Winding sticks consist of two straight edges that can be placed on a plank or board to assess if, or how, it is twisted.
By sighting up along the length of the plank, one can check to see if one of the sticks is askew relative to the other. If the sticks line up perfectly, then there is no twist. But if they do not, then by looking at the orientation of the sticks you will be able to determine the hight spots and low spots and plane accordingly.
Up until now, I have made do with some metal winding sticks, made from aluminium angle. They work fine, but they look terrible.
My next project, therefore, will be to make a pair of winding sticks from this old mantelpiece. I’m not sure what wood it is; utile? mahogany? Let me know what you think.