Practice Practice Practice

admin

Hi gang,Thanks for all of the tips so far in my other couple of threads. I've been doing a lot of practice joints on scrap tubing sections. I figured I'd start practicing on multi-tube joints like I would be doing on actual frames. This is a typical head tube area for the smaller mountain bike frames that I currently braze. The down tube is 1-3/8" OD and 0.032" wall. The top tube is 1-1/4" OD and 0.028" wall. The head tube itself is 36.0 mm OD (just over 1-3/8") and 0.044" wall. I have been setting my machine (Lincoln Square Wave TIG 175) at around 40 amps max. I'm using a 1/16" thoriated tungsten ground to a needle point, gas lens, #7 cup, 0.035" filler, and I'm using the pedal.One place I really struggle is when I get started, my beads tend to be smaller in width than I want. Then, as I come around to finish, there is a mismatch in width. So that's one area I'm working on. A lot of guys are saying it also looks like I'm too hot, so I'm trying to increase my travel speed. Also, I'm trying to keep my motion as smooth as I can, but it gets a little herky jerky, especially underneath the down tube in the tighter angles. And my torch angle gets away from me if I'm not totally focused on it. And I am probably starting and stopping far too often. There's a lot to think about! Anyways, I'm hoping I can get some feedback from you guys. Too hot? Too slow? Under-filled? Torch angle problems? Other things I should be thinking about? Thanks in advance!Last edited by zank; 05-18-2011 at 02:08 PM.
Reply:That is a huge tungsten for 40 amps, isn't it?__David Hillman
Reply:By the looks of it. you will be to the point where you want to be very soon.Myself i think it looks very good. In the words of the great philosopher Quagmire.Gigedy Gigedy Gigedy Gigidey Goo.
Reply:Originally Posted by David HillmanThat is a huge tungsten for 40 amps, isn't it?
Reply:Originally Posted by wskynajarBy the looks of it. you will be to the point where you want to be very soon.Myself i think it looks very good.
Reply:The only technical flaw I see is your stop. It make a pin hole. Try to avoid pinhole releasing pedal slowly to let the entrapped gas to be released. Other than that you know pretty much what to aim for!! Nice continuity, no undercut .... ! Keep welding
Reply:Be aware that welding on a thin head tube will distort the tube ID--creating a challenge for bearing/shaft installation and alignment.Blackbird
Reply:Originally Posted by alteredThe only technical flaw I see is your stop. It make a pin hole. Try to avoid pinhole releasing pedal slowly to let the entrapped gas to be released. Other than that you know pretty much what to aim for!! Nice continuity, no undercut .... ! Keep welding
Reply:Originally Posted by dave powelsonBe aware that welding on a thin head tube will distort the tube ID--creating a challenge for bearing/shaft installation and alignment.
Reply:I cannot tell by those welds that your a beginning TIG welder.  Looks good!!!!!  I have the same machine and will be firing it up tomorrow for a small aluminum job.  It does a fine job for me.  What type of tube will you make your mountain bikes out of?  My brother-in-law and I have threaten to make a bike but we have not settled on frame material.  Again, doing great.GeezerPower Mig 255C185 TIGBlue 175 MIGRanger 8 Kohler 20HP1974 5K Lincoln/Wisconsin Powered (Cherry)Victor/Harris O/AK 487 Spool Gun
Reply:looks good lets see the in side
Reply:Looks great from where I am sitting..First timer eh?You have the skill and now run with it.Still lots to learn about this and that but you are on your way..Fun stuff isn't it?...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:The photos you provide shows a couple of things.First.....you know how to make a close up photo. Amazing how many close up photos are so blurry and you can't tell if it is a photo of a welded pipe or an elephants trunk. Thank You. Second.....your welds look great. A little more practice and my welds will look like yours!
Reply:Originally Posted by ed maclooks good lets see the in side
Reply:Originally Posted by StevefromOhioThe photos you provide shows a couple of things.First.....you know how to make a close up photo. Amazing how many close up photos are so blurry and you can't tell if it is a photo of a welded pipe or an elephants trunk. Thank You. Second.....your welds look great. A little more practice and my welds will look like yours!
