-2018, 02:07 PM
Best piece of advice I saw above was from loose nut - leave a gap between the pieces. It always "seems right" to butt things up tight, but what happens is, the first weld shrinks and pulls the whole thing out of square. A gap of 1/16" is fine; it'll give the weld more penetration. It means that once the first 2 tacks are in place, you can make sure the whole thing is square, get a 3rd tack in, recheck, then weld it up.

3" box, especially in that wall thickness is a doddle to weld. The hardest weld will be the one tight inside the vee - the rest will be easy.

Ian

DICKEYBIRD
04-18-2018, 02:33 PM
Wow, fantastic advice gentlemen; thanks! Many factors mentioned here I never thought about. I've only burned 7018 on a few occasions but really liked it. Hopefully my local welding store will sell me fresh stock in small quantities.

Definitely planning to clamp the pieces back to back but I'm still looking around for a way to get the diagonals held down flat in relation to the long pieces. The only really-flat & sturdy surface I have around is the ground flat top on the Brute table the machine is being built on. Should'a done this little welding job before the linear slides & ballscrew for the first axis were mounted & aligned on the table. (Dumb-a$$!)

Tweaking & shimming the assembles to compensate for the inevitable distortion won't be a problem though as long as the axis' slides end up in proper alignment to the other.

Is there a favored choice of electrode polarity for this?

loose nut
04-18-2018, 02:48 PM
A lot of people think 6011, 6010 are a good general purpose rod. Not really. They are a fast freeze rod used mostly for gap welding on pipe joints to be followed by 7018 filler and cap passes. And they don't make nearly as pretty a weld as 7018!
.

6010 and 6011 are primarily used for open root welding where fast freeze is desirable, as you said. They are considerably weaker then 7018 welds because of hydrogen enbrittlement IE: not low hydrogen rods. 6013S will give you a nicer looking weld but it is still not as strong. It is generally referred to as a farmers rod because they it is used for repairs around the farm with a simple A/C buzzbox. Most 7018 rods do not work well with most A/C machines but if a DC machine is available then 7018 is the rod of choice. There are other rod which will work. Personally I prefer 6010 on open roots like pipe joints because the flux on 6011 tends to "toenail", burn more on one side then the other. Lincoln 5P or 5P+ is an excellent 6010 rod and our first choice at work, back when I did that sort of thing.

loose nut
04-18-2018, 02:51 PM
Is there a favored choice of electrode polarity for this?

Usually reverse polarity is used with stick.

danlb
04-18-2018, 03:49 PM
Many say that welding is an art, but it's really a science. Do it exactly the same way ten times and you should get exactly the same result. That's what the books of Authorized Welding Procedures is based upon.

Figuring out the settings for your particular machine and setup can often seem a black art, but once you make some practice welds it should work the same on the real one.

Lincoln put out this instructional video ( https://www.youtube.com/watch?v=2vuGlcbDwKY ) back in 1945. It addresses preventing and controlling distortion while welding. I strongly recommend it if you have not had other instruction in the area. It's only 18 minutes. :)

Dan

DICKEYBIRD
04-18-2018, 05:47 PM
Great video Dan, I forgot all about YouTube welding videos! I'll be in a trance for a while. :cool:

Black Forest
04-19-2018, 01:18 AM
6010 and 6011 are primarily used for open root welding where fast freeze is desirable, as you said. They are considerably weaker then 7018 welds because of hydrogen enbrittlement IE: not low hydrogen rods. 6013S will give you a nicer looking weld but it is still not as strong. It is generally referred to as a farmers rod because they it is used for repairs around the farm with a simple A/C buzzbox. Most 7018 rods do not work well with most A/C machines but if a DC machine is available then 7018 is the rod of choice. There are other rod which will work. Personally I prefer 6010 on open roots like pipe joints because the flux on 6011 tends to "toenail", burn more on one side then the other. Lincoln 5P or 5P+ is an excellent 6010 rod and our first choice at work, back when I did that sort of thing.

Most "farmers" like the 6013 because it is easy to restart unlike 7018 that requires you to knock the flux off the tip of the rod to get a restart. The end of the 7018 craters when you end a bead so one is required to bang it on something or file it back. When I did a lot of "stick" welding I had a 6" piece of an old hoof rasp in a leather cuff that strapped to my non stinger arm. It made for a very good and quick method to knock the flux off. I don't like banging the rod as it wears the stinger jaws prematurely.

