Plastic material source for a small enclosure

I want to create an enclosure for a prototype. It's a small project, roughly a 1" cube. I really want something lightweight (the electronics, display and battery weigh 15g) but it also needs to have some rigidity. It must be opaque or an easy way to make it opaque. It also needs to be a material that I can cut and drill and glue so that I can fit it, allow the display to poke through, and also the buttons.

I think this may be harder for me to make than the electronics and software.

Any ideas?

You can get several layers of Plexiglas or Acrylic sheets. You cut profiles into the layers to form a cavity for any components inside. You can drill four holes on the corners and fasten them together with screws, or bond them together. The result is transparent and easily customization to many designs. It is not water proof. IP 41 at best.

Here is the general idea

And something like Onshape to design the layout.

The electronics supply shops (even Radio Shack or its equivalent in your country) will have a big variety of different plastic boxes. There is probably one in the range which will do what you want. If you are buying from online stores like Mouser or Digi-Key, they have literally thousands of different boxes.

I must advise you that most of my mistakes in electronics started from trying to cram the project into a box which was only barely big enough. Always buy one size larger than you think you need because all sorts of components like switches and receptacles are much bigger on the inside of the box than when you had them sitting on the bench next to the box.

I use styrene sheet. You can get it in various thicknesses. The thinner the more translucent. I have used 3mm sheet and drilled blind holes in it to mount LEDs in and you don't see them until they light up. This video shows it on a project.

Arduinocaster

You can also use styrene round, tube angle, channel, and I beam to construct things:- http://www.evergreenscalemodels.com/Shapes.htm

Here I used it as a light baffle between LEDs http://www.thebox.myzen.co.uk/Hardware/Econo_Monome.html

Find a near-by makerspace. Make a few friends. Have them help you machine it from HDPE or ABS (or wood) (or aluminum in the case of my local makerspace). ABS / wood will be more rigid than HDPE.

Or, hire these folks to print something... http://www.shapeways.com/ (A local makerspace will very likely also have a 3D plastics printer.)

Or, if it is powered from AA or AAA batteries I use a battery cage with the one or two cell areas for the PCB. Epoxy has been working great to hold things in place.

Or, find something close from Hammond (or one of the other "project box" vendors).

Or, if you are willing to use wood send dimensions to me. I have a hankerin' to make another tiny box.

My first thought was acrylic as I have some on hand but at 3/32" it's just too thick. I don't know where to get thinner acrylic. And I've found it to be difficult to cut and drill in the past.

An off the shelf box is a possibility but it would just be a start. Given the modifications I'd need to make to a box with a hinged lid I might as well just start with the raw material.

Styrene sounds pretty good. It comes in very thin sheets. It's a little lighter than acrylic. And since it's the choice for modelers it can't be that hard to work with. I'll have to get some and play with around with it.

There is no battery cage as it runs off of a single coin battery attached to the underside of the main board.

Wood is an option, especially since this is just a prototype. It's cheap, light and readily available. Yeah, why not wood?

I was thinking of looking into 3D printing for the final version. That's down the road though. I need to learn how design PCBs first.

[quote author=Coding Badly link=msg=2410491 date=1443130447]Or, if you are willing to use wood send dimensions to me. I have a hankerin' to make another tiny box.[/quote] What kind of wood do you use? What sort of joins do you make? Glue? Screws?

I use acrylic all the time. I use a 90 degree router bit to make boxes. When I make wooden boxes I usually use oak. Joints are either "box" or "mitered"

This may give you some ideas: https://m.youtube.com/watch?v=OiETlYskTrY

What is that round thing that seems to make the cuts but we don't see being actually used?

It is a circular saw blade with 90 degree teeth.

I use a router with a 90 degree bit:
Camtool.jpg
90.jpg

Thanks, not seen one of those before. I suppose the trick is getting the cut depth "right" to allow you to snap it.

Actually, it is very easy using a router table. You use double stick tape to hold the plastic sheet to a sacrificial 1/4" squared off board. The plastic faces the table and bit tip. Set the 90' bit height to just under the plastic thickness. Set a fence at the wall height to the bit center. Run the plastic sheet over the bit on all 4 sides.

I make most boxes out to 1/16" material. .

jboyton:
What kind of wood do you use?

Depends.

First, the ones I will never use…

Maple - I am very allergic to it.

