Welding Tips and Tricks

Hey all, first time post here.

I prefer to TIG weld copper and I make counter tops, etc..

I need to weld a seam on a cylindrical copper shape. I will roll the copper in to a large tube, then I need to weld the long seam down the length. I'm not worried about accomplishing the weld, but I'd like as clean a joint on the inside as I can get.

It seems copper will weld to just about anything, I have purposely welded it to other metals and other metals will fuse to copper when attempting to use them as a backer. I have made crowned stainless steel backers bent on a press brake with clamping lips on both sides and a crown where the weld is, just to hold parts together while welding, but that is not a direct backer touching the backside of the actual weld joint.

Does anyone know of a material than can be used to clamp tight to the backside of a flat seam weld of copper that the copper will not fuse to, and can be removed after the welding? I've made the mistake of using aluminum behind bronze and it fused, I assume the same thing will happen even more with copper. I know stainless and steel will fuse to copper, so I'm at a loss.

Perhaps use a Ceramic based backing(-tape)?

Example:

http://www.esabna.com/us/en/products/in ... y&catId=61

Should be pretty much inert as far as bonding to the (molten) copper goes.

Might also be able to use carbon blocks, but that may draw carbon into the weld although I have no clue if that's an issue on copper or not

Bye, Arno.

Thanks Arno,

I was wondering if there were non-metal materials out there that could be used as a backer. I'll look in to this, if its truly a tape and flexible it could be perfect for the curvature of the inside of the tube I need to weld/create.

I'll see if I can contact ESAB and also do more research on ceramic backers.

Here's a source for ceramic weld backing:
http://catalog.gullco.com/viewitems/cer ... ld-backing

I've used this a lot in MIG welding, but never tried it for copper, or even TIG. Carbon blocks are another option, but it sound's like you'd have to shape those to the specific need.

Ceramic tape is not "flexible", per se', but rather is short segments with a tape over them that can conform to curves.

Steve

Thanks Otto, I'm finding these products are only available in boxes of multiples and pretty expensive for a one-off small job.

Its good to know that it seems the community here apparently agrees that any metal used as a backer will fuse to the copper. I have used aluminum to back stainless for years, but backing copper is a whole different animal.

I dont need a total food grade or other special application weld seam, just one that holds liquid and and a slight amount of pressure. Copper often beads a nice penetration on the backside of a joint (.040" thick sheet in my case here) and I have bent stainless brakeformed strips with a valley behind the weld and clamping lips on either side to hold a joint flush. I've done this with backsplash end caps on copper countertops with good success. But it does leave a bead or welt on the backside which in the case of this cylinder I am making would be acceptable. I have an 18" long flat seam to weld and keeping it from warping is also important for aesthetics. I may even polish it if the weld comes out really nice.

If I can remember I'll come back with some pics to share when I do this.

Why not buy a piece of unglazed ceramic tile, snap off or cut bits to fit around it , and tape it with aluminum duct tape?

thespian wrote:Why not buy a piece of unglazed ceramic tile, snap off or cut bits to fit around it , and tape it with aluminum duct tape?

I've actually looked around on the web for some ceramic not sold as welding stuff. So far everything I found is pretty expensive. I would probably need the round version because the weld seam I'm trying to do well is down the length of a 12" dia. 18" tall cylinder.

I haven't thought about looking around at tile places, but I'm sure most of what they will have will be glazed. This gives me the idea to look for places that supply artists who do ceramics.

Is there some reason the ceramic tile can't be glazed? (My hunch is that the glazing melts at a much higher temp than the copper.)

Lightning wrote:Is there some reason the ceramic tile can't be glazed? (My hunch is that the glazing melts at a much higher temp than the copper.)

Its my assumption that the glazing would interrupt the tile's ability to dissipate heat. "Breathe".

Also my instinctual sense is it could sort of explode, not catastrophically, although maybe, but more in pops and crackles. But that is not based on any actual experience. I know concrete will do that if you try to weld right on it. I've had concrete pop and send shards in to me.

Suppose you back the copper with hard-anodized aluminum? That melting point is going to be significantly higher than the copper, with the aluminum behind the anodizing as a heat sink.

I've not tried it. Just thinking out loud.

Steve

I'd have to try it on scrap first. Anodized aluminum is a no-go for welding it directly, but as a backer, I dont know. I'd be real careful and experiment on some copper that I could do without first. Worth a shot just to prove it one way or the other.

