I have been reviewing the photos and drawings of the sled configuration for the Haas style box but I cannot see how keystoning is incorporated. Any help would be appreciated.
Thanks

From what I've seen, although I can't find any pics of it, you let the fresnel hang from a piece of doweling so that its free to pivot at the top. Then you make a series of notches or grooves along the side of the case to rest the dowling in. Pretty simple design. Gravity keystone as they call it. Haven't built one yet as I'm waiting for parts to come in, but I plan on building the Haas with gravity keystone.

Run thru Tescorp's builds in the trading post. There's a lot of pics in there and probably some of the keystone mechanism I'm talking about.

Hope this helps.

here you go

one more view

Hey TESCORP,

How come there are more than one set of notches for the keystone? Is that to adjust depending on where you need it placed?

Thanks

Warren

Gravity keystone makes sense, but wouldn't it be a problem that the fresnel becomes off center when it swings? Would a better solution be to put the dowel in the middle of the fresnel with a little knob to manually keystone?

WarrenW:

you got it right, forward for floor mount all the way back for ceiling mount.

cabe:

I have had no problem with the set up swinging at the top, all it does is move the image that forms on the triplet up and down to compensate for the trapazoid effect that would occur if keystone was not used. you only have so much play though, about 20 degrees before the image is shifted out of the range of the triplet's field of view.

In that case I might feel more comfortable just putting the axis of rotation in the middle of the fresnel rather than the top, and having a little knob on the outside of the projector to manually adjust keystone. I'll be projecting at a steep angle, and don't want to risk having any problems with fresnels going out of focus!

Keep the axis of rotation in the middle of the fresnel to keep alignment, and just glue some lead weights on the bottom of the fresnel so it still will swing when tilted. Yes?

Tawny

I havent tried a middle mounted fresnel but you still only have so much lens to work with before the image moves out of the field of view. lead weights would probably work. I like to keep the outside of the enclosure "clean" no knobs or things on the outside. no reason you couldnt put an adjuster for the keystone on the outside though. but I like the weight idea. auto keystone. if you are going to have the pj on a steep angle, I suggest a tilting screen to compensate.

Ooh, very good idea with the lead weights guys! That'll work out perfectly for me since I'll be masking off my 5:4 screen to be 16:9 and have a little room to work with on the top/bottom of the fresnels.