Jeff2016 wrote: ↑Tue Jan 11, 2022 5:37 pmMaybe just a bit of refresher... Does the height of the arc above the workpiece tend to establish how wide the bead is ?
Yes, but that is also a function of time, and torch angle.
Jeff2016 wrote: ↑Tue Jan 11, 2022 5:37 pmAnd, does a shorter arc (tungsten closer to the workpiece) generate more heat in the workpiece for the same amperage and travel speed?
Thanks again.
Jeff
No, it generates less heat (because the voltage is lower and the heat input is related to the wattage, aka volts x amps), BUT don't confuse that with not being able to produce a molten weld pool; IOW it doesn't mean that it isn't as effective, because it is not significantly less, and the shorter arc length changes the shape of the arc cone (a little narrower), and thus it will be more concentrated over a smaller area, so the power density (watts per square mm²) can still be high enough to create sufficient heat to produce a molten weld pool. All that science talk aside, if you can maintain a consistent arc length equal to approximately one tungsten-diameter, you'll be fine for pretty much any scenario you will encounter.
This is great advice, too. Not that science will make me a better welder; but, it does help me understand the process better, and how my technique is affecting the welds.
Jeff - there’s a significant aspect to your trials that hasn’t been discussed: the pedal.
Your pedal has a specific range of movement regardless of the amperage. For sake of discussion, let’s say it’s 2” of total travel. If you set your machine to 60 amps total, then the amount of change in travel is very small (60 amps / 2”). But, if you set your machine to 150 amps, the incremental change in amperage for 1/4” of travel is much higher.
As you learn to modulate heat through the use of the pedal, it is far easier to have more amps set in the machine to allow minor adjustments in your foot pressure to taper/add heat to the welding. If the increment is so small, your foot adjustment has to be very precise to make a difference. Understand the point?
So with thin material, set your amps to 130-150 and try again to control the heat with the pedal (I know guys who set their machine to max amps once, and never change it, they just use the pedal to modulate their work). You’ll find you don’t need to move the thing nearly as much to see an effect in the arc.
Another great practice drill is to “foot pulse”. Step on the pedal and get your puddle. Then as you move, back well off the pedal, pause, step, dab, back off, move, pause, etc… You will see a distinct change in the arc intensity, and you can see how much foot pressure is needed to get the puddle at each pause. And if you stomp the pedal, you’ll blow out the material.
Do that drill slowly so you aren’t rushing to get/keep the puddle. Puddle, off the pedal, move, puddle again. Your step onto the pedal should be smooth and controlled (like I mentioned yesterday). Your pedal is not a cockroach, don’t crush it. Think of it as an icy surface you need to walk across- easy and smoothly.
Upping the amps on the machine and using the footpedal to do get the puddle right appears to be a great option. I didn't set the machine as high as you suggested for the initial try. I set it to 90. I'll bump it up to 130 the next time I have some time.
Although I've been using the footpedal, I've always been a little cautious about using it for anything that required a lot of finesse. I have enough trouble with my eyes and my hands, I didn't want to bring my foot into the equation at the same time. Surprisingly, it's not as awkward feeling as I thought it would be.
I'm not sure if I will get more time at the table today; but, I'll focus on the pedal.
Not becoming comfortable with the foot pedal will only steepen the learning curve in the long run. While not as entertaining, I'm a very big believer on running a bead pad on thicker material to become more proficient at anything you struggle with, practicing joints raises the difficulty and the cost of material both, and running beads on thin material necessitates quenching and recleaning your material for every pass if it's not aluminum, master the basics 1 or 2 things at a time until they're second nature and then you can tie it all together without issue later on.
As a relatively decent tig welder by most standards, it's been my experience that most people struggle with tig or get nowhere when trying to improve because they're trying to run before they can walk. If you can't run a bead on a thicker piece of plate without actively thinking about any of it, the feeding, the torch height, the pedal, when you practice on joints, especially T joints or out of position, pretty much everything is going to go wrong at once and it'll be very hard for you or others to recognize exactly what the problem is, since prepping joints is going to take a lot more material or time, it's not usually a good situation.
