Goal

By the end of this stage, your X axis will look like this:

X axis rails

# Component Qty Type 949 X end motor 1 Printed 948 X end idler 1 Printed 947 X carriage 1 Printed 339 X idler cover 1 Printed 917 Fan mount 1 Printed 934 8mm x 426mm smooth rod (X axis) 2 Hardware 287 LM8UU Linear bearings 3 Hardware 199 Igus clip bearing – 8mm 4 Hardware 279 623 bearing 1 Hardware 408 Nema 17 motor 1 Hardware 782 18T MXL pulley and grub screw 1 Hardware 242 M3x16mm cap head screw 3 Fastener 112 M3x25mm cap head screw 2 Fastener 212 M3 washer 2 Fastener 258 M3 nut 3 Fastener 918 #4 x 1/2″ button head screw 2 Fastener

Start by fitting the Igus bushings into the x ends. These bushings need to allow the Z smooth rods to slide easily but without much slack. In order to achieve this, you will need to fit an Igus bushing into position and slide a smooth rod through it.
The bushings can be curled up slightly to fit in downwards. The rims are retained by slots in the 3D-printed parts. Do not attempt to put the bushing in with the smooth rod running through them – this will break the printed part. Put the bushing in on their own, then run the rod through afterwards to check them when they are in place.
If the fit is too tight, remove the igus bushing, then remove a small amount of material from the X end. Either use the half-round file to remove material, or clamp a 9mm drill in a vice and run the X end up and down it by hand. Take care – it’s better to remove too little and to have to repeat the procedure, than to remove too much irrecoverably.
Try the smooth rod through the bushing again. Repeat this procedure for all four bushing positions.
Repeat for the other X End.
Take one M3x16 cap screw and insert it through the hole in the centre of the part as shown. No washer is needed.(The bushings are missing some of the following photos, but they should be left in place).
Then insert this assembly through the 623 idler bearing.
Insert the X idler cover onto the cap screw…
…and secure with an m3 nut.
Next insert two M3 nuts into the slots on the back of the idler bracket. These are intentionally a tight fit, so you may need to use a long-nosed pliers in order to grip them. The nuts should go in sufficiently far that the holes of the M3 nuts line up with the small holes in the end of the idler bracket.
Insert 2 M3x25 cap screws through each of the two holes in the end of the X idler and into the nut.
Next begin to assemble the axis. Take the 426mm smooth rods and insert these into the large holes in the end of the X idler bracket. Then proceed to slide the linear bearings onto the smooth rods. Note the orientation of the bearings, when looking at the top/complex side of the idler bracket, two bearings go on the top bar with the one remaining bearing on the bottom bar as shown
Ensure the rods are completely inserted into the X idler bracket, then insert the free end of the rods into the X motor bracket

X Motor

As before, the pulley has a threaded hole in it for a grub screw to hold it on the motor shaft. This should be supplied fitted, but if not, screw the grub screw into the pulley a short distance.
Push the MXL pulley onto the motor shaft, taking care to note its orientation. Install the pulley with the pulley teeth closest to the motor body. Leave a gap of about a millimetre between the pulley and the motor body, so the pulley can turn freely, and not rub against the motor body. The motor shaft has a flat on it; align the grub screw with this, and tighten the grub screw using a 1.5mm Allen key.
Attach the motor to its bracket with two M3x16mm cap head screws, with an M3 washer under each. Like the Y axis, the X axis motor is mounted in slots, so the belt tension can be adjusted Put the motor at the inside end of the screw slots (i.e. as close to the idler end as possible). Note the orientation of the socket on the motor relative to the bracket; this is important for wiring routing later.
Push the linear bearings on the X axis into their slots on the X carriage. THE BEARINGS SHOULD ONLY BE PUSHED IN FROM THE SIDES, PUSHING THEM IN FROM THE FRONT WILL RESULT IN THE X CARRIAGE SNAPPING. The bearing should be a snug fit. But if they are a little lose, simply wrap a layer or two of Kapton tape round them (take care not to get bubbles under it or creases in it)
Cut off a small length of belt approximately 82mm long (the width of the X carriage), and press this into the slot of the carriage with the teeth facing upwards. This fit is deliberately tight and you may need to use a small flat head screw driver to push the belt into the slot. The belt should be pushed to the very back of the slot.
The fan-mount fits on the other side of the X carriage, using two #4 self-tapping screws.

Finished X axis

The completed assembly.