Cracked bowl ok to turn?

Discussion in 'Newbie' started by Antonia Edinger, Mar 29, 2017.

  1. Antonia Edinger

    Antonia Edinger

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    Can I patch this up with epoxy or is this just firewood?:eek:
     

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  2. hockenbery

    hockenbery AAW Advisor Staff Member

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    It's up to you. Your decision is likely to be weighted by the number of crack free dried bowls you have on hand.

    If you can get epoxy into the crack it will be stronger than the wood.
    It seems to be a small bowl about 6" in diameter if you have a 2" tenon so there is not a lot of mass to hit you if it did come apart. The risk comes from just getting the epoxy on the surface so you cut it away.
    It also seems to have a thin wall already. After you turn the outside, it may be too thin and vibrate too much for you to turn the inside without using an aid like steady.

    In any event do WEAR A FACESHIELD.

    That is a particularly hard shape to dry successfully. It is also a common shape for new turners for two reasons
    1 new turners tend to rough the blank into a cylinder instead of roughing a curved shape and
    2 the gouge wants to cut a straight line following the bevel which makes curves hard to get.

    Most turners have a high success rate in drying hemispherical shaped bowls.
    You might consider turning bowls wider than tall.
     
    Last edited: Mar 29, 2017
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  3. Zach LaPerriere

    Zach LaPerriere

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    In addition to what Al said, it looks to me like your bowl may be too thin to finish round—in other words, by the time you true the bowl to eliminate warping from the drying process, you may have little to nothing left. On the other hand, this might just be a photo illusion.
     
  4. Antonia Edinger

    Antonia Edinger

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    I meant to put the measurement in there... it's a 10 inch bowl and it's almost an inch thick. It is a funky shape and I am definitely still learning but I was wondering if epoxy could save it. I do have quite a few blanks so this one may sit around until I get better. Thanks for the replys!
     
  5. William Rogers

    William Rogers

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    I don't turn bowls with cracks anymore. The picture below is a cherry bowl I was turning. I noticed about a 1" crack in the end. Very tight crack, not open. I finished sanding and a little dye and wood burning on the outside. There was a little tearout and I put thin CA on the crack and just taking light cuts to reduce/eliminate the tearout. The tool evidently caught the crack and exploded. I was out of the line of fire and no injury, but did feel several pieces hit the faceshield. I was turning at top speed for that size bowl and that didn't help.
    I really liked this bowl.
    IMG_0814.JPG
     
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  6. Antonia Edinger

    Antonia Edinger

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    Awww man that would have been a beautiful bowl. Great advice I appreciate. Definitely going to move on to pieces without cracks.
     
  7. Mike Johnson

    Mike Johnson

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    If you have a piece with a crack you can wrap the outside or put a support on the inside
    of the piece while turning. Many turners do this on a regular basis when turning billets
    with natural voids to keep the piece from coming apart.
     
  8. Zach LaPerriere

    Zach LaPerriere

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    That sounds like an appropriate thickness. It might be worth reaching out to local turners. I'm sure you could find someone who has experience with epoxy, could look at your bowl, and also offer some guidance that only an in-person visit could give.
     
  9. Antonia Edinger

    Antonia Edinger

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    Ah good point thanks. I'll hang on to it until I get a chance to go to a meeting.
     
  10. Richard Coers

    Richard Coers

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    Looks like firewood to me. You should strive for an even wall thickness when rough turning. Near the bottom of your bowl has to be way thicker than the rim.
     
  11. john lucas

    john lucas

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    I prefer wood without cracks but in my many years of turning and struggling I have patched many many cracks. First and most important, as you saw above, a cracked bowl can explode any time. The crack probably extends further than you see. Here is what i do. First I mount the bowl between centers. If there is a crack I readjust the centers until I can turn and get rid of the crack. that obviously reduces the size and often changes the shape of the bowl but in the end it's worth it because I have a bowl with no cracks.
    when your turning, if you stop for any reason put a plastic bag over the piece to keep it from losing any moisture. When your turning the inside spray the outside occasionally with water to keep if from losing any more moisture. If the outside starts to dry while turning it will crack because the inside is still wet.
    OK you've rough turned it and set it up and it cracks. YOu can put a butterfly patch on the crack to keep it from coming open but obviously that stands out when your done. That can be a good thing or bad depending on what you want. Cracks can be filled with epoxy and it holds pretty good. Thin cracks are difficult to get the epoxy down very deep and when you start turning you might simply go past it. CA will fill cracks but doesn't really hold well to impact your impacting it once per revolution.
    I use strapping tape. If I've finished the outside of the bowl I use blue painters tape for the first layer and then cover that with strapping tape. Some use Duct tape but it's just so messy and if you cut even a tiny nick it can tear really easy. Nylon strapping tape will not ever tear unless you cut it with a knife. I turned a piece once that had huge voids. The voids were so large that if I put tape on it would sink down into the void and I would cut into it when hollowing. I put some hardware cloth screen over the void and shaped it like the curve. Then covered that with tape and was able to turn the inside safely.
    When doing any of these things, stay out of the line of fire if at all possible. that doesn't guarantee you won't get hit by an exploding piece but it sure as heck reduces the chances.
     
