can't get square

[nstringer04]

I recently purchased a woodmizer lt40 super hydraulic mill to cut drag mat timbers with.  I have only cut around 4 cants so far because I can't seem to get them square.  One end is 8x8 while the other end may be 7 1/2"x 7 1/2 or something other than a perfect 8x8.  I am new to milling and have not received my manual yet from the guy I purchased the mill from.  The lengths I am cutting are 16',18', and 20'.  I have noticed that I can pick up on the open side of the head and tilt it a good bit.  Is that normal or should i adjust something to tighten up that slack?  I am lost until I get the manual and I really don't want to wait any longer.  Thanks for the help in advance.

[Cedarman]

For squareness, step one is to make sure the square has not been damaged and shows true squareness.   If it is square, then check that blade is parallel to deck as it moves down mill, measure both sides of cant to make sure they are same thickness.  If parallel, then check with square that back stops are square to bed with cant clamped in. If mill is sawing a different thickness, then either the log  is bowing up as you saw or the log deck is too high at one end, the thin end.  Check for those 2 things first.

[Dave Shepard]

Yes, you can pick up a little on the outside of the head, that isn't a problem. There is an adjustment on the bottom rail to minimize this, but it doesn't affect sawing quality. What year is your mill? The thickness variation sounds like internal stresses in the log, especially if you are sawing 20' hardwood logs. Welcome to the Forum.

[VictorH]

What you describe is not what I would refer to as square you describe what I would call taper.  When you get a manual you need to align the blade to all the bunks - which are the parts of the mill that the log sits on.

[Magicman]

First, Welcome to the Forestry Forum, nstringer04.

Just to be sure, measure from your blade to the bed rails on each end.  I suspect that they are the same, and that your problem is that you are dealing with stress in the log/cant.  The logs and cants must be supported from end to end, and also should not be allowed to rise above the supports.  Logs & cants often need to be rotated 90° or 180° to maintain contact with the bed rails.

[giant splinter]

I agree with Victor on this one, the first thing I think you should check is the toe boards and on the end that is being effected. Look to see if its all the way retracted or if its below the deck bunks, might have a chunk of wood hanging it up. It could be a bunch of other things but start there and eliminate the other stuff one at a time. Also take a look at the movable bunks on the ends to see if they are properly adjusted and nothing is bent or damaged, all it takes is something as small as a pencil under those end bunks to throw things off. Run a stringline down your main rail to prove you are true to straight, checking your mill and bunk allignment.

[nstringer04]

Thanks everyone. Dave, it is a 2002 with 600 hours.

[Dave Shepard]

Thanks. That will help us to know which generation features you have.

[giant splinter]

Nstringer04,
What is happening when you cut on the way down the cant, is there any movement in the slabs or flitches such as the end of the material at the top of the kerf curling or jumping up off the cant?.
I think Dave and others may be on the right track with the stress idea also, is it just on two of the faces of the cant or all four?.
Is the cant laying on all of the bunks when the first or second pass through the log is turned with any sawn face down and laying on the bunks.?

[ladylake]

I'd vote for stress also, if they need to be perfect the only way is to cut a little oversized then take a skim cut. For crane mats I'd think a little off would be fine..   Also make sure your mill is supported good on both ends and in the middle..    Steve

[GAB]

nstringer04:
I do not disagree with what the others have written.
Check to make sure that the legs are low enough and don't keep the cant from laying flat on the bed.  I had the same problem once when the leg on the control side behind the wheel was not low enough and supporting the cant just enough to cause that kind of results.  If a toe roller is not down enough the results could be the same.
Good luck,
Gerald

[nstringer04]

I did notice one or two slabs popping up on the end once I finished the cut. I just drove down to the mat shed and measured several different timbers. Most of them were tapered a little also. I measured finished mats as well. Same thing. Must be normal on the long hardwood cants.

[Nomad]

I did notice one or two slabs popping up on the end once I finished the cut. I just drove down to the mat shed and measured several different timbers. Most of them were tapered a little also. I measured finished mats as well. Same thing. Must be normal on the long hardwood cants.

     No, it isn't normal.  Something is wrong.  My best guess is stress, as said above.  What do the side boards look like?  Or are you just cutting slabs to get the timber?  Checking mill alignment would verify it's a problem with the logs and not the mill.  If you can't get the manual from the previous owner, it's available from WoodMizer and not expensive.

[nstringer04]

I'm just cutting slabs. Is there a PDF manual for the woodmizer available?

[ladylake]

 
   Over here I'd think about 50% of hardwood cants have a fair amount of tension in them and will not end up perfect unless taking a skim cut.  Steve

[JustinW_NZ]

   Over here I'd think about 50% of hardwood cants have a fair amount of tension in them and will not end up perfect unless taking a skim cut.  Steve

yip agreed!
skim cuts are annoying but needed a lot of the time.

Cheers
Justin

[drobertson]

I never caught on to the size of the logs you are using, and have to believe the mill bed is level and true,  It sounds like to me you might need to saw a few logs through and through, and get an idea on how the logs react to taking off side boards. If you required precise dimensions it will almost require taking 4 face cuts then four side boards, trims cuts happen as well. rotating as the stress dictates.  Keep the cant supported with the rails, and look for the reaction after each cut , the cant will bow in the center or raise on the ends.   Most of this has been mentioned, sometimes we have to hear it again and again. Seeing is believing.

[Dave Shepard]

If you are taking heavy slabs, that may also contribute to log movement.

[nstringer04]

The man I am selling my cants to came and spent a few hours with me yesterday morning.  He has been in the business his entire life and been building mats for many years.  He said that the cuts I have been making are good to go and said that most cants are the similar at his mills.

[Cedarman]

That is good news that your cants meet the specs of your customer.  Still, understanding why they are tapered or not square is important because the next customer's specs may be tighter.

[5quarter]

x2 what Cedarman said. you definitely need to nail down whats going on. One bad saw job can cost you 10 down the road. Most customers will not appreciate the fact that their logs may have tension and cause you trouble. All they will see is that you can't cut straight lumber. I would take the time now, with this guy, and get these beams right. anyone can run a sawmill, but not everyone can make good lumber. If you figure this out now, that's more knowledge and experience you take to the next job, and so on.

[Chuck White]

Absolutely agree, even though your customer is satisfied with your cants/mats, you still need to get your mill squared up!

Your next customer might not be so agreeable!  :

[ladylake]

No reason at all for crane mats to be perfect, when the time comes to get perfect lumber with logs that have stress you will have to take skim cuts.   Steve