Raspberry Pi 4B Heatsink Mk3 Frame Tpp Mount

prusaprinters

I wanted to mount an PRi4B at the top of the MK3 frame to enable a nozzle camera. I fitted the large RPi4B heat-sink to ensure no heat issues. The design is meant to minimize any air flow restriction.The RPi4B frame mount has multiple fingers which fit into the slots of the RPi4B heat-sink on the underside of the RPI4B board. These secure the bottom of the RPi4B heat-sink assembly.Two M3x25 screws attach the top clamp to the component side heat-sink.RPi4B heat-sink preparation.The PRi4B component side heat-sink must be per-prepared using an M3 tap to form an M3 thread in the two “second-from-the-outside” slots in the heat-sink.Care should be taken to form a thread parallel to the heat-sink face, and as close as possible to it. Using an M3 tapered tap, I found it was relatively easy to slowly do this with no pre-drilling.The thread will, of course, not be complete and that is why a long screw is used in fixing.Assembly:Two M3 nuts should be pressed into the back of the frame mount before fixing it to the frame.The top clamp is attached to the frame mount using two M3x10 screws which rely on those nuts.The two M3x10 Z-Axis Top-Left printed part mounting screws are replaced by two new M3*20 screws. Those existing two M3x10 screws are re-used to fix the top clamp.In fixing the top of the RPi4B frame mount, two M3 nyloc nut are required, screwing onto the protruding length of the longer M3x20 screws.Three new M3x10 screws fix the bottom of the RPi4B frame mount to the frame.Endoscope camera cableThe endoscope camera cable is held vertical in a cut-out when the top clamp is fixed to the frame mount.There are two versions of the frame mount and top clamp. One is for using the camera cable alone and another for using a camera cable fitted with 4mm spiral wrap.The cable of the soft cable version 3.9mm endoscope camera seemed somewhat floppy to me when used alome. Wrapping it in a 4mm spiral wrap did improve on that.The 4mm spiral wrap version has a larger diameter section which clamps the spiral wrap as well as the cable itself.I sourced some 4mm spiral wrap here:https://www.ebay.com.au/itm/234789875361?var=534581694984An alternative endoscope is to the semi-rigid cable version.That does work but is an inconvenient as really big cable loop is needed to minimize the semi-rigid cable stressing the extruder movement and the camera clamp on the extruder.The soft cable version, fitted with 4mm spiral wrap worked best for me, with no concerns about stressing the extruder assembly.  Two cable fixing clips are provided behind the X-Axis stepper motor shield which is there to prevent the endoscope cable interfering with the X-Axis stepper motor during Z-Axis movement.The endoscope lighting control should tuck neatly behind the shield.Cable ties could be added if overly concerned about that happening.