"Terry Coombs" wrote in message
news

One of the locals brought me a part from his brush hog , it's the
pivot yoke that carries the rear wheels (I think) . The sleeve that
fits it to the pivot pin on the body of the machine is worn , and
had broken the weld on one side , sleeve was split most of the way
up .

I'm machining him a sleeve from some 4140-type (acts/welds/spark
tests/hardens just like 4140 but ...) and I will be welding it to
the angle iron frame of the yoke . I can either arc weld it with
7018 or 6013 or I can TIG weld it with ER70S2 (or 308 or 309 SS) -
my baby MIG ain't got the ass for something this heavy . I know they
TIG 4130/4140 tube for chassis's , but that's a lot thinner cross
section . This part will be ~1.250" ID x 4.5" long with about a
.625 wall thickness , the original had a 3/16" wall . I don't want
to have this thing fail because of a HAZ failure ... I'm thinking I
might need to preheat (after tacking in place) then control cooling
to avoid localized hardening . Thoughts , opinions (about the job!)
your experiences in the same/similar situation welcomed . If you
think I'm an idiot for taking this on , keep it to yourself ...
--
Snag

Could you weld on a larger tube of more forgiving mild steel and then
press in the 4140?

I'd pick a tube ID within the range of one of my adjustable reamers,
and turn the sleeve OD last to fit.

-jsw