when i asked my 'expert' woody mate, graham about the joints, and why there was no mention of them being necessary in the instructions - he reckoned it was because most shop bought 2x2, 2x3, 2x4 timber was a little smaller than 2 inches whereas mine was sourced direct from a sawmill and was the true 2 inches. the starplate grooves actually take 1 1/2 inches so i made these tapered joints for all 25 struts -- that's 100 joints !! so prepare yourself for some chiselling!