Thursday, July 11, 2019

King Bed Headboard - Part 4: The Posts and Request for Input

The posts for the headboard were to be 3" wide and at least 2 1/2" thick.  I glued them up from 6/4 stock and ended up getting about 2 5/8" thickness.
A post blank glued and in the clamps
After squaring up the blanks and cutting to 51" length, I marked out the mortises.  The following pic shows the extents of the initially 8" wide upper rails, the upper extent of the rail after 3" will be cut away to create the curve on the upper rail, and the 1/2" shoulders.  The heavy line shows where the mortise will go; I haven't yet used a mortise gauge to mark the lateral extents of the mortises.
Mortise locations for the upper rails
Unfortunately I marked them on the wrong side.  I had oriented the posts so that the little bit of sap wood that was left after planing would be on the inside faces.  Fortunately I caught the error long before any mortises were to be cut.
D'oh!!
And here's them marked on the proper side, with mortise gauge lines delineating the lateral extents.
Mortises ready to be cut
These mortises were to be 2 1/4" deep and I wanted to keep them as square to that inside face as possible.
I find that orienting myself along the length of the workpiece helps me chop vertically
But I still use a square to verify
First one chopped, cleaned up and complete
This was quite a chore, so I ended up boring out the other three mortises.
Boring out most of the waste
Boring 2 1/4" deep took about 40-42 turns of the 5/16" bit and it got quite hot.  I kept a bowl of water nearby to cool the bit after each hole was bored.
Cooling down the bit
The lower rail will have a double tenon, so the mortise is 7 inches long.  The middle 1" will be only 1/2" deep, but the rest will be 2 1/4" deep.  So I cut the two deeper parts first and then joined them using a saw and 3/8" chisel.
Double mortises done, but center section not yet removed
Used a saw for the sidewalls of the middle part and chisel to remove the waste and level the bottom
I made the mortises this way to help me get the 2 1/4" deep end walls next to the central section as vertical as possible and to get those end walls at the marked location.  If I had chopped/drilled out the center section while I was mortising the two deep sections it would have been harder to get those walls perfectly positioned.

If any of you have read this far, it's time for audience participation.  I'm getting closer to glue-up and have been giving it a lot of thought.  The 78" total length of this headboard is far longer than any clamps I have.  I've thought about ganging clamps together to span that length, but it's really tough to do that by myself.  So I'm thinking about using the draw-boring technique.  I've done this before (maybe only once or twice) but never in cherry wood.  So I did an experiment with some scrap that was about the same thickness as my long rails (just under 1").
Chopped a mortise, prepared a tenon, drilled some holes and made some pegs
Offset the holes in the tenon by about 1/16" from the holes in the mortise
Tapped in the cherry pegs to draw the joint VERY tight
Front side (pegs entered here) after clean-up
Back side after clean-up - there's a tiny crack extending from one peg-hole to the other
In my headboard, I'll place two pegs in the 4" wide mortise/tenon of the upper rail, but the two pegs won't be anywhere near as close to each other as in the above test piece.  The lower rail with twin 3" wide mortises/tenons will have one peg per tenon.

So, here are my questions.  First, does anybody have experience with draw-boring in cherry?  Cherry can be a bit brittle and I'm just a little concerned.  I know I can mitigate cracking like I got in my test joint by off-setting the holes so they don't lie along the same grain lines, but I don't like the look it gives.  Any my holes for the headboard m&t joints will be much farther apart.

Second, I'm making the pegs out of cherry also.  While I'm making them from as straight-grained stock as I can, do I need to worry about them breaking apart from the hammer blows used to drive them in (that wasn't a problem in my test, but my test piece was thinner)?

Finally, the headboard posts (the mortised component) are 2 5/8" thick, so the pegs will be going through more material than in my test piece.  Should I be worried?

Any advice would be helpful.

4 comments:

  1. Clamp a piece of wood about 18-24 inches from the tenon on the rail. Put a clamp from the leg to that board. If you have wooden adjustable clamps they will work in place of clamping a board to the rail.

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    1. I think I see what you're saying, Ralph, but I'd have to clamp the piece of wood to the rail extremely tightly for it not to slip. I might look into ratchet straps in combination with wedges, too. Thanks for the input.

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  2. - "ratchet straps": modern version of Spanish windlass.
    When using ratchet straps (or Spanish windlass), protect the piece, otherwise, the strap/rope will mare the corners of the posts.
    - "While I'm making them from as straight-grained stock as I can". The best is to split wood to make the pegs.

    Sylvain

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    1. Thanks for the tips, Sylvain. I did a dry-fit with ratchet straps today and it worked very well. I taped pieces of scrap wood to the posts so the straps would not hurt the posts. So I'll probably go without the draw-boring method. As for the split stock for draw-bore pegs, that's how I did it in my test piece. But the pegs didn't split out perfectly straight, so I had to plane them a little bit.

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