Spent a long time on this but finally got the basic mechanism in and lined up. The doors now meet in the middle consistantly.
Then if you pull the doors open and tug on the "screen" and twist, it opens in the right place! I had to carefully trim away material inside to get the screen in and the doors shut, it has to pull back a long way into the head to give enough clearance. Not only that but the back corner of the screen protrudes above the line of the doors so the lid of his head will have to be scooped out a bit too.
The brass bar that the screen is on slides back and there is just enough head to cover it, its all a bit tight. Now the fun bit, getting it to open and close automatically. I played with a few ideas, boiled down to 2, 1st was to have a screw/ worm drive to move the slider in and out, but for this the screw would have to extend the length of the rod and there is no room. So had to go for option 2, a cable inside a tube..... like the brake cables on a bike. I found a suitable tube, rc car antenna pipe, with a bit of heat they bend and stay in shapes. For the wire I got a reel of wire and found that 3 strands twisted together gave the best trade off between strength and flexibility.
After yet more hours of faffing about I came to the conclusion that having the doors srung shut is not going to work
the force needed to open them is quite high, this needs to be done by the screen twisting 90 degrees open at the end of its travel on the brass rod. However im going to push from near the pivot point, it needs a huge amount of force to lever the doors open which isnt going to work, the cable (doing the pushing) will bend.... use thicker cable? cant it needs to make a 90 bend from the body up, turn then out to the screen. SOOOOO im thinking I need this U shape bit that I will mount the door springs to....... then when its pulled back the doors close AND have tension on them, but pushed forward the doors are free to open. I just need to somehow get the cable to open the doors THEN push the screen out all the way.
Did that make any sense? prolly not, in short, this is a ball ache.