My WM LT28 is showing no interest in cutting square. When I'm cutting a 12" cant it will be out of square 1/8" to 3/16" when checking with a framing square. I have tried making cuts then roll log 180 degrees, also tried making cuts then roll 90 degrees so fresh cut is on back stops. Nothing seems to affect the problem. Is this a by-product of the cantilever saw mill, or do I have a issue? Oh yeah, cutting SYP.
I have no experience with an LT28, but you can forget the idea that the cantilever design is at fault. That doesn't mean that you may not have an alignment problem. I would wonder if your "dog board" (the last board left on the deck after you saw a cant) is exactly the same thickness from side to side? That saw head alignment has nothing to do with your side support alignment.
After flipping 180° and opening the second face, flip it back over 180°. Make a skim cut. Is the blade square and cutting evenly across the original cut? I suspect that you will be cutting a thin wedge. A slight adjustment with your blade guide should correct this.
I'm assuming that the blade guides are the same as on the LT40.
Here's my opinion, I have an LT-40 not 28. Agree with Mr. Magicman just a few more details. You're on the right track if you have your square out. 8) 8)
First two basic alignment checks. You have to make sure you're cutting parallel to the bed rails. Check the blade alignment as per the manual, and importantly, whether boards are the same thickness on both sides. If they're not obviously nothing is going to be square. Then check your uprights for 90 degrees to the bed rails, and that the sawn face is square to the face against the uprights. Should take care of things. If not, then you might not be clamping flat against the upright (out of square with the new face), or lifting one side off the bed rails in clamping.
With an aligned mill, the focus is on cutting the first two sides square, then making sure the board is flat on the bed rails thereafter. Talking about the small uprights, not the large ones. It is very important to be able to eyeball the face against the uprights being vertical (square to the bed rails), especially if winging it using only the large uprights.
I'm often tweaking the clamp up or down to adjust that tilt if it doesn't look square.
I run a different brand but a good torpedo level is always in my side pocket and even though mill is all plumb i always check for level when i roll it after first cut either i put flat side on the stops or put flat side to the blade cut to save blade life. It might eat a little time up but the second cut is the most important for making square cants.
all the above advice is valuable. You say you turn the cant 180 degree? To get your 12" cant square, you must turn your cant 90 degrees at some point prior to the finish cuts. Ya have to have,at least one corner a true 90 degree before you can square the cant. Maybe you are already doing this? Anyway,if you keep flipping it 180 degree you will only get a parrallegram.
With the cantilever head you can get up to 1/8" pull down out on the edge of a wide board and I'd think the pull down would vary with sawing speed. To me that would make it hard to keep things square on that type of mill. I know when I used to have WM mills saw for me 3 x3 and 4x4 were most times out of square . Steve
You might check the accuracy of your framing square before tweaking anything. I've seen a few pretty far off in 12".
It's likely your mill is just breaking in and needs a twink here or there or both.
I'd suggest getting out the manual and going through the alignment procedure. If you run into trouble, call for Wood-Mizer tech help.
All the above is excellant information, but when I experienced this problem I discovered my first face cut had debri laying between the face and rail, and sometimes even twist due to stress, each will throw additional cuts out of square. I'm kinda leaning towards Bibbyman's suggestion. Good luck in getting this worked out.
The only times I make out of square cants, either there was debri on the bed rails, the mill is out of adjustment, or I pushed the new style clamp in so hard I lifted the cant off the bed rails
there is no inherent lack of ability to produce uniform lumber in a cantalievered woodmizer ....... LT 40 1995 to 2009 LT 70 2009 to present ....3/4 million bd ft
When I first got my mill, I ran into an issue like this and it turned out to be movement in the dogs. They would square up when not clamped, but when clamped they would tilt. Setting them up correctly then tightening everything down again solved the problem. The manual covers the steps to do this. :P
I'm sure you WM guy get your can'ts fairly square but with varying amounts of pull down how do you adjust your stops to the blade which will determin how square the cant ends up. Unless sawing slow there will be pulldown on a WM. Steve
Quote from: ladylake on January 07, 2011, 07:04:32 AM
I'm sure you WM guy get your can'ts fairly square but with varying amounts of pull down how do you adjust your stops to the blade which will determin how square the cant ends up. Unless sawing slow there will be pulldown on a WM. Steve
Good golly you are only talking a 16th of an inch in two foot of distance. ;D
I know I was concerned about the same thing before I bought my mill. But I do got to say that after following all the steps to get the saw head leaved and square it holds that position very well. The bed area gets a good work out having logs rolled around on it and the stops being clamped against and this is the area on both the Cooks and Woodmizer where a cant can get out of square. Also with the four-post design of the Cooks, a rusty chain jumping a tooth on the sprocket will cause more problems then 1/16".
