un-even cut

[k and g]

So, I am just getting warmed up on the woodmizer lt-40 i bought a few months back.  Really didnt have the time to run it until the last week or so, and i have spent a good many evening on here reading thru various topics and have learned a lot via reading, but i encountered a problem today i havent really seen anything about.  
I was trying to cut a 14' 4x6 and when i measured it after i cut it, the midsection was right on at 4", but where i began the cut and where i ended the cut both measured 4 1/4"... so i went thru leveling the blade to each "bunk"(?) and calibrated for the same height all along the mill and set another board up on there to experiment and same thing happened.  I cut it down to 3" and the entire length of the board measured 3" with the exception of the beginning 12-18" and the last 12-18", with each progressing to 1/4" over.  To account for maybe the board bowing, i cut the board 1/2" then flipped it and cut another 1/2" off the opposite side.  When i cut an 8' 1"x8", I am not having this problem.  The little fold out extra bunks on each end that swing out seemed to be level with the mill....what am i missing???

[GAB]

So, I am just getting warmed up on the woodmizer lt-40 i bought a few months back.  Really didnt have the time to run it until the last week or so, and i have spent a good many evening on here reading thru various topics and have learned a lot via reading, but i encountered a problem today i havent really seen anything about.  
I was trying to cut a 14' 4x6 and when i measured it after i cut it, the midsection was right on at 4", but where i began the cut and where i ended the cut both measured 4 1/4"... so i went thru leveling the blade to each "bunk"(?) and calibrated for the same height all along the mill and set another board up on there to experiment and same thing happened.  I cut it down to 3" and the entire length of the board measured 3" with the exception of the beginning 12-18" and the last 12-18", with each progressing to 1/4" over.  To account for maybe the board bowing, i cut the board 1/2" then flipped it and cut another 1/2" off the opposite side.  When i cut an 8' 1"x8", I am not having this problem.  The little fold out extra bunks on each end that swing out seemed to be level with the mill....what am i missing???

k and g:
I think what is happening is that the cant you are sawing is drooping at both ends.
My suggestion would be to turn the swing outs so they suport the cant the longest possible.
I've encountered a similar experience when sawing wet white pine.  The boards get thinner at the ends as the cant gets thinner then the bottom piece has thick ends and the proper dimension in the middle.
Hope this helps you.
Gerald

[Sawmill Man]

Make sure you are not preloading the last support leg to much as you can force a bend in the tube that the mill rides on. You just want that leg touching the ground not supporting a lot of weight. After running the mizers for years I bought a new super lt40 and almost had a heart attack when I started sawing perfect 12x12s on both ends that measured 11.5x11.5 in the middle. I pulled a string tight on tube and it had a bow in it that disappeared when the weight was removed from that leg.

[Chuck White]

Welcome to the Forestry Forum, k and g!

[millwright]

What they said. A lot of times you can get a lot of sagging on the ends with a heavy cant, that's where fao's are nice as you can easily make small adjustments.

[mike_belben]

Youve got it parked on a good stable ground bed?