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  12. hockenbery

    hockenbery AAW Advisor Staff Member

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    One problem that Is often overlooked is turning wood that is already cracked. Those treasures from the a neighbors firewood pile that have been sitting out for weeks or sometime days have developed radial cracks. These often are not seen in a chainsaw cut. They open up when the piece begins to dry.
    Ripping fresh cut logs through the pith lets the wood move without deloping racial cracks.
    Wood sealer on the endgrain slows moitpsture loss.

    My list. If the habits of successful green wood turners:
    1. Use Un-cracked Wood - wood sitting around iftennhas cracks you won't see until the open up
    2. Work Relatively Fast - cover the wood with plastic if you leave for minutes
    3 Balance The Grain - this lets the warp evenly distributing the stress
    4 Turn Pieces With Flowing Curves - this lets the wood move right angles block wood movement
    5 Turn Even Wall Thickness - the bottom can be thinner to include the tenon in the thickness
    6 Control The Initial Drying - paper bags, anchor seal etc whatever method works in your region

    As you can see the deck is stacked against novice turners. The good news is you won't be a novice turner long. A multiday class with a good instructor or a club mentor will get you to the intermediate level on 2,3,4,5.
     
  13. Antonia Edinger

    Antonia Edinger

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    Wow thank you for the detailed reply. I really appreciate it.
     
  14. Antonia Edinger

    Antonia Edinger

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    Okay thanks. That is from a log that was sitting around quite awhile. I've had good success so far with my bowls drying in a refrigerator/kiln without cracking. That one and another from that same log cracked. It's maple and it's spalted so I was hoping it would make it :(
     
  15. hockenbery

    hockenbery AAW Advisor Staff Member

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    Wood turning is full of trade offs what to do with a cracked bowl is a trade off of time and how you wish to spend it. How much wood you have at the time affects the decision. How nice is the wood.
    How dear is the wood.

    My consideration: Roughing a bowl takes a lot less time than repairing cracks. I am more likely to spend an hour roughing out 2-3 more bowls than I am to spend an hour repairing cracks.
    Unless I get a vision of repaired cracks looking spectacular in my mind I won't repair them.
    My usual treatment of a crack is to leave it open and highlight it with a wood burning tip.

    I spent a lot of time stabilizing pieces from the Wye oak- largest white oak in America.
    My reverence for that magnificent tree trumped the logical arguments.
     
  16. Antonia Edinger

    Antonia Edinger

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    It only takes you an hour! Haha ok seeing as I have a ton of cherry and oak I'll just keep working on those. Thanks for all the advice.
     
  17. hockenbery

    hockenbery AAW Advisor Staff Member

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    I've been practicing a while. If you have 30 minutes you can see how I rough out a an 11" diameter bowl. The demo speed generaly runs about 3 times the time it takes in my own shop.
    Also I am not particularly fast.



    View: http://www.youtube.com/watch?v=Lo0bGSafZq4
     
  18. Antonia Edinger

    Antonia Edinger

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    I thoroughly enjoyed your video and learned so much. I will definitely watch it again as it has a lot of great information. I need to fix my gouge as it has an improper grind on it and has the low point at the top. Thanks so much for sharing your video.
     
  19. hockenbery

    hockenbery AAW Advisor Staff Member

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    Thanks for the kind words. These are the types of demos we do at our club every month.

    A properly ground gouge is a huge asset. Any gouge with a continuous convex edge wing to wing is ok. Flats are fine. Dips are not good and frequently cause catches

    A group of AAW members are reviewing YouTube videos. Those they have reviewed and found to show safe and effective practices may be found on:

    http://aawvideosource.org/
     
  20. Antonia Edinger

    Antonia Edinger

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    Thank you for the link. Ive started watching the videos. I'm going to try and join my local association. It's about and hour and a half away but I think it would definitely be worthwhile.
     

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