Black Forest
04-19-2018, 01:26 AM
Great video Dan, I forgot all about YouTube welding videos! I'll be in a trance for a while. :cool:

Just run over to my place Milton and we will weld up those things in 5 minutes. I have the perfect welding table for your project. In the picture I have set up the pieces to be welded for the end frames on some picnic tables I was building.

Click on the picture to see a bigger version.


https://www.use.com/images/s_1/d05ab7dc53583d8a1dcd.jpg (https://www.use.com/OgmRZ)

DICKEYBIRD
04-19-2018, 08:05 AM
Just run over to my place Milton and we will weld up those things in 5 minutes.No problem! Soon as I get enough UnobtaniumŪ extracted to refuel my largest TransporterŪ beam, I'll be there in 1.29482 nanoseconds.;)

loose nut
04-19-2018, 08:24 AM
Many say that welding is an art,

Machinists are tradesmen, welders are artisan's.

Dan


Most "farmers" like the 6013 because it is easy to restart unlike 7018 that requires you to knock the flux off the tip of the rod to get a restart. The end of the 7018 craters when you end a bead so one is required to bang it on something or file it back. When I did a lot of "stick" welding I had a 6" piece of an old hoof rasp in a leather cuff that strapped to my non stinger arm. It made for a very good and quick method to knock the flux off. I don't like banging the rod as it wears the stinger jaws prematurely.

If you pause in the puddle and then run back a little bit you don't get the crater. You learn that fast if you are welding chrome pipe because if you don't you get a tiny hole that goes right to the root pass. Farmers frequently use a/c buzz box's and they don't take well to 7018 but love 6013. That is why farmers use it. The deposit on the end of the rod is a kind of glass and it is a pita but if you get a good wrist action going you can knock it off easy enough when you re-strike the rod. Better still though it away and use a new one but then I wasn't paying for the rod..

Black Forest
04-19-2018, 08:31 AM
If you pause in the puddle and then run back a little bit you don't get the crater. You learn that fast if you are welding chrome pipe because if you don't you get a tiny hole that goes right to the root pass. Farmers frequently use a/c buzz box's and they don't take well to 7018 but love 6013. That is why farmers use it. The deposit on the end of the rod is a kind of glass and it is a pita but if you get a good wrist action going you can knock it off easy enough when you re-strike the rod. Better still though it away and use a new one but then I wasn't paying for the rod..

I was referring to the crater on the tip of the welding rod not a crater in the actual weld. Sorry for the confusion.:cool:

Captain K
04-19-2018, 09:43 AM
I don't much care for the implication here and elsewhere that farmers are either not smart enough or are too lazy to learn to do something properly. i.e. farmer rods There are shining stars and turds in our business, same as all of yours. Some of the worst looking welding I've seen has been on this BB and in the magazine. Seems HSM guys often can't be bothered to spend the time to learn to weld properly, even after spending many hours getting the machine work as perfect as possible. If you still think farmers are not too bright, lazy or sloppy I suggest you check out some of Tundra Twin Tracks threads here.

P.S. I don't believe anybody here was deliberately disparaging farmers, it's just a personal rub of mine when the "dumb farmer" stereotype is thrown out.

danlb
04-19-2018, 12:04 PM
P.S. I don't believe anybody here was deliberately disparaging farmers, it's just a personal rub of mine when the "dumb farmer" stereotype is thrown out.

It's funny how two people can read the same sentence different ways. I thought that the stereotype farmer was one of resourcefulness. Tales abound of farmers who are pressed into service as welders, mechanics, electrician or veterinarian due to the remote location.

So when I read 6013 was "farmer's rod" I read that as a good general use rod if you could only have one on hand.

reggie_obe
04-19-2018, 12:11 PM
P.S. I don't believe anybody here was deliberately disparaging farmers, it's just a personal rub of mine when the "dumb farmer" stereotype is thrown out.


It's funny how two people can read the same sentence different ways. I thought that the stereotype farmer was one of resourcefulness. Tales abound of farmers who are pressed into service as welders, mechanics, electrician or veterinarian due to the remote location.

So when I read 6013 was "farmer's rod" I read that as a good general use rod if you could only have one on hand.

I'd tend to agree with what Captain K says could be implied about that stereotype.
I can recall somebody getting bent out of shape with the mention of "Hillbilly" repairs.

