k2
In the last part, we wired up the backpack and all drives. Now, you might be tempted to keep building and - say - wire the toolhead. If so, you may skip to the next part of this build log. However, I would strongly recommend taking a break to turn on your printer and verify both the assembly as well as your wiring. You’d be surprised at the issues you find, ranging from something as simple as the wrong motor being wired, to the Z drives being upside down (yes, the latter happened to me).
⚠️ DISCLAIMER - Incorrect wiring can pose a serious health risk. The instructions in this post are my effort to be helpful, but they should not be taken as expert device. I accept no responsibility for any damages you might experience by following these instructions.
You could choose to finish all wiring before turning on your printer. I recommend that you not do this, and instead test things incrementally. I chose to keep my printer powered off while wiring things, and then would turn it on to test each new thing that was wired up.
Take a look at the eDrawing to see where everything goes inside the backpack.
Mounts Let’s get all the mounts attached first.
UHP power supply Insert 1x M3 tall heatset insert into each mount as shown below
Hold your power supply next to a mount to figure out which of the two adjacent holes the second heatset insert needs to go into.
Put the heatset insert into the correct second hole.
For the toolhead, you have a choice of extruders and hotends. I chose to use a Mosquito (clone) and Sherpa Mini. I also chose to use the (optional, but strongly recommended IMO) Mosquito Net to keep your hotend rigid.
Toolhead heatsets Insert tall M3 heatset inserts into the holes shown below:
If you’re using the mosquito net, insert tall M3 heatset inserts into the bottom of the part:
Hotend As stated at the beginning, I’m using a mosquito clone, but the instructions should be adaptable to your hotend of choice.
The gantry has four tensioners: two on the stationary X rails and two on the Y. The X tensioners are identical (not mirror images) to each other and the Y tensioners are identical to each other. Printed parts are identical for all four tensioners.
X tensioners and Y cross BOM For each tensioner, you’ll need the following:
Printed parts 2x Long M3 heatset inserts (not pictured) 2x Short M3 heatset inserts (not pictured) 2x M3x10 SHCS 2x M3x16 SHCS 2x M3x40 SHCS 4x M3x50 SHCS 4x M3 Washers 2x M3 Square nuts Heatset inserts Each tensioner has two heatsets at their bottom and two on their right side when looking at the printer from the outside in.
Let’s build the gantry motors and idlers. There are two versions: Short Motor, Tall Idler and Tall Motor, Short Idler.
Tall Motor, Short Idler BOM 1x Printed parts (mind you get the right accent part, the “ears” are slightly shorter) 1x Printed pulley alignment jig 1x Motor (missing from the picture below) 2x 12mm pulleys 2x 625 bearings 6x M4 heatsets 1x M5x35 shaft (missing from the picture below) 2-3x M5 washers 4x M3x10 SHCS 2x M4x20 SHCS 4x M4x50 SHCS 4x M4x55 SHCS Aligning the motor pulley Place the pulley in the jig with the hub down:
In this part, we’re going to build and install the frame that the bed sits on. We’re also going to install the bottom plate, feet, tighten the Z tensioners, and bolt them in. Let’s get started.
Building the bed frame Take a look at the eDrawing and note the orientation of the four extrusions that make up the bed frame. The two extrusions with holes through them sit “vertically” at the back and front, the remaining two sit “horizontally” at the sides.
Installing the Z belt Pick a corner to work on. Take your roll of 12mm belt and unroll it so that you have about 4 feet of belt to work with. Feed the end down through the Z idler:
Feed it through the bed lifting part:
Feed it up through the drive, over the pulley and back down:
Z tensioner BOM For each Z tensioner, you will need:
Printed parts 2x 5mm x 30mm steel shafts 8x long M3 heatset inserts 2x M3x35 SHCS 2x M3x50 SHCS 4x M3 washers Refer to the eDrawing to figure out which printed parts you need.
BOM For each Z drive, you will need:
Printed parts Laser-cut stainless steel parts, bottom and top Motor 4x M4x45 SHCS 2x M3x45 SHCS (the eDrawing said M3x40 when I built mine, but those were too short) 2x M3x8 SHCS 2x M3x8 Flat-head or Pan-head tapping screws 1x Worm gear 1x Spur 1x Thrust bearing 1x 5mm x 60mm steel shaft 3x 625-2RS bearings 1x 9mm toothed pulley 2-3x M5 x 3mm spacers 1-4x M5 x 1mm shims/washers The variable number of spacers at the end is because we might need to make adjustments based on your worm gear and spur.
Preparing the rails After you unpack the rails, pour some 99% Isopropyl Alcohol into pot/vase/similar container, about 5-6 inches off the bottom. Put zip ties into both ends of each rail, slide the carriage down to one end and stand the rails inside your container. Ensure that the carriages are fully submerged, leave for about 24 hours. Afterwards, lift one rail at a time, slide the carriage back and forth and use a paper towel or cloth to wipe the rail.
After sourcing all the parts for an Annex K2 Summit Edition, I finally started building it. I’m documenting my build process here along with pitfalls I ran into and how I overcame them.
Preparing the extrusions I chose to get unprepared extrusions, so I had to drill and tap them myself. The printer’s repository has STLs with jigs and fixtures for drilling if you’re using a hand drill. I used a cheap drill press that I bought for this purpose, so I didn’t end up using any of the printed jigs.