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Thread: Hidden bed bolts

  1. #1
    Join Date
    Feb 2004
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    Perth, Australia
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    Hidden bed bolts

    The two beds are nearing completion of the joinery. The last report was making loose tenon using the Domino DF500 to create the mortices.


    The rails are 125mm x 26mm. The mortice is 115mm x 10mm ...



    These are the bed ends. It is relevant to note, as the tenons extend just 28mm into the end rails, they are not in danger of coming apart from the posts. The stresses (racking) will be on the side rails. In any event, the tenons will also be pinned.





    The challenge now is to hide the bed bolts which will connect the side rails. Generally, the bolts run through the post and terminate in the side rail. My aim was to retain the clean, uncluttered line of the tapered posts. There are mechanical fasteners available, but I have used these in the past and the lighter, single beds are vulnerable to racking in my experience.


    The end result needed to look like this ...


    I began by adding double 40mm x 10mm wide x 12mm deep mortices in the posts ...



    These were initially made with the Domino, and then the ends squared with a chisel. Why squared? Because I find it easier to fit tenons exactly when they are squared than when they are rounded.


    The tenons were planned to be 10mm x 10 mm. These were made with a router and a simple fence ...




    The fence is positioned by a depth stop (top left).





    ... flipped, set up, and routed again ...





    Saw and chisel to a matching fit ...





    The ground work is set for the bed bolt. Insert a dowel centre between the tenons ...





    Insert the tenon end into the mortice end, and this will mark to position where the bolt will go ...



    Drill and insert a steel thread (wet the wood to make tapping easier) ...





    I am using a M8 stainless steel bolt (cut the head off) ..





    A short pilot hole is drilled, using a Stanley #59 dowel guide ..





    This is extended with a long 6mm drill bit, taking care to aim for a slight angle towards to inside face. The reason for the slight angle is to reduce the depth for the bolt. The bolt hole is widened to 9mm.


    The bed bolt extends to the centre of these two forstner-made holes.



  2. #2
    Join Date
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    Smaller holes are added for a spanner, and the end is squared for a washer and nut.






    Time to begin adding finish and glueing up the end rails.

    Regards from Perth
    Derek

  3. #3
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    Always nice clean work, Derek. You might consider using Zipbolts for that application in the future. Much easier to tighten/loosen.

    John

  4. #4
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    Thanks John. The Zipbolts look strong but a little more bulky than desired. There was nothing special about the hardware I have used, but it does the same thing. Agreed, probably more more though.

    Regards from Perth

    Derek

  5. #5
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    There are different size Zipbolts. You could still use the insert in the leg, as you did. The business end is no larger than the area you excavated in the rail, likely less. I made a little template to route the recesses. You can glue a strip of wood into the dado section that you have to cut to install the Zipbolt, if you want to minimize the amount of wood removed. Just a suggestion.

    I look forward to the rest of your build.

    John

  6. #6
    Just a suggestion:
    A piece of round bar stock (say 1-1/2" diameter steel or aluminum) could be cutoff and tapped, crosswise, through its center to create a threaded insert That way the mortice for its installation could be achieved by means of a simple round counterbore in the bed frame. And the metal insert would neatly fill the counterbore.

    "Anything seems possible when you don't know what you're doing."

  7. #7
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    Andy, thanks. I am aware of these fittings. All the counterbore set ups I am familiar with are required to be drilled where they are visible, or interfere with the mortice-and-tenon from the end rails. Thoughts?

    Regards from Perth

    Derek

  8. #8
    Quote Originally Posted by Derek Cohen View Post
    Andy, thanks. I am aware of these fittings. All the counterbore set ups I am familiar with are required to be drilled where they are visible, or interfere with the mortice-and-tenon from the end rails. Thoughts?

    Regards from Perth

    Derek
    The single counterbore I refer to can replace the series of counterbores in your photo. No need to be visible or interfere with the tenons. Would provide a more finished appearance.
    "Anything seems possible when you don't know what you're doing."

  9. #9
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    Do you have a photo, Andy?

    Regards from Perth

    Derek

  10. #10
    Quote Originally Posted by andy bessette View Post
    Just a suggestion:
    A piece of round bar stock (say 1-1/2" diameter steel or aluminum) could be cutoff and tapped, crosswise, through its center to create a threaded insert That way the mortice for its installation could be achieved by means of a simple round counterbore in the bed frame. And the metal insert would neatly fill the counterbore.

    Those cross dowels are commonly used with through bolts. https://www.rockler.com/heavy-duty-c...nd-bolt-8-pack It's not clear to me how you would use them in Derek's blind fastening situation.

    I have never liked those threaded inserts due to the difficulty of threading them into hard wood and winding up with the bore square to the surface. In this case I would consider modifying the end frame joinery from one wide to two narrower ones leaving material to pot the bolts in epoxy. The thread engagement could then be nearly the full depth of the post.

  11. #11
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    Thanks Kevin. If your link is the one, then it would not be applicable in my situation as it could not be used blind. It is designed to be used through the post, exiting at the front - which is what I am avoiding.

    Regarding threading inserts into hardwood, I mentioned wetting the wood inside the drilled hole before threading. This softens the end grain enough. Jarrah has a tenacious grip! Those inserts are not coming out. The threaded bolt is then attached with Loctite 222. This is enough to hold the bolt, but can be broken by twisting the bolt.

    Regards from Perth

    Derek

  12. #12
    If I can suggest, I would use a half moon washer in the mortise. Les work mortising and the pressure is spread out over a larger contact area.

  13. #13
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    Edward, these washers are not available locally. They do look good, and I would have used them if it was possible, but I used what I could find. There were 8 ends to build. It is not like I was going into production. A few chops with a chisel, and done. This is all hidden on the inside of the bed, and under the rails for the cross pieces.

    Regards from Perth

    Derek

  14. #14
    Quote Originally Posted by Derek Cohen View Post
    Do you have a photo, Andy?...
    It is a concept. Best I can do is a photo of my sketch.

    Along the axis of your bolt hole you counterbore for the "insert". The "insert" is a piece of round metal bar stock through which you cross-drill and tap the appropriately sized thread to match your bolt. The "insert" fills the counterbore completely and provides the threads into which the bolt is screwed.

    "Anything seems possible when you don't know what you're doing."

  15. #15
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    Andy, I assume that the bolt enters between the tenons and is seated in the round thingamajig? Where is the other end of the bolt, and how does one tighten it? Presumably on the other side of the post? In other words, not hidden?

    Regards from Perth

    Derek

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