Willy
04-19-2018, 02:21 PM
It's funny how two people can read the same sentence different ways. I thought that the stereotype farmer was one of resourcefulness. Tales abound of farmers who are pressed into service as welders, mechanics, electrician or veterinarian due to the remote location.

So when I read 6013 was "farmer's rod" I read that as a good general use rod if you could only have one on hand.

Exactly!
The 6013 is the go-to rod for guys that need an easy to use rod that doesn't require drying oven storage, doesn't over penetrate and yet still does an adequate job of keeping things operational. The farmer is the perfect example of the guy who doesn't usually have a small fortune invested in welding gear, doesn't do a lot of welding and so usually the 230 Amp AC welder will do for the bulk of every day welding chores. Not everybody wants or needs to have the equipment and training to do X-ray quality welds.
Not that there aren't farmers out there that can't do a very good job welding a broken tractor spindle using pre-heat, nickel rods, and post-heat after completing a very challenging repair.

The connotation associated with the word "farmer" lies strictly with the individual. I think it's a complement myself as it indicates to me one who possesses many skills.
While I have many types of electrodes at my disposal, the farmers rods are used regularly and they have yet to fail me when used within their limits. This country lives off of the backs of farmers so I take their choice of rod as an endorsement.

Black Forest
04-19-2018, 02:46 PM
Exactly!
The 6013 is the go-to rod for guys that need an easy to use rod that doesn't require drying oven storage, doesn't over penetrate and yet still does an adequate job of keeping things operational. The farmer is the perfect example of the guy who doesn't usually have a small fortune invested in welding gear, doesn't do a lot of welding and so usually the 230 Amp AC welder will do for the bulk of every day welding chores. Not everybody wants or needs to have the equipment and training to do X-ray quality welds.
Not that there aren't farmers out there that can't do a very good job welding a broken tractor spindle using pre-heat, nickel rods, and post-heat after completing a very challenging repair.

The connotation associated with the word "farmer" lies strictly with the individual. I think it's a complement myself as it indicates to me one who possesses many skills.
While I have many types of electrodes at my disposal, the farmers rods are used regularly and they have yet to fail me when used within their limits. This country lives off of the backs of farmers so I take their choice of rod as an endorsement.

Damn Willy, you running for office! You should be serving pancakes to go with all that syrup.

Captain K
04-19-2018, 02:49 PM
Should have taken it as a compliment to us farmers I guess. My bad. Apologies if I offended.

loose nut
04-19-2018, 02:59 PM
I don't much care for the implication here and elsewhere that farmers are either not smart enough or are too lazy to learn to do something properly. i.e. farmer rods There are shining stars and turds in our business, same as all of yours. Some of the worst looking welding I've seen has been on this BB and in the magazine. Seems HSM guys often can't be bothered to spend the time to learn to weld properly, even after spending many hours getting the machine work as perfect as possible. If you still think farmers are not too bright, lazy or sloppy I suggest you check out some of Tundra Twin Tracks threads here.

P.S. I don't believe anybody here was deliberately disparaging farmers, it's just a personal rub of mine when the "dumb farmer" stereotype is thrown out.

Your reading to much into it.

I didn't mean farmers couldn't weld, only that it is the rod that is generally used on the farm (hence the name "farmers rod") because they usually have a cheaper ac buzz box that can't use 7018. 6013 is a general purpose steel rod, not as strong as 7018 but usually strong enough to get the job done. 6016S will give you a smooth-ish finish if handled well, some times called 6013 Satin Weld.

loose nut
04-19-2018, 03:11 PM
I was referring to the crater on the tip of the welding rod not a crater in the actual weld. Sorry for the confusion.:cool:

I realized that after it was written but I just didn't bother to delete it.

I usually just dropped partially used rods in the bucket. My welding instructor always said "one bad x-ray will buy a whole lot of rod so don't cheap out". A lot of the rods we used where $100/LB and it was still cheaper to throw rods away then take a chance F#(%!^g up a job with a bad spot in a weld. Working at home where you buy your own rods and the welds are not so critical, 'nother story.

Captain K, at one time it was said that if you failed at everything else you could always be a farmer but times have changed and it isn't a simple job to survive on a farm these days. Takes ability and skill.

Willy
04-20-2018, 02:40 AM
Damn Willy, you running for office! You should be serving pancakes to go with all that syrup.

So this means I can count on your vote? :)

Black Forest
04-20-2018, 03:55 AM
So this means I can count on your vote? :)

Willy for President!:cool: