Creating A Plastic Housing Container

What type of CNC do you have?

Some router / spindle CNC machines is known as 2 and a 1/2 axis. That is can cut contours, vectors and arcs in 2D and step the 3rd axes separately. It is still possible to cut 3D but may take longer.

It is also possible to buy containers / enclosures of the shelve and machine it to your requirements.

Casting an enclosure in one of the many epoxies is another possibility.

Hi,

You haven't mentioned injection molding, centrifugal casting, etc.. so there must be lots you aren't telling.. does it need to be transparent on one side, or lensed? Does it need to be air/dust/water tight? what are the min and max temperature and pressure restrictions? What are the overall dimensions? Is the optical device also electronic? does it require post assembly servicing? or maybe potting will suffice? I'm guessing you have economic constraints? I've never heard of a cnc that is 2-dimensional.. unless it is just an x-y router table... but there is no shortage of 5-axis machines out there.. more data please. pictures are even better.

Chris

How about a Santa Claus machine? These 3D CAD systems can build up virtually anything you can imagine without the common limitations of other techniques. Of course they aren't cheap but you can make things that there is not way to make otherwise.

Most CNC machines are 3 or more axis. A 3 axis machine could make your box provided the tool used has a long enough shank to go into the block to cut out the inside of the box.....

It really depends upon the type of material and the size of the box....Please give us more details if you wish for further assistance......

Hi Steve,

I don't know anything about CNC. Have you thought about using acrylic sheet and forming/glueing that for your purpose? It's relatively cheap, very adaptable and strong. Regards, John.

Lucite can be seam welded to make it air tight using a Resin-Bond soaked sponge for a short time (experiment first).

Thin plywood can be assembled first then W.E.S.T. systemed (wood epoxy saturation technique) and is probably the cheapest and easyest. Supplies for this excellent method are available at your local marine supply, and some marinas carry patch kits in varying sizes. The stuff is addictive to tinkerers and hobbyists.

CAD prototyping machines from Stratasys (SSYS for you on Wall St.) will do just about anything, with a variety of plastics that are tough enough to replace production machinery parts.

Carl

You lost me with the 3-D printer?

Have you thought about forming Lexan. It is like plexiglass but more flexible. No heat is required to form it.

When you say box for optical purposes I think of an under water camera. Is this your intended use? Come on, don't keep us guessing!

I used to make plexiglass structures by using methylene chloride with plexiglass dissolved in it as a glue when I worked at Union Carbide. This was not production stuff though, just for own use and you have to be careful with that stuff.

Any cnc I have seen has x, y, and z... 3D right?

Can you scan in a sketch or draw it on cad or graphics program and post as a jpg? A picture is worth how many words?

see:

http://www.answers.com/topic/stereolithography

http://computer.howstuffworks.com/stereolith.htm/printable

http://www.protocam.com/html/video.html

there are a number of people out there that can do very high quality small proto type parts from various stereolithography for around $1500-$2000 -

Jim

I didn't know this process existed. That's very cool. Thank you!

Steve,

We previously CNC-modified standard plastic boxes as small electromechanical equipment cases ... until the offshore supplier changed polymer, mixed polymer, upset the shrinkage, eliminated gluability, upset the machinability ...

Had always wanted different dimensions, extra features anyway, so we got serious.

Because we only need 50 per batch, probably 200-300 per annum, we devised a suitable in-house procedure. We CO2 laser-cut from extruded medium-impact acrylic sheet, a kit of castellated-edge panels. Bond them with gapfilling cyanoacrylate using simply rubber bands to register the parts! The castellated structure eliminates any need for jigs during assembly and gives amazing bond strength to all joints.

Prior to bonding we can detail machine any clearance patches, etc.
Post bonding we perfect the outside finish on a wet sanding disc.

Then we spraypaint with satin oil-base enamel. Our whole design procedure has changed. Now we can achieve recursive shapes that you cannot readily vac form or injection mold - and we can make design revisions on the fly. Sure, there's hand work involved but we achieve precisely what we need, hold no stock, gain design flexibility.

If you contact me directly I can email you pics to further explain.

Mark Bingham
Relativity PL - Fourth Axis
info (at) fourth-axis.com

Hi ..199,

Some more info would be nice, such as intended use, thickness of plastic, clarity properties, strength, etc.

3D printing may be a good way to create a nice quick form for Vacuum forming, you may also construct something from wood, the cost of course is relative to the size, but will give you some flexiability for small volume production. OF course the shape can not have under-cuts etc, as it needs to be removable from the vac form.

As for the CNC, it sounds like you need a third axis.

Tell us more!

Undercuts are possible with the 3D printer I mentioned earlier, even hollows within the structure, pilot holes, register tabs, etc. Google Stratasys Inc. Thier website explains the process, available material compositions. and requirements. I believe they also have a link to companies that are willing to rent thier 'idle time' to others for one-off projects. If a portion of the project is to be in clear plastic, or to have access panels, doors, relief, gaskets, or any other add-ons, the precision is there to accomplish this, and only limited by your drawings. Size may be another consideration.

I should get paid for this!!!

Carl

Hi Carl,

I know a thing or two about the 3D processes, as my company is involved in resale and providing the service.

I am well aware that under cuts are possible on the 3D model, however what I was saying was that when you Vac form over it, you have release issues of the plastic if you incorporate under cuts.

Try this to get an insight of some 3D printers out there,

www.canstampconsulting.com/video_links.html

I was under the impression that this was to be a one-off or limited production project. What you say is true if it is to be a mold for a production run.

That said, the composites used in the aforementiond process are suitable for direct use. Temperature and durability concerns can be tailored to the design parameters. Intracacy surpasses lost-wax methods, tolorances are industry standard +- .003 inch, durability is good enough to create replacement parts for continuous run production machinery. At least untill that 6 month backorder part comes in.

One drawback is that the art of Ye Olde Modelmaker may be lost, like drawing and building wooden boats from scratch.

Carl

I think the OP has gone...

Steve,

I am currently designing a small optical device, a line scan camera, 3mm x 15mm x 15mm which I will have prototype housings manufactured in plastic using a 3D printer. Prototype lens will be diamond turned. Production of lens and housing will be injection molded.

I have not as yet selected the plastic for the housing. Obviously the camera body must be opaque and block all light up to the IR spectrum. It must also have a degree of precision and be dimensionally stable.

How large is your optical device.

Check out forecast3d.com