Luan - I am very allergic to it. And it’s just crap. It’s soft, it produces an annoying fine dust when machined (i.e. sawn / cut), and it has a pathetic appearance.

Second, the “scrap” I use…

I have an oak plywood that I cannot get rid of. No matter how much I use, the garage always produces more. I think it’s somehow procreating. I don’t mind it. The “oak” is an amazingly thin veneer which is attractive. It’s not particularly strong. It machines well. I use it for prototypes.

Finally, the good stuff…

A very good choice is Baltic birch plywood. Especially for anything you expect to endure temperature extremes (it is “dimensionally stable”). It is very strong, machines well (with one exception), and is reasonably attractive. The one exception is when machining with a CNC router. The wood is “stringy”; you will have to clean off “hair” after machining.

Purple heart is a beautiful wood but not at all strong. However, Minwax Polycrylic dramatically increases the strength. (Polycrylic strengthens all woods. I suspect it is especially effective with purple heart because of the very large pores.) Because the wood is soft it machines very easily. It oxidizes which changes / dulls the color. If you use it (or anything with the same property), it is important to cut, sand, assemble, seal in as short a time as possible (think “a few days”).

Padauk is very similar to purple heart just orange instead of purple.

Zebrawood has a beautiful dramatic look. It is similar to Baltic birch for strength and machining.

Note: Especially colorful woods (like purple heart and paduak) will discolor other woods (don’t store purple heart with padauk).

I love / hate working with mesquite. It is amazingly strong. Except that there can be seams running through the wood that have zero strength. It is knotty. Or not. The grain runs every which way. It is, by far, the most difficult to machine wood I have ever worked. But, if you can pull it off, there is nothing else that has that amazing appearance.

I have a quarter-sawn wood that I really like but I cannot remember the species. It’s strong, machines well, and has a cool spotty look.

The oddballs…

I had a wood that was denser than water. I think it was kingwood. I remember it being very strong, difficult to machine, and attractive. Strange interesting stuff.

I like oak. It’s obviously very strong, attractive, and machines well. It’s in this section because, in my experience, it devours tooling. I rarely use it because there are other choices that always have an advantage. I would only use it when strength was paramount.

What sort of joins do you make? Glue? Screws?

If what I’m making is largish, glue and screws. Otherwise just glue. Quality modern wood glue is always stronger than the wood itself. I use screws to hold pieces together while the glue dries (and because of paranoia; just in case the glue does not hold).

I have a desktop CNC machine so my current favourite joint is the finger joint. They are easy to draw (CAD), easy to machine, align well, are strong, and can be made reasonably attractive.

Wow. Now I have more information than I can digest.

Thanks for all the advice.

In case you missed it, I am serious (conditional on time constraints)...

Or, if you are willing to use wood send dimensions to me. I have a hankerin' to make another tiny box.

Yes, I saw that. It's a very nice offer. But I'm not sure how I'd specify it well enough to have someone else do it. I breadboarded it first, that was nice and neat. But this second prototype is kind of a loose ball, made up of three off the shelf adapter boards wired together with an LCD display dangling by a cable. I haven't even attached the buttons yet, but it will fold up into something close to a one inch cube, slightly wider because of the FFC adapter board.

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I can't quite wrap my mind around exactly what I'm going to need to do, much less detail it for someone else. Not yet anyway.

Mock it up.

Onshape.com ->Send drawings/dimensions of your box to whomever.

Circuitmaker.com ->Get a nice board made. Send to Oshpark.com

Just begin. It is an iterative process. You will likely go through multiple ideas or designs.

Use Google "SketchUp" (Free) to design the enclosure. HERE

But I'm not sure how I'd specify it well enough to have someone else do it.

The first step is to design the user interface (the case intrusions). For example, if the device has a display and is meant to be held in the hand, position the display so the device can be comfortably grasped without covering any part of the display. Once you have the user interface designed, the rest usually just falls into place (e.g. if the display is here, the PCB has to go here).

Start with "what do I want"; worry about "what can I do" later.

It's pretty simple in concept: A screen in the front, four buttons on the sides and an access on the back for changing the battery. Some way to program it as well. And someway to hold the parts in place. I'm hoping I can put this all on a single 1" square PCB but I may be dreaming. Two boards would still be okay.

Simple in concept but not trivial to do.

Thanks for the links and all the ideas.