Results 1 to 7 of 7

Thread: timbers on circular sawmill half inch smaller on trailing end

  1. #1

    timbers on circular sawmill half inch smaller on trailing end

    Recently increased the lead on the blade because I felt the blade was making too much contact with the cant. The cant was usually a little thicker on the end furthest from the blade. Then I changed the teeth because I decided they had become to narrow and that was the cause for too much blade contact. Now instead of the trailing end of the cant being 1/4 bigger it is 1/4 to 1/2 smaller. This is aggravating me because I am trying to cut large timbers for a timber frame so I want what is left on the sawmill to be the same size on both ends. I suppose 1/4 is not too bad but the last one I cut was 1/2 inch smaller and that really irritated me. I don't think it is forces on the cants causing the problem because I am actually only shaving an inch or 2 off each side. I am recutting old dried cants to get rid of the twists that occurred as they dried. I am going to put a string on my tracks to see if they are straight and then maybe adjust some of the lead out of the blade. I really don't see why too much lead would do it though because it seams to me that too much lead would cause the end of the cant away from the blade to be larger. It seems like the trailing edge of the blade would be pushed in by the board you are cutting off and so that would cause the front of the blade to be pushed out. Maybe that is not the way it works.

    Thanks

  2. #2
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    12,298
    I have zero experience with a circular saw mill other than having watched one years ago; I have a bandmill. That kind of error would be unacceptable to me. I have no idea how the saw, rails, and cant are aligned and mechanically supported, but with that much off I would wonder first about the alignment then if there was any play in the structure allowing something to flex or move, following the blade in the kerf. I wish you lived down the road from me, I'd love to look at it.

    JKJ

    Quote Originally Posted by Jonathan D Cook View Post
    Recently increased the lead on the blade because I felt the blade was making too much contact with the cant. The cant was usually a little thicker on the end furthest from the blade. Then I changed the teeth because I decided they had become to narrow and that was the cause for too much blade contact. Now instead of the trailing end of the cant being 1/4 bigger it is 1/4 to 1/2 smaller. This is aggravating me because I am trying to cut large timbers for a timber frame so I want what is left on the sawmill to be the same size on both ends. I suppose 1/4 is not too bad but the last one I cut was 1/2 inch smaller and that really irritated me. I don't think it is forces on the cants causing the problem because I am actually only shaving an inch or 2 off each side. I am recutting old dried cants to get rid of the twists that occurred as they dried. I am going to put a string on my tracks to see if they are straight and then maybe adjust some of the lead out of the blade. I really don't see why too much lead would do it though because it seams to me that too much lead would cause the end of the cant away from the blade to be larger. It seems like the trailing edge of the blade would be pushed in by the board you are cutting off and so that would cause the front of the blade to be pushed out. Maybe that is not the way it works.

    Thanks

  3. #3
    Join Date
    Sep 2006
    Location
    Shenandoah Valley in Virginia
    Posts
    919
    Sounds like the head blocks are not the same distance from the edge of the carriage... Run the front head block up to the blade and set it a certain distance from blade, say 10inches... then push the carriage until the rear head block is at the blade and measure the distance... be sure not to turn the blade so you are measuring from the same tooth both times.

  4. #4
    Quote Originally Posted by Ed Aumiller View Post
    Sounds like the head blocks are not the same distance from the edge of the carriage... Run the front head block up to the blade and set it a certain distance from blade, say 10inches... then push the carriage until the rear head block is at the blade and measure the distance... be sure not to turn the blade so you are measuring from the same tooth both times.

    Thanks that sounds like a very good idea. Should have thought of that. I think I have done that years ago but did not think about it now for some reason. I did also recently adjust the tension on them because they moved so easily that when I tried to move the lever to adjust the distance to the blade they would move instead of the ratchet system. That does not seam like it would have changed the distance, but maybe. Also things just get out of alignment I guess because of the stresses. I will look at that as soon I get out there today.

  5. #5
    My dad had a circular sawmill in the fifties. That's a long time ago and I was a kid so memories may be inaccurate...

    That mill was very sensitive to the issue you are having due to how the teeth were sharpened. The sawyer would sharpen the teeth as consistently as he could and they would pull the blade into or out of the cant. My dad decided to sharpen the teeth somewhat randomly using the theory of compensating errors. The sawyer thought he was crazy but with the random tooth sharpening the saw cut straight.

    What do you think? Inconsistent tooth sharpening saved the day on that mill.

    C

  6. #6
    Join Date
    Mar 2015
    Location
    cleveland,tn.
    Posts
    385
    think about what a few even slightly damaged teeth on one side does to a chainsaw cut, you can not keep it from pulling to the sharp side. maybe there are similarities.

  7. #7
    I remember seeing this issue in action on a real circular sawmill.

    My dad also invented a new sawmill tooth shape that solved this problem. He never patented the idea but it solved this problem. I wish I had one of those teeth but I don't.

    C

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •