Tig Welding a Steel Alloy Bike Frame

Tig Welding a Bike Frame with .032" wall alloy steel tubing and with WeldMold 880 Tig rod and then smashing it with a hammer.

Bike Frame fixtured on a Stronghand Tools Welding Table and welded out using both ER70s-2 tig rod along with Weldmold 880.


I wanted to shoot  a video   on welding thin wall (.032")  steel tubing... the kind used for building  bike frames.


Mikes Zanconato of Zanconato Custom Cycles was kind enough to provide the coped tubing bike frame kit...

so... a big shout out and Thank You  to Mike.!!!

Seriously, you should check out some of his work at his website Zanconato.com ... .  Mike is a craftsmen.


I remember checking out some pics of his practice tig welds on his blog some time ago when he was first learning to Tig weld.
 
In not much more than a year, I checked out his blog again and what I saw was  near perfect tig welds.

Anywho....thanks to Mike, Instead of just sticking a couple of pieces of tubing together I was able to fixture up a bike frame and talk about some of the challenges bike builders face in fitting and welding bike frames.

Now understand this....I am no bike builder. I just thought welding the joints of a bike frame would make for an interesting video.

...and besides,  this bike frame is never,  ever going to be ridden...like...ever.

Why?

Because after the welding was done, I exposed it to the BFH. ( big freakin hammer)

Here is a bit of info on the tubing as quoted from one of Mike Zanconato's  comments on the last Youtube video

"Compared to 4130, this alloy has about half the carbon and chromium content that 4130 does, but it has about 3 times more manganese and also vanadium added. The result is an increase in tensile strength and yield strength of 60-70% depending on heat treatment.This allows the wall thickness to be reduced to 0.016" in some cases. This particular´╗┐ tubing is on the thicker and heavier side of what we'd use on custom frame."

 
For filler rod, I uses ER70 S-2 as well as some Weldmold 880 filler rod.  .035" diameter.

 I tig welded up the bike frame using some of each rod.  The front half with the larger tubes with the weldmold 880 rod and the back part from the seat post tube backward using ER70S-2 .

All of the bike was tig welded using pulse tig. 

33 pps
33% pulse on time
33% background current.

I call these settings  the "rule of 33".

There is no magic to these parameters...they just work very well on thin wall tubing or sheet and the best part is they are very easy to remember.  

After welding, I took the bike frame outside and beat on it with a sledgehammer. 

I was able to cause some tearing on the toe of the weld on the bottom bracket which I am pretty sure was 4130 chromoly because it had the typical brown mill finish like normalized 4130 has.  That might account for my being able to fracture that weld on the toe where the thin tubing met the weld. The weld probably picked up enough carbon from the 4130 to harden just a bit .

Either way, it took quite a bit of beating with the big hammer to make a weld fail so I would definitely ride a bike welded with either rod without fear of a weld failing.


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