Dovetail batten guidelines?

  • June 01, 2025 11:19 AM
    Quote
    Message # 13505407
    Ray Tice

    I'm looking for a reference with guidelines for sizing and placement of dovetail battens to control warping of a solid panel. Say roughly 24 high by 13 wide with horizontal grain in an environment with large humidity swings.

    That's potential for a good bit of movement. I'm considering tapered dovetails to ease fitting, and I guess would need to be unpinned. Or would those work loose? Are untapered dovetail battens a better choice?

    (I got shot down on using floating panels, or composite panels, for stability instead of solid panels.)
  • June 02, 2025 6:48 AM
    Quote
    Reply # 13505659 on 13505407
    James Russell (Administrator)

    I have been dipping my toe into AI to see if it has any uses for woodworking. For the most part, I have found the responses accurate and useful. Sometimes the responses are somewhat misleading and, on one or two occasions, (in my opinion) wrong. In general, the usefulness of the answers is related to the completeness and quality of the question asked. I put your inquiry to Microsoft CoPilot and got the following response.  I found it useful. I hope this helps.

    Chat GPT Response
  • June 02, 2025 9:55 AM
    Quote
    Reply # 13505711 on 13505407
    Tim Holiner (Administrator)

    Really interesting answer from AI. In terms of pinning, I think it would be safe and useful to pin the narrow end of the batten to avoid it working out of its dovetail slot.
  • June 03, 2025 10:34 PM
    Quote
    Reply # 13506469 on 13505407
    Ray Tice

    On the pinning, I'd think some care is needed. If you pin the narrow end of a tapered dovetail and the wood swells, it's going to compress the panel - will that split the dovetail? Crush fibers? 
  • June 03, 2025 10:55 PM
    Quote
    Reply # 13506477 on 13505407
    Ray Tice

    Thanks for the suggestion James. Sometimes AI is great at summarizing, and sometimes confidently and utterly wrong. Like last night, when I was looking for a configuration file for the micro-controller I'm using for the motorized router lift I'm building. (esp32-s3 and esp32-c3 chips are different!) On the other hand, sometimes it opens up new avenues of search, or gives dead-on correct answers.

    At work, I claim "It's like pair programming with an over-caffeinated 12 year old."
  • June 03, 2025 11:13 PM
    Quote
    Reply # 13506481 on 13505407
    Ray Tice

    e.g. "If possible, align the radial grain in one piece with the long grain in the other piece to minimize movement across the joint."
  • June 04, 2025 10:23 AM
    Quote
    Reply # 13506620 on 13505407
    Tim Holiner (Administrator)

    I wouldn't worry about wood swelling in the dovetail batten. If it were a problem, half the mortises ever made would have failed (they haven't). The amount of change in the size of that piece would be in the range of a few thousandths of an inch. Also, why not just put a bit of glue on the end of the dovetail slot? Seens simpler, akin to gluing the center of a breadboard end or drawer support.
  • June 05, 2025 6:11 AM
    Quote
    Reply # 13506949 on 13505407
    Ray Tice

    It's movement of the panel from swelling that I'm concerned about. (Copilot says an extreme movement of 5.5% or 4/3 inch in this case). If the tapered dovetail is snug and the panel swells, the narrow end needs to move. If the dovetail is snug and the panel shrinks, then the wide end needs to move. Theoretically. But, the taper is pretty slight - about 1/16th of an inch across the width of the panel, or about 4 thou over the course of the wood movement. That's dwarfed by the batten swelling, and I don't see people concerned about the friction from batten swelling impeding the panel movement, so maybe it's just not a practical issue.