My astronomy project:
Building an Observatory
(or a playhouse for big boys and girls)

Content:

1. Frame
2. Roof
3. Roof mechanics
   1. Different designs of roof mechanisms
   2. Building the mechanism for the roof
   3. Hatch Hinges adjustment
   4. Roof Rail Mechanism
   5. Arm Rail Guiders and Stoppers
   6. Counter weight arm
   7. Counter weight
4. Floor

Note:
I take no responsibility or liability for what are written here, you use the information on your own risk!

Page III.5: Arm Rail Guiders and Stoppers

The arms are not rigid enough to hold the roof in exact position.

Here you can se how I added a wooden lathe inside the arm to guide it in correct position. No rollers and the friction maybe could be high. I will rubber a candle against the wood as a grease and get the friction low.

Here is a adjustable stop for the arm in open position. In the big hole there will be an adjustable bolt.

Covered by the trim list.

The arm has moved the roof to the open position and rest against the stop.