The neverending How-Tooo... This time we're back with friggin laser beams. We're still building our HD projector. Today we'll nearly finish up mounting all the components. We're almost done, soon we'll have our HD projector running, plenty of screen shots, and some sweet tweaks of our own. Oh, and if you need to catch up, check out:
- Build your own HD projector (Part 1) - concept and parts
- Build your own HD projector (Part 2) - LCD teardown
- Build your own HD projector (Part 3) - build process and mounts
- Build your own HD projector (Part 4) - chassis and lens
Last time, we clamped our enclosure together to get a rough idea of what it would look like. By clamping things together this way, we were able to position all the pieces just how we wanted them.
We lined everything up, drilled holes, countersunk for the screw heads, and locked everything down using two inch fine thread drywall screws.
We put two screws per side into the edge of each piece and got the clamps out of the way. We're not ready to glue things together until the end. We want to be able to disassemble things as needed.
To mount the lamp base we whipped up last time, we pulled the same trick - we drilled slots into the mount side of the base to keep the mount adjustable.
A pair of drywall screws equipped with washers serve perfectly to get the base mounted.
With the lamp in place, we need to mount the reflector. It needs to be just behind the lamp envelope.
We traced around the reflector, and drilled for holes into the rear panel of the enclosure.
To get screws the right length, we lopped off the ends of a few drywall screws.
We carefully used the screws to mount the reflector. It's a crude mount, but it should suffice for testing. (This looks like a great excuse to buy that new milling machine.)
Next we need to mount the projection lens. We marked the three screw holes when we test-fit the lens. Now we're drilling out those locations so we can lock things down.
We picked up a few 100mm m4 stainless steel machine screws and some washers to get the lens mounted.
It was a tight fit, but now our lens is mounted to the carrier. (Some lens cleaner might be an order -- we've managed to grab the glass a few times since we got going.)
To line up our drawer slides, we separated them and used our t-square to square them up with the carrier. We chose an arbitrary height, but we'd suggest centering them with the lens.
We had to measure the offset from the lens center to mark our mounting locations on the enclosure. Once done, we screwed the slides down with the screws that came in the set.
With the slides mounted, we slid the carrier into the tracks and the lens is ready to rock. We still need something to lock the lens in place for focusing, but we're getting there.
On one of our parts runs, we picked up a two foot by four foot piece of quarter inch birch ply at the hardware store. We'll be using it to cover the large open spaces top and bottom of the enclosure around the lens carrier.
We notched the top and bottom of the front of the enclosure.
Our 1/4-inch ply will rest in the slot we cut.
While we were at it, we hit the bottom of the enclosure as well.
Then we glued an some strips of plywood to the inside of the enclosure so we can solidly attach the panel.
To reassure ourselves, we double checked our alignment with a laser level. Everything seems to be on track for success.
As the projector progressed, we decided to revise our mounting system for the LCD and fresnels. Instead of mounting the frame to the enclosure, we're building it into a pair of thin plywood panels. We picked up a couple pieces of 8-inch by 12-inch 3/32 aircraft plywood at the hobby shop. We also snagged some slow CA adhesive (aka superglue, but in bigger bottles).
To make up for the thickness of the plywood, we used our tablesaw to cut 5mm of wood from the side of our frame with the shallower cut.
Now the frame and the plywood should fit into our 17.5-inch wide enclosure.
To line things up, we laid the plywood end to end and glued down the two small riser blocks that the LCD panel will rest on.
With those placed, we glued the frame panels in and a pair of thinner strips for the lamp side Fresnel lens and a piece of UV filtering Lexan.
The LCD fits our framing panels perfectly. Phew. We're not loading that thing back in until we're ready to leave it for good.
We scored a piece of Lexan from Home Depot. To cut it down, we clamped a straight edge (our plywood) and made several cuts with a utility knife. Once it was deep enough, we just snapped the piece cleanly away.
Test fitting yeilds a perfect fit. We might need to sand down the edges just a bit so it'll have room to expand when things heat up.
Since we'll be mounting the control electronics for the LCD to the outside, we decided to reuse the internal shielding from the display.
We traced around the upper piece with a pencil, then got cutting with our tin snips.
After some cursing and a sore hand, we came up with this. We mounted it with some machine screws left over from our last CNC project. Remember that one? (Here you go: parts one, two, and three).
Using progressively bigger drill bits, we drilled a 3/8-inch hole through for the LCD cable to pass through.
With the wire passed through, we mounted the boards to the lower panel, and installed the cover. Not too bad looking -- just don't let the wife see that angle and you're fine. Plus we get access to all of the connectors. We're not done here, but the cover will stay on to protect the sensitive electronics.
Believe it or not, there's only one more part to the series. Next time we'll lock down our mounts, add the cooling system, finish up the enclosure and add some finishing touches. Then we'll walk our new photon cannon though its paces and see if she's got the right stuff.