Plastic Case Question - Page 1
Forum section: electronics / projects

author: docmur
author_rank: Regular Contributor
timestamp: September 12, 2013, 12:51:07 pm
content: Hey EveryoneI've been working on a new project, an embedded system that does autonomous navigation and more. It's a homebrew project and I've been thinking I want to give it a nice plastic shell, something like the Roomba might use. My question is done anyone know how to go about designing and ordering something like that? I'm assuming I would have to use some kind of cad software to build it but then where do I order it from?I've never really given my projects a professional touch like that, I assume it has to be possible so I'm just wondering if anyone has any ideas.ThanksAndrew

author: rdl
author_rank: Super Contributor
timestamp: September 12, 2013, 01:59:40 pm
content: Unless you have lots of money, and/or expect to sell thousands of this device, then it's probably best to find an off-the-shelf case and design the item to fit it.

author: Psi
author_rank: Super Contributor
timestamp: September 12, 2013, 02:04:19 pm
content: You could get custom enclosures made by shapeways if the product makes enough money for it.http://www.shapeways.com/

author: MacAttak
author_rank: Unknown
timestamp: September 12, 2013, 02:08:29 pm
content: When you say "nice plastic shell", I'm guessing you are referring to injection-molded plastic. For that, you need to be prepared to spend a fair amount of time designing it, or paying a specialist to do the design. Then you can figure roughly about $10,000 or so for the tooling needed to create the molds, which will also take several weeks at least. And finally, you will need to have them made in batches of several thousand items, minimum.

author: docmur
author_rank: Regular Contributor
timestamp: September 12, 2013, 04:38:07 pm
content: Okay. I guess I thought it would be cheaper. I know some people with 3D printing gear, I might be able to get them to help me.

author: rdl
author_rank: Super Contributor
timestamp: September 12, 2013, 04:51:00 pm
content: It's really hard to say what your best options are without more details of what you actually want to build. Injection molding was my first assumption as to what you were looking for. However, if you can live with its limitations, vacuum forming may be a good low-cost, low-volume solution.

author: fcb
author_rank: Super Contributor
timestamp: September 12, 2013, 04:51:42 pm
content: Vac forming.

author: unagi
author_rank: Newbie
timestamp: September 12, 2013, 07:19:20 pm
content: Hey,Sounds like a fun project. As far as packaging the thing goes you'd be amazed at the options. Years ago I consulted in the medical device field as a hobby/side-job (electrical and mechanical designs). It used to cost us $1k for a fragile rapid proto plastic part. Today I can have one knocked out for $5--$150 and the materials are soooo much better--metal is even an option.Feel free to shoot me an email and we can discuss your project. I'm sure I could point you to the right places to have your parts built. If you'd like help designing a cool enclosure for your project I've got high end CAD tools on the home PC.It should be noted that I am not associated with any rapid proto/fabrication company and get nothing in return for doing this. I'm just a nerd who does R&D for a high tech company by day and runs/bikes/canyoneers in the evenings.

author: marshallh
author_rank: Unknown
timestamp: September 12, 2013, 09:32:54 pm
content: Design your part in solidworks with injection molding in mind. Have it 3d printed at shapeways. Confirm fitment, but also note molded parts will shrink after cooling by a small amount.Protomold has a very streamlined mold machining process where you can have dies made for $1k with minumum run of 100 pieces (which is a hell of a deal), using a choice of several pellets. There is tons of info on their site with regards to designing for ABS/PS/PP injection molding. Their tools will run automated fluid simulations to see if there are any fill problems. Overall it is the best thing I've found yet.

author: docmur
author_rank: Regular Contributor
timestamp: September 13, 2013, 12:54:36 pm
content: So basically what I'm trying to build to keep it simple you can think of as a Roomba at least size / shape wise. The project is progressing slowly so I'm not going to give a lot of details out yet as things could change a lot before I'm done. So ya I think I've got some ideas on what to do :-) as for anyone offering help thanks :-) I'll consider it. I don't really want to pick a shell to start with as I'd like to finish the project first and then be allowed the room I need to fit everything together. There is no point limiting myself this early on.

author: MacAttak
author_rank: Unknown
timestamp: September 13, 2013, 03:47:32 pm
content: Well, if it is the same size and shape as a Roomba, and it is just for a one-off project for personal use... you could always just find a used roomba on ebay and gut it.

author: voice of reason
author_rank: Newbie
timestamp: September 13, 2013, 07:44:09 pm
content: I am agreement to the consensus here that unless you want 1000,s, probably 3000 min, then use what you can find, gut it, cut stick whatever you can.When you can afford a few 1000 try some injection moulding companies to see if they can cover the cost of tooling. Although tooling for injection moulding is very expensive.There is another way though. You will have heard of 3d printing. I DO NOT mean a desk top shitty 3d printer. I mean a proper full on professional sla printer or the likes.Those companies are calledrapid prototypingcompanies if you want to look them up.OK, that will cost you in the region of $500 for your product. But you will need to supply them with a cad and that could cost you $300 ish.Just a thought.

author: voice of reason
author_rank: Newbie
timestamp: September 13, 2013, 07:46:24 pm
content: Aghh! in my laziness I did not read the whole thread and I see that MARSHALLH has already mentioned this.

author: docmur
author_rank: Regular Contributor
timestamp: September 16, 2013, 05:12:18 pm
content: LOL actually I was consider getting a Roomba case off Kijiji or Ebay for like $20. I might also try to use a 3D printer and make parts. That will come later, I'm still working on the Layout and Design.