When to use a butterfly to stop splitting/checking of a large slab

[Paul Richard]

Hey All,

I have a buddy who scored some beautiful ash logs that he milled to 8/4 x 36" slabs. The material has been in his yard on the ground for at least a year and he recently milled a few of them. One of the logs that he milled in the spring now has split running about 16" up the one of the slabs. He's had them stickered in his unheated garage and has been careful in handling them.

When is the correct time to use butterflies to minimize the growth of the split? Or, is there some other method to do so? He did paint the end grain before milling, but not when they were first cut down.

Thanks for any feedback or direction - I'm just learning... and goodness gracious there is a LOT to learn! :-)

Regards,
Paul

[Andrew Hughes]

If it's a straight split then rip it in half and glue it back together.
Thats what I would do.
Easyer said then done right.;)

[Jim Becker]

It's always a "judgement call" on something like this and it's usually to prevent an existing split that goes a short way into the material from increasing its presence. If the split is longer than a "short" part of the length, I'd probably prefer what Andrew recommends and/or use that slab for material for lesser components of a project while selecting a better quality slab for the "main feature".

[Kevin Jenness]

If you put in a crossgrain butterfly before the wood is dry you run the risk of making the split worse. The most effective thing to prevent splits is to seal the log ends immediately after felling. If sealing is delayed until checking has begun, waste a few inches of length by cutting off the checked ends and sealing the fresh cuts.

[Prashun Patel]

Can you post a picture? Depending on location and the proximity to knots or changing grain direction, you may choose to rip and separate instead of attempting to keep it together.

[Mark Gibney]

I've held more than one slab together with clamps while it dried. Had to tighten the clamps as the slab shrunk.

I wouldn't put a butterfly in until the wood is stable. And a large fissure like this is often what clients want in a slab piece, it adds that elusive character.

[ryan paulsen]

I haven't tried it myself, but i have heard people drill a hole at the very end of the split to stop the split from progressing.

[Paul Richard]

Huh, that sounds interesting. How big a hole?

[Mike Henderson]

I haven't tried it myself, but i have heard people drill a hole at the very end of the split to stop the split from progressing.

I know that a hole at the end of a stress crack in cast iron (for example) can stop a crack from growing longer, but I wonder if that would work in wood. The wood is cracking because of the uneven shrinkage of the slab - the end is shrinking more than the middle. I would think that if the problem continues, the hole will not do much to stop the cracking.

You need to address the way the wood is drying and try to make sure it is drying evenly.

But it won't hurt to try the hole - I'd try maybe a 3/4" hole. Let's see what others say.

Mike

[John C Bush]

A big slab sawyer I use--has a 56" horiozontal band saw--drives "S" shaped retainers(??) into the endgrain at spits, or potential spits, before he sends the slabs to the kiln.

[Danny Hamsley]

I agree with several posters. Let the slab dry to the in use moisture content, and once it is fully dry and stable, then add the butterfly. The split will be stable if the slab is dry and will not worsen, and the butterfly will be a very nice design feature.

[lowell holmes]

http://www.finewoodworking.com/2006/08/10/a-lesson-in-butterfly-keys