XL Left Side 5x Sensor Mount

The Why:

Now that I have a Sunlu S4 (and prior G2 fan variant single bay one as well) as well as a fully implemented modular dry box system, it was time to consolidate the filament sensors to one side of the printer, so while I could have flipped the existing on over it'd look funny and be upside down.

Further, I wanted to be able to relabel this part if I ever get around to metering out the pinout for the 5 pin Molex's and change that in order to have all 5 feeder tubes in 1-5 order, vs the 1,2,3, x , 5, 4 they currently are in, and to do that I needed a clean step file.

The Part:

This is essentially the existing sensor subassembly holder part duplicated, and union to land both boards in a single part, however I did do a full on cleanup of that union, merging all co-planar faces, and eliminating any other “boolean” artifacts (which are really NURBS trims on faces under the hood) by cleaning up any coplanar and potentially manifold edges.  In short, the part is absolutely clean from a NURBS standpoint, and matches the existing Prusa one in all dimensional aspects where the subassembly sensors interface with the part.   

 

You'll Need:

1x - replacement Model cable, longer than the stock Prusa one.  I got mine from mouser:https://www.mouser.com/ProductDetail/Molex/15135-0506?qs=jFK2DQXLaBzN1OZf0p2Rdg%3D%3D&countryCode=US¤cyCode=USD

2x - 2.5mm x 4mm OD PTFE tubes, roughly 5' long.   

Fixing the Cable Pinout:

Note that the mouser sourced Molex cable is wired “null modem” style in that its pinout is:

Pin 1 → Pin 5

Pin 2 → Pin 4

Pin 3 → Pin 3

Pin 4 → Pin 2

Pin 5 → Pin 1.

This is the exact opposite of what you want as the XL's modex's are wired:

Pin 1 → Pin 1

Pin 2 → Pin 2

Pin 3 → Pin 3

Pin 4 → Pin 4

Pin 5 → Pin 5

To change that you'll either need Molex's specific pin removal tool, or you can fashion your own (which I did using a spare generic pin removal tool from a cheap set on amazon, and 3 minutes with a Dremel tool with grinding wheel attached).   You'll want the width of the probe to be < 1.25mm across and as thin (height wise) as you can get it.

Pulling the pins is shown on the molex site in the documentation for the pins.  You just have to have the right sized tool, and a bit of patience until you get the feel for how far you have to push the pin removal tool in and how to apply pressure to lift the latch at the back that holds the pin in place.

The easiest way to do it is to pull pins 1 & 5, swap those on one end, and then swap 2 & 4 to ensure you don't lose track of which is which.  3 stays put.

Then you'll need to replace the existing Right Filament Sensor cable with this new one.

The Cable Swap:

It's easiest to accomplish if you remove the perforated panel, the dwarf board cover panel, and and the main board cover panel (this is the channel the cable runs in).

Unplug all 5 extruders (making note of where they'll need go go back in) and demount the Wifi Antenna.  Be careful with this as it's very fragile, and will want to fall between the main board and the dwarf board edge card connector when you pull the board to get unplug and replug extruders 3-5.

You will NOT be able to fit both the “new” side sensor cable and the old one in the slot the old one goes through, rather it will need to come out and OVER the printed edge piece in the same slot the other non sensor cables run through.

Assembly:

You can either just pull both side sensors and mount them both in my replacement part (how it goes together is identical to the stock parts, it's just that you're mounting both sensor assemblies in this one vs 2 separate ones.   

Follow the Prusa instructions for replacing the side sensor as though you were just swapping the sensor sub-assemblies out and remount them in this part.

You can also rebuild the side sensors with the current Prusa printed parts, my XL came with E1 Rev parts and they're (at the time of this writing) on R3, so I printed the current parts and rebuilt the sensor assemblies with that.

If you choose to go this route, getting the springs out is a bit fidgety, it's helpful to have some angled, very small precision angled side tweezers to use to push the springs up from the bottom FURTHER into the assembly (ball bearing side up) to get the bottom edges of the spring free so you can get it out of the slot.

Above the spring is a very tiny magnet that's the same diameter as the spring itself.  Once both the spring and the bearing are removed from each of the the 3 “slots” in the sensor assembly you should be able to get the short arm of a very small (Like 1 or 1.5mm) Allen key in the slot the spring was in to push the ball bearing of of the sensor from the inside out through the top as it's just a friction fit.

Take care during this to not launch the springs, magnets or ball bearings airborne as they're very tiny and could easily get lost in carpet.  Once the springs, magnets and ball bearings are transplanted into the newer version printed part, assemble them with this part.

You'll harvest all the PTFE fitting collets off the existing side sensors and transplant them to this one.    They're small, somewhat fragile and can be a bit tricky to get all 4 “blades” compressed to go into their new homes.

Post Assembly Mounting:

This will mount on the left side using a single one of the mounting bolts you scavenge from the factory side sensors into the same T Nut the previous left Side sensor used.

You'll also need to replace the 2.5mm x 4mm OD PTFE for extruders 4 & 5 with longer ones to make the (now) longer trip to the side sensor.  Take care when detaching and replacing in the clips for the PTFE path as they're fairly fragile.

Testing:

Make sure the feeder and output PTFE tubes are in place before testing the sensor positions, as if you just stuff filament through from the front you can easily send one of those small collets flying on the back side, which will be a huge PITA to locate.  Having even a short chunk of 4mm OD PTFE in both the input and output sides will preclude that, or just wait until you've replaced the PTFE for extruders 4 & 5 and completely connect everything up before testing.

Make sure the dwarf board is fully seated prior to powering up and testing (it's easy to forget to push back Prusa's printed “helper” parts you use to disengage the board in the first place and end up not completely seated.