I did a kerf joint on the back plate of my bass project. Which led me to this question; how strong is a kerf joint? and how does it hold up over time? seems odd because its only a 3/32" sliver of wood with a bead of hide glue. Do they ever get cleated?
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Double Bass How strong is a kerf joint?
- Thread starter ctregan
- Start date
Matthew Tucker
Commercial User
- Aug 21, 2002
- 2,686
- 387
- Disclosures
- Owner: Bresque Basses, Sydney Basses and Cellos
Matthew Tucker
Commercial User
- Aug 21, 2002
- 2,686
- 387
- Disclosures
- Owner: Bresque Basses, Sydney Basses and Cellos
A kerf is a saw cut. I think what Arnold is questioning is whether it's actually a "joint".
When i do a back bend like that, I re-cut the kerf with a back-saw once the plate is bent; this makes the edges of the cut parallel, then I fill the kerf with a strip of wood, a bit like inlaying purfling. Plane flush and brace or cleat. My cornerless bass is done this way and I'm not sure whether it needs to be braced. I am thinking of light bracing "just in case".
But if the bend is actually two separate bits of wood cut on a slant and glued together, that's a joint, but a scarf, not a kerf, and would need reinforcement.
When i do a back bend like that, I re-cut the kerf with a back-saw once the plate is bent; this makes the edges of the cut parallel, then I fill the kerf with a strip of wood, a bit like inlaying purfling. Plane flush and brace or cleat. My cornerless bass is done this way and I'm not sure whether it needs to be braced. I am thinking of light bracing "just in case".
But if the bend is actually two separate bits of wood cut on a slant and glued together, that's a joint, but a scarf, not a kerf, and would need reinforcement.
was it a struggle to close the hinge? did you hear or feel noticeable protest from the wood..am i wrong in suggesting not doing a thing with bracing untill your fitment is correct w/ top & sides..and that being the case maybe brace at the bouts and one over the center joint...i have faith in NY cherry.
Matthew Tucker
Commercial User
- Aug 21, 2002
- 2,686
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- Owner: Bresque Basses, Sydney Basses and Cellos
Would it be a scarf a kerf or a butt...
or a smerf or a barf or a kutt ...
How about a "Kerfed bend"?
It is still one piece of wood (barely), with a bead of glue inside the kerf holding things together.
It makes me wonder if the hide glue will shrink and expand with the wood?
I was considering cutting the back and reattaching the angle with some kind of splined joint; it seems like it would have been more structurally sound but less pleasing visually.
Jake deVilliers
Commercial User
- May 24, 2006
- 6,349
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- Owner of The Bass Spa, String Repairman at Long & McQuade Vancouver
Seeing as how that 'joint' is all end-grain, I'd be doing something to help keep it together. 
Maybe a series of little angled cleats?
Maybe a series of little angled cleats?
Matthew Tucker
Commercial User
- Aug 21, 2002
- 2,686
- 387
- Disclosures
- Owner: Bresque Basses, Sydney Basses and Cellos
No don't do that, glue's not a good filler. I suggest you do what I said before - cut through the kerf again gently with a panel saw just enough to clear out the glue. you can clean out the channel with your purfling pick. Then make a thin strip of wood to fit nice and snugly and glue it in place. That way you have full thickness backing for the thin bend, but retain the integrity of the long grain fibres (what's left of them).
Or just glue a brace along the bend.
Or just glue a brace along the bend.
