Results 1 to 6 of 6

Thread: Wood moves and sometimes it moves back

  1. #1

    Wood moves and sometimes it moves back

    Attachment 415860

    I set up my Sjobergs 1500 bench in the Cave of the Modern Neanderthal about a year ago (Sept 7, 2018). Picture above was from the first day after it was all carted up the stairs to the Cave and assembled. I was particularly pleased that the top was really flat. I was puzzled and bemused about the care and maintenance guide that came with the bench. It started out with a defensive paragraph and graphs about wood movement and fungal growth with moisture.

    https://www.woodcraft.com/media/W1si...d3afc852b28a9f

    I confess that I had not done my usual deep dive into internet analysis and review of this bench before purchasing it. After reading Sjobergs' disclaimer, I proceeded to search out and read many reports and of how bad beech was as a workbench wood (baloney), how several Sjobergs benches warped badly when stored over the winter in an unheated warehouse in coastal Canada (not surprising), and various other negatives. I believe the disclaimer was a response to the criticism. I began to have doubts about my purchase but by then the Elite 1500 was already in its new home and I would just have to flatten it if it warped or bowed.

    The climate of the room in which the bench lives is completely relevant to the story. The Cave is not at all a moist, underground cave. It is a room on the top floor of a four floor building and it is actually the home of the two air handlers for the condo. The condo has two levels. The air handlers are "open plenum" , meaning that a huge return air duct pipes air into the Cave from the top of the two story foyer. The air handlers draw from the room. The room is, in effect, part of the return duct. When both units are running, quite a force is needed to pull the door closed. Also, since the duct is at the very top of the foyer, the Cave tends to be the warmest place in the condo. This description should convey the environment in which the bench exists. It is a a warm, conditioned, well-ventilated space in Atlanta, Georgia. I do not have a thermometer or hygrometer in the room, but tools in the room have not accumulated any rust so it must be about 50% RH in the summer. Probably quite a bit less in the winter. I would rate the Cave as good a place for a bench as you could reasonably expect to have in the Southeast United States.

    I was disappointed but not surprised that I was able to detect hump in the middle of the bench after about 6 months. Wood does move. My measurement was a 2 foot ruler which I oriented cross ways (perpendicular to the grain) on the bench top. It rocked a bit. When I pressed down on one end, the other end would be a 3 or 4 mm off the top. It was not bad and the curvature was more at the edge than the middle. The breadboard ends were straight so the distortion was just a mound in the middle of the main slab. The bench manufacturer cannot anticipate where a bench will live. To me, flattening a bench top should be considered routine maintenance not a defect. I took to Google and looked at several videos of people tackling the flattening process. My thoughts were that I could easily make matters worse. Anyway, I did not have a lot of time in the shop to take on the job.

    Well today after a summer at the lake, I am back in Atlanta and the bench is flat again. This is a lesson in the happy consequences of procrastination. I mean it is really, really flat. Here are the best pictures I could take to illustrate. The ruler applied lengthwise is 4'. I see no gaps. A 2' ruler placed laterally does not rock. It is hard to get a good photo of the edge. Trust me it is flat.

    Lengthwise
    StraightEdge1.jpg
    Lateral
    StraightEdge2.jpg


    Congratulations to the bench for acclimating successfully. Thanks to the wood scientists at Sjobergs for successfully kiln drying the 4 inch wood with so little internal stress and for accommodating movement due to moisture acclimatization without creating more stress. I still like this bench quite a lot.

  2. #2
    Join Date
    May 2013
    Location
    Liberty, SC
    Posts
    575
    Good things come to those who procrastinate. Best wishes with your work.
    You never get the answer if you don't ask the question.

    Joe

  3. #3
    Join Date
    Apr 2015
    Location
    Bay of Plenty, New Zealand
    Posts
    67
    I do wonder a bit about the Sjoberg benches and benchtops. On thing I cannot clearly see from the photo's on the web is if the breadends are glued in or allowed to slide.

    I'm in the middle of making a "Swiss cheese butcher block" and after I brought a 7' x 2' x 1" laminated piece of European beech home I took the plastic wrapping off and it warped within an hour. Next day it was dead flat again. That alerted me that I needed to make allowance for movement even that the top is going to be only 17" ~ 18" wide.

    It took me a little while to figure out how to ensure solid support and keeping everything solidly flat while allowing for the wood to move.
    Last edited by Marinus Loewensteijn; 09-13-2019 at 7:37 PM.

  4. #4
    It is unlikely that your ruler is flat.

    The proper way to test it is with two parallel thicknessed beams that are near the full length of your bench
    This way you can pair them together to check for light, you can flip one around to make sure these beams are not bowed in the same direction.
    If they are any shorter than the length it will cause problems.

    If you use your bench for total reference you will double the error matching two lengths

    That's just my 2cents
    Other folks like to hack their benches up
    Tom

  5. #5
    Join Date
    Apr 2013
    Location
    Okotoks AB
    Posts
    1,272
    Quote Originally Posted by Joe Tilson View Post
    Good things come to those who procrastinate. Best wishes with your work.
    When I was a kid, my dad had a lecture or saying for every fault & misadventure I had, and one of his favorites went something like "never do today what you can put off until tomorrow" or something like that. Maybe I didn't remember it correctly

  6. #6
    Quote Originally Posted by Marinus Loewensteijn View Post
    I do wonder a bit about the Sjoberg benches and benchtops. On thing I cannot clearly see from the photo's on the web is if the breadends are glued in or allowed to slide.

    I'm in the middle of making a "Swiss cheese butcher block" and after I brought a 7' x 2' x 1" laminated piece of European beech home I took the plastic wrapping off and it warped within an hour. Next day it was dead flat again. That alerted me that I needed to make allowance for movement even that the top is going to be only 17" ~ 18" wide.

    It took me a little while to figure out how to ensure solid support and keeping everything solidly flat while allowing for the wood to move.
    The breadboards are attached with two lag bolts. There are large flat washers and presumably enlarged holes in the breadboard to allow for movement. Glue would be a bad idea. No evidence that the joint is glued.

    Good luck on the butcher block.

Posting Permissions

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