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Step 8: Chopping and Fitting

Picture of Chopping and Fitting
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As always the cases needed some dismantling & modification before they'd be ready for use, so I set to with the rotary tool to tidy up the insides, once I'd stripped out the original circuits.

The intercom was first, I had to chop out a plastic post to make room for the webcam, cut a hole for the wide angle lens (bought from Tiger) and sand away lots of protrusions to make things like the speaker easier to fit. Once I had a blank canvas I then thought about how to fit in the various components. I needed to make space for:

- A new speaker

- Two lever microswitches

- The wireless doorbell circuit

- The webcam

- The cable connection block

- The small protoboard circuit for the LED

...as well as the original switch and mechanism - this had looked spacious at first but now I was beginning to wonder.

To make the process easier I used a handy tip from my Hitachi Pi TV conversion, and first built a perspex chassis to hold all of the components. Perspex is absolutely ideal for this, as you can see through it when marking where to cut holes. First I cut it roughly to size, then drilled holes so that it would fit onto the intercom's existing screw posts. From here I added components one by one, drilling and cutting holes to either fit or make space for them. The other benefit of doing this was that I was able to test that everything was working before the final assembly!

To make the webcam fit I had to carefully chop away a lot of its plastic case, so that it would glue directly behind the wide angle lens - if you need to do this start by prying the front off it, don't hack away at the back with wire cutters and pliers as I did!

I was less fussy about the cassette player, and ruthlessly stripped out all of the circuits & components leaving just an empty box. Cosmetic parts like the big buttons were just hot-glued in place, and I filled a small broken lamp window hole with a red push-button.

To make the pi sit in the right place behind the tape window I first hot-glued a Lego plate to the underside of an old (obtained at the Pi 3rd birthday party!) Pi case. I then hotglued a matching plate inside the cassette player in just the right position, to make a nice semi-permanent fitting - the GPIO pins would be accessible with the tape door open, but I wanted to make sure I could get the Pi out to swap SD cards etc without any trouble. I've learned the hard way to plan ahead for future disassembly and maintenance! Lastly I chopped some slots in the exterior of the cassette player so that the USB and HDMI ports would still be available after assembly just in case.