Welding Bearing Races To Mild Steel

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Hello from a new guy!  Hope this question doesn't sound too odd...  I part out motorcycles for a living and over the years I've accumulated a pretty large pile of parts that there isn't a big market for.  Pack rat that I am, I hate to throw anything away so one project I decide I want to try is to turn a set of transmission gears mounted on a hollow shaft into a table lamp.  My idea is to mount the gears upright onto a piece of 1/4 inch mild steel channel which is where I've run onto a problem.  The shaft I'm working with has a set of pressed bearings on one end, the edge of the bearing races sits flush with the end of the hollow shaft  and I thought if I could tap some threads inside the shaft I could run a nipple through a hole drilled in the channel base into the threads I tapped and nut it tight from the bottom.  I knew cutting threads into a transmission shaft was going to be a task, so I started by heating up the end of the shaft to a dark red glow then drilled out the hole to the correct diameter for the tap - so far so good (but it sure kills a drill bit fast!).  I've tried this on a couple different shafts and have ended up breaking the taps when I try to thread them (high dollar OSG taps to boot!).All of which has taken me back to my first thought of just welding the edge circumference of the bearing race onto the 1/4 inch mild steel channel.  I originally rejected that idea because, A:  I don't own a welder (but I can borrow a friend's MIG if need be).  And B: I was concerned that I wouldn't be able to get enough penetration on that bearing race to get a weld that wouldn't just fall apart from the weight of the shaft and gears (about 20 pounds).  What has me re-thinking trying to weld it is that when I was heating up the end of that shaft (using a MAPP gas torch) in hopes of annealing it enough to tap threads into it, the bearing races heated up hot and fast to a bright red glow.  So, what I am wondering is if the bearing races might have annealed enough to allow me to get adequate penetration using a 90 amp hobby welder (a Miller 140).  Any thoughts or suggestions would be greatly appreciated!ThanksDave
Reply:I assume you have a torch. Is it o/a? You could braze the parts and it would add to the artist feel. A few dabs of brass is all it would take.You could likely weld the two but the weld wouldn't be very strong... but likely strong enough for a lamp.Have you looked at some of Mario's (ironheart_ram) work? He turns old parts into masterpieces. Until recently all he used was an old stick welder I believe. This is just one of his many creations.http://weldingweb.com/vbb/showthread.php...1-The-predator
Reply:I just noticed you have a mapp gas torch not o/a. You might consider silver soldering the parts. That should be in the realm of mapp gas.If your interested in brazing with mapp gas the trick is insulation.http://weldingweb.com/vbb/showthread.php...anything-thick
Reply:I have welded lots of tool steel punches to mild steel handles.I always tack the pieces, preheat, weld, post heat , normalize and then re-harden punch end as necessary.
Reply:Heat treat state should not affect weld penetration, However pre-heating will affect penetration. For a lamp it shouldn't be too critical to get great penetration, you should be able to get by with enough to keep it together if the lamp were to tip over and fall.
Reply:You cannot weld the bearing, the carbon content is too high and it WILL crack.  But, you can braze it with silicon bronze or any silver braze over 45%.