Your last lap joint really isn't' bad except for the start and finish, and I'd say you're ready to be practicing lap joints, but at the same time going back to a plate can really feel like a "vacation" where you're free to experiment and dial things in. Also remember to sandblast or grind the oxidation off the opposing side where it's present as it'll mess up your puddle far more than you'd think.
I'm still working to be consistent with a bead on 16 Ga.
Two pictures are attached.
The first is a front pic of a two 16 Ga 8" long coupons joined with a butt weld. The #1 circle shows one example. The #2 circle shows a second pass.
The second pic shows the backside of the same two welds.
(The #2 circle, front view, looks a lot hotter in the pic than when I look at the actual coupon. Not that the weld is anywhere close to perfect... just not as hot looking in person.)
From what the backside shows is the weld getting closer to correct?
Thanks,
Jeff
Attachments
Front 20220117_065157 1920 x 1080 res.jpg (167.7 KiB) Viewed 9995 times
Rear 20220117_065312 1920 x 1080 res.jpg (141.1 KiB) Viewed 9995 times
The backside shows plenty of penetration, which is not always required just because it’s a butt weld (this is more common on thin material). But they’re fine.
The #2 circle, did you weld over the first pass with more filler, or simply walk the arc (“wash the weld”)? I can’t think of a situation where a second pass on 16ga would be expected or called for…?
cj737 wrote: ↑Mon Jan 17, 2022 10:24 am
The backside shows plenty of penetration, which is not always required just because it’s a butt weld (this is more common on thin material). But they’re fine.
The #2 circle, did you weld over the first pass with more filler, or simply walk the arc (“wash the weld”)? I can’t think of a situation where a second pass on 16ga would be expected or called for…?
Thanks for your input.
With #2, it was a virgin weld. I was working with shorter bead runs and alternating ends of the joint, so that I didn't heat the metal up too much. I actually started #2 out too hot and was able to bring it back a little...
Jeff2016 wrote: ↑Tue Jan 11, 2022 3:05 pm
Hi Guys,
Can someone tell me what is causing the defect shown on the attached picture? Is it only because of the high heat (yes, I know it is much too hot), or could this also be due to the tungsten being too close to the puddle? (The line in the center of the of the weld is what I am interested in.)
Thanks,
Jeff
This pic is from a previous post. I'm not creating this same defect as often; but, it still happens. I under thanks to GDarc and CJ that it's mainly because of too much heat. I'm not sure if I am falling asleep with the filler rod... but, it's something I'm still trying to correct.
A question... Once that happens the puddle definition disappears and there's a lot more red that I'm seeing through the helmet optics in and to the side of the weld. I get that it's too hot. What is the best way to recover from this during the weld. I've been trying to add filler more quickly, and also back off the pedal a little and pick up my torch speed. Is one of these more helpful, or is better just to terminate that weld and start a new one?
Once the base metal gets too hot, really only dropping the arc will cure it. Stuffing filler helps cool the puddle, but the base material has saturated beyond the puddle.
So to answer you question: chicken or egg? Both. Stuff filler and taper off the pedal. I don’t like to snap off the heat because it can create other problems in the puddle that surface later, or require NDT to identify.
cj737 wrote: ↑Wed Jan 19, 2022 9:24 am
Once the base metal gets too hot, really only dropping the arc will cure it. Stuffing filler helps cool the puddle, but the base material has saturated beyond the puddle.
So to answer you question: chicken or egg? Both. Stuff filler and taper off the pedal. I don’t like to snap off the heat because it can create other problems in the puddle that surface later, or require NDT to identify.
