My new, (very) open tailgate is progressing well. Completed all the drilling and refinement of holes today, made some new springs (that I'm not happy with), and mounted the mirror for a test tonight. I breathed a huge sigh of relief when my dob collimated well and focused well too. It's clear that the mirror's centre point relative to the mirror box has moved a little bit, and I had to fuss for a while with the collimation. However, I would say that mirror's centre point is now where it should be as the wooden tailgate appeared to mount the mirror ever so slightly off centre, as evidenced by a difference in the location of collimation bolt holes between the metal and wooden tailgate. The metal tailgate weighs only approx 500g more than the wooden tailgate, so I still need a counterweight on the mirror box - bugger
Now I need to clean up the metal work, prime and paint it, and start using it!