Reply:Originally Posted by zapsterLooks great from where I am sitting..First timer eh?You have the skill and now run with it.Still lots to learn about this and that but you are on your way..Fun stuff isn't it?...zap!
Reply:Originally Posted by geezerI cannot tell by those welds that your a beginning TIG welder.  Looks good!!!!!  I have the same machine and will be firing it up tomorrow for a small aluminum job.  It does a fine job for me.  What type of tube will you make your mountain bikes out of?  My brother-in-law and I have threaten to make a bike but we have not settled on frame material.  Again, doing great.
Reply:Zank sez: "Yeah, I wanted a look too to check penetration and burn through. I've got a lot of work to do, especially in the tight angles. There was no penetration into the root on the underside of the down tube as you can see in the second photo (this sample was at a 55 degree angle, which is common for that joint). There was burn through as well inside the head tube. I'm going to do some more samples this week with my heatsinks in the head tube and also back purging the tubing. It'll be interesting to see the interiors of those samples.Any tips on getting into the root on those tight angles?"1-"Penetration" is widely mis-used term. If a weld bead creates some melt and fusion into the parent surfaces, without any cold lapping between the bead underside and the parent surfaces--that's as strong as the joint's going to get. (Thicker structural welds by the nature of the beast and sometimes process spec's.--will sometimes show or require deep fusion (penetration...but with thin tube sections, it's a different 'Mary-Ann'.)First image below is of a 1/4" to 1/2" steel spray setup coupon with cold lapping outlined in RED and fusion outlined in BLUE. 2-Blowup of your head tube cross section-below.Light sanding, then polishing of the BLUE OUTLINE will show either weld bead fusion into the parent tube wall or incomplete fusion with a cold lap line.(From the heat seen on the tube inside of this tight tube connection, I'd suspect that you do have fusion with little or no cold lapping.)Melt thru, especially on thin tube sections, doesn't add to structure strength, but detracts from it, can act as a crack initiator and limits stress distribution thru the rest of the tube structure.Excessive heating creating the melt thru, will produce maximum distortion. The head tube shows significant bowing.It's a ticklish effort to achieve fusion without melt thru and many to most race bike/car/aircraft structures will show some melt thru--to lots of it. Most of these structures still show good service life in spite of these defects; due to design redundancy and design strength.All of the above is a reason 'why?' doubler or fish plates may be used at high stress load tube intersections.On TIG setups/techniques--the longer one runs a bead, the hotter the parent material becomes; and more susceptible to melt-thru--unless one keeps backing off on the heat.If you see the bead wet out-then flatten down--that means it's melted thru the inside.Consider pausing, do cool down with post flow, relax--then fire up again.You're re-positioning-anyway, as you run the bead around the tube joints.-Using .040 electrode may help, in addition to pulsing, and firing off on the rod-not the parent material, with the idea of solely creating fusion and not melt thru (this takes some practice and coupon verification).----You're put forth an amazing amount of effort into trying to get things dialed in (something that's not seen here-that often, with new folks)....and even earned a compliment from Zappy--who doesn't give those lightly.http://weldingweb.com/attachment.php...1&d=1306005862http://weldingweb.com/attachment.php...1&d=1306005877 Attached ImagesBlackbird
Reply:Dave, thank you for the response! I really appreciate it. I'll be reading it a few more times to digest it all. I will cut more areas around the weld and polish up the sections to see if there is any cold lapping. I'll also try the 0.040" electrode next week. Thank you as well regarding my prep. I work a lot running my business, so I want to make the most of the limited practice time that I have. It would be a waste of time and materials to just go at it haphazardly. I have to say though that I am really enjoying it, and I really appreciate you guys taking the time to look at my work and making these suggestions.