The "pull down" as you call it is caused by a very slight bending of the mast when the saw is in the cut, and also by slack between the various moving parts (e.g, track bearings, mast bearings).
Bending is minimal because the masts are stiff enough for the job. The more powerful motors that might bend the mast a little more are also heavier, so they pre-load the mast. The pre-loading automatically gets compensated for when tuning the mill.
Slack comes out very quickly under relatively small loads, and doesn't change after that. As long as the blade is buried in the wood, the slack will be taken up.
Properly tuned, the outboard end of the blade is 1/16" higher than the inboard end.
I aim for a maximum of 1/64" off square in and 8" width, and I won't accept anything worse than 1/32" in 8". Timber-framers are always commenting on how square my timbers are -- and they prefer buying from me, even though my prices are higher than other locals'.
The only time I've not had the head pull down was when I was skimming the top of some 24" wide glued-up braces. The owner just wanted me to flatten out any irregularities in the glue-up job so the top of the blade was out of the wood. There were 4 braces and they were exactly 1/16" thicker at the outside end. It was so consistent the owner just compensated for the taper in the brace pockets.
Getting small timbers (4x4, 3x3) square is difficult because the side stops are so low when you make the second cut. You need to pay extra attention to squaring the stops during setup to be sure they are still square when they are that low. I rarely cut stuff this size out of a small log -- it's just too time consuming. I'll typically cut them FOHC from 8x10 or 8x9 cants. It's easy to square up the larger cants and from there cutting square small stuff is easy.
There's a lot of myths out there about the deflection on a cantilever head. That's all they are -- myths.
I wouldn't call pull down a myth and common sence would say the more pressure apply to the band the more pull down. I'm sure you can get nice square cants by taking your time with a nice steady feed rate. Steve
Quote from: backwoods sawyer on January 08, 2011, 12:06:40 AM
Quote from: ladylake on January 07, 2011, 07:04:32 AM
I'm sure you WM guy get your can'ts fairly square but with varying amounts of pull down how do you adjust your stops to the blade which will determin how square the cant ends up. Unless sawing slow there will be pulldown on a WM. Steve
Good golly you are only talking a 16th of an inch in two foot of distance. ;D
I know I was concerned about the same thing before I bought my mill. But I do got to say that after following all the steps to get the saw head leaved and square it holds that position very well. The bed area gets a good work out having logs rolled around on it and the stops being clamped against and this is the area on both the Cooks and Woodmizer where a cant can get out of square. Also with the four-post design of the Cooks, a rusty chain jumping a tooth on the sprocket will cause more problems then 1/16".
If your talking about a chain that lifts the head up and down that would have to get fixed right away, just a maintaince item of keeping the chains oiled and tight. Steve
Roxie,some day when you have some time get the manual and follow the procedure, as one thing affects the outher, don't skip steps.Be sure the set in your bands is even from side to side. Frank C.
All I can say is that I cut over 1.5 million bf per year on a Wood Mizer and if it won't cut square I would not have bought my 3rd one.
This is like saying I wouldn't by a Chevy truck cause I had one and it got stuck. There might be some room in there for operator error.
And all I can say, is that we are cutting wood, not building a piano.
Quote from: ladylake on January 08, 2011, 04:57:59 AM
I wouldn't call pull down a myth and common sence would say the more pressure apply to the band the more pull down.
Nope, pull down isn't a myth. Common sense and physics say there will be more deflection in the mast if you apply more pressure to the band. But ... the deflection of the mast is very, very small.
As I said before, most of the movement occurs when the force of the blade pulls out the slack in the various parts of the carriage. It doesn't take much pressure at all to do that. Once the slack is out there's no more to take out.
Quote
I'm sure you can get nice square cants by taking your time with a nice steady feed rate. Steve
I wouldn't know. I keep my feed rate right up to the max. In other words, push it until the motor just starts to slow down.
A slow feed rate dulls the blade sooner and eats into production.
