Hello All,
I've wanted to build PJ since I first heard of the DIY PJ crowd years ago in college. Now that I've got some money and time, I can finally start my first PJ project! I've already bought some parts, so now I know I'm serious. My goal is to build a working 17" long-throw projector for a mostly-dark dedicated medium-sized movie room (about 12x14 ft). With a 17" LCD, 457mm lens, and a throw of about 10ft, I get a projected image of about 100" diagonal 4:3. The LCD I'm working with is an older 4:3 one, so that's what I'll start out with. I may make a second 16:9 1080p projector later, it's all on the wishlist.

Here's the parts I have:
18" (457mm) Beseler Opaque lens
400w LL eBallast
400w MH bulb
mogul socket
thermal controller
17" Xerox LCD
Sound (Logitech z-5500 5.1 speaker system)
650mm pro fresnel
220mm pro fresnel
pro reflector

Parts I need:
IR/UV/Heat block (haven't decided what yet)
Enclosure (probably DIY wooden)
Wiring
Screen (probably blackout cloth or painted MDF to start)

My plan is to make a simple straight-shooting projector. Eventually I'd like to have a smaller/compact enclosure, or a vertical folded design. However, I figured it'd be easier to figure things out in a straight design first, then add fun stuff (like pre-condensors, FS mirrors, etc). I'll try to update this as I go along, and of course pictures when I finally get the parts and start building. I'm a kind of measure-twice, build-once guy, so expect things to go slowly. But now that I've actually got most of what I need, I can't wait for this thing to get started!

My next step is to figure out a heat shield. As far as I know, my options are:
-tempered glass
-lexan
-hot mirror (aka uv/ir filter)

Lexan should be easy to get from Home Depot (around $6), and they have 12x24 sheets. However, it may not block as much heat and will not be as heat resistant. A hot mirror is beyond my budget, since I'm trying to keep things simple/cheap for the time being. Tempered glass seems like the most appropriate choice, since it blocks out enough heat (both IR and UV? Haven't figured that out yet) and will be relatively cheap and easy to get.

Plus, I have an old scanner or two that I can use the glass from. The scanners are smaller than a full 17" LCD, so I assume I'm going to have to put the tempered glass closer to the light source (where the light path is smaller than at the LCD).

Some questions on my mind:
Does tempered glass block UV and IR, or just IR? How about lexan?
Can I use a small piece of tempered glass (like from a halogen work light) right next to the bulb?
What kind of light-loss am I looking at for tempered glass? Lexan?

Hi, were you aware that an old oven door is tempered glass? You should be able to find one at a very reasonable price locally even for free down the tip (dump).

- Only if it's treated on has a film applied for that, specifically.
- Yes. You'll probably want to keep it about an inch or so from the bulb. You can probably find a real inexpensive work light with tempered glass at Walmart.
- Dunno, but if you do a Google search of the LL site (like the one linked below), you might find your answer. Maybe use search terms like: site:lumenlab.com +light lost OR loss +"tempered glass"

Google: site:lumenlab.com +glass +flatbed +scanner

I wasn't aware, but it makes sense. However, I'd think that an oven door would be thicker than the usual 1/8 inch, right? I think the scanner might work better for me, since I have a scanner (or two) and it's thinner, and easier to work with. Plus, I wonder if an oven door would be


I'm still trying to figure out what I need for my PJ. It's confusing, since some posts say that I need UV and IR blocking, while others say that just a sheet of tempered glass is enough. I think perhaps the best practices have changed, but it's hard to figure out what is the current best practice in the forums. I might just go with a sheet of tempered glass right now since it's easy, and just monitor LCD temps. However, do I have to worry about long term future UV damage to the LCD? If so, it might be easier for me to just get a piece of lexan/optix from home depot and get the UV taken care of too.


That's exactly what I was thinking about, since I used to have one of those. I'll use the scanner instead, but the work light would make another good source.


I've been reading through those and other threads, slow going but very informative. From what I've gathered, tempered glass is decent, lexan has better light transmission and (sometimes) UV blocking, and acrylic might be slight more transmissive while still blocking UV. Also, the plastics have a working temp to about 200 degrees C, while tempered glass is more around 400.