Reply:Hi guys,It's been awhile since I last posted, but I've kept up my practicing. I wanted to get your input. I've been backpurging and using heatsinks, so the melt through and concentricity of the head tube, seat tube, and bottom bracket have been much better and the tubes are a lot easier to ream, tap, and face post-welding. I don't want to cut this one up because I'm hoping to ride this frame, unless you guys tell me otherwise. Bead consistency is still a struggle for me, as are consistency in my starts, stops, and tie-ins. In the fourth picture down, you can see I missed my tie-in by a bit on the top-side of the down tube. I'm working on it though. You can also see that I still shake. For reference, these tubes are 0.028 wall butted against a 0.044 head tube. I've been running at 75 amps to get the puddle going quickly and then backing way off the pedal. 1/16" thoriated tungsten. 0.035 filler. Gas lens and #7 cup.Any input and/or tips would be greatly appreciated. Many thanks in advance!
Reply:Looks great, I'd ride it.How much did it end up weighing?Buy American, or don't whine when you end up on the bread line.
Reply:Alright........We know you can make some really nice dimes.Now let's see some riding skillz!Build that puppy up and show us some wheelies and stoppies!
Reply:Nice looking welds bro keep it up!Miller Diversion 165Rage 2 Chop saw
Reply:I don't want to highjack this thread because I'm learning so much from it. So if you please, explain for me what back purging is and then keep going. Thanks.Poly
Reply:Polywave- Back purging is when you fill the space on the back side of the weld with shielding gas. In this case you fill the inside of the tubes. Zank - wow. very nice. looks just about perfect. you ought to try a ti frame next.Ian TannerKawasaki KX450 and many other fine toolsZank, that's significant improvement in less than six months - nicely done. Don't cut it up for inspection here if you're going to ride it... But if you have a few left-overs, burn 'em and cut them up so we can see how much the back purge and heat skinks have increased the quality.  I'm sure many of us would like to see.Miller Dynasty 200DXMillermatic 210 w/ Spoolmate 3035Hypertherm Powermax 380JD Squared Model 32Multiple fabrication tools & equipmentFull Powder Coating Setup
Reply:Thanks, everyone. WeldingMachine, I just have the front triangle done so far. I'll weigh it up for you when I get the rear end on.Polywave, I'll get some pictures of my purging setup and show you what I do. fortyonethrity, ti is in the plan. I have some tubing samples coming to test. That will really tell me if my purging setup is doing the job. millerfab, I'll do that.
Reply:Those welds look wonderful! Id drive those to 200mph any day.
Reply:The more you learn, the more you realize how little you know. I have a few coming back from paint later this week. This one will go out tomorrow. A lifetime of practice to come.SF 29er by Zanconato Custom Cycles, on FlickrSF 29er by Zanconato Custom Cycles, on FlickrSF 29er by Zanconato Custom Cycles, on FlickrSF 29er by Zanconato Custom Cycles, on FlickrSF 29er by Zanconato Custom Cycles, on FlickrLast edited by zank; 04-29-2012 at 05:08 PM.
Reply:Looks great. The practice will all help toward attempting titanium. With titanium, all I remember is that avoiding the rainbow of discoloration is a goal to shoot for.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:Yeah, I've been practicing on some titanium cut-offs that one of my buddies gave me. It's such a nice bright puddle pretty similar to stainless. It's kind of interesting how the filler seems to want to "stick" to the part. He gave me a tip that you want to dip more towards the center of the puddle than the leading edge of the puddle. That seems to help.The nice thing is that I've been working hard on my backpurging system with the steel bikes in anticipation of some day working on titanium (and as a choice I've made for steel). The steel practice frames I have cut up have been nearly colorless on the inside due to the backpurge, so I feel like I am getting most of air out of the inside. It will certainly take some more fine tuning as there were a few dead zones in those cut-up frames where there was some color, which would not be acceptable for ti.
Reply:The first one back from paint...Team Blue by Zanconato Custom Cycles, on Flickr
Reply:Very impressive work.
Reply:Originally Posted by zankHi guys,It's been awhile since I last posted, but I've kept up my practicing....Any input and/or tips would be greatly appreciated. Many thanks in advance!