When I saw this debate had to run out in the cold, dark and snow to see how square the 6X6s were that I cut yesterday. I measured them yesterday and was amazed they were exactly what the setworks said they would be but I didn't check them for square. Well I was happy to see that in 90 % of the places I checked they was no out of squareness and the worst spot maybe 1/16. pretty good for a mill that I leveled in about 5 minutes by someone who hasnt got a clue about sawing. I think my new woodmizer did just fine. I pushed it hard on a couple of boards I cut to see what would happen and the blade dove like crazy. I don't THINK the mast was deflecting though. I think that would happen with any mill. The front of the blade will tend to go down and the back will buckle up in the cut. Somthing I did notice that happened to me quite often was the cant would rock up a bit when I set the clamp. somtimes I had to reset the clamp a couple of times before the wood would sit flat on the bed. So far I think I made the right choice when choozing woodmizer. I'm sure they would have changed the design by now if pulldown was a troublesome issue. There has to be an adjustment you can make roxie that will fix your issue.
If you push the feed rate too hard, the engine (and the blade) starts to slow down. That leads to wavy cuts. So that's why you want to push it just to where you here the motor start to drag. If your blade is dull you'll have to go a little slower to avoid the waves -- so change the blade.
The mast on the LT70 is much stiffer than on the LT40's (I imagine because of the bigger engine), so you aren't going to have a problem with it deflecting.
Pushing too hard on the clamp can lift the cant and/or deflect the side stops. You want just enough pressure to hold the cant down. And sooner or later you're going to go a little light on the pressure and learn all about cutting spiral cants :(.
From what I've seen cut, bought cut and cut myself when it comes to rough sawn lumber 1/16 deflection is absolutely impeccable in my eyes. :)
I would rather build with lumber straight off the saw then the crap then I'm forced to buy and deal with in construction.
If I could buy lumber with 1/16 deflection on a daily bases I just might consider working for free. :)
BTW what Brucer says makes perfect sense to me as I have a vast mechanical background.
Quote from: gator gar on January 08, 2011, 07:07:26 PM
And all I can say, is that we are cutting wood, not building a piano.
But my mill sings when things are perfect! 8) 8) 8)
I had the same problem with my Lt 28--Turned out I was clamping the cant too low and too hard, tipping the cant a little. You just have to check every time that you are flat against the uprights.
I cut logs as fast as it will cut with a 51 h cat no dive and all square. wood mizer is the best 8) 8) for me. ;D
If a Wood-mizer couldn't cut a 6x6 square, reliably, because of pull-down, as is being entertained here, then what would 24" wide boards look like which are cut as fast as surface quality permits? They'd be wedges. I cut wide boards like that all the time. Mine are the same thickness on either side. Within a 64th, 32nd or 1/16 I'm not sure, sitting here, but no way off by any amount that matters.
One factor not mentioned so far...JR's mill has a newly built pineywoods turner/clamp. The clamp and the turner are one and the same. When clamping a cant, it is quite easy to lift the back side of the cant slightly. There is a learning curve..
Quote from: pineywoods on January 08, 2011, 11:33:18 PMThere is a learning curve..
To keep it from turning up on it's side ???
We bought our LT28 in april and it seems to need tweaking every once in a while. I suggest making sure the rails are 90degrees from the backstops which they should be if they haven't been adjusted (mine have been good every check) Then continue adjusting the blade for square cant off the bed. This will of course produce an uneven board with each adjustment but you should be able to get eveness from the cant into the 32nds. NOTE from personal experience: Make sure the cant you are using to do the adjusting isn't stressed rising in the middle or either end. We also adjusted the bottom board thickness successfully twice so far. I just call it growing pains... Like sawing stickers...
I really should stay out of this but here goes. The comments above should help, here are some other ideas for all band mills owners not just WM.
Round log take one or two cuts with the log clamped, turn log over 180 degrees, make sure you are not Rambo and over clamp ( pulls the log off the bed rails), most times the weight of the log will hold the log down if it is against the back supports or dogs. Take one or two cuts on this face, turn log 90 degrees clamp log, get a framing square and check to see if you are square from the bed rail to the flat side of the log. ( you should have round side, bark, top and bottom and a face on the back support and a face against the clamp.) If not reclamp, do this for a few logs and look from the operator station down the log and note when it is square and what it looks like. Your eye is a percision instrument. Once you get in your head what square looks like put the square away.
And --- when you turn 180 the log should be against the back support square when clamped, this would be you last face to open.
Now if your mill is cutting curved lumber or the mill is out of align then this will not work. When I train a new mill owner I like to show them this, it seems to help. It also will not work if you only turn the log 90 degrees.
Hope this helps,
Marty