General Cycling Discussion - Weld Quality ?

Is it possible to gauge the quality of frame welds by eyeball?

Does a "fatter and / or bigger" weld equate to higher quality?

I have welded a bit, years ago, and while I'll not pass myself off as an expert, my feeling is that you can get a good feeling for the weld just by looking. Does it simply look nice, with an even bead? Or is it uneven and sloppy looking? Any splatter at all? If it looks nice, my feeling is the weld is as well.

It is all about how well filled the joint is... good welders tend to make their welds look as good on top as they are below but I have seen some very pretty welds fails and some butt ugly work hold up under everything that got tossed at it.

You can join two pieces of metal with a fairly thin bead, the additional material that gets laid up adds strength and prevents stress risers.

Does a "fatter and / or bigger" weld equate to higher quality?

"Fatter and/or bigger" welds equates to aluminum frame tubes vs. steel. It's a material rather than a quality indicator.

You can if you're trained to do so, but that only give a general idea about how good the weld is. Like 65 said, the real quality of the weld is hidden and can only be inspected with x-ray machines or destructive testing. When a welder is tested and certified, they make a weld that is cut up, bent, etched and internally inspected. If they pass the test, an inspector will generally know that the welder is able to make a quality weld and will only have to visually inspect the welds on a project. Inspectors have been known to make a company grind out the welds made by a non-certified welder and have a certified welder do the job.

Joints are typically sized per wall of the tubing, so a large weld on a thin wall tube is not necessarily a good thing. It can weaken the tubing and make it brittle which if it breaks will do so just outside the weld.

Also different weld processes will have different surface appearances, which do not necessarily relate to differences in quality.

A rough weld can, to a fair extent, be ground and polished smooth, and what looks like better welding may simply be more work done after the fact.

i have done my share of welding and sometimes the welds are not the prettiest but the have the right amount of penetration to do the job they are meant to do. i have seen some seen some very crappy looking weld on some steel frames and i have seen some very nice welds on some aluminum frames. you should see the bike i am currently riding. the front shock mount for my rear shock is only be held by 5 small tack welds and i have been wait all winter to hear them snap but they are still holding. the welds on my bike are in are not ugly but they are strong.

Prior to moving into frame building I worked in industry and saw my fair share of welds from many perspectives... nothing left the shop without being magnetically tested.

We repaired a lot of equipment and a fail in the welding shop would result in a failure down the line when you went to re-machine a part and when time is measured in the hundreds of dollars per hour and timelines were tight the welders had to know their stuff.

It's amazing what you see sometimes. There was a welder at a shop that I worked at who thought he was God's gift. His welds looked great, but I ended up popping every single weld of his on some frames he had put together. Beautiful welds / NO penetration. :eek:

In general, if you know the thickness of the joint, then it's possible to determine the weld quality by visual inspection. Unfortunately, it's not that easy to inspect the ID of a bicycle weld joint. The use of NDT dye-penetrant like IIA after welding can significantly improve the chance of spotting weld defect.

a skilled Welder can look at another welder's bead and tell how much coffee they had.

It's amazing what you see sometimes. There was a welder at a shop that I worked at who thought he was God's gift. His welds looked great, but I ended up popping every single weld of his on some frames he had put together. Beautiful welds / NO penetration. :eek:

Exactly... the same thing happens with brazing as you can make it look great from the outside while having poor penetration and if your temperatures are not right the bonds can also fail.

We see a lot of this at out shop... we have found faults with frames that were built by "masters" as well as production level frames.

You won't find us using any filler in our frames because the brazing work was shoddy.

Newb that I am I can tell good from bad and where people took short cuts in their work and prefer an ugly but functional joint over one that was just pretty but the goal is to do both.

nm

If it looks like one I would've done, it's probably bad. ;)

They don't do any bad welding on bike frames... :innocent:

http://inlinethumb27.webshots.com/41370/2091867770066886751S600x600Q85.jpg

Aaron :)

They don't do any bad welding on bike frames... :innocent:

http://inlinethumb27.webshots.com/41370/2091867770066886751S600x600Q85.jpg

Aaron :)


Wow! :eek: Get a tissue. It looks like someone sneezed on that joint.

THere was a company that used to build frames in Canada with what they called Lazer Robotic Technology (printed on a sticker on the frames). THe welds looked like clumps of bird poop wrapped around the joints. I have seen hundreds of those bikes leave the shop, and there were thousands and thousands of others as they were sold under several different brands, but I have yet to see one with a failed weld.

Wow! :eek: Get a tissue. It looks like someone sneezed on that joint.

Yup, then painted it and sold it...

FWIW it hasn't failed...yet. If it does I will fire up the buzz box and reweld it. If that doesn't work we break out the "real welder" LOL

Aaron :)

http://www.lincolnelectric.com/assets/en_US/Products/K1170/300x300.jpg

http://www.millerwelds.com/products/images/products_shots/BigBlueAirPakDLX.jpg