Where did I go wrong? Cracked end grain board.

[Grantx]

A friend of mine asked me to make him an end grain chopping board. He sent me a photo of a metal helmet he had made and asked for a religious-themed inlay.
I used Walnut, Maple and Titebond 2.
In the attached images I have highlighted the obvious mistakes.

#1 was a miscalculation on the edges. I was left short with gaps that needed filling. Easy to remedy on the next one.

#2 Not sure why it's cracking on the edge...well obviously expansion but how to avoid this?

#3 Inlay text was too close together and I lost detail. I've learned now and this can be avoided on the next one.

#4 During the glueing phase I was merrily sanding the edges and wasn't watching the other side which got demolished. Will be avoided in future by using my brand new, DIY, tight a..e, el-cheapo, belt sander.

That cracking on #2 though. Why? I left it in the workshop for a few days and it was perfectly fine. Bought it into the warm house overnight and it cracked. Is that due to moisture leaving the board or being absorbed? Are my walnut and maple grains not lined up correctly? How do I avoid this in future?

 

[TheTiddles]

The layup you have there is the very maximum of movement you will get in wood, all endgrain. So you need to get all the material as close to the conditions it’ll see in use before you build it. The end of a board might be drier (or wetter) than a piece halfway down it’s length etc

If it was me, I’d have cut a stringer down each edge and used a continuous piece glued in to help hold the edge together, but that might not have held it still if it was still on the move.

This time of year, moving pieces in/out of an unheated workshop does this

 

[Grantx]

it was me, I’d have cut a stringer down each edge and used a continuous piece glued in to help hold the edge together

Thanks for your input, what's a stringer and what do you mean by glueing a continuous piece along the edge?

 

[Ollie78]

I agree with TheTiddles.
I suspect your Walnut was not at the same moisture level as the other wood.

Also you have them layed in "rows" with the grain in a similar direction. Perhaps if you used square pieces you could rotate half of them 90 degrees. This may lessen the movement in one direction.

Ollie

 

[Jacob]

Everything you could possibly want to know about end grain blocks here Repairs to butcher's block

 

[TheTiddles]

Thanks for your input, what's a stringer and what do you mean by glueing a continuous piece along the edge?

On the sides, rout a slot down the centre of the edge, maybe 10mm deep and 15mm wide, glue in a strip of maple that will fight against the movement of the blocks perpendicular to it.

 

[Grantx]

On the sides, rout a slot down the centre of the edge, maybe 10mm deep and 15mm wide, glue in a strip of maple that will fight against the movement of the blocks perpendicular to it.

Ahh ok, that sounds like it would actually be a nice feature. The grain direction of the inlay would be opposite to the rest of the board I presume?

 

[TheTiddles]

Ahh ok, that sounds like it would actually be a nice feature. The grain direction of the inlay would be opposite to the rest of the board I presume?

Yep, that’s it, should fit with your overall look and also be structural. I’d sort any remaining problems before you do it