Fillet undercut pic..need advice

admin

Hi guys,  it's been a while.  I've been busy with baby and work. Anyway,  I had a chance to practice fillet tig the past couple of days.  The main problem I have is the undercut.  No matter how low the setting was(enough to melt the joint so they would weld and blend in),  I get this bad undercut.  It makes me wonder if this is normal or there is a special technique that I need to learn.  ......should I do way much lower amps and dwell on the joint longer???  right now,  it takes around 3 seconds for the joint to melt and join prior to adding filler.  I've been adding filler on top and just let it flow to the base.My settings:Miller Maxstar with pedal control max at 120 amps.......tungsten 1/16"  filler 1/16"  Here are my pics.  Advice is greatly appreciated_______Miller Maxstar 150 STLLincoln ProMig 140Hobart Handler 210
Reply:1)  Ditch the 1/16" tungsten, and go with 3/32 minimum.  2)  CLean off the millscale before welding.You'll see the undercut go to nearly nothing, or disappear.Use enough heat that your puddle is the width of bead, with no weaving or other movements needed.and if you're pulsing with your foot, STOP IT NOW!!
Reply:Yeah, CLEAN the mill scale off.  That alone could be your problem.  Your arc should be about the size of the electrode.Dip closer and use more filler. Do it again, more pics please.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Yep, lose the mill scale and most if not all of the undercut will go with it!Tighten up the dips- each dip wants to overlap the previous by at least 50%
Reply:I was having the same problem undercutting fillet welding tubing together. Original reason I signed up on this forum  (God now that I look back on mine the fillets look terrible on all accounts)I was curious had I a longer piece that I was fillet welding together if the undercutting would go away. From the looks of yours you seem to have the same issue and your piece is longer. I ran out of material to practice on so I don't have any further results. It was also a pain to get in a comfortable position with the torch.Miller Syncrowave 180SDMillermatic 175
Reply:Originally Posted by hotrodderYep, lose the mill scale and most if not all of the undercut will go with it!Tighten up the dips- each dip wants to overlap the previous by at least 50%
Reply:Thanks for your input guys!  I'll follow-up next post.  I didn't know about the overlap thing at all.  Next plan of attack:1.  Slower movement of the torch2.  narrower bead3.  cleaner materialTo be honest, that's the most decent one I've got.  The first try was awful!  Im melting off the vertical part and figured to initiate the arc on the flat plate and then swing it up as the material heats up.  I'll let you know how it went.. with pics of course _______Miller Maxstar 150 STLLincoln ProMig 140Hobart Handler 210
Reply:The advice I give my students and use myself is Feed high and drag low!   Hold your wire high and bring your acr to it...when wire melts...push wire into the puddle and then hold wire high and drag the puddle low...up high, dont let your tungsten go higher than your wire or you will heat the top base metal too much and cause more undercut...Also follow the otheer guys advice of clean your material well...no mill scale and try going to 3/32" tungsten (but you can do the same thing with 1/16" tungsten)Jonesy
Reply:Originally Posted by stormNext plan of attack:1.  Slower movement of the torch2.  narrower bead3.  cleaner material
Reply:Jonesy70,I'm curious about your technique.  Did you mean,  apply filler at the top vertical plat at an angle like this   \  and then swing the arc towards it??  Desertrider,Thanks for the visual.  I didn't realize that I'm not dipping as often as I should which probly causing the undercut in the first place.  right now, I'm dipping once each move.  I would now dip at least maybe 3 times each pause.I'll add dip more often on my checklist.Thanks//stormLast edited by storm; 04-28-2008 at 09:19 PM._______Miller Maxstar 150 STLLincoln ProMig 140Hobart Handler 210
Reply:I am currently building a bender made mostly from 1/4" x 2" x 2" square tubing.  There are a lot of fillet welds.  One thing I learned with welding steel is you need to dip a lot and close together.  Make short movements and dip often. When you look at the bead it will have small close together ripples.I do not think it is possible to get that nice stack of dimes in steel like you see in SS or AL, but you can get some very nice looking beads on steel with the close dipping and you can also try a gas lens.  All I use now is a gas lens for everything so far.I also use to get under cut on the top of the fillet welds, I found I was using too much heat and not enough filler.  I did try dipping at the top of the fillet tonight and it worked fine.  I normally did not have under cut when dipping near the middle, but it makes sense to dip near the top to help fill and cool the vertical part a little with filler.As for prepping the metal, be sure to use a flap disc and make it clean.  I then always wipe with acetone before welding.  The beads come our nice and shiny when done and no junk floating in the puddle when welding.Just some of my experiences...Last edited by malich; 04-28-2008 at 09:21 PM.Build a Barstool Racer at BarFlyRacers.com!
