Topic: Plastic housing

I've never dealt with manufacturing a plastic case. Can someone explain what is needed and how much things cost? Friends have told me that molds can be very expensive.

Re: Plastic housing

Good question...I'm interested to know the answer to that too. Chumby has 3 hard plastic components, surround and 2 bits to house the daughter card, and 1 soft TPE or TPU surround. There are some details here, but they don't quite answer your question.

Re: Plastic housing

Well you could always take the provided IGES files and submit them to a few manufacturers and get quotes, most manufacturers for injection molding will accept plain IGES files as that's what their hardware requires.

From what I understand of the process, it's a lot like making PCBs; there's a fixed cost for setting up the machine, and all of the rest just comes on how much consumables you're using (making the number of units made as important as the size of the unit being made). I've got a family member that works designing parts for making extrusion-molded window frames, I could probably ask him for a better answer, but to put it simply, "not cheap"..unless you're making thousands.

Re: Plastic housing

I only have a virtual Chumby (the drawings) to look at, but it seems to me that anyone who makes a daughter card with a connector on it is going to want a new case. It's going to be a problem if molds for new cases cost $20K.

Re: Plastic housing

Making plastic parts is generally very expensive, which is one of the many reasons why we wanted the main chumby housing to be something a little more accessible to the common person (e.g., fabric). Plastic parts will require a 3D drawing (IGES, an industry standard format, which we make available on the site) and can be produced in a number of different ways. For our initial plastic part builds, we used Protomold (www.protomold.com), a rapid prototyping house, which was not cheap (but, very fast). Typically you would have a mold made (whether out of aluminum or steel, depending on the expected quantities of parts you'd make from the mold) for a specific injection molding machine and then "shoot" the parts. The major expense is the NRE charges of the mold, which is timely and expensive to make. Once the mold is done, getting parts is cheap, since you're essentially paying for the cost of plastic plus some overhead. Other rapid prototyping options might include vacuum forming (which we didn't do for chumby but it could certainly be done for your own custom housings/hacks).

So, the short answer is making plastic parts currently is difficult without the right equipment or money, but not impossible. You could also just re-use the plastics that come with the chumby and save a lot of time and effort.

Joe

Re: Plastic housing

You can make plastic stuff at home with Polymorph. Its plastic that melts in boiling water. From what I remember, its fairly cheap. You can't really injection mould it, but you could do some cool stuff with it.

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http://www.nophus.com/useru
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Re: Plastic housing

Polymorph appears to be called "Friendly Plastic" in the US.

It is available everywhere, this is the first one I clicked on:
http://www.jewelrysupply.com/craft_supp … ticks.html
http://www.jewelrysupply.com/craft_supp … llets.html

It can be drilled and filed after it hardens. You can also remelt and reform it for mistakes.
Certainly looks worth a try for making basic prototypes.

Another idea is 3D printing companies. I found several service bureaus from Google that will print parts for $200-300 each on a Z Corp printer.

Exploring these areas is definitely worth a write up on the wiki.

Re: Plastic housing

Ah yes, both great resources! Neither will have the strength and durability of injection molded plastics, but depending on what you want to do it could be fine!

Joe

Re: Plastic housing

I have posted a more craft/DIY, rather than industrial, response to this in the craft section.

http://forum.chumby.com/viewtopic.php?pid=1579#p1579

Re: Plastic housing

hi ,everyone
maybe i can answer you question ,our company is specialized in  injeciton mold making and plastic products,meybe you can visit  our website:http://www.bh-mould.com

and if you need and help ,please contact me:sophia@bh-mould.com

Re: Plastic housing

There's an aphorism in certain industries that says it bluntly.

"Serial #1 cost someone $1Million that someday reverses to Serial #1,000,000 has a cost of  -$1"

Nope, not a typo, that's NEGATIVE $1.

That comes from selling your process tech and spinoff research etc.
Then again , there are the niche markets that defy categories.
I suspect that Chumby may yet escape that niche and become mass marketed.

Which could drive the price point to lows that we can only drool at.

"More Chumbys beside beds than any other device of it's kind.
Because there is no other device of it's kind"

Re: Plastic housing

if you want to build a plastic mold, but also want to reduce the cost, maybe you can contact us, We are manufacturer of injection mold. and most kinds of plastic components in China. you also can visit: www.rainbow-mould.com
this is Alern. you can send me email: alern@rainbow-mould.com or 316388884@163.com.