Type of wood to make enclosure other than MDF

cbm5

Member
2005-03-14 12:47 am
Arkansas
You want to go with something relatively stable. Plain wood planks will try to warp with varying moisture and heat. MDF is pretty stable but only when not under too much load; otherwise it will sag. Particle board will sag no matter what. Chipboard is too nasty to build anything. Poor-grade pine plywood can have some warping problems, high-grade birch or oak plywood 1/2" thick or above will be very strong and stable but also very heavy. Aluminum is a good framing material, and a good paneling material if you can get sheet aluminum. Steel is not used much but is easy to form and weld if you want an all-metal projector. Acrylic is relatively expensive in structural sizes and difficult to cut without cracking, but it is easy to heat-bend. That makes it a bad idea to use near the lamp, and it's normally clear so everything must be painted opaque. Lexan is easy to cut but more flexible than acrylic, and not any cheaper. Polystyrene board and other plastics I haven't seen used in this application yet, but some materials exist that would be useful if they can be obtained cheaply.

MDF has the best compromise for stabilty, heat resistance, workability, and expense. Metal is probably best for lightness and permanence. Thick birch plywood is probably the best option if someone is building for permanence but has no metalworking experience.
 

cbm5

Member
2005-03-14 12:47 am
Arkansas
No, using it for putting the various elements on a sliding axis.

I had some success a while ago using similar construction to make a DIY CNC mill. I have extra stepper motors and drivers, might even put in a power focus and keystone. Probably not, but I guess it's a reminder that you're NEVER done with a DIY project. Always one more thing to add or tweak.
 

politicorific

Disabled Account
2005-08-14 6:55 pm
rather than make another thread, bumping this one makes sense rather than rehashing what has already been said.

Few have ventured outside wood for use as construction material. Wood is safe, relatively easy to work, stable, and cheap. However, there are a host of other elements besides carbon to work with. The thought occured the other day to investigate alternative construction methods. Would it be possible to fool people into believing that these projectors were produced by a large electronics corporation? (as a side not, if these deviced are relatively easy to make, why haven't any companies explored manufacturing these devices en masse?)

Could plastic, brass, steel, aluminum, or even chrome could be used to create some very extravagent looking projectors which may divert attention away from the impressive capabilities of the machine itself. Plated, anodized, or treated with acid solution could create some interesting effects. Take a look at the computer modding community. Today all sorts of cold cathode clad, acylic window sporting machines are everywhere. What is holding back this community? Cost? Difficulty of construction? Heat issues? Or some other consideration which must be taken into account?

How much weight could be saved by going the all metal route? This must be important for some when considering a roof mount option. Why bother with a light weight electronic ballast if coupled with heavy building materials?

Projectors are essentially 4 parts, 1)lamp&lightbox 2)fresnel and LCD assembly 3)Projection lens&focus 4)ballast&electronics. Why house all this in 3/4" building material?

[IMGDEAD]http://img385.imageshack.us/img385/3392/skeleton9aa.th.jpg[/IMGDEAD]

Think of this as a sort of roll cage. Electronics and ballast enter from underneith the unit with their respective wiring feeding to the necessary areas. The main question is whether this can be implemented without having to weld anything while maintaining strength. Fabricating the structure looks to be the most difficult part - it could be made out of wood if one wished. Copper Pipe could even be used - want to cut down on heat and noise? Why not watercool your projector?

One could use an assortment of metals like this:

http://www.onlinemetals.com/merchant.cfm?pid=4588&step=4&showunits=inches

to cover the skin. Computer sides are about this thickness. Here should be just enough material to house the projector for under $30 and shipping should not be too bad.

So, here are a dozen different ideas. I'll be heading to various hardware stores this week in hopes of finding a material which whill make up the skeleton.
 
plywood on 1 by 2 frame

I used 5/16" smooth plywood on a 1" by 2" frame, glued and screwed. The plywood does not seem very strong, but once the glue sets up, you get a box you could put 200 pounds on.

The only problem is that some things like the core & coil ballast are so heavy that I had to add a bit of thicker plywood on the inside to spread out the weight.
 
I have 2 questions kinda related.

1. If you cant line the insisde part of the box by the lamp with alluminum right against the wood than what do u put in between it so it doesnt burn the wood? Or is there another method?

2. What are most people using to hold the fresnels, uv glass, lcd etc onto the frame or inside of the box?
 
in between metal and wood

You put free air space in between: That means that most of the metal surface area is not in contact with the wood, and the air that gets heated by the metal surface can circulate and get replaced by cooler air. You can also use some tricks like polishing the lit side and painting the dark side with flat black paint. That way the lit side absorbs less heat, and the dark side transfers more heat into the air.

You can use wood strips (like 1" by 2"s) to hold the metal off the wood surface, as long as most of the surface is not being insulated by wood contact.

The problem occurs when you have metal exposed to the lamp light. The metal gets energy from the lamp side, and can't dissipate that energy on the other side because the wood acts as a pretty good thermal insulator. So the wood just gets hotter and hotter. Eventually it gets hot enough to char the wood. You will know it, if you happen to be in the room, because it smells like burning wood. If you are not in the room, then I suppose it could get hot enough to start a fire.

For fresnel and LCD frames, you can use wood, plastic, or aluminum. They don't get very hot, that far from the lamp. I have used 1" by 2" pine pieces screwed together to make frames. I have also used pieces of aluminum extrusion from Hoem Depot. The L-shaped one works very well. I hold the LCD to a such frame with tiny machine screws between the LCD's original frame and my larger frame. Others use RTV glue and routed MDF frames. Seems too permanent to me.