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DIY Injection Molded iPhone 4 Case [message #41999] Sun, 15 January 2012 19:41 UTC Go to next message
avatar basketjammer  is currently offline basketjammer
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Registered: October 2011
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Hey guys!

I just wanted to share with you a project I've been working on for a little while. I had the idea of trying out WSF as a hard mold material for injection molding a rubber iPhone 4 case. I designed the case in Google Sketchup, and from that case I designed a two part mold to be printed in WSF. It arrived in early January, and I was recently able to make a few test castings. WSF is not a bad hard mold material, but you need to make sure that you spray it down thoroughly with a mold release spray, otherwise you'll never be able to release your rubber cast from the mold (trust me, my first test casting was a total disaster because I was too timid when applying the spray).

Here's the two part mold after a few test castings (dirty!)
index.php?t=getfile&id=13452&private=0

Chemical materials and mixing/measuring tools. The rubber I used was a urethane rubber by Smooth On (mixed two parts in a 1:1 ratio), dyed with black dye. I made sure to spray the mold down REALLY well with mold release before injection molding my case.
index.php?t=getfile&id=13450&private=0

Injecting the liquid rubber into the hole at the bottom of the well-clamped mold. An air hole at the top of the mold allowed the air to escape as it was replaced by the liquid rubber, and also told me with the mold was full.
index.php?t=getfile&id=13451&private=0

Finished product, unmolded after 16 hours!
index.php?t=getfile&id=13448&private=0
index.php?t=getfile&id=13449&private=0

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Re: DIY Injection Molded iPhone 4 Case [message #42041 is a reply to message #41999 ] Mon, 16 January 2012 07:54 UTC Go to previous messageGo to next message
avatar underitall  is currently offline underitall
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That's pretty impressive, thanks for sharing!
I really would not have thought WSF would be a good material to use for mold making, very interesting.
Tom.
Re: DIY Injection Molded iPhone 4 Case [message #42044 is a reply to message #42041 ] Mon, 16 January 2012 09:42 UTC Go to previous messageGo to next message
avatar Dotsan  is currently offline Dotsan
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Very cool, I like it.
V


www.dotsan.com
Re: DIY Injection Molded iPhone 4 Case [message #42061 is a reply to message #42044 ] Mon, 16 January 2012 16:53 UTC Go to previous messageGo to next message
avatar tessman  is currently offline tessman
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Would finishing the WSF with, say, several coats of acrylic finish, make the mold easier to use (by smoothing it out and filling in the pores)? Does the porous texture of the WSF make the final product more interesting?
Re: DIY Injection Molded iPhone 4 Case [message #42065 is a reply to message #42061 ] Mon, 16 January 2012 18:31 UTC Go to previous messageGo to next message
avatar basketjammer  is currently offline basketjammer
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The rubber cast is actually very easy to unmold as long as you spray all the mold faces thoroughly with mold release, but finishing the mold with acrylic may very well make it even easier... The rubber cast is actually a bit textured due to the grain from the WSF (which is actually not too bad), so finishing the mold with something would probably make for a nice smooth finish on the cast!
Re: DIY Injection Molded iPhone 4 Case [message #42068 is a reply to message #41999 ] Mon, 16 January 2012 19:43 UTC Go to previous message
avatar Tamert  is currently offline Tamert
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Registered: November 2011
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I have used a similar casting approach with WSF. I found that that polishing the inside of the case with a soft dremel buffing bit worked wonders. The rubber I was using (Sylgard) has a very low surface energy which allows it to run into even the tiniest pores which WSF is known to have in spades. Buffing the surface closed up the pores quite nicely.

To make the process faster I heated the mold up in the over to ~120F before buffing. At room temperature the nylon material doesn't flow very well. At 120 it flows quite easily. I tend to think something like a hot air gun combined with a dremel buffing bit would work the best. I was concerned that I might be deforming the mold by heating the whole thing. A heat gun would allow for a local heating to be applied. Or perhaps just a heat lamp would suffice.

Of course, this process only works well for easily polished molds. Anything of significant complexity would require a lot of hand time. Though a quality mold in the long run will save a ton of time if you're making a lot of the design.

 
   
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