Reply:thanks Malich,  I think the pictures I've seen are from Aluminum and my mind subconsciouly try to imitate the looks.  It just make sense that diff metal  have diff properties.  I shouldn't pump the pedal as well.  Next time I'll just find the sweet spot and decrease amps as metal heats up.  I've been working the pedal like crazy... I can't wait to try some new techniques.._______Miller Maxstar 150 STLLincoln ProMig 140Hobart Handler 210
Reply:Storm,         Here is a video that might give you some ideas.http://www.metacafe.com/watch/795776...elding_basics/
Reply:Nice Vid Scott. Most that I have seen dont actually "show" what is going on /w the arc.Syncrowave 2ooMillermatic 21oHypertherm 6ooAnd a grinder to grind, grind cuss and grind
Reply:Goodevening guys!  I got home around 10p.m. this evening itching to apply what you have suggested.  It's too late to do some grinding so I went ahead and welded without cleaning.... (bad boy) ...  Just with what most of you suggested,  I already see improvement on the undercut.... not perfect but a big improvement.  No footsteps like gouge from the bead anymore.Here are the changes:1.  I lowered amp from 125 to around  1152.  I brought the tungsten closer to the joint3.  used 3/32 filler, dipped more often and slowed travel to increase overlapI'm excited to practice this weekend.Thanks for the advice.  Here are the pics:_______Miller Maxstar 150 STLLincoln ProMig 140Hobart Handler 210
Reply:Just a little more help.  If the tungsten gets contaminated even a little bit, STOP and re grind it.Looking better, but you missed the best part.  CLEAN IT!  You will be amazed at how much better it works.HUGE improvement.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Storm,Here are some pics from pieces I welded in various TIG welding classes.  None are perfect, but they should help you visualize what you're trying to achieve.The first pic is a fillet and a lap joint.  3/32" tungsten 3/32" filler (er80s-d2); and about 55 amps, if I remember correctly.  The material is ~16 gauge mild steel.There is still some undercut, because these were made on my 2nd or 3rd day of TIG welding, and they're free hand welds.  You might have some better luck if you lay the filler wire in parallel to the joint, and dip it by sliding it horizontally.  Don't pull back too far or you'll oxidize the end of the filler and it will get too cold.  with a little practice you'll find that you can dip, almost like a sewing machine; varying the frequency of dips and how much metal you push into the puddle, to get perfect fill with no undercut.Keep that arc length short, 1/16" or less, and your tungsten sharp.  This will keep the heat focused on the joint.  If the heat spreads too much, you'll be temped to turn up the amps, which will only cause the vertical base metal to melt and undercut. You can also run these joints by laying the wire in the joint and simply passing the welding arc overtop the filler.  However, it's very easy to create a linear pore at the root of the weld.  Dipping the filler allows for better penetration and prevents this hidden defect from forming... Attached ImagesLast edited by A_DAB_will_do; 04-30-2008 at 07:50 AM.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Here are some pics on stainless steel; where the bead ripple is even easier to see.  The last picture is a lap joint on titanium; which is even easier to see the ripple pattern. Attached ImagesBenson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Thanks for sharing those pictures!  It shows me what to aim for.  Most TIG I see are aluminum and they look different than MS that I'm practicing on.   I'll be buying more metal and start cleaning my tickets next time.  Thanks for all the info and support!  Take care//storm_______Miller Maxstar 150 STLLincoln ProMig 140Hobart Handler 210
Reply:[QUOTE=storm;182814]Jonesy70,I'm curious about your technique.  Did you mean,  apply filler at the top vertical plat at an angle like this   \  and then swing the arc towards it??  Feed wire to the top of the fillet, filling any undercut that may form...then without moving the wire...just move the tungsten down, which moves the puddle down to the bottom of the joint, which also carries the filler wire down then move back up but never move the tungsten higher than the wirehold a count of 2 while adding more filler wire and repeat...this shouold give you a nice fillet...practice it and you will see what Im trying to explain...with my students, I usually have to show them once or twice before they pick up my meaning...I hopwe you getting quicker than some of them do!!  Good luck and let us know how you make outJonesy
Reply:I have attached a photo of a fillet weld I did on my bender.  The material was 2" x 2" x 1/4" square tubing.230A, 3/32 Tung., 3/32 Filler.  I was not using all the heat obviously..  I was dipping about 2-3 times per second with slow movement to all the fillet to fill up.  This actual fillet is nice and flat if you can not see it in the photo.  I also beveled 1/8" in the underside for better fusion.It was kid of difficult to do because there was 4" separating both legs.  I had to put the short cap on and get a position that worked.  It turned out better than I expected. Attached ImagesBuild a Barstool Racer at BarFlyRacers.com!
