Its been a very long gestation period.. when my projector was out of use... but my projector lift is finally finished! (ish).
Background:
I would have loved to have my projector downstairs, but owing to concrete ceilings and wooden floors there was no way I could ceiling mount a projector as nowhere to run any cables. This meant a separate set-up upstairs in the spare room where I could access the ceiling space... and doubling up my cinema setup from downstairs too as I wanted to keep surround sound system with my Loewe TV
Why a lift:
To make matters more complicated... my spare room has a dormer window and this was the only place I could mount the projector.. this meant a projector lift was needed as a) it is the spare room where people stay occaisonally and b) the projector would be in the way when not in use.. and could be seen by people walking by and looking up.
DIY Option:
I looked around on the net for projector lifts and couldnt really find any that a) were less than about £800 b) looked nice when down and c) could fit between the joists. DIY it was then
The Build:
A few sketches were made, trying to sort out how the thing was going to work.. I discounted anything electric as too complicated and too expensive. Linear motors would have been nice, but again couldnt find anything that was cheap. Quite a few sites had ones for raising plasmas out of boxes.. but again too expensive.
Stages:
1) Cut hole in plasterboard between joists.. no going back now! (pic 2) Space between joists extremely tight for projector size.
2) Noggins in the way on each side... so had to pry/cut these out and fit new stronger ones as they were going to hold some weight (pic 3)
3) Build the box that would go into the hole. This was a four sided affair, tall enough to completely enclose the projector when in up position (pic 4). I used thicker wood at the sides and routed two channels in each into which the sliding arrangement would fit. The whole arrangement was painted, and then the slider rails fitted. The box was fixed together on the outside using angle brackets. These had to be routed too so they did not stick out else would foul on the hole in the ceiling.
4) The four sided, open top and bottom was then fitted into the ceiling and screwed into the joist/new noggins on all four sides (pic 5). Tolerances for the whole things had to be in the region of <2mm
Once in place, the gaps were hidden by some wooden beading as you can see half fitted in the picture (5).
5) Then had to build the bit the projector mount would screw to. This had to fit exactly in the box with very small gaps else would look unsightly. On the top side was two uprights in line with the rails to which two small wheels were attached each end. (Very dodgy bit of DIY went on here). The underside was painted and the Vogels mount fitted.
6) The manual mechansim was then put together. To ease the weight having to be pulled up and down I used a 3:1 pulley system with some small blocks bought from an online sailing shop. A secondary system also added a 2:1 system with a counterbalance weight. The first pulley system is being tested in pic 6.
7) See if it works! The board and mount arrangement with the guide wheels was lowered in from above, and the projector fixed to it.. pics 7 & 8. It sort of went up and down and with a bit of adjustment... seemed to work OK! I had to make sure the c.o.g. was right in the middle owing to the single attachment point.
8) Once know this was OK, bought some curtain pole and fitments to hold the lower board in place, so just looks like a loft hatch when in up position. 9) Pics 9 and 10... now you see it, now you don't!!! Pic 11 view of dormer with projector down.
There was a lot more too it than this.. but in general the above steps show the progression. The main problems were the access to the bit of roof above the dormer window... a nightmare of having to be half wedged between the sloping roof joists to reach through
and those ****** rails the whole thing slides up and down on. I ended up using drawer rails.. but if was doing it again would search longer and harder for some decent metal rails with ball bearing movement.. such as found in computer rack rails. Trouble with these is the limited height in the roof space.
Anyway.. very happy with how it looks down as well as up. Some of the ones you could buy looked horrible down, with the pantograph mechansims looked very indistrial.
Feel free to post any questions and I will do my best to help if anyone else is motivated into building one themselves by this post!
EDIT:
Dimensions requested... have added extra picture with some of the dimensions. Front to back was limited by space between joists... sideways there were some noggins which I removed and replaced by studier pieces of same height as joists. 18mm MDF was used for the sides of 'box' and 12mm MDF for front & back.
The interior of the box is 44.0 cm wide x 44.5 cm front to back. The actual sliding mechanism is 2.5mm smaller all round than the box interior to allow room for movement... then there are the curtain pole pieces holding the bottom peice of wood in place which cut into the area available for the projector. This could be limiting depending on the size of the projector.. OK for SP4805 which is small and should be OK for larger ones such as AE900 and Z4.. just. I did check before hand so if I upgrade I wouldn't be stuffed!
The vertical space for the projector and mount between the upper and lower pieces of wood (18mm and 12mm MDF respectively) is 24.0 cm. The mount is the small Vogels. This could be got rid of completely and mount the projector directly on the top piece of wood... but with no lens shift I wanted the image/screen lower so could live with the drop. Mounting the projector directly could cause problems of adjustment though, i.e. having none!... and front to back space could be a problem also for running the cables from the back of the PJ.
Projector Lift - My DIY Experience! 
Linear Mode
