I have an HD1000u that I just installed last week and a PMS mount that I got at mountsdirect. When I installed the mount/projector I found what seemed to be the stud closest to where I wanted the center of the screen to be on the adjacent wall. Unfortunately the ideal place it now seems is about a 10" over, and the next stud is about 18" over. Since my projector only weighs 6.5 lbs (+ the mount) would it be a a bad idea to use six drywall screws and mount it in the ideal location? Or am I just asking for a disaster? I have read terrible things about keystoning, so I would like to avoid it if I can, but it seems like many people would have faced this problem. BTW- I have tried moving the screen to better suit the current projector location, but moving it over 1' is causing me a lot of grief in a 12' wide room.

Many will tell you to just use drywall anchors and not worry much about the ceiling joist location. (By the way in the USA you will find them located ether 16” or 24” on centers.)

I personally like to see things of the weight and value of a projector mounted more securely. Don’t compromise your screen location based around where the joists are located nor compromise PQ with using the keystone.

Depending on how much work you want to do and how handy you are there are two methods you could think about using. The first is getting into the ceiling and adding some bracing where you need it behind the drywall. (not easy to do) unless you have a crawl space above.

The second method is to bridge the area between the two joists with some kind of a plate. Depending on how nice you want it to look I have seen people take a piece of plywood and run a router around the outside shape and then paint the plate to match the ceiling or the projector etc.

If you do go with the drywall anchors get the ones called Molly bolts or expanding bolts sometimes called butterfly bolts. IMO they spread out the load the best.

I wouldn't use drywall anchors on a ceiling mount. I was prepared to use Bud's second method above to bridge the area between the joists, but lucked out in a) finding my joist, b) having it be the perfect location for my projector, and c) having it right next to the ceiling outlet I installed.

But I did use the bridge method to attach my screen to the front wall. Way too heavy for drywall anchors.

Please do not use the dry wall screws. Too risky.

You can use molly bolts, which are quite strong, but cannot practically be removed from the ceiling. Toggles are very strong, but a pain to use.
I'm using two toggle bolts to hold up a DIY screen that probably weighs 40 pounds.
Here's a website with various anchors.
http://www.naturalhandyman.com/iip/inffastener/infanchor/infanchor.html
Brian

If you check my photo gallery, I had to add a 10 inch long 1x4 that I bolted to the studs in my ceiling and then just mounted my pj mount to it. After filling the screw heads with putty, sanding it down, and painting it, I am quite happy and comfortable with the results. I know it is not going anywhere. I though of using the drywall screws that are rated to 50lbs, but felt that this method, though more involved, was the right way to go. You will regret not doing if your pj ends up falling on your significant other.

well, I decided to go with a 2X4x26" piece of white wood that is mounted to both beams and the projector is mounted to the wood. Since the wood is painted white it looks good enough. Since I have a wierd setup (my home theater is in a loft and the projector is mounted somewhat precariously near a good 15' drop) I didn't want any chance of it coming down and getting destroyed. The wood worked wonderfully and I now have no keystone and the screen is now mounted to work well with the speaker placement.

I’m glad things worked out. :)

Don’t be a stranger around here and enjoy that setup you have now. :D