Tool steel for needle bearing repair

[Matt_Maguire]

I've been digging in boxes again... Below are pics with yellow arrows pointing to repaired needle bearing surfaces for Funk gearbox output shafts.

The weld parameters were H-12modified tool steel wire .035", single pass. I have done with cold wire tig and short circuit mig automatic process.

Cold wire tig is around 3/16" arc gap, then wire feed and amps are adjusted to achieve 1/16" to 3/32" running arc length. The applied filler runs 54-56 Rockwell "C". The lower the volts (arc length) the harder the filler gets (less chemistry lost). Just enough power to "stick it at the edges".

With mig the parameters were in the 160amp range with the lowest voltage possible and still maintain a stable arc (no stubbing). Both C-10 and C-25 mixtures work well. The resulting hardness ran 56-58 Rockwell "C", which is the max for this filler. The co2 mix does cause oxides in the weld, but they seemed to work out as good as the tig for this application.

Anyway pics below of the finished parts (I'll see if I can find pics of the welded surface later).

Matt

[irish fixit]

Ooh. Nice work there. I need to look into that. I can think of several jobs that I've had to rig or turn down because I couldn't do that.