Original Posted By:> pietflyr(at)bellsouth.net
Something to said for gas welding. Don't have that problem. Tig and Mig is fast=2C but I'll take gas any day of the week. The best sheet metal men almost always use gas. You can weld 4130 without preheating or fear of cracking. You can weld all weldable aluminum=2C stainless and titanium (Haven't done that one yet.) With tig or mig even the slightest breeze will blow the gas off the weld. With 4130 the area will need to be preheated to prevent cracking. Tig and mig have thier place=2C especially in a controlled production environment. I bet if you exhaust was gas welded by a competent welder it wouldn't have cracked. Just my .02Doug DeverIn beautiful Stow Ohio
RE: exhaust manifold [was Re: Pietenpol-List: humped center section]
RE: exhaust manifold [was Re: Pietenpol-List: humped center section]
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Actually, the repair on the way back from OSH was made by a professionalwelder, TIG welded. It lasted nearly twice as long as the first one (50hours). It cracked too. At the weld.You've confused me a bit - in your 5th sentence you said "you can weld 4130without preheating or fear of cracking." Then 3 sentences later you say"With 4130 the area will need to be preheated to prevent cracking". Whichis it?Anyway, to some extent I agree with you - I like oxyacetylene welding.However, for some applications TIG is far better. I've tried gas weldingaluminum, I'll leave that for the pros. I also tried gas welding stainlessand burned up a lot of test material without any good welds. MIG I have noexperience with, but I know Champion Aircraft uses MIG to build Citabriasand Decathlons (at least the Citabria I helped rebuild had a lot of littletwigs of welding rod stuck to it like MIG tends to leave behind).This was just a tip given o me that I passed along. I have not tried it,but it makes sense to me. Your mileage may vary.Jack PhillipsNX899JPRaleigh, NC _____
Actually, the repair on the way back from OSH was made by a professionalwelder, TIG welded. It lasted nearly twice as long as the first one (50hours). It cracked too. At the weld.You've confused me a bit - in your 5th sentence you said "you can weld 4130without preheating or fear of cracking." Then 3 sentences later you say"With 4130 the area will need to be preheated to prevent cracking". Whichis it?Anyway, to some extent I agree with you - I like oxyacetylene welding.However, for some applications TIG is far better. I've tried gas weldingaluminum, I'll leave that for the pros. I also tried gas welding stainlessand burned up a lot of test material without any good welds. MIG I have noexperience with, but I know Champion Aircraft uses MIG to build Citabriasand Decathlons (at least the Citabria I helped rebuild had a lot of littletwigs of welding rod stuck to it like MIG tends to leave behind).This was just a tip given o me that I passed along. I have not tried it,but it makes sense to me. Your mileage may vary.Jack PhillipsNX899JPRaleigh, NC _____
Pietenpol-List: exhaust manifold [was Re: humped center section]
Original Posted By: "David Paule"
A few points:Gas welding has a much steeper learning curve than TIG.TIG equipment is much more expensive than gas.Aluminum is FAR easier to weld with TIG than with gas.MIG is just plain messy and difficult to control, especially with light gauge metal.ALL welding for aircraft use (whatever method) should really be done indoors, shieldedfrom any air currents, since if the welds are not allowed to cool in stillair, you're asking for trouble. The resulting weld, and adjacent materialwill not be Normalized if there are moving air currents while the weld is cooling,and will likely develop cracks.When TIG welding 4130, preheating is not necessary IF the material thickness is1/8" or less - which in the Pietenpol, would be any of the metal parts.(2 more cents)Bill C.Read this topic online here:http://forums.matronics.com/viewtopic.p ... __________
A few points:Gas welding has a much steeper learning curve than TIG.TIG equipment is much more expensive than gas.Aluminum is FAR easier to weld with TIG than with gas.MIG is just plain messy and difficult to control, especially with light gauge metal.ALL welding for aircraft use (whatever method) should really be done indoors, shieldedfrom any air currents, since if the welds are not allowed to cool in stillair, you're asking for trouble. The resulting weld, and adjacent materialwill not be Normalized if there are moving air currents while the weld is cooling,and will likely develop cracks.When TIG welding 4130, preheating is not necessary IF the material thickness is1/8" or less - which in the Pietenpol, would be any of the metal parts.(2 more cents)Bill C.Read this topic online here:http://forums.matronics.com/viewtopic.p ... __________
