r/stonemasonry

We started from a block of tervoux (a french stone from Poitiers ) to make part of a mullinoed window (that's what google translate said‚ idk if it's very accurate.) The finished aspect that I chose is from the stonemasonry axe (idk why it's called in English) that was used in the medieval ages.

I made this animation to explore how changing the rise of a masonry arch affects the geometry of a course-based stone layout (sometimes called stepped-extrados).

To make the comparison clearer, the stone count stays fixed while the rise changes.

The first part shows a 3 m (9’10”) span with the height varying from 0.2 m to 1.5 m (8” to 4’11”), while keeping the stone count fixed at 19. Each case is shown first as a one-centred arch and then as a three-centred arch.

The second part does the same for a smaller span of 1.3 m (4’3”), with heights varying from 0.2 m to 0.55 m (8” to 1’10”), using 9 stones, again comparing one-centred and three-centred outlines.

What interested me here is that changing the rise affects not only the outline of the arch, but also the position, proportions, and shape of the voussoirs in a course-based construction.

The animation was generated with a Swift program (that I’m trying to turn into an app for working with arches.) For each frame, the main inputs are the span, rise, and stone count, together with a few construction settings such as course height and joint thickness.

More generally, it seems that with enough geometric and construction information (which isn’t a lot), an arch can be described precisely enough to reconstruct the individual stones that make it up.

this was an arch above a window in a 600mm thick solid stone wall behind blown render. The render is removed and the is collapsed and was rendered over like this. What should be behind the arch going through there is nothing now ,and a concrete lintel on the inside.

I can rebuild the arch no problem, but as it should be a solid wall I can't think of what to do behind it. I've done loads of stonework 35+ years ago but can't remember ever doing this. This is my own house, just over 200 years old.