Riser crack

[Bodork]

What causes a riser to crack at the arrow shelf? A takedown I made for myself has developed a crack at the belly side of the arrow shelf and I'd like to know how to prevent it in the future.
Thanks! Mike

[Crooked Stic]

Pictures always a help. If it's where the shelf and window meet then could be not radiused etc. Could be bad wood stress over time etc. I have fixed a few with water thin CA no accelerator and let it wick in. Don't always work tho.