An Epiphany and Two Flat Bottoms

An Eccentric Anomaly: Ed Davies's Blog

TIL that the backing plates for my post-top purlin joins aren't quite a symmetric as I'd assumed.

As expected, Saturday was wet - the evening and night torrentially so. Sunday was a bit drier from midday but very cloudy and there was no opportunity for the wood to dry out so I only had a short visit to the site in the afternoon to sort out a lose bolt on the drill stand which had stripped its nut.

Thinking more about the problem of the purlin steps in the evening I wondered if maybe the steel plates making up the bracket were at least part of the problem. This morning I laid two backing plates on top of each other one way up, lining up the bottom right hole:

Not perfect but not too terrible. Flip the top one over, though:

…and they're noticeably off. If any inaccuracy in my drilling happens to add to that error, rather than cancel it out, it's easy to see why bolts are not lining up with the holes.

Today I did two post tops, the ones on the south side between the kitchen and bathroom and the bathroom and guest bedroom, taking care to match up the best side of the backing plate with the associated front plate then keeping it in the right orientation for drilling.

Both got the bolts lined up nicely enough (the second was a bit of a push but didn't need drilling back or anything) and both resulted in the bottom faces of the purlins staying nicely flat:

So, I'm a bit cheesed off with myself for not thinking to check the hole alignments before. Still, the curve on the front brackets did make this all a bit less obvious than you might think.

So that's the available posts and their associated purlins for the south side done. I'll need to drill a few joist holes and make up the tie beams to go across between them then they can all go up.