Hammering long dowels… how long a dowel?
dadthemetal
| Posted in General Discussion on
I am mending an old cherry chair and need a 1/4 or 3/8 dowel deep within the material. My question is, how long can my cherry dowel be before I have problems hammering it in? I am adding structural strength to the repair and need to come from the bottom of the leg up, through the repair.
Replies
Impossible to say with any certainty (depends on how tight the fit is, how straight grained the dowel is (not store bought but riven if possible), how accurately you can hammer the dowel on center, etc.), but have you considered just making it a slip fit, rather than hammering it in? If you cut a decent sized groove along the length of the dowel for any excess glue to escape, and use a glue with good gap filling properties such as epoxy, it should be fine.
The worst thing that could happen is for you to try to hammer in a dowel and have it crack and break before you get to the spot you are trying to reinforce.
If you decide to go the route of an interference fit, maybe try the smaller size first, then if it breaks you could drill it out and try the larger size dowel.
Just my opinion...
Wow chelor! I've been too focused with tight-fitting joinery that it didn't occur to me to leave the dowel slightly skinny and fill it with epoxy. Thanks!
Another alternative from the timberframing world: Instead of a round dowel, which assumes 100% surface contact and way more friction than you probably need, try an octagon-shaped dowel. The octagon cross-section reduces friction so you can more easily drive it in, and the edges of the octagon create nice bite into the surrounding material. It allows for slight deformation of the dowel edges and the surrounding wood so the two are under constant compression. It also reduces the wedge effect of a round dowel. At the small diameter you need, I would turn a round dowel into an octagonal dowel with a spokeshave - very quick work.
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Chloe is right. Trying to hammer a small diameter dowel longer than 3" is pure folly.
As for an 8 sided dowel, if you drill a hole for a 3/8 dowel and take a 3/8 dowel and make it 8 sided by shaving it down, it will be loose in the hole. That's not how timber framing pegging is done.
macanbard and Dovetails7: I hear you both. Maybe starting with a bigger dowel to make an oversized octagon would work, but I don't like the lack of contact all around. So far, I am going with chelor's idea (post #2). Thank you both for the comments though.
Correct - to do the octagon approach, you have to start with a slightly oversized dowel. It needs to bite the edges of the hole; it should not be loose or sloppy at all.
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