I usually run my rails/pins to failure rather then do a pin turn. I had a mechanic tell me to change sprockets out, way before they get pointed to extend rail/pin life.what are your thoughts on this. when do you throw on new sprocket segments.
If your rails are sealed and lubricated with few or no dry joints, then yes by all means change out sprockets when they get worn. Sealed chain, or SALT chain with dry joints, the center distance between pins gets longer and longer due to internal wear, so putting new sprockets on can make for some interesting noises as the bushings no longer line up with the gullets between teeth.
We've changed many sprockets without changing track chain, lot of variable to consider roller and idler wear, operating conditions and operator as well. If you plan on running it into the ground a new sprocket would help get a little more life but just depends on bushings
The issue should also depend on the size and type of machine. I'm seeing oversize bushings on lots of track chains now on the smaller size dozers. Small oval tracks will generally run to destruction economically. The extra material means the rail heights are usually worn out by the time the bushings are through the hard material and the sprocket teeth are sharp enough to shave with. I've done D6 through D8 size machines without turning bushings and just changing the segments out when the chains run around 65% worn. You have to monitor things pretty close to do that economically though.