not cutting same height

[REGULAR GUY]

I appreciate everybody's time and responses.  I've measured and measured the blade (with tension on it), to every rail and they all measure the same.  I'll try slabbing lighter as I've been just straight to sawin cants, and then into 2" by 8"s.  I've put a straight line across rails and all is good.  Yesterday I cut a 12' white oak log and it did the same thing, on different rails the front of the log was setting high in front...with a new blade.  By different rails I mean it was not the same rails than the longer (20') pine log.  I always kinda go slow into the face and after blade is into log speed up slowly to "proper' cutting speed. I'm not at all unpleased with the mill, it's a small (hopefully) adjustment somewhere just gotta find it. I'm thinking, as a few said, that it may be the center jacks to tight. I'll loosen them and clean up again the area.

[Magicman]

If I am following what you said in the OP, the first reply, and again in your last reply, the log/cant is raising up off of the sawmill bed (rails) and causing the end to be thinner?  Is that correct?  If so, then you do not have a sawmill problem, you have a log with tension problem.

[barbender]

If you are slabbing straight to your cant dimensions, that could well be your problem.

[REGULAR GUY]

After putting the log on and doggin it down, I'll take the first cut, sometimes slabbing the first cut to the can't dimensions sometimes not, then flip the log 180 degrees to the flat spot on the rail/bed.  When I flip that log, it is setting approx. 5/8" off the rail at the face ( where the blade goes into the log), with the rest of the log laying flat on the rails.  I wasn't at the mill today to try anything new, but yesterday, with a new blade,  either with a 20' pine log or a 12' oak log, ( the 12' log positioned farther back from the saw head ), there was a gap between the log and the rail. For example, after flipping the log to flat spot,  I set the blade at 10"s,  cut the entire log,  and the first several inches of the log (where I first saw into it) is approx. 9 3/8" and the end (rear) is 10"s. I almost always position the log with tapered end toward saw head. This is baffling me, I'll try relieving the tension in the center jacks. Thanks again for all ya'lls input and help. Regular Guy   

[REGULAR GUY]

Forgot to mention......I'll try slabbing different.  Thanks,  Regular Guy

[Ga Mtn Man]

In your post above you said "I've put a straight line across rails and all is good".  Did you mean to say you put a straight line across the bunks...?

[Tom the Sawyer]

Certainly a curious predicament...

With all the things you have checked this might be redundant but, who knows?  After your initial opening face, and before you turn the log, have you measured the height of the new face from each of the bunks?  Are they identical?  Have you checked the flatness of the opened face with a straight edge along its length? 

Is there anything else touching the bottom of the log, either for the opening pass or after it has been turned (toe board, clamp, turner arm, etc.)?  Watch your clamp very closely as it contacts the log.  If out of adjustment, as pressure is applied it may be lifting the log slightly.

Hope you find the source, it can certainly be frustrating when things don't go as they should, especially when you can't figure out why.

[5quarter]

Dollars to doughnuts Its you're sawing speed. If you are creeping into the log and slowly picking up the pace, you're going to see that happen on nearly every cut, to a lesser or greater extent. You should be entering the log at or near regular sawing speed. watch any production saw operate. it feeds at one speed from beginning to end. You may have to slow a little through large knots or max width cuts, but the rest of the time saw at the max feed rate that your saw will allow. you're blade is really designed to be pushed to its limit. You should get better cuts and more bf per sharpening if you maintain a steady feed rate through the entire length of the cut. just today I was sawing a practically petrified bur oak with a blade that I wasn't sure if I had sharpened or not. On my opening cut, I crept into the log trying tell if it was a sharp blade or not. turns out it was, but the resulting cut had dipped on entry about 1/4" for about the first 3 feet because of my dinking around trying to tell if my blade was sharp.   :-\
Anyway, give it a whirl and let us know how it goes.

[LeeB]

When you pulled the string line, did you block the string up an equal amount on each end, say 1/2"? If you have a slight bow down the lenght of the frame, you might not notice the string is being pushed up if you don't raise it slightly above the bed. You don't want your string to actuall touch the bed.

[Brad_S.]

My mill (Timber Harvester) was built with an intentional camber in the frame. It needs to be jacked up and supported on both ends prior to sawing. It is easy enough just to sight down the edge rails and see whether you have jacked it up level or if it still has a high spot in the center. I am not familiar with TK but imagine you can do the same.
My money is on the frame not being leveled crew.

[ladylake]

The easy way is to run the head too the front, if the back jacks are loose you have too much pressure on the middle jacks  Steve

[terrifictimbersllc]

The mill bed (tops of the rails) isn't necessarily a straightedge unless it is jacked to be so.  Imagine the mill bed is very curved or "crowned" along its length, with the mid-point being the high spot.  The head  tracks the curved rail so that the blade is always the same distance from each bunk.  That works fine for cutting flexible boards.   But the cant is not flexible.  So think of a curved cant now being flipped 180 degrees.  The belly of the curved cant is down and the belly of the mill is up.  Both ends of the cant are off the corresponding rails by a certain amount, or if one end is pushed down , the other end is twice as high.  Not hard to come up with 5/8" in 15-20 feet.  Nothing wrong with the mill.  Sight along the rails when jacking it up, and jack it so that the rail is straight along its length, not crowned or dipped.

[drobertson]

Four post mills must be very sensitive to being level,  I have to say, it is a head scratcher, if the alignment was good when the mill was put up, one would think it would be there when restarting.  Alignment can cover many facets of a mill, from the blade guides and parallelism, to bed rails and main frame.  This issue has captured my full attention for sure. I really would like to know the final result.

