Now I will first start by saying I am not a machinest or line borer. Out of pure curiosity I am wondering how they find the exact center of a worn out pin bore that is severely out of round? I've been around but never watched close enough or asked the question. Wondering if you line bore experts could answer my question! Thank you!
Not an expert, but usually you have an outside boss you can indicate to or part of the hole that is sort of undamaged. Typically it's not critical that the hole goes right back in the factory location. I mean, they were still using up right up to the point they called the line borer. Anything he does will be an improvement.
I have a couple sets of line up cones. Well several stes. They are aluminium tapered cones bored to a sliding fit over the boring bars. If the whole is oblong you can shim one side of the cones to hold them centered from a good part of the old bore. Very quick and easy to do. I put locking collars behind them to keep the tight in the bore and then slide the bearings on the bar. Weld the bearings in place, loosen the locking collars and pull the bar out to get the collars and cones off.
Usually cone will find an orginal part off the bore, ,which good tigthen the cones into place with some from of clamp and jack system on the bar. Check the measurements with the less damged bores and as low your with 1/2mm or so thats pretty much it. As the machine will have more slop and play in the joints to allow if not quite spot on. Or the long winded way with dti in the bore then you can get bang on.
Generally if I have one oblong it's only or mostly in one side of the hole. I'll center my bar with my cones, weld my brackets and then figure roughly the original hole dimension and use a t-gauge to center the bar against the unworn part of the bore.