Aluminum Designed "Roll Cage" Projector - Insight wanted

[politicorific]

After completing my first projector - a plywood ordeal - I've learned about a lot of shortcomings my first design had. Rather than try to retrofit the existing setup I've decided to scrap it all together.



This is only the beginning to see if my 3d cad skills were up to task. My measurements aren't correct

The roll cage setup has one major advantage over plywood or MDF - weight. It would also be much easier to suspend in the air.

Home Depot has 3/4" angled aluminum in 34" lengths for not too much money. Combined with "Roofing" Aluminum - 14"x10feet for $10 there is plenty of material available to construct this for about the same price as a similar plywood or MDF enclosure.

Fresnels and LCD are mounted using screw/bolt/washer/spacers. Removing the top panel would allow access to fine tune components and replace the bulb.

Ballast would be mounted behind the lamp on the exterior of the unit. 120mm fans would be mounted above and below the lamp.

2 snags so far

1) Drilling acurate holes in aluminum is a hard and requires very sharp drill bits. Cutting isn't so bad. Air powered cut off discs makes short work of the angled pieces. Also, getting holes to line up on the computer is easy, but getting them to line up in reality may be a bit hard.

2) Not sure where to place the LCD circuitry. My FFC-less LCD extends past the bottom of the design, but the controller circuitry can be mounted basically anywhere. Mounting arms can be easily devised by additional screw holes placed on the side - who knows, maybe someone knows of a decent auto keystoning(aside from angling the screen) and focusing mechanism.

So, should I continue with this computer drafted experiment? Or is there something important I've forgotten? Will the whole thing transfer heat too well and melt my components?

[tjh]

Looks pretty good really. The one thing you might have to worry about in that design, although it doesn't look like it from the picture, is that the angle of the forward part doesn't cut off any light. Other than that I can't see any problems with the design.

As far as auto key-stoning goes I've seen a handful of people hang the field (front) fresnel from a dowel and let it rotate freely. Thus gravity will take its course and the fresnel will hang parallel to the wall, correcting any key-stoning up to about 15 degrees. (You could probably do more but that seems to be the agreed upon max in the DIY community without degradation of the image.)

[politicorific]

Some more work, my skills are very rusty, although I had fun with the fans.

I'll find my student copy of photoshop to draw in the rest of what I'm thinking in a set of pictorials. The fans are much larger that I thought, maybe I'll go with some 92mm panaflos instead, although I still haven't figured out the duct work.

[politicorific]

MSpaint would've sufficed

The rear of the unit will probably be larger. The LCD I have sticks down past the "superstructure" if you will(represented by black). An additional box may be affixed, or the links supporting the fresnels extended.

This isn't looking as small as I once envisioned.

[politicorific]

I did a quick tally to see how much angled aluminum is required for the current design. So far it's up to 822cm, roughly 27 feet of aluminum. I know that my local Home Depot doesn't have this much available and in prior research discovered there are a few outfits online which offer better prices.

http://www.onlinemetals.com/merchant.cfm?id=63&step=2

To get an idea of cost, if 5 6 foot lengths are ordered the cost comes to around $20. It shouldn't cost that much to ship 3 lbs, but a 5 foot package is a bit unweildly. I noticed I would be charged $4.50 in cutting charges - guess they get some large pieces and cut them down to size. The custom cut options are available, but going that route ends up costing twice as much.

Next snag, the cheapest aluminum is 1/2" not 3/4", no reason to use the heavier stuff.

With $15 shipping, the total comes to $35, add another $10 for the roofers aluminum and then mounting hardware and it totals up to about $60 in material to go this route. And the design isn't perfect yet.

[Hezz]

politicorific,

I really like your design. I think that it is a good approach and will be a relatively easy to mount and low mass design.

[politicorific]

thanks

Messed around with this over the weekend and still have some fundamental problems to sort out, although one of the original advantages of this design is that with a short list of lengths required that it could be easily copied.

Maybe I'll post another screen shot of what I've restarted. I began placing screw holes on the assembly to see where drilling would be required.

I don't have a drill press, which may make accuracy decrease, although I think I did solve the electronics placement, I have yet to figure out the fan ducting so as to prevent light leakage. But I just got an idea. Hope to implement it later