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Wood cracking, heeelp!!

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  • Wood cracking, heeelp!!


    I've been working with the Worthington wall clock for a quite a while now and I was SO proud of myself last weekend when I had finally put all the final touches in place and it was officially finished. It's my first large clock and it's going to be a birthday present for my dad. Boy, am I thrilled to see what he says when he sees it!

    But then the reality hit me hard. The clock has been hanging on my wall for a week for a test run. Today I took it down to be packed and wrapped and ready to go tomorrow. And I found a very bad crack in the most prominent piece, the gable ornament. The wood is red oak and it had cracked along one of the brown stripes or rays.

    There was no crack there three weeks ago when I assembled the clock. There was just a small scratch-like crack two weeks ago when I did the finishing (2 coats of Danish oil) and a week ago it was just the same. Now it's 1 mm gap all way through. I inspected the clock very closely and found several small cracks. Actually they all were in the pieces cut from the same board. Can it be coincidence?

    I need your advice for three things:
    1. What am I going to do with the gap? I have wax putty in almost perfect colour. But if I'd add it and sand it down it'll ruin the finish. On the other hand I need to give it away tomorrow. I guess I'll need to ask it back and fix it later.

    2. Is there any way to prevent the other small cracks cracking wide open, too? I was worried about the joints holding with just glue when the humidity changes, but it never occurred to me the wood would be so fragile itself. Now we are in ca. 40% humidity (from 60% while assembling) and it'll drop down to 20% in winter.

    3. What was I *supposed* to do in order to prevent the cracks all together. I mean, is this typical for oak and should be treated accordingly? All the cracks are in the brown rays. Yet I'm relatively new to woodworking, I haven't seen anyone mentioning this before.

    Any ideas appreciated,
    Attached Files

  • #2
    Satu, is there any way you can get a clamp, rubber band or tape to hold it together after gluing it? I would use Elmer's Glue All or Aleene's Tacky Glue. They both dry clear. Good luck with it.
    Mick, - Delta P-20

    A smile is a small curve that straightens everything out.


    • #3
      This is a tough question to answer not knowing the moisture content of the wood before cutting, the width of the board and the types of joinery used. In regular woodworking such as furniture or cabinetry, boards are never used wider than 2 1/2 inches. The beginning moisture content should be no more than 8%. Boards are edge glued together to become wider boards...each board opposses one another to stabilize the board. If you looked at the ends of the boards they would smile, frown, smile, frown etc. A crack like you have appears to be a combination of too much moisture in the board, and the ends of the clock are holding the board from shrinking properly. It's kind of like holding the ends of a piece of paper..if u pull hard enough it will tear.
      There is not too much you can do to stop the movement now. Here's how I'd fix the crack. 2 part super glue. pour the super glue generously into the crack and then wipe off any excess from the surface and back of the wood. then pour in the catylist/hardener, and immediately clamp the joint as best as you can. You have to work super fast..have that clamp ready before you start because that glue is fast. use your wax stick to level any imperfections in the crack. You dont have to sand or refinish with a wax stick..this is actually meant to be applied after finishing not before. Rub it in, then use a plastic spatula to remove the excess. That's about all you can do without re-cutting a new piece. At least it appears you kept the oak natural..that always helps with repairs.
      Jeff Powell


      • #4
        Hi, here is a sight for you, they will send you a free catalog too. but they sell ca glue. they have 3 kinds. great for filling those piskey craks. the name of the glue is CA glues. try#'s 08x11 and 08x21 and 08x31 . they have lots of great glues you could try. lots of empo. don't worry. it is fixabale. I live in calif . too. and wood just does some darn things here. it just adds caricture. if thats a word. buy the way from what i can see. your cutting is pretty nice. can we see the whole clock. bet it looks great. seems like red Oak. is one of the hardist woods. but it will crack, in just a breath of air. darn it any way. don't know why I keep using it. LOL. Evie


        • #5
          I have made literally dozens of that particular clock over the years until the price of red oak got out of site for price out west here so the last half dozen I actually made with baltic birch plywood and stained it to an oak color.
          Here is one in red oak and maple accents . I still have one of the BB ones on my living room wall and from a couple feet back it is hard to tell it from solid oak.The secret to making a BB clock look like a real oak one is in the staining and hard film finish applied.

          I always used quarter sawn red oak in my clocks rather than flat sawn because it is so much more stable and I have those clocks sold all over Canada and the USA and a few overseas and I have never heard of one cracking anywhere yet in the last 15 years . I attribute a lot of that success to applying several coats of laquer after sealing with oil on every bit of the clock both inside and out so it is better protected from changes in atmospheric conditions and also the use of quarter sawn wood..

          Sorry to hear about the crack in yours but you got some good advice here for a possible fix for it. Hope you manage to repair the crack so it is hardly visible..
          If worse comes to worse you can always remove the crest and replace it with a new one providing you used Aleene's tacky glue for construction. With that glue you can heat the wood with a hair dryer blower and slide a sharpe knife under the piece and you will be able to remove it.
          I don't know of any other glue that has that property and that is why so many people use it for fretwork. If you happen to use CA glue for any part of a repair or assembly, , just remember that you will probably never be able to get it apart without damaging the piece and also the piece that you are trying to remove it from.
          The reason I know that can be done with Aleene's glue is that someone pointed out a panel that I had accidentally assembeled upside down in a Rhinelander clock long after it was sold. I took the clock apart with the above method and re-assembled it and apologised to my customer for my mistake and she was very happy that it didn't cost her anything because it was my mistake and I was glad to make it right for her..

          The task ahead of us is never as great as the power behind us

          Delta P-20 Scroll Saw, 14" x 43" Craftex Wood Lathe and Jet 10" Mini Lathe .


          • #6
            I had to give the clock away on Sunday so there wasn't much I could do now. What I did was a cosmetic emergency rescue: I took a small bit of the wax stick, warmed it in my hands to make it slightly softer and pushed it to the crack. Then broke away the excess. It reaches only 1 mm deep in 6 mm thick wood, but now the crack is visible only in closer inspection.

            I guess I'll wait and see what happens during the winter and ask the clock back for maintenance later to fix all the possible cracks in one go. You're right about the wax stick. I made a test swatch and it finishes nicely without sanding. Previously I have used it prior to finish in knot holes and planer chip-outs. I have melted the wax and dripped it in place. It smears the surrounding and needs sanding in unfinished wood but apparently can be easily scraped off if applied after finishing.

            The wood I used for the cracked pieces was a 12" wide board made of two boards glued edge to edge. It was as dry as possible in my power. I bought it in mailorder and received it in December. Since then I have stored it indoors, not in the carage/workshop. Unfortunately I cannot stop seasons from changing and it happened to be fall, the most humid time of the year while assembling the clock. What would be the ideal conditions in a workshop, temperature & humidity in your opinion?

            The piece that now broke was and will be stretched, no question of that. However, small cracks also appeared in pieces that are not being stretched. That's what surpriced me most. For example in the shelf there is a V shape pattern in the edge. First I thought I had accidently made a saw kerf mark in the edge, but no, it's cracking and looks like an A at a moment. Is there any preventive or protective methods for that (for future projects) or should I just sit and wait and glue the pieces back when they eventually fall out?

            Thank you for your advise,
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