[ladylake]

Every mill has some flex in it and the jacks need to be set right when cutting long, plain and simple.   Steve

[slider]

I don't disagree with proper placement of the jacks .My mill is only a 20 footer but I have had it rocking on the center jacks due to soft ground and some laziness on my part and it has never done this.Sawing tension wood is a whole different story.I had some popular a while back that every cant was trouble.

[REGULAR GUY]

Sorry fellas, I haven't been back for a while on the computer and started up again on the mill after doin other things a bit.  After trying different things,  I cleaned up the mill (underneath and around), changed my blade entry speed etc., and something was still  off so I retightened the jacks  makin sure the center jacks were not to tight (creating  a crown in the center), and after that,  the mill cuts great. That little crown in the center, (which didn't  show up when I measured the height of the blade on each rail ?!!? ), allowed for the second cut (180 degree turn) to be off approx. 5/8" because the log was above (lifted off ) the  rail nearest the cutting head 5/8". I hope my explaining makes sense. I thank you all for all your help and input. Regular Guy


9or

[Magicman]

Thank you for following up with your fix.  Everyone, regardless of their sawmill manufacturer, learns when problems are identified and solved.  Every possible solution that was offered was the result of someone's experience with a similar problem.

The FF Encyclopedia Rocks.   :P   

[drobertson]

Makes perfect sense, hard to believe it took this long to figure it, not being critical, cutting methods can often times cause trouble shooting troubles,  glad you have it figured out,

[reswire]

I used to have a TK 1600 and never experienced that problem.  I never set up on a solid (concrete or the like) surface, always adjusted the bed as level as possible, and never had a problem.  I can't remember who made the post, but they offered the suggestion that you might have something under the center of your mill, propping up the cant.  Sounds reasonable.  I would also check for sawdust or other foreign objects that seem to accumulate on the bed rails; even though the head is extremely well built and heavy, you can have an issue with trash that is normal on all four post mills.  I also started into the wood slowly, and built up speed while sawing,,, no problems there.  I did have problems with the original blade guide assembly, but Timberking sent me new blade guides at no cost, which fixed a problem I had with wavy cuts.  Talk to Matt at TK, he is very knowledgable, and probably your best bet.  The mill bed is rock solid, never considered it to be, nor was it ever a problem.  If you bought the mill second hand, maybe the previous owner could shed some light on what he may or may not have done with the mill,,,, if he's honest.  Good luck

OOOPPPSSS!  Just saw where you figured out the problem.   I was reading from the start and skipped to "POST".    If you have any problems send me a PM, maybe I can help if problems persist.  I know there are a lot of TK owners on the forum, they are good mills.

[LeeB]

Sorry fellas, I haven't been back for a while on the computer and started up again on the mill after doin other things a bit.  After trying different things,  I cleaned up the mill (underneath and around), changed my blade entry speed etc., and something was still  off so I retightened the jacks  makin sure the center jacks were not to tight (creating  a crown in the center), and after that,  the mill cuts great. That little crown in the center, (which didn't  show up when I measured the height of the blade on each rail ?!!? ), allowed for the second cut (180 degree turn) to be off approx. 5/8" because the log was above (lifted off ) the  rail nearest the cutting head 5/8". I hope my explaining makes sense. I thank you all for all your help and input. Regular Guy


9or

Using the blade to bunk measure will not tell you if you have a crown along the length of the frame. Pulling a string tight from one end of the frame to the other   and measuring to the bunks from the string will tell. Be sure to block the string up an equal distance on each end.

[delvis]

I would say stress in the wood, but if it's happening every log and it's only happening on one end, it's more likely the mill is not sitting true.  You can tell if it's stress after you flip the log 180 degrees and saw a few boards off, the front end should relax and settle toward the bed.

I had a Timber Harvester mill which was a 4 post mill and the rails needed be checked a lot when first setting it up on each job.

If you can get some machinists blocks that measure 1" to put on the bed rails you can run a string the length of the mill to verify whether it is sitting flat or not.

[delvis]

Sorry fellas, I haven't been back for a while on the computer and started up again on the mill after doin other things a bit.  After trying different things,  I cleaned up the mill (underneath and around), changed my blade entry speed etc., and something was still  off so I retightened the jacks  makin sure the center jacks were not to tight (creating  a crown in the center), and after that,  the mill cuts great. That little crown in the center, (which didn't  show up when I measured the height of the blade on each rail ?!!? ), allowed for the second cut (180 degree turn) to be off approx. 5/8" because the log was above (lifted off ) the  rail nearest the cutting head 5/8". I hope my explaining makes sense. I thank you all for all your help and input. Regular Guy


9or

Using the blade to bunk measure will not tell you if you have a crown along the length of the frame. Pulling a string tight from one end of the frame to the other   and measuring to the bunks from the string will tell. Be sure to block the string up an equal distance on each end.

You have to remember the head rides on the frame not parallel to it, so if the rail is crowned the head is going to ride it like a roller coaster. 

[ladylake]

As mentioned earlier the easy way is to run the head all the way to the front, if the back jacks are loose the center ones are too high.  Really no need to run a string.  That little bit of flex can be used to your advantage when you are cutting stressed lumber and don't have any extra cant to do a skim cut as you can jack the back or front up a bit to make the cant lie on the bed.   Steve