Prusa MK4 Camera Lighting

Although the Raspberry Pi camera has a good view of the Prusa MK4’s extruder, there’s not much light under there:

There’s also not much room for a lighting fixture on the printer where it must mount, so I modified a trio of nominally 12 V / 4 W COB LED panels:

Their “4 W” rating seems aspirational, at best, as a 12 VDC supply pushes only 75 mA through the panel, so they tick along at 900 mW. If you expect cheap eBay / Amazon components to live up to their specs, dream on.

The modifications:

• Unsolder the pins
• Crunch off the surprisingly precise 27.4 Ω SMD resistor
• Clean up the rubble
• Wire the panels directly in series, ignoring their bridge rectifiers

The 15 LEDs on each panel are arranged in five parallel chains of three LEDs for a total forward drop of 8.3 V, so putting three panels in series works with the MK4’s 24 V power supply.

Stick them onto the MK4 power supply case with foam tape and wire them directly to the 24 V terminals:

There’s very little clearance between the machine frame and the X Axis carriage on the threaded rod. Putting the LEDs in a 3D printed case and routing the wires lower on the column would be nice touches:

The panels start at 30 mA when cold and drop to 25 mA as they warm up in the 63 °F = 17 °C Basement Shop. Each panel dissipates 250 mW: bright enough for the task, dim enough to avoid overpowering the camera’s limited dynamic range, and definitely within whatever power rating they should have.

Looking over the camera’s shoulder in normal shop lighting suggests it’s about right:

A staged scene with the shop lights turned off:

Call it Good Enough™ for the purpose.