Another bowtie spline...

[Doug Rasmussen]

Caution CNC content.

This is a bit different way to make bowtie splines or any other shape of spline you want. The process is commonly known as vcarve inlaying. This pocket was cut with a 90 degree router v-bit leaving angled walls. The inlay is also cut using the same bit making angled edges on the inlay. With a v-bit both the pocket and the inlay have sharp corners (no hand work required). 60 and 45 degree bits can also be used for steeper walls.

Software to program these is available as open source, free, F-engrave. The Vectric software included with the type routers sold by Rockler and Woodcraft do this too.

First picture is a computer rendering of the inlay. Next picture is the pocket and inlay ready for gluing. Maple inlay into mahogany.








Once the glue is dry the remnants of the inlay backing is cut off and the work is sanded smooth. The spot in the upper right corner didn't get sanded down enough, which I didn't notice until looking closely at this picture. Otherwise, it appears to be a nice fit of the inlay.





Another inlay done long ago

 

[Richard Coers]

The purpose of the bowtie is to hold the wood from cracking more, right? How effective is a tapered wall bowtie when the wood shrinks and puts a load on it? It seems you design relies entirely on the glue to hold and not the wood strength.

 

[Bill Boehme]

The purpose of the bowtie is to hold the wood from cracking more, right? How effective is a tapered wall bowtie when the wood shrinks and puts a load on it? It seems you design relies entirely on the glue to hold and not the wood strength.

This should only be done on dry wood. Once wood cracks, essentially all of the stress has been relieved. The patches are mostly a decorative feature and not something that is used on a functional piece.

 

[Emiliano Achaval]

This should only be done on dry wood. Once wood cracks, essentially all of the stress has been relieved. The patches are mostly a decorative feature and not something that is used on a functional piece.

If they could speak, lots of ancient Hawaiian craftsman would disagree with that. Their bowls were all functional, some had dozens of pewa and other repairs. It was easier to repair them than to make a new one...

 

[Doug Rasmussen]

The purpose of the bowtie is to hold the wood from cracking more, right? How effective is a tapered wall bowtie when the wood shrinks and puts a load on it? It seems you design relies entirely on the glue to hold and not the wood strength.

As Bill said, you probably would only do this with dry wood.

I understand what you're asking, with the 45 degree tapered spline if the glue began failing it wouldn't have much hold. The inlay could be done with a 45 degree v-bit so their might be less chance of it coming loose under load. I suppose you could dowel the spline in for extra insurance. The main advantage of this method is ease of installation and spline shapes only being limited by your imagination.

 

[Bill Boehme]

If they could speak, lots of ancient Hawaiian craftsman would disagree with that. Their bowls were all functional, some had dozens of pewa and other repairs. It was easier to repair them than to make a new one...

I'm aware of that, but that's not why patches are used these days. It's much less work making a new bowl than installing enough patches to keep our soup from leaking out. I think that Kelly Dunn has done some repairs of the sort that the ancient Hawaiian craftsmen made.

 

[Richard Coers]

Wood moves every season. I have old work where I can feel every joint. I just think that between the seasonal wood movement, and some slight glue creep, this tapered bowtie will have a more pronounced change than the traditional shape. But as mentioned in another post, I'm not a fan of cracked work anyway.

 

[Emiliano Achaval]

I'm aware of that, but that's not why patches are used these days. It's much less work making a new bowl than installing enough patches to keep our soup from leaking out. I think that Kelly Dunn has done some repairs of the sort that the ancient Hawaiian craftsmen made.

Pewa are definetly not appreciated outside of Hawaii as much as they are here. I have lost sales because the bowl didnt have any... 90% of custom orders the client requests them, not always possible to have a crack, LOL, so I just repair knots or imperfections. I sent 2 sample bowls to a mainland buyer, for a bigger order. A company get together in Hawaii, they were given a bowl to all former CEO and others. She asked that if possible not to have those little thingies on the bowl! LOL I have repaired old bowls for clients... Recently one came with a bowl in 3 pieces, I told him I can make you a new one!