Grade 8 bolts are listed as "Medium Carbon Alloy Steel, Quenched and
Tempered" with a proof load of 120,000psi and a minimum tensile of
150,000psi. Welding them up with a 70kspi weld rod does not sound like
the best approach.

http://www.americanfastener.com/tech...ings_steel.asp

DE wrote:



I'm working yet again on my aging fleet of farm equipment and have
a few metalworking questions for the group.

The machine is a 60's vintage OMC mower conditioner and the
parts are of the sickle drive area. Specifically a couple of 7/8"
grade 8 bolts that have wear on them. Maybe 1/32 deep X 1"
long on one side. I want to build up with arc welding and turn down
on lathe for a precision fit on bearing. Any reason not
to do this? What rod will give max wear and still be machinable?
7018?
Is the HAZ zone a issue on *8 bolts if welded? I suppose spray arc
would be best but not an options for me. Durability is desireable.
It will get new bearings.

I replaced these bolts maybe 20 years ago and can't complain
about the service , just enjoy utilizing the shop and usually can
improve upon the factory design in the process.. I still have the
origional bolts to play with. The bolt/bearing fit is not real
precise to begin with, needs to be dissasembled regularly for
servicing the cutters.

This is a recipocating drive and get hammered @600 strokes/min. I
know I should just replace em but would rather spend the money on shop
tooling of course.....

Interested in any thoughts...

DE

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