Cart lodge ‘Frontage’ executed correctly!
OK, I admit, I’m a snob! This is not my usual cup of tea, but when a colleague asks, needs must!
What we have here is a structural ‘frontage’ for a new cart lodge. Although I have executed this correctly! We must have all seen dozens of cart lodges with the oak posts & curved braces on the front elevation only, at a glance they look great right? I would suggest this depends upon your point of view 😉
So what’s all the fuss about, some posts and a top plate? What could go wrong with five primary timbers and some braces…
Firstly, lets look at the top plate, in particular how the two pieces of timber are connected. The span of the overall opening is something near 6.5m, that is way too long for a single piece. Therefore a quality connection is needed in the centre, directly above the post.
What you might typically see at best is a half-lap joint, or at worst two timbers butted together:
These less traditional connections require mechanical fixings, such as coach screws and bolts and are generally weaker.
I prefer to consider the forces exerted on the timbers in particular positions and use a joint suitable to resist those forces. In this case the thrust is outwards, therefore a face half scarf is a suitable joint:
Here’s a picture from another frame, showing a similar joint apart:
The Fixed with four pegs at the ends, plus additional support with the central post pegging. Most of the joint detailing is hidden behind the brace jointing.
From another angle before the hand drawn tapered oak pegs (not dowels!) were cut.
Note the curved braces, though small, are cut from curved grained timber. The tenons are cut so that the ends are pushing against their associated mortice ends, which means they are properly laterally bracing the frame. This image hopefully clarifies this point, the red area should be under compression. The shoulder of the joint should also be nice and tight (as per pics above!).
The reason why I’m pointing this out, is many of the ‘pattern cut’ frames use an additional third shoulder on the end of the brace tenon. This allows for a sloppy, non functioning joint to be hidden. The blue areas on the following picture imply a gap at the end of the tenon.
Even worse is if they are straight timbers with a curve scalloped out of the inside edge, yeuch 🙁 – note butt joint above post on this example
So there we have it, rant over. Hopefully this might enlighten a few to the many differences between hand scribed and machine pattern cut frames.