In other news, fedex just dropped off my LL order! I now have my fresnels and pro reflector, so really I have everything I need to start assembling except the wood for the enclosure. I'm going to try to stop by the hardware store this week to pick up some MDF and start a mockup projector. My plan is to setup a test rig to try out distances and placement before I finalize a design.

Thanks both for the input, I'm going to try to keep this very PLOG-like, ie. each step and hurdle chronicled. It may be a little redundant or verbose, but I figure it'll help someone else out to see the whole process.

I understand that all glass has some UV protection but particularly tempered glass. Early posts (2005) here on LL have details.

Hence the idea of the scanner glass has merit. Bear in mind that part of the reason for the 'barrier' is for UV, i.e. to protect the LCD from light damage, but it is also to protect all the components from physical damage if the lamp explodes particularly the 400w ones. Hence the thicker glass will do better but I have read that scanner glass does fine. Just for general information oven glass is approximately 6mm thick and a typical oven door sheet weighs 2.5kg.

Here's some pictures of the parts. First off, the Beseler 18" FL projection lens. It's huge! I've heard the measurements before, but somehow I was still expecting something smaller.

Mine has dirt/oil/fungus on the lens elements, looks like even on the inside. I'm going to have to clean that out eventually.

Next, the LL Vue eBallast. Also big, but this one I was expecting to be large.

I also got a temp controller thrown in. Not sure if I'm going to use it, but seems like it could come in handy for cooldown after lamp poweroff.

The lamp and socket. Again, much bigger than I expected.

The lamp has crap inside the inner element. Is this a normal part of firing, or is mine burning out? Haven't fired it up yet.

The pro reflector, still under wraps.

The pro fresnels (220 and 650).


Now all I have to do is setup a test rig and start figuring out optimal distances for all the elements. Also, I'd really like to get a light meter and measure lumens at each stage (without reflector, with reflector, distances, etc). But I might get lazy and just do it by eye.

Jumpfroggy,

Have you checked out the Focal Calc yet? I'll guess you have, but it you have not, download it for free from LumenLab to know where to start for your measurements.

BTW... A 17 inch LCD is a great size, as you will be able to achieve 720p from your projection. However 10ft is a little close to the wall. You will probably find that you will want your picture to be bigger, and your 17" screen will easily give you good definition, even as the image is stretched larger.

Cheers!

Fulcrum

The stuff in the inner capsule is the stuff that makes the bulb work. I read somewhere here that when you first fire it you should run it a good hour or two and burn it in the position that it will be in when your projector is finished. I dunno how much you have to baby it but I followed that advice and things worked out pretty well.

I know what you mean about the beseler lens. It dosn't really hit home how big it is till you have one of them in your hands.

Same here!

That looks cool, if you're not going to use it send it my way. And coincidently, I was born in Hitchin, Herts, UK. Not in the CAL factory though.

That's great mate! You look like you're off to a good start with those items.

Yes I agree with you regarding the Beseler (or a Buhl for that matter) they are a lot bigger than you think they are going to be. And heavier for that matter at around the 2 kb plus mark if I remember correctly.

Good luck with the build.

Thanks Bluedog.

My status right now: waiting. I thought I had everything I needed, until I held the fresnels up to my 17" LCD and thought "Gee those look small". After some rulers, high-school trigonometry (it's been a while) and finally seeing the specs on the LL website, I realized that they accidentally sent me the standard fresnels instead of the pro fresnels. Yikes! I left a message, got a call back a couple days later, and they're sending the pro fresnels out and scheduling a pickup of the standards from my house. Awesome support! It's refreshing to see a company that handles these situations right... I was preparing for a struggle.

So when those come in, the building begins. I haven't yet decided how I'm going to build it, but I figure I'll just do cardboard or wood mockups till I figure out what works best for me (split, unsplit, keystoned, etc). And if I decide to do a folded vertical, I'm going to have to get a mirror. For now, however, my plans are a haas-style big box.

You will be happy with that setup with 16/9 movies, I have almost the same thing but remember that the edge focus will be a little soft.

Have fun with the build

Replying out of order here... I'm having trouble receiving notifications from this thread, for some reason. I've played with focalcalc a bit, but haven't written down numbers yet since I'm still trying to figure out where everything's going to fit in the box.

10 ft is pretty close... if I was going to only use it in that room, I'd have gone with a standard 15" setup instead. But this PJ will also be used in a 2x bigger living room (for group movie nights), so the long-throw and 17" will be more useful there.

