Well, without weighing them it'd be an assumption, but I think it'd be a pretty safe one that because the bolts are such a thin gauge and not made from a heavy steel, I'd assume that they would actually be lighter than the timber removed, then because they are not filling up the entire space of the removed timber as they are recessed and the thin plastic cap would also be much lighter than the timber removed in its position, so I think this bolted bridge would be lighter than if it wasn't bolted! The only way to know for sure would be to weigh a bridge before the holes are drilled, and then re weigh the same bridge after and add the bolts on the scale.kiwigeo wrote:One negative to bolts in the bridge is the mass it adds to the bridge. I bust my nuts to keep bridge mass as low as possible (walnut sandwiched with CF ala Gore and Gilet) so a couple of bolts would be going backwards for me.
In saying that, if a person wanted to heavily reduce the the weight of a bridge it could be scalloped out on top, or several well orchestrated holes cut through it to create a artistic pattern. I'm not familiar with the text in the book. I'd read on the forum raving reviews about it and went to buy a copy only to see the price. I closed the webpage very quickly.