Archive for casting

Mold Making

Posted in DIY, Electronics Projects, molds with tags , , , , , on June 9, 2012 by Nilsen

After the “pain” I had when creating the wonderfully clear and smooth finish, the crazy sanding with 60 grit belt sander, then 200, then 600 water paper then 1200 water paper then hours of polishing it just was not feasible to make these things more often but since I had a shape I wanted I ordered some mold making silicone.

It comes in a tin with a catalyst which you obviously mix together, stir vigorously and pour around your item which you have encased in some sort of box.This produces a negative of the item which you can then easily use to replicate as you just pour in your resin and it does not stick to the mold. Brilliant.

I used some acrylic and a hot glue gun to quickly make this box.

Acrylic is perfect as it’s non porous meaning the silicone mold will easily pop right out when I remove the walls.

Box with device hotglued into it.

 

Unfortunately as can be seen in the first picture, when mixing the silicone many bubbles are introduced through the process of stirring so to remove them I could use a vacuum pump but I don’t have one so I found the “bombs away” method on Youtube. This method relies on the fact that the silicone is so viscous that if you let it stretch thin enough no bubbles can survive the thin end of the stretch. Maybe better explained in the below pictures.

Here my silicone in a cup with a hole made in the bottom covered with sticky tape.

Look at it go!

 

Here you see the silicone stretched extremely thin by gravity and the viscosity of the liquid

 

Make sure to land next to the object, not on it else you could introduce more bubbles, let the liquid flow over the object from the bottom of the mold box.

 

Nearly done.

 

The bottom of the mold box.

 

Here the completed thing.

 

Completed.

 

Now I will add another completed circuit and pour in some resin. Lets see.

Results!

Posted in DIY, Electronics Projects with tags , , , , on May 19, 2012 by Nilsen

Here they are! The cast products.

Firstly I am a little disappointed that I have not yet been able to buff the initial test cast to a clear glass like finish. It just won’t buff up even though it is so smooth now and I have tried various polishing compounds including a brasso equivalent (or maybe not) and a metal polish for chrome.

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Orange tinge is due to the cardboard box leaking some colour

I sanded the piece with 600, 800 then 1200 water paper and subsequently started to polish it, unfortunately it is not reacting the way I had hoped. I even attached a polishing wheel to my drill press but even that only left the resin dull. I know it is crystal clear as before I sanded the top it was like water.

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Another View

Here the trigger before sanding the cardboard mold away.

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In it’s little conffin.

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Coffin Removed!

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With backlight, my work needs a little work 🙂

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Bottom

And here some other projects I have on the go, please welcome the Nilsen Slider – Control box.

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Controller being assembled.

More to come in a separate post.