> RE: exhaust manifold [was Re: Pietenpol-List: humped center sect
Original Posted By:> owner-pietenpol-list-server(at)matronics.com
> .net>> > For those contemplating stainless steel ehaust systems=2C let me share a> little pearl of wisdom that I learned just a bit too late:> > My original exhaust system on my Pietenpol was TIG welded stainless steel=2C> welded by my neighbor (who also welded my aluminum fuel tank). The welds> looked good=2C but after about 30 hours of operation=2C the left stack broke off> and was only kept from departing the airplane by the SCAT hose on the heat> muff. I had my neighbor re-weld it=2C with an additional strut to help> distribute the load. Then I flew the airplane to Brodhead and OSH (this was> in 2005). On the way home=2C the right side stack broke off and was again> held in place by the SCAT hose. I had to find a local welder make emergency> repairs so I could make it home.> > I decided that stainless was simply not a good choice and made a whole new> set from plain carbon steel=2C which I could weld myself. No problem with it=2C> except that it has begun to rust. In another 10 years or so I'll have to> replace it.> > Meanwhile=2C I was talking to a fellow who makes exhaust systems for race cars> (TIG welded stainless)=2C telling him of my troubles. He asked "What did you> do to shield the inside of the tubing?"> > I just looked at him with a stupid look on my face (fairly easy for me to> do)=2C and said "Huh?"> > He said=2C "TIG shields the area around the weld with argon gas to prevent the> weld from burning=2C but with such thin walled material=2C the metal on the> inside of the tube is just as hot as the outside. You've got to shield it> as well."> > He said that when he does a job like this=2C he plugs one end of the tube=2C> then turns on the gas from the TIG torch and uses it to flood the entire> tube with Argon. He tests to see if he has enough by striking a match and> inserting it into the tube. If it doesn't go out immediately=2C he knows he> doesn't have enough Argon to shield the weld.> > So when it comes time to replace my exhaust system again=2C I may give> stainless another try=2C using this technique.> > Jack Phillips> NX899JP> Raleigh=2C NC> > -----Original Message-----
> .net>> > For those contemplating stainless steel ehaust systems=2C let me share a> little pearl of wisdom that I learned just a bit too late:> > My original exhaust system on my Pietenpol was TIG welded stainless steel=2C> welded by my neighbor (who also welded my aluminum fuel tank). The welds> looked good=2C but after about 30 hours of operation=2C the left stack broke off> and was only kept from departing the airplane by the SCAT hose on the heat> muff. I had my neighbor re-weld it=2C with an additional strut to help> distribute the load. Then I flew the airplane to Brodhead and OSH (this was> in 2005). On the way home=2C the right side stack broke off and was again> held in place by the SCAT hose. I had to find a local welder make emergency> repairs so I could make it home.> > I decided that stainless was simply not a good choice and made a whole new> set from plain carbon steel=2C which I could weld myself. No problem with it=2C> except that it has begun to rust. In another 10 years or so I'll have to> replace it.> > Meanwhile=2C I was talking to a fellow who makes exhaust systems for race cars> (TIG welded stainless)=2C telling him of my troubles. He asked "What did you> do to shield the inside of the tubing?"> > I just looked at him with a stupid look on my face (fairly easy for me to> do)=2C and said "Huh?"> > He said=2C "TIG shields the area around the weld with argon gas to prevent the> weld from burning=2C but with such thin walled material=2C the metal on the> inside of the tube is just as hot as the outside. You've got to shield it> as well."> > He said that when he does a job like this=2C he plugs one end of the tube=2C> then turns on the gas from the TIG torch and uses it to flood the entire> tube with Argon. He tests to see if he has enough by striking a match and> inserting it into the tube. If it doesn't go out immediately=2C he knows he> doesn't have enough Argon to shield the weld.> > So when it comes time to replace my exhaust system again=2C I may give> stainless another try=2C using this technique.> > Jack Phillips> NX899JP> Raleigh=2C NC> > -----Original Message-----