What I just found today that I might try is ceramic knife sharpening rods. They are really inexpensive on Ebay compared to the rods sold as backup tape. I'm thinking I can make the v-shaped back support brakeshape out of stainless sheet like I was planning already, but make it so it "saddles" the rods and together clamps on the backside with the rods in compression contact with the seam, it will have flanges on either side for clamping, and then maybe some stainless flat bar on either side of the front side of the joint to keep everything tight and in line. Using stainless clamping bars rather than aluminum because heat dissipates through copper so fast anyway, that's what makes it harder to TIG weld copper and is why helium is a better gas for TIG welding copper...helium produces a hotter gas envelope allowing the immediate area to come to temp faster.

This is where using anodized aluminum can be counterproductive. Rapid heat loss.

Aluminum is a "chilling" metal for clamping and I use it all the time for stainless. Not only will stainless not readily fuse to it, but the chilling action of the aluminum reduces warpage. With copper you have the opposite problem of heat racing away from the weld joint too fast, so using stainless bar on the sides of a weld joint would help retain that heat locally and accelerate the time it takes for the weld joint to become molten and stable. Copper is freaky to weld, it takes a good hand and senses to be able to move the TIG torch slower and faster as needed. Copper will sit there and look like its not melting, then BAM! you've burned through it if not careful. And I use the same sheet stock, stripped on a shear, in to wire, as a filler metal, so there are no additives to help stabilize the puddle like silicon...AND that custom filler wire gets hot really fast! You have to have several strands of it handy because you have to put them down and switch to a cold one as you are welding, the heat races up the wire so fast it becomes hard to hold...and I'm a barehanded TIG wire feeder.

I hate a glove on my filler wire hand. I dont know any good welder that can weld productively that uses a glove on the filler hand except in super high amperage situations like thick aluminum. Most welders I know often dont use any gloves when TIG welding, especially for stainless and steel welding where the heat isn't as bad. I almost always use a glove on my torch hand by habit...I like to have my hand closer to the torch end than some people. I laugh when I see video of someone TIG welding and their torch hand is way back on the handle and a big fat glove on the filler wire hand; they are either a student or work in a place that insists on it due to safety rules. The real men I know usually remove safety devices! Too hard to productively work around! and yes we get burned and injured...in my upbringing even at 16 years old in my first year of welding class, we were taught that being a welder meant getting hurt, deal with it and sacrifice your body for the weld! I dont think they teach that way anymore in school...especially high school Vo-Tech...what remains of those in today's America...and that's why its hard to find really good productive welders anymore...not enough real men out there to fill the jobs...and is why you see very few women in the field...they simply would rather not get hurt! And you WILL get hurt at some point in a metal shop...or you are not working hard enough!

Sounds like moonshine might be involved

Toofpik wrote: I hate a glove on my filler wire hand. I dont know any good welder that can weld productively that uses a glove on the filler hand except in super high amperage situations like thick aluminum. Most welders I know often dont use any gloves when TIG welding, especially for stainless and steel welding where the heat isn't as bad. I almost always use a glove on my torch hand by habit...I like to have my hand closer to the torch end than some people. I laugh when I see video of someone TIG welding and their torch hand is way back on the handle and a big fat glove on the filler wire hand; they are either a student or work in a place that insists on it due to safety rules. The real men I know usually remove safety devices! Too hard to productively work around! and yes we get burned and injured...in my upbringing even at 16 years old in my first year of welding class, we were taught that being a welder meant getting hurt, deal with it and sacrifice your body for the weld! I dont think they teach that way anymore in school...especially high school Vo-Tech...what remains of those in today's America...and that's why its hard to find really good productive welders anymore...not enough real men out there to fill the jobs...and is why you see very few women in the field...they simply would rather not get hurt! And you WILL get hurt at some point in a metal shop...or you are not working hard enough!

This whole paragraph is hogwash. Sorry, but you are dead wrong and your habits are ill-advised. One good reason to use a glove while TIG welding is to protect your skin from extremely harmful UV light which WILL cause skin cancer. Not might, WILL cause it.

To eschew safety gear is absurdly stupid. "Real men" are smart enough to know the merits of it. What good is a "real man" to himself or family with a permanent disability from a work-related injury where he ignored all practices and policies and thus is not eligible for compensation? He will sit on his fat arse on his couch living off Welfare raising his kids to be stupid. Yeah, that's a "real man" for you You will only get hurt if you are negligent, stupid, or ill-prepared. It may be trite, but safety is no accident. Yes, there are times when machinery or equipment failure cause unforeseen injuries, but those injuries can be heavily mitigated by wearing proper safety gear. And if you can't TIG weld with a glove on your feed hand, you can't weld for sh!t.

Apologies for the hijack, but this type of irresponsible crapola needs to be called out by responsible people.