I found this with a bit of searching...google can be your friend
Good luck
G Vavra
Not sure what size bar bolts are on the 395XP, But Bar bolts
are typically 5/16 – 18 tpi, assuming SAE grade 5, the bolts should hold a
clamping force of 3300 plus Lbs, and a load force of 4400 plus lbs on the bolt
nuts when the bar nuts are tightened to about 17 ft-lbs or 204 in-lbs. However the tensioning screw is typically a #
10 – 24 tpi, and is being used in the load force position, Not clamping when
tensioning the bar chain. The torque value of a #10 carbon steel , grade 5 machine
screw is about 25 in-lbs, with a load force of 1000 plus lbs, and is being used much like a “screw
Jack” to tension the chain onto the bar. Never mind offset tensioning screws
that use a small pinion gear, which would require a few more calculations. Oh,
also metric grade bolts are fairly close to load sizes if comparing a comparible
size like a M6 metric to a #10 standard screw, since it’s the dimensions of the
screw and grade that are important.
So what does all this
mean, the tensioning screw should be used just to tension the chain onto the
bar, and Not to hold the load that is exerted onto the bar and chain by some
external force like a Granberg small log mill. (Also I’m not sure how much
force can be exerted onto the bar and chain but obviously If its bending or
breaking the tensioning screw its more than a 1000 lbs plus.)
So here is what I would suggest or try: Use the tensioning
screw to tension the chain onto the bar, Next use the Bar nuts to clamp the bar
in place using the correct torque values on the bar nuts.
I also suspect that the bar nuts maybe loosening up a bit to
allow the bar clamping to be reduced and slip, so I would try a few drops of “blue”
mild strength “Loctite” for threads or equivalent thread lock. Do Not use Extra
strength thread compounds because you do want to take the bar nuts off in the
future.
Finally, after everything is tight, I would then take a turn
or turn and a half off of the tensioning screw (CCW), because If the bar Nuts
are clamping properly you should not get any movement, and this will prevent
the force of the Granberg from being exerted onto the tensioning screw.