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Author Topic: Production of Plastic Enclosures?  (Read 3942 times)
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That is nice. Any pics of eat post-sanding?

I would love a step by step guide please.

Roughly how much would it cost to make a box that size?

Cheers,

Mike
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I buy it by the trial size, that box took less than a half bottle so about $20.00 +/-.

I'll see if I can get a detailed step-by-step done this weekend.

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Do you have a part number?  I wasn't sure which plastic you used.
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Do you have a part number?  I wasn't sure which plastic you used.

I use the Smooth-Cast 60D, this is a semi-ridgid plastic 50/50 mix. It is still soft after it comes out of the mold, but after 72 hours it is hard like ABS and not brittle at all. I also use the black So-Strong color tint to make it black. The natural color is clear amber.

Here is another thing I like to use it for, this works great for those wet areas. Using the Smooth-on OOMOO-25 liquid rubber, I make a rubber mold that can be used over and over.

Picture of the wood negative mold and resulting rubber mold, in it you can see a bad spot on the rubber - this is from not mixing it good so be sure to stir it well, but it is OK for this application;


Here you can see the circuit board sitting on top of the stand-offs I designed into the mold.


Now, if there is anything you don't want the plastic to flow into, cover it with clear packing tape, like those green connectors.


Then I mix the 60D plastic and mix in some color tint. First I pour some in to make sure it gets completely underneath the board, then I set the board onto the stand offs and finish filling the mold.


De-mold time! it peels right out.


Then I clean up the edges on a sander, drill 2 mounting holes and vola! a water sealed circuit suited for mounting in an engine compartment.


I should have the box demo done this weekend, I got a good start on it.
« Last Edit: January 16, 2009, 07:08:09 am by Jassper » Logged

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Thanks for all the info. and pictures it is greatly appreciated.

It can't find any suppliers of Smooth-On in the UK so I would have to order from the US, which would put the costs up (especially if I got stung by Customs for VAT like I have twice lately).
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It can't find any suppliers of Smooth-On in the UK

United Kingdom
Bentley Chemicals Ltd.
Rowland Way
Hoo Farm Indust. Estate
Kidderminster, Worcestershire DY11 7RA
England
Tel: 011-44-1562-515121
Fax: 011-44-1562-515847
Contact: Chris Warren
info@bentleychemicals.co.uk
http://www.bentleychemicals.co.uk/

Bentley Chemicals ltd
Elm Bridge Hall
Fyfield
Ongar Essex
CM5 0TN
Tel/fax: 01277 899568
Mobile: 07760 177700
Contact: Chris Warren

Bentley Chemicals ltd
Marshall's Yard
Trout Road
West Drayton
London
UB7 7RS
Tel - 01562 515 121
Fax - 01562 515 847

4D Models Shop
120 Leman St
London E1 8eu
Tel: 0207-264-1288
Fax: 0207-264-1299
Contact: Zyg Jarzembowski

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Great. I didn't come across those in my search. Thanks.
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Here is a link to the "How To"
Custom Project Enclosures
I haven't proof read it yet, so when I get a chance, I might go back into it and give a bit more detail.
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Jasper that is absolutely fantastic. Thanks for taking the effort to do that for us. That document should go up on the site somewhere.

Question - is it possible to polish the material to a glossy finish?
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Question - is it possible to polish the material to a glossy finish?

Don't know for sure, I haven't really tried. I don't think the semi-ridged plastic will, it's just a bit too soft for a good polish. The ridged plastic might however.

EDIT
Updated the file, corrected some grammer and spelling. Also corrected my email address.  ;D
« Last Edit: January 20, 2009, 06:48:40 am by Jassper » Logged

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Link to a pdf version of encasing an electrical board.
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We are just about to try out Ponoko laser cutting service http://www.ponoko.com for our bespoke enclosure.  
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thanks for the awesome guide Jasper!
i'm looking forward to giving it a shot when the need comes up for something custom.
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Well done Jasper!

Although I have been working in automation for the past 6-7 years, I spent the previous 25 years in product development for the injection moulding and prototype industries.

During that previous life, I frequently . . . as in several times per week, met people who were disappointed to learn about the cost and complexity of even low-volume injection moulding.

However as Jasper has so well illustrated, and a few others have suggested; there are some alternatives that work well for low volume requirements.

Possible manufacturing methods for the production of low volume enclosures:

•      Fabrication (cutting and gluing) from flat stock . . . best for very low production runs

•      Additive fabrication using various rapid prototyping methods (SLA, SLS, RepRap, MakerBot, etc.) . . . also best used for very low production runs

•      Machining from solid blocks . . . depending upon the complexity of the enclosure, material selection and production volumes, CNC machining can sometimes be a cost effective method

•      Casting using simple moulds (usually RTV moulds cast from master models produced by fabrication and/or machining). Today there is a wide assortment of both casting resins (acrylics and urethanes primarily) and RTV (Room Temperature Vulcanizing) materials

•      Low volume injection moulding from soft tooling. Soft tooling ranges from aluminum reinforced cast tooling epoxies (not recommended) to temporary aluminum cores and cavities.

•      Custom machining of OTS (Off The Shelf) enclosures . . . many enclosure manufacturers offer custom machining, painting, membrane switches, Lamacoid services, etc; to help create a custom look

•      Unfortunately, vacuum forming sheet stock over temporary or permanent moulds is frequently overlooked; however from the standpoint of tooling cost, tooling delivery, part cost and design freedom this method has a lot to offer . . . most notably in large enclosures

At any rate it is important to understand, that like any engineering endeavor there are some compromises that are required. Most notably, every one of the above manufacturing methods placing unique technical requirements related to product design (form), material properties and performance.

It is not enough to draw an interesting shape and then go shopping for the cheapest price. The first step is to establish the production quantities; product price point and delivery time to market . . . these factors will be the largest influence on what manufacturing method will be best suited to the project.

Once the quantities, price and production method have been established, then the product can be designed . . . taking into account the limitations of material selection, wall thickness, corner radii, mounting bosses, cooling slots, etc. required by the chosen manufacturing method.

Mike Mc, unfortunately all of my contacts from the industry are on the other side of the big pond so I cannot make any recommendations regarding suppliers, but I would think that there would be some businesses in the UK that could do the work. Usually it is best to do this kind of work locally as issues can be resolved more easily than if you are working long distance.

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Jassper:

Those are both great documents; a link to this thread, and links to those documents should be placed in the playground, probably here under a new section called "Enclosures":

http://www.arduino.cc/playground/Main/ElectroInfoResources

CSingleton:

Your comments on low-cost/low-run prototype production techniques should also be placed in the same section.

I think all of this needs to be documented there.

Bravo!

 smiley
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