> RE: exhaust manifold [was Re: Pietenpol-List: humped center
Original Posted By:> owner-pietenpol-list-server(at)matronics.com
> > > For those contemplating stainless steel ehaust systems, let me share a> little pearl of wisdom that I learned just a bit too late:> > My original exhaust system on my Pietenpol was TIG welded stainless steel,> welded by my neighbor (who also welded my aluminum fuel tank). The welds> looked good, but after about 30 hours of operation, the left stack brokeoff> and was only kept from departing the airplane by the SCAT hose on the heat> muff. I had my neighbor re-weld it, with an additional strut to help> distribute the load. Then I flew the airplane to Brodhead and OSH (thiswas> in 2005). On the way home, the right side stack broke off and was again> held in place by the SCAT hose. I had to find a local welder makeemergency> repairs so I could make it home.> > I decided that stainless was simply not a good choice and made a whole new> set from plain carbon steel, which I could weld myself. No problem withit,> except that it has begun to rust. In another 10 years or so I'll have to> replace it.> > Meanwhile, I was talking to a fellow who makes exhaust systems for racecars> (TIG welded stainless), telling him of my troubles. He asked "What did you> do to shield the inside of the tubing?"> > I just looked at him with a stupid look on my face (fairly easy for me to> do), and said "Huh?"> > He said, "TIG shields the area around the weld with argon gas to preventthe> weld from burning, but with such thin walled material, the metal on the> inside of the tube is just as hot as the outside. You've got to shield it> as well."> > He said that when he does a job like this, he plugs one end of the tube,> then turns on the gas from the TIG torch and uses it to flood the entire> tube with Argon. He tests to see if he has enough by striking a match and> inserting it into the tube. If it doesn't go out immediately, he knows he> doesn't have enough Argon to shield the weld.> > So when it comes time to replace my exhaust system again, I may give> stainless another try, using this technique.> > Jack Phillips> NX899JP> Raleigh, NC> > -----Original Message-----
> > > For those contemplating stainless steel ehaust systems, let me share a> little pearl of wisdom that I learned just a bit too late:> > My original exhaust system on my Pietenpol was TIG welded stainless steel,> welded by my neighbor (who also welded my aluminum fuel tank). The welds> looked good, but after about 30 hours of operation, the left stack brokeoff> and was only kept from departing the airplane by the SCAT hose on the heat> muff. I had my neighbor re-weld it, with an additional strut to help> distribute the load. Then I flew the airplane to Brodhead and OSH (thiswas> in 2005). On the way home, the right side stack broke off and was again> held in place by the SCAT hose. I had to find a local welder makeemergency> repairs so I could make it home.> > I decided that stainless was simply not a good choice and made a whole new> set from plain carbon steel, which I could weld myself. No problem withit,> except that it has begun to rust. In another 10 years or so I'll have to> replace it.> > Meanwhile, I was talking to a fellow who makes exhaust systems for racecars> (TIG welded stainless), telling him of my troubles. He asked "What did you> do to shield the inside of the tubing?"> > I just looked at him with a stupid look on my face (fairly easy for me to> do), and said "Huh?"> > He said, "TIG shields the area around the weld with argon gas to preventthe> weld from burning, but with such thin walled material, the metal on the> inside of the tube is just as hot as the outside. You've got to shield it> as well."> > He said that when he does a job like this, he plugs one end of the tube,> then turns on the gas from the TIG torch and uses it to flood the entire> tube with Argon. He tests to see if he has enough by striking a match and> inserting it into the tube. If it doesn't go out immediately, he knows he> doesn't have enough Argon to shield the weld.> > So when it comes time to replace my exhaust system again, I may give> stainless another try, using this technique.> > Jack Phillips> NX899JP> Raleigh, NC> > -----Original Message-----