Opinions on Quality/Skill Sort

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Hi guys, I was wondering if you could take a quick look at this photo and let me know your opinion on the quality of the welds.We are making motorbike parts in asia, this is the work from a guy who works for us, where we are its very good quality but I was really wondering how it appears to the eyes of some pros such as yourselvesThanks alot for your time
Reply:Hi, I have seen much worse but I also have seen considerably much better, it's a bit hard for me to tell from that picture but from what I can see,  it appears too have a lot of undercut, not enough filler for the weld bead, (Did he TIG it and actually use filler?) the bead isn't consistant almost like it's been done too hot and the welder had to go faster otherwise he would blow through. I would probably say that there are some sections in there where he has blown through and just patched it up and there are a few sections where it looks like the weld has sagged.  Personally I wouldn't buy it.However, if that's the best welder you can get then I would try to get that welder to practice on a few scraps to work out the best settings for that job. I think he has potential but just needs to fine tune the settings on the welding maching that you are using. I take it this has been done with a TIG as it looks too clean for a MIG, just my 2 cents worth.Last edited by Ed.; 07-24-2010 at 03:01 AM.Miller Auto Invision 456 + S-62 wire feederC6240B1 Gap bed lathe16 ft3 air compressor16 speed pedestal drillHafco BS-912 Bandsaw
Reply:yep, i agree with ed. it looks too hot and not enough filler, the throat looks concave rather than convex
Reply:Don't take this the wrong way, because I'm sure its 2 totally different markets, but an exhaust with welds like that would not sell in the US market.  I'm guessing the exhaust pictured is for a small motorcycle, 250cc or less?  If its for a small bike, at a low price, that is what I mean about 2 different markets.  In the US, most sales are directed at larger bikes and sell for fairly high prices.Depending on the thickness of the tubing and the welds, if it is fairly thin, a large v-twin motorcycle could cause that exhaust pipe to fail.  If it is going on a CB 125 however, it will most likely never be a problem.For examples of good looking welds on motorcycle exhausts, check out Tigcraft and Sato (Sato is, or was known as Babyface in Japan).http://www.tigcraft-japan.co.uk/
Reply:After looking at the tigcraft link above, and taken in context, the sample makes more sense to me.Kyuusoko, the fitup and transitions look good but the welding appearence may be helped with a cold wire tig setup or using a "pulse" capable power supply.I can definately see these being prepared and sold "as is" and not polished, for a real hand built custom look.Matt
Reply:Hi Guys - firstly and above all thankyou everyone for your quick and intelligent replies, its much appreciated.Indeed it was built using a TIG machine, the mild steel is 1mm thick and its use is for a very low CC (probably around 130) but relatively high horse power (around 15-24) 2stroke motor.One of the main problems we always have doing anything here is that everyone tries to do everything TOO fast and too quick because they think quick means good, in some ways of course it does, but for welding im not so sure. To summarise your opinions as I understand them negative points1 alot of undercut :now this I dont quite understand 2 not enough filler :so this is the material used to bridge the gaps between the segments - it wouldnt surprise me if this was skimped so I will set about to make sure that this is improved 3 too hotthis is interesting - this may be a symptom on of the speed problem mentioned above do you think?4 throat concave not convex :so Im assuming this to mean that the joints between the segments should always be raised higher than the surface around them.  5 cold wire tig / pulse capable power supplyIm not at this time aware of the meaning of this but will certainly look into it, whats the advantage of a pulse power supply - I guess more strength but that would mean more heat? but ours is already too hot so i obviously havent grasped this yet.The exhaust is a sample made for a customer who provided us with an original sample to reproduce, this is a photo of the original sample supplied :In your opinion - does this sample then look alot better than the one our guy has made?This sample was made in Germany.I also attach another sample - this is made by our guy but stainless steel instead of mild steel - I assume you feel the same problems apply or if not then that would be curious as perhaps hes better at stainlessNormally the exhausts we make we dont sell for a very high price - always less than 100US but they resell them in Europe much higher. I wonder if the low use of the filler material is a sympton of cost saving typical in this part of the world. Thanks again everyone its really appreciated.
Reply:Kyuusoko re: #4, yes slightly convex for strength and appearance.Re: #5, cold wire tig is a process where filler is added with a wire fed under the tig torch. It is shown here with a hand torch mounted in a Bug-O tractor welding 1.5mm 409SS. [ame]http://www.youtube.com/watch?v=_1EPnAqWWuo[/ame]Pulse tig allows for slowing down the process, focus the arc and maintaining a lower heat input, shown here with no filler welding .063 (1.5mm)SS; [ame]http://www.youtube.com/watch?v=2NkFRlbJNZk[/ame]And here welding thick wall CrMo tubing with filler (in this case the weld is very high pulse with a long low background current for a slight tempering of the weld); [ame]http://www.youtube.com/watch?v=GIkBDI_4oSg[/ame]And your English is outstanding!Matt