I got my first test fire on my projector! I finally got all the right pieces in (LL originally sent me the standard fresnels instead of the pro's, fixed), so I cut the fresnels to size, disassembled the lcd, and lined everything up. And it worked! The image is really dim right now, and the lamp wasn't lined up vertically (it's going to be mounted horizontally later), but I did see something and that's great.

First, I figured out how big I wanted the fresnels to be. Slightly smaller than the enclosure, bigger than the LCD. Then I put tape on each side of fresnel and marked where I could make the cut. Then I clamped a straightedge to the waste portion and used a razor to score the LCD (about 10-15 times, medium pressure). Then remove straightedge, clamp it on the "keep" side (with paper in between to prevent scratching), and pressed down on the "throwaway" side on one corner. With light to medium pressure (if the scoring was deep enough), it'll crack just a bit and you can press down along the score to break it off in one piece. If it only partially breaks, I start on the other side, and then use pliers to carefully break off the remaining pieces. It's not perfectly smooth, but straight enough.

Clamping the fresnel to score it with a razor:



After the cut, just a few little pieces leftover:



Then I made a cardboard mockup to hold everything in place, and fired it up.

At first the bulb wouldn't fire, so I got nervous. I unplugged it and tried again, and it started up. Took a while to get bright (5 minutes?) and much later was just slightly brighter still (15 minutes?). Lots of ambient light from reflections, and I'm projecting onto a shower curtain. I also tried projecting onto an extra-white piece of printer paper. The brights were slightly brighter, with a red-shift. The blacks were much lighter and washed out, due to the paper reflecting more ambient light. Interesting.







You can see the screen door from focusing on the last couple of pictures. It's more pronounced in person, since I didn't have a tripod for my camera. That's the 720p HD trailer of Speed Racer, by the way (just happened to have it on my desktop). I'm really excited to see everything working, but also I'm starting to realize just how much light is lost through the LCD, lamp, etc. It's sad that we have such bright bulbs and use so little of the light. I keep thinking that it'd be amazing to have a huge parabolic reflector, since that would capture so much more light. For now, I'm just going to add the pro reflector, and possibly add a pre-condenser in a little while.

Next is to build the box, mount everything, and make sure cooling is adequate. Then... my first movie! Can't wait.

PS. What's with the annoying image limits and flood control settings on this board? I tried to post this update, and had to break it into two due to image limits. But the board doesn't say how many I can post, just that I have too many (!!!!). So I have to keep retrying till I figure out how many is too many. Then I go to post the second half, and it says "Please wait, flood control". Really annoying. Then I wait, post again, and get "Sorry, but when your post merges with your previous post, you will have used too many images in your combined posts." WTH? Why the heck is this board trying to combine my separate posts?? It seems this board was setup to annoy people. Boo.

I think you have to wait one minute between posts or the board will try to amend your last post with the new content. I know it's annoying, but we have to live with it. At least you're hosting your pictures externally.

Looking good!

Wow, can you be anymore polite about this. A nice private message to the site's owner 'BRAINCHILD' inquiring about this would of been suffice. Let's have a bit of respect for the man, shall we? Afterall, it is his house your playing in.

I do apologize, I usually wait a little while before posting anything to make sure I'm not being an arrogant jerk, but in my impatience (and suffering from sickness and an all-day headache that wont go away), I posted without thinking. So yeah, I was being a jerk and I'm sorry. And I will PM brainchild with my (censored/filtered) comments, to see if there isn't a way to improve things.

You are free to leave.

I set the limits to "prevent" the legions of spam-bots that will happily spam the forums ad infinitum.

I'm sure you'd be complaining about the spam if the boards were set otherwise.

Maybe you are a spam-bot?

Hi man, nice job!!!
I'm thinking on buying the bulb and ballast from LL too, can you send some pictures to my email?
I asked the LL staff about information but there was no response!!!

Email:
ton.df@ibest.com.br
elkmgatinho@hotmail.com

My apologies, like I said I usually wait so as not to be a jerk when I reply. This time I fired off a flame without thinking first. While it's annoying, I understand you had to make compromises. I'm sorry again, I know that was a callous way to complain.


What pics do you want? Just pictures of the bulb/ballast? (Different from the ones above?)