My background isn't in engineering as such. I've built a 5" Polly and run and maintained a Romulus for the past 5 years. I'm learning as I go along, helped by club members and YouTube and the likes of this group, and it's a constant grievance to me that two of my uncles were toolmakers and now when I could use their expertise and guidance they are no longer with us. Started a build on a hybrid Clarckson/Young/Breeze A3, (Clarkson castings, Young frame, Breeze simplicity, I can fully appreciate the Don Young design but boy is it scary from the viewpoint of someone with my capabilties), but stopped after driving the Polly 6 for a couple of years and even at 6' 2" starting to find the stretch over the tender trying. Now looking at a large narrow gauge 0-6-0, with an already almost complete riding truck that's marginally less comfortable than my armchair!!