how to make a cheap custom case for low volume production? - Page 1
Forum section: electronics / projects

author: FrankBuss
author_rank: Unknown
timestamp: June 05, 2013, 09:48:15 pm
content: I plan to create a product, maybe I can sell 100 of it. Would be nice to have a custom case for it. It should look like this (bottom and top side of the two case parts in one image) :The longest side is 7 cm, wall thickness is 2 mm. I've uploaded the STL model to Shapeways and it would cost EUR 39 to 3D print it, which is too expensive, because the whole product should cost maybe EUR 80.I've found a price calculator for injection molding athttp://www.sourcing-cn.com/moldcalc_input.aspand this would require a setup fee of about EUR 2000, but the per unit price would be less than EUR 1. But still EUR 21 then for 100 units. Is it possible to produce it for maybe EUR 5 for this low quantity?

author: Thor-Arne
author_rank: Unknown
timestamp: June 05, 2013, 10:24:56 pm
content: I get most of my boxes fromhere. they also accept customs orders.Qualityand price is good, and the seller is quite good to communicate with.

author: ftransform
author_rank: Frequent Contributor
timestamp: June 05, 2013, 10:27:38 pm
content: that looks like a electrical outlet box...I'd consider something on the marke.t

author: fcb
author_rank: Super Contributor
timestamp: June 05, 2013, 10:41:37 pm
content: That case looks alot like a small Hammond 1593. They are available in at least black/white and translucent blue:http://www.hammondmfg.com/dwg8TBU.htmIt's going to be tough to hit your budget AND make just 100, i'd redesign for something available... Your customers will not care I suspect about the exact mfr of the case, just the function.

author: FrankBuss
author_rank: Unknown
timestamp: June 06, 2013, 04:01:46 am
content: Thanks, the Hammond case looks really good. Maybe a good idea to search for a case which has the right size and then designing the PCB so that it fits. I plan to do it as a Startnext project (like Kickstarter, but in Germany, because Kickstarter doesn't offer the service here). Could be a stretch goal to design a custom box, e.g. if I get the money for 300 units.

author: Unknown
author_rank: Unknown
timestamp: June 06, 2013, 04:44:47 am
content: If Hammond's project cases are built anything like the high voltage enclosure I just sold on ebay, I'd recommend them without hesitation. That thing is built like a TANK. I bet I could run over it with one and it wouldn't even scratch.

author: EEVblog
author_rank: Unknown
timestamp: June 06, 2013, 04:47:03 am
content: Many of the major box manufacturers do custom cutouts and modes to their cases. Hammon, Polycase etc.

author: FrankBuss
author_rank: Unknown
timestamp: June 06, 2013, 06:17:14 am
content: Quote from: EEVblog on June 06, 2013, 04:47:03 amYes, this would make it easier for me, because I'm all thumbs when it comes to mechanics, drilling etc.Another idea would be to 3D print the cases. I've just printed my test model over night with my BitsFromBytes 3D Touch printer (needed 3.5 hours) and it looks quite good, and it is stable:The small 2 mm round screw holes were not printed, but the rectangular holes and the round edges are really nice and smooth, and the round holes can be drilled after printing. So I could print two boxes in one day: one starting in the morning and the other starting in the evening. Need to move the printer in the cellar, the fans and stepper motors noise is a bit annoying.100 cases would be done in 50 days. The price calculator of the software says the half case which I printed costs $1.21 (with PLA). I wonder if the printer survives 50 days nearly non-stop printing.

author: Unknown
author_rank: Unknown
timestamp: June 06, 2013, 06:23:21 am
content: I would think there would be some intangible costs relating to wear on the 3D printer and the amount of time it takes that would make the actual cost much higher than it appears at first glance. It might still be more cost effective to purchase the cases if you can find a decent price - even if they cost a little more than the actual outlay of just the materials required for 3D printing.

author: FrankBuss
author_rank: Unknown
timestamp: June 06, 2013, 06:35:18 am
content: Right, this would be expensive if I had to repair the printer after the production run. But good for a prototype for a stretch goal on the Startnext page, if I get enough money for injection molding. So now I'll try to find a good case and then ask manufactures about custom drilling, cutouts etc. for it.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 06, 2013, 07:39:53 am
content: QuoteI'm amazed that some people don't realise this is the way to do it.The PCB is by far the easiest and cheapest thing to customise to fit.All the major case manufacturers offer a customising service, but there will be tooling costs, minimum order quantities and leadtimes.If you want the miminum up-front cost solution, use a case with flat front or end panels, and use PCBs for the panels. Cutouts and printing add minimal cost, with minimal tooling cost.laser-cut panels are another possibility.

author: Chet T16
author_rank: Frequent Contributor
timestamp: June 06, 2013, 08:48:25 am
content: Quote from: mikeselectricstuff on June 06, 2013, 07:39:53 amSomeone should do a video on that ;-)

author: FrankBuss
author_rank: Unknown
timestamp: June 06, 2013, 09:04:57 am
content: If I were a designer, I could do some interesting construction just with PCBs, like this one:http://hackaday.com/2011/10/16/we-want-this-led-ball/

author: sleemanj
author_rank: Super Contributor
timestamp: June 06, 2013, 10:17:12 am
content: You could use your 3d printed part, create a few silicone moulds from it, and cast it in resin a lot quicker than printing them all out. No idea what the cost would be though.A fellow kiwi did something like this (except he made a basic wooden mould, not silicone)...http://hackaday.com/2011/04/25/diy-resin-cast-project-box/

author: gregariz
author_rank: Frequent Contributor
timestamp: June 06, 2013, 10:28:41 am
content: Quote from: mikeselectricstuff on June 06, 2013, 07:39:53 amI sent off a request for quote for 500 plastic cases to be customized - each case was only a couple bucks. I heard nothing back and after a few more emails they suggested I approach a local machine shop. They just were not interested in any job that wasnt going to wind up being more than a couple thousand. YMMV depending on the case vendor.As for laser cut panels for extrusions, I always order mockups for panels from pololu. I can usually get something for about $25 and its amazing the number of spins required to get the hole locations and sizes right to overcome datasheet lies. Only after I have that right do I get an aluminium one done.Mechanical jobs are some of the most problematic and expensive aspects of any job I find. A while ago I ordered a 1/4" thick piece of aluminum (12" by 12") that I needed for a base mounting plate for a project. It cost about $15 from Amazon. So I went down to the local waterjet shop with autocad cutout file in hand... $700. Sometimes its just cheaper to buy a CNC.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 06, 2013, 01:16:33 pm
content: Quote from: mikeselectricstuff on June 06, 2013, 07:39:53 amyes i'm amazed that for "hobby" or "non-fully-professional non-massed" production, this has to be the wayps: i mean, for the damn serious pro product, its the other way around. infact, that thousands of $ moulding setup the OP mentioned, polycase et al is out of question.

author: FrankBuss
author_rank: Unknown
timestamp: June 06, 2013, 03:43:25 pm
content: Quote from: sleemanj on June 06, 2013, 10:17:12 amNice, the result looks quite professional. Once I experimented with silicone molding forms:http://www.frank-buss.de/giessen/The "Biresin G27" resin cures in half an hour and unlike other resins, it looks and feels like wood after curing. But it can be difficult to create a mold for complex shapes. And when I do it, the result doesn't look professional