Mig question

[h=2]Re: Mig question[/h]MIG will work OK to weld a ball bearing to a shaft, but if you've got a good old fashioned arc welder with a stainless steel rod you should get a better weld as the s/s rod will act as an alloying agent much the same as using a dissimilar rod would.

leftandfred
 
That's primarily because of the chromium content of the E52100. Most any s/s rod or wire would be better than a typical ER7-x series wire. But there would be no problem I can see using the ER70 wire, as long as you achieved good penetration.
 
If your going to MIG these parts... Figure out some way to set it up so that you can spin the part as you weld. Being a machining forum, I know you guys would yell at me to no end if I suggested clamping the part in a lathe and welding it...:scared: but that is the idea to go for. Maybe find some bearings and an old 3 jaw chuck, and make some kind of pulley setup off of your lathe or mill so that your not welding directly on top of your shiny precision machine equipment, but far enough away to keep the mean spatter off of it.
Pre-heat the ball bearing to somewhere around 200 F to 300 F and cool it off slow. When you start seeing the water on the surface from the torch vanish, your around 200F, when you touch your leather glove to it and it smokes your somewhere near 400 F to 500 F. Or just go get some temp indicating crayon from the welding store and take the mystery out of it.:) The exact degree isn't as important as putting some kind of heat to it before you weld it. A quick little mig weld will be hard and brittle with how much carbon is in that grade... :yikes:
Cooling off slow will help as much as preheat, the slower the better. Ceramic fiber insulation works wonders, an old set of welding leathers works too and even burying it in a box of sand will help more than letting it cool off in air.
Stainless rod or wire would work fine if you have it, I'd still wave the torch over the bearing a few times but with the stainless its not as important. Preheat and low carbon wire works too and is a lot cheaper.
Hope this helps
:welding:
 
I've found cat litter/ floor dry can keep things hot for hours if you bury it deep enough.
Dan


Master of unfinished projects
 
I gave an old susperspacer to a welder one time and he connected a spare wire feeder motor to it for a rotary positioner....worked beautifully for spinning work. I tried it, but I couldn't coordinate the foot control for the TIG and the foot control for the positioner at the same time very well. He was a superb welder, and made good use of it. We left the 3 jaw chuck on it.
 
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