You need to attach a support beam to every wall of a cave tile to prevent the tile from collapsing. You cannot mine a reinforced tile, but it will help to prevent cave collapse.
'''Hint:''' If you are making the support beams outside of the mine, your best approach is to leave it unfinished (e.g. requiring a shaft or a ribbon) and place them in a cart as more unfinished support beams will fit in to a cart than where finished oneswill not.
[[Category:Carpentry items]]
[[Category:Babel/S]]