Trimming bottom of door

I do hundreds of doors, 7 more yesterday so on average I do 7 to 12 a week, its a great little part time money earner job I do for a few carpet companies. I use a track saw to cut the std house doors, its quite easy, I have a flat aluminum bar I use to mark a line 32mm from the floor, that bar has a pair of small 3mm diam legs on it that will go through a slot in old carpet then sit on the true floor under old carpet, they were made from 3mm bolts that are now filed to a point to get through the slot easy, that line is just a reference line as they all don't get cut along it at 32, today's doors as the new carpet and underlay was 23 then they were cut at 29mm from the floor, so were cut 3mm away from the line, also as house doors dont all swing square to the floor as they open, then I mark two lines, one with the door shut and one with the door fully open, so with most doors the gap under the door changes as the door opens, so with today's doors some were cut some where it was cut more on the handle side than the hinge side to allow for the gap getting smaller when the door swings opens, as we needed 29 at all places under the door. I also use a sharp kniife to cut through the surfact of any veneer doors or cross grain timber doors to stop tear out from the saw, it has a thin saw blade with 56 teeth but will tear out veneer were it pushed through too hard or fast so the cut line stops that, I only use a router if they are furniture quality doors, these I cut in stages as the full door thickness is too much for the cutter, many wardrobe doors need a router cut, but by far most doors I do are cut with the track saw as its clean and fast, you cant spend a long time cutting when you have ten doors to mark, take down and cut then put back up, so the 1200mm track saw is very efficient and paid for itself many times over. N