LED Light System for Prusa Enclosure

Design

I designed this system to fit the Prusa original enclosure (with my MK4S inside). But the system and parts are flexible enough for it to work with other enclosures (I have a plan to make one for my CoreOne+ soon).

The system is based on using a 16ft long strip of LEDs that may be cut into pieces of 50mm multiple lengths. The one I used is 12V with an included plug-in power supply and dimmer. (I did not want to mess around with using enclosure power.)

I designed it for a strip to be attached to the 4 rails around the top and 3 of the 4 vertical rails (I have a Prusa LED strip on the front left side). If you don't have the Prusa LED strip, you can make another one of these. If you think this is too much light, make less. The number of strips you use is up to you.

Design Details

I calculated each strip to be about 18" or 450mm. The LED strip comes as a continuous reel that has marked places to cut segments every 50mm. This enables a very convenient cut at the 450mm mark.

As my print bed cannot print anything this long, I designed the holder to be split into smaller pieces that could be printed with snug fitting joints.

My Fusion 360 design (included, as always) has variables you can set to result in the holder parts totaling that length. I made the "jointExtraLength" and "segmentLength" variables specifically for this. {Note: the added length of the optional wire-tie extension is not added into this LED calculation, but needs to be considered in making the entire holder fit your available space.} These are the parameter values I used:

Note: My numbers result in 5 pieces, each with a magnet, which space out evenly 110mm apart. If you want more magnets, you could add another segment and center piece for a total of 7 pieces with magnets.

I also split the diffuser into 3 pieces of 150mm that total 450mm.

I have included test pieces you can print to check the joint clearance and magnet clearance.

Hardware

For strip holders

• LED Light Strip, 16ft, Dimmable

• 35-40 8x3 magnets

• 10-12 Wire connectors

For dimmer mount

• 2 M3x8 screws

• 2 M3 nuts

For wire holders

• 3-6 8x3 magnets

Optional power extension

• Male & Female Barrel connectors 

Alternative Options (not tested)

• Screw-on connectors

• Crimp-on connectors

• Snap-on connectors

Printing

There are no special requirements; no support needed. I printed all of the holder parts in PETG at .20 layer height. I printed the diffuser pieces in PLA as I don't have any clear PETG – time will tell if I should have used PETG, but it should not be a problem as my enclosure temperature has never exceeded 40C.

Assembly

The Holders

Each holder has:

• left endcap, left segment, center, right segment, right end cap

• 5 magnets, one in each piece

• a 450mm long LED segment, with electrical solder pads (+ and -) on each end

• wiring connectors on one or both ends

• optional wire-tie hole on each endcap for tying down wires

Although the holder segments have a snug fitting joint, I added a drop of super glue. The magnets are the same, a snug fit with super glue to be sure. Attach, and glue, all 5 parts and their magnets.

You need to decide how you want to make the electrical connections.  There are solder, snap, crimp, and screw on types available. {I used the snap type for my MK3 IKEA enclosure.} I chose to use solder connectors for this project so it would fit under the diffuser. {If you go with the other types, the diffuser pieces will likely not fit.}

Cut an LED strip of 450mm and solder on a connector to one end. The vertical segments are not connected at the bottom end. The horizontal segments need a connector at both ends. Also prepare a 3-way branch connector for each corner that has a vertical strip.

Decide which way you want the magnets to attach to the enclosure. You can have a stronger attachment with the open side of the magnet touching the metal of the enclosure – if you trust the magnets to stay in the plastic holder. I have had the magnetic attraction pull the magnet out of my plastic devices before – even when glued in! Or you can flip it over and keep the thin layer of plastic between the magnet and the metal – not quite as strong an attraction, but good enough for this project – and no pull out risk.

Peel off the sticky backing tape from the LED strip and attach it to the holder. Repeat for each strip/holder you plan to use.

Slide the diffuser pieces onto each holder. Ideally, the diffuser ends should just cover the solder joints.

Wiring

The wiring is fairly straightforward. The LED's are wired in parallel on the strip, so if one fails the others are still OK.

The only rule is to always connect with same polarity: + to + and – to -. You may "T" or branch off as long as you maintain polarity. And leave any unused strip ends unconnected.

Note: You do not need to "close the loop". It will work just fine wired in a long straight line with branches off of the main line. If the run was very long, you could have some voltage drop with the far end LED's being a little dimmer. In this short configuration, there is no dimming. So, it is your choice whether to connect the strips at the front left corner. 

My enclosure has a Prusa LED strip in the front left corner. If you don't have one, you may add another strip/holder there. Just add another 3-way connection like the other corners.

Wire Holders

In each corner you will have several wires coming together. I designed a small, simple holder to clean this up. It uses a magnet to attach them to a top rail.

Dimmer Mount

The beginning of the reel of the LED strip has a barrel connector for attaching to the dimmer and power adapter. You need to plan where to have this enter the enclosure. I only found 2 places (without cutting a hole in the enclosure); a hole in the center rear of the lid, and another where the LCD screen wiring passes through in the center front of the bottom plate. In either case, you need to allow for extra wiring to reach the first strip. I used a male and female barrel connector and some 22 gage wire. I put a piece of shrink wrap on the wires to help protect them from the edge of the metal opening.

I chose to mount the dimmer to the front right corner of the enclosure and run the wires inside through the LCD cable hole.

Attach the mount with M3x8 screws and nuts. To install the dimmer, tilt in the left side, then snap in the right side .

I used 2 wire holders to clamp it to the front rail of the enclosure.