Reply:JOnesy,Thanks for the tip.  I kinda found that out myself last night.  I discovered that you can manipulate the flow of the puddle by pointing the tungsten to whereever you want it to flow.  I did that several times and worked great so I have an idea on what you're talking about.  it just felt awkward since I have to anchor my forearm instead of my fist... I do have a very small workplace in my garage.  As soon as I'm able to build my worktable I can hone that technique.  Thanks for explaining.Malich,that's one gorgeous looking weld!!!  wow!!  Mind if I ask what welder you're using?? I'll save that pic and aim for that quality.  Thanks for sharing.  It looks to me like you're building one of those gottrikes bender.  I have their plans and have started myself but was disappointed with my skills and equipment when I started drilling holes on the legs.  Holesaw drills 1/16" bigger than what it claims.... labeled 1" but makes 1 & 1/16" holes.   Project on hold until I find somebody who can drill accurately for me.  Take care guys//storm_______Miller Maxstar 150 STLLincoln ProMig 140Hobart Handler 210
Reply:Hey Storm,I am using a Lincoln Precision TIG 225.  Nice machine!!I am building the same bender you are.  I will give you a tip on drilling the holes.  Harbor Freight sells a set of large drill bits for around $30.  They are all the sizes you will need for the bender.  As long as you keep them oiled while drilling they will last the project.Next, When drilling the holes for the legs and swing arm, first measure out and draw X where the holes need to be on one of each.  Then be sure they are exactly the same length and tack them together.  Then if you have a drill press get a drill press vise and get the first hole lined up by aligning the cross makes for the first hole with the drill bit point which is more like a line.  Rotate the chuck to both cross marks and when aligned lock everything down.  Now all you need to do is slide the part in the drill press vise and you already have half of the hole lined up and then just align the other cross mark and drill.  Now you will have a perfect match for left and right sides.I would recommend a drill press and not a hand drill unless you have a lot of time on your hands.  The stuff takes a while even with the drill press.  I ran my drill press on the lowest speed because of the large size holes.Sorry for the change of subject....Hope that helps you...Build a Barstool Racer at BarFlyRacers.com!
Reply:Thanks for the tip Malich!  It looks like I'll be able to proceed with my project sooner than I thought.  I've been eyeing the PT225 myself.  I just need to prove to myself that I can acquire the skills to weld decently.  My maxstar has been excellent as a trainer TIG welder but I'll need AC capability down the road.  Thanks a lot!!//Jomar_______Miller Maxstar 150 STLLincoln ProMig 140Hobart Handler 210
Reply:Just get the PT 225 you will learn, I did.  I started out with a Pro MIG for FCAW and MIG, got good at that (self taught) then needed TIG for a roll cage project.  After 6 months of practice I am a lot better than I was when I first started and I built the bender as a first project for TIG and I have learned a lot just from building a real world project.  That was also how I learned FCAW and MIG.  You can only learn so much on scrap.Good Luck!Build a Barstool Racer at BarFlyRacers.com!