Reply:Thanks for the compliments and keep at it! It's a ton of fun once you start seeing some improvement and, more importantly, understanding why something did or didn't go well.
Reply:zank, what OD tube are using for the seat tube? I will be doing the an insert on the next frame. It's a nice option instead of brazing a sleeve and opens up post diameter option.Strange I'm asking here since I saw this on last week's FNL. I need to pm too tall so I can post over there.
Reply:Yeah, get Josh to get your permissions set up to post on FNL. We need more builders to post!For those mountain bikes, I used True Temper 1 1/4" seat tubes. The piece I welded on top was a 1 1/4" OD x 0.095" wall 4130 that I bored to 27.2 mm ID. I turned a step to slide into the seat tube and then welded the seam. It was 3" long overall with a 1/2" long step. It worked out nicely because the seam was below the top tube and seat stay welds. Hope that helps!Last edited by zank; 05-08-2012 at 11:11 AM.
Reply:Gotcha. I'm planning on using straight gauge 4130 for the st.Cheersmantooth
Reply:I think it's safe to say that those welds are as good as it gets.  Is there a PWHT process that is employed?  It's been my understanding that even far-less-than-perfect welds will be stronger than the heat-affected zone.  How much effect does using heat sinks and back-purging have on the HAZ?  It seems that keeping as much heat as possible out of the weldment would certainly help to maintain more consistent grain structure.  I am planning to do some work in an industry in which PWHT is rarely used.  So, I've seen LOTS of structures fail at the HAZ (in 4130, 6061/7005 Al, 3/2.5 Ti...).  Once I get my welding skills dialed in, I will make sure to employ those techniques!
Reply:I can't believe it's been a year since I started this thread. A huge thank you to all of the experienced folks who contribute here on WW and provide so much guidance and information. It has really helped me along the way. You guys are the best!IMG_0003 by Zanconato Custom Cycles, on Flickr
Reply:The outside looks good, Zank........now show us the inside of the same joint.Blackbird
Reply:Originally Posted by dave powelsonThe outside looks good, Zank........now show us the inside of the same joint.
Reply:I tried to get as best a shot as I could with the lighting I have here in the shop. My backpurge still needs some tweaking and I still get some melt through. If you click on the photo, you can view a bigger version on my flickr account. Any feedback or tips would be appreciated.By "inside", is this what you meant or did you want me to cut up the joint? I was hoping to paint this one and ride it IMG_0011 by Zanconato Custom Cycles, on Flickr
Reply:That's good. Apparently no melt thru, little heat soak, NOW....I'm impressed.Blackbird
Reply:Thank you, sir. That means quite a lot.
Reply:I love welding, and I love riding.  I've been riding longer than welding, and now every time I look at a bike the first thing that I notice is the welds.  Saw a huffy that I was eyeing to get for the lady, looked at the welds, and promptly laughed and walked away.  Keep posting, I want more!  Im sure everyone over in welding projects and pictures would love this.  Thanks!
Reply:Nice stuff.  Thanks for posting.  You are on the money checking penetration to check on what's really happening rather that relying on appearance.  Kudos.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Thanks, fellas!
Reply:Back to 0.035 wire. I kept getting feedback from other bike builders that 0.045 wire is the holy grail. I've been using it for 6 months or so, but just never got comfortable using it. While using the thicker wire certainly made deposition easier, I felt like I had to pump a lot more heat into the tubing to get the puddle to melt the filler. I'd get a lot of melt through on the inside of the bottom bracket, head tube, and seat tube. And I would get very convex beads no matter how small I attempted to make my dabs. So I went back to 0.035 wire. Different strokes I guess. David W by Zanconato Custom Cycles, on FlickrDavid W by Zanconato Custom Cycles, on FlickrDavid W by Zanconato Custom Cycles, on FlickrDavid W by Zanconato Custom Cycles, on Flickr
Reply:With such a nice look I wouldn't even want to paint that.