Hi Jeff,
With your pedal, if set your amps on the machine and then put your foot only 3/4 of the way down it gives you the ability to add amps as/ when needed but also seems to help dropping amps off quickly when needed. If you are not already, try to set up your amps and pedal so that the amps you want to use are in the 3/4pedal position, this will give you a good bit more responsiveness.
Smile and melt stuff.
Gdarc21 wrote: ↑Wed Jan 19, 2022 7:24 pm
Hi Jeff,
With your pedal, if set your amps on the machine and then put your foot only 3/4 of the way down it gives you the ability to add amps as/ when needed but also seems to help dropping amps off quickly when needed. If you are not already, try to set up your amps and pedal so that the amps you want to use are in the 3/4pedal position, this will give you a good bit more responsiveness.
Smile and melt stuff.
CJ had recommended setting the box higher, too. (Maybe it was in a PM as opposed to here in the thread, I haven't gone back to look.) His reasons were very similar to yours.
I'm still beating myself up with the 16 Ga. (Call me a glutton. Until I can consistently produce good welds, I thought I would keep going until I run out of metal.) I know the rule of thumb is 1A per 0.001". Rather than setting the machine at 63A I have it set at 120. I'm using pedal to try control the puddle. Not sure if setting the machine a little lower would be helpful, or not.
Some days my vision seems really good... some days it's a really tough drill. The joys of getting older. lol
Yep, getting there. Notice how widely fanned out the HAZ is near the end of your weld? That’s an indication of too much heat for too long. That is also why the end of the seam blew out before you arrived.
With material that thin, you need to use chill blocks, run shorted duration, or move a LOT faster. It would also be advantageous to put a small dab of filler at both the end and beginning of the seam to start on, and finish to. (Prevents blow outs.)
Well... I thought I posted a reply... just not sure where it went. If it appears, this reply will be kind of redundant.
Thanks for the advice.
It's a challenge getting the weld hot enough; but, not too hot.
For best practice, what would the length of an acceptable shorter bead be? You're suggesting running a bead (maybe staggered), letting it cool and then running another?
Maybe you can help me understand the HAZ, too. Looking at the back side of the plate, there is a zone around the joint itself that is fairly consistent, although probably still too hot. Then there is the discoloration on the front and back the fans out as the weld gets hotter. Is that actually the HAZ to be concerned with, or is it the one that is more pronounced around the joint. (I know that heat created the other, as the weld continued and the metal got hotter. Just not sure if that is more surface related, or if it changed the metal.)
I suspect the area bordering the weld as you look at it is the actual arc cone (indicating a large cup or too long an arc length) while the HAZ is the discoloration front and back. As to whether you are altering the metallurgy, no, not if you don’t quench the material or otherwise push the coloration any further.
As to how long is short enough, well, that depends entirely on too many factors. I’d have to be under the hood or over your shoulder to say “When” because only a live view of a puddle can tell it’s secrets.
The blowout was actually from when I was tacking the coupons together. That's something I have been working on... getting a little better punching out a quick arc and then letting off to create a nice little tack. When I get out of sync (too much current or not enough current for too long).
On a different subject... I don't believe I have read too much about the color of the arc. I'm trying to figure out if there a white arc is best. If a blueish arc is acceptable. And when the metal gets too hot and it has a red hue to it, the arc is harder to see. I haven't looked very hard for information; but, I don't recall seeing anything that talks about the arc color.
The arc should be white. If it is turning blue, that is often an indication of contamination on the tungsten.
If the base metal is turning very red around the puddle, you’re overheating it. That’s where some more experience comes in, “reading the puddle”. As soon as you see the puddle going from orange to red, get off the heat or start jamming filler in there.
When tacking thin material, light up on one side and not in the joint. Wick the arc over just as you add filler for your tack. If there’s any gap, definitely don’t point at the seam. You’ll blow it out in a single heartbeat.
cj737 wrote: ↑Thu Jan 27, 2022 10:02 am
The arc should be white. If it is turning blue, that is often an indication of contamination on the tungsten.
