gap filler?

[doctorwayne]

I prefer to sand the bevelled mating surfaces to a sharper angle so that only the visible portions contact one another. The next step is to align the mating surfaces so that they're square to one another and use solvent-type cement to affix a strip of square .100" or .125" styrene to either one of the wall sections - push it tight into the corner thus formed, but cement it to only one of the walls. Next, coat the angled faces of both walls with solvent cement, along with mating surface of the reinforcing strip. Wait a few seconds while the plastic softens, then recoat all mating surfaces and assemble the parts, clamping or otherwise supporting them so that they're square. Let the joints harden fully - at least a couple of hours, but preferably overnight.
The exterior of the corner can then be cleaned-up. Scrape off any oozed-out plastic, and re-scribe mortar lines where necessary, then lightly sand to even out the surface. There should be no need for any filler, and the joint will be strong and permanent.
This was the method used for the corners on this structure, and also for the vertical butt joint at the midpoint of the long wall.



Wayne