If the base metal is turning very red around the puddle, you’re overheating it. That’s where some more experience comes in, “reading the puddle”. As soon as you see the puddle going from orange to red, get off the heat or start jamming filler in there.
When tacking thin material, light up on one side and not in the joint. Wick the arc over just as you add filler for your tack. If there’s any gap, definitely don’t point at the seam. You’ll blow it out in a single heartbeat.
Thanks once again.
You're probably thinking this is about like teaching an entry level welding class.
Good to understand about the blue, and contamination. I get that sometimes when I haven't (or don't believe I have) come close to the puddle with the tungsten.
Question about the orange color... is that acceptable, or should I start backing down at that point, too?
That's great advice for arcing to the side of the joint. I'll give that a try.
Orange is the limit of where a you want to be. So, do you want to ride down the middle of the road at dark, or stay in your lane?
I’ve got a test for you. After all this practice with thin material, grab some 3/8” or better coupons. Up your filler to 1/8”. Use a grinder and bevel the edges. Now weld these together and see “what you see”. Your weld will be very, very different and the arc, puddle and timing will also change. But it may also teach you a few things…
It’s little value to only be able to weld with thin, or only thick. You’ve practice diligently with thin, swap in something much larger and see what you’ve learned. This is the distinction between “knowing what you’ve been taught” or “having learned what you know”.
I've been reading the forum on occasion. Life has gotten in the way of welding a little...
I know that by me focusing on thinner material, I'm going against the advice of a lot of you for a beginner. I get it. I just don't intend on welding anything thicker than 3/16", and honestly most of it 1/8", or less. So, I'm reasonably content to put up with the slower learning curve.
Fillet welds have been driving buggy; but, I think my eyes are finally processing what they're seeing.
I feel like I'm cheating; but, I've been playing with pulse on the fillet welds. It has helped with my confidence.
Another newbie question... Welding autogenously on 16 ga fillet welds I appear to get pretty good penetration and I can prevent burn-throughs. When I try to add filler to the mix I tend to get screwed up and then I burn through the joint. So, the question is, when is autogenous welding acceptable (with proper penetration) and when is the filler critical? These welds are on non-structural parts that are mainly cosmetic.
When you introduce filler, are you still on pulse? If so, I suspect the amps are too low so you are having to loiter to get the base and filler to wet together. Thin metal absorbs heat super quickly and then the filler chills the puddle increasing your wait time.
On 16ga, what filler size and what amps? (Pulse rates too if you’re using them)
Jeff2016 wrote: ↑Sun Jun 05, 2022 2:01 pm
So, the question is, when is autogenous welding acceptable (with proper penetration) and when is the filler critical? These welds are on non-structural parts that are mainly cosmetic.
Hope all you guys are well.
Jeff
it depends on what material.
stainless (at least the typical 3 series) is very often just autogenous welding. with aluminium a couple grades do, the rest don't. without filler the welds are weak and crack easily.
edit: you also have to remember that you need to add metal if there is a gap, otherwise your robbing material and making it thinner ie undercut.
cj737 wrote: ↑Sun Jun 05, 2022 3:22 pm
When you introduce filler, are you still on pulse? If so, I suspect the amps are too low so you are having to loiter to get the base and filler to wet together. Thin metal absorbs heat super quickly and then the filler chills the puddle increasing your wait time.
On 16ga, what filler size and what amps? (Pulse rates too if you’re using them)
For the 16ga I had the machine set to 105A, pulse was at the lowest setting for the CK MT200 welder at about 1 pulse/sec. Background amps set to 40%. Filler rod size for the 16ga is 0.045 ER 70S 6. Tungsten is 3/32".
Working with the 11ga the current setting on the machine was 130. Pulse at 1/sec. Background amps at 40%. Using 1/16" ER 70S 6. And, tungsten at 3/32".
