RepRapPro Huxley y axis assembly

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Introduction | Frame assembly | Y axis assembly | X axis assembly | Z axis assembly | Heated bed assembly | Extruder drive assembly | Hot end assembly | Wiring | Commissioning | Printing | Maintenance | Troubleshooting | Improvements

A notice about these instructions!

These instructions are open to editing by everyone and anyone.
For the official, and most up to date, instructions, see the RepRapPro wiki here

NOTICE: This page is currently being updated. If you are following these instructions to build a RepRapPro Huxley, you may find some discrepancies between the kit contents and this page. The changes should be completed in the next couple of days.


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



You will need the following tools:

  • Phillips screwdriver
  • Adjustable spanner
  • 1.5mm hex key (Allen) for M3 socket set screw (grub)

Step 1: Sled assembly

RP parts Quantity Reprappro-huxley-section-1-components.jpg
Reprappro-huxley-bearing-holder-fixed.png 1
Reprappro-huxley-bearing-holder-float.png 1
Reprappro-huxley-belt-clamp.jpg 2
Reprappro-huxley-belt-tensioner.jpg 1
Hardware Quantity
Lasercut frog 1
LM6UU Linear bearings 3
M3 x 12 screw 4
M3 x 25 screw 4
M3 nyloc nuts 5
M3 nuts 4

Assemble the parts of the Y sled as shown:


Push the bearings in from the side. Don't try to clip them in from the top. They should be an interference fit and should stay where they are put.

Reprappro-huxley-bearings-from-the-side.jpg Reprappro-huxley-bearings-from-the-side-b.jpg

When correctly fitted, the linear bearing should protrude by the same amount from each end of the bearing holders.

The screws should be inserted from the top of the frog (the side without the markings). Use the 12mm M3 screws and nuts for the bearing holders and the 20mm M3 screws and nylock nuts for the Y Belt Clamps.


Fit an M3 nyloc nut inside the hexagonal recess of the belt tensioner, then loosely attach this to the frog assembly using four M3 nyloc nuts. The belt tensioner has a boss at one end. This should be fitted nearest the camera as shown in the image below.


Adjust the gap between the 270mm Y rods at both ends so they are parallel and their inner edges are 103mm apart. Don't tighten their clamps yet.

Slide the 270mm Y rods partly out of the machine, put the sled onto them, and refit their free ends into the frame:


Ensure the linear bearings slide freely along the smooth rods. If the bearings are a little tight, insert the smooth rod into a power drill, then spin the rod for a few seconds whilst holding a scouring pad over it. Clean the rod with a cloth, then try the bearing fit again.

Slide the Y sled back and forth. It should run completely freely. If it doesn't, that means that the rods are not quite parallel - move their ends a little bit using the nuts either side.

Gradually tighten the ends of the rods, checking for free running right from end to end all the while as you do so.

Step 2: Y motor and idler brackets

RP parts Quantity Reprappro-huxley-y-section-2-components.jpg
Reprappro-huxley-y-idler-cad-1.png 1
Reprappro-huxley-y-idler-cad-2.png 1
Reprappro-huxley-y-motor-cad-1.png 1
Reprappro-huxley-y-motor-cad-2.png 1
Hardware Quantity
623 bearing 1
M3 x 16mm screw 4
M3 washer 5
M3 nut 1
NEMA 14 stepper motor 1
M3x10mm socket set screw (grub) 1
14 Tooth moulded pulley 1

The next stage is to fit the Y axis idler and motor assemblies. Each end is made up of two printed parts and some hardware. Each end is in two parts to enable printing these components without the need for support material.

Motor end

The pulley has an encapsulated nut. Insert the set screw and tighten it all the way until it breaks out into the centre hole. Clear out the plastic.

The hub of the motor has a slight swelling to accommodate the encapsulated nut and make it stronger - it is deliberately not concentric.

Fit the 14-tooth pulley to the Y axis stepper motor, ensuring the teeth face in towards the motor (the Y axis belt will not fit with the pulley the other way around). The pulley should slide over the front shaft (the one with a flat), and is fixed to the shaft by tightening the M3x10mm socket set screw. Leave about a millimetre at the bottom of the shaft so that the pulley can turn freely. Don't tighten the screw too much with the pulley mounted otherwise you could break the pulley apart.


Screw the motor to the Y motor bracket using the three M3x16mm screws with washers under their heads (if the screws are a little short leave out the washers).


The Y motor goes at the back of the machine, with the motor to the left when looking from the front of the machine and the wires pointing in towards the 626 bearing slot.

Fit the the Y motor bracket either side of the 626 bearing, and between the serrated washers on the top cross bar.

Move the Y sled to be at the same end, and make sure that the motor is positioned so that the bearings line up with the centre of the two holes in the sled that will hold the toothed-belt clamp.

The Y axis motor end will now look like this:


Note the orientation of the stepper motor, with the wires pointing in towards the machine and the motor on the left of the bracket when looking at the machine from this end.

Idler end


The Y axis idler end is also constructed from two printed parts. Screw them together with the bearing inside as shown. If the 16mm screw is a little short for the idler part, leave the washers off.

Move the Y sled to the front of the machine (i.e. the opposite end to the Y motor you just fitted) and use the Y belt holes to get the idler bracket in roughly the right place.

Measure the gap from one of nuts holding the motor bracket to the nut along from it that holds one of the smooth Y bar clamps.

Adjust the idler bracket so that the gap between its corresponding nut and its Y-bar-clamp nut is the same. Tighten the nuts to hold the Y idler bracket.


Step 3: Y axis belt

For this step you just need one 600mm T2.5 PU toothed belt.

Reprappro-huxley-y-belt-fitted 2.jpg Reprappro-huxley-y-belt-fitted 3.jpgReprappro-huxley-y-belt-fitted.jpg

Slide the belt under the belt clamp at the Y motor end and tighten the clamp ensuring the belt in centred. Don't do it up too tight, or you will bend the clamp excessively.

Route the belt through the Y axis motor end, around the 14-tooth pulley, under the bearing, along to the idler end, under its 626 bearing, around its 623 bearing and back under the other belt clamp. Do not pull the belt too tightly at this stage, but nip up the belt clamp enough to enable you to slide the sled to either end of the smooth rods without the belt escaping.

Line the belt up by eye. The top should be in line with the bottom and the belt should be square where it sits under the clamps.

Pull the belt tight (gently - it needs to be taught, but you don't need to be able to play it like a harp...).

While holding the belt tight, tighten the idler-end clamp. Don't do it too tight, or you will bend the clamp excessively. Your T2.5 belt may have been supplied as a single piece used for both the Y axis and X axis assemblies, so when you cut off the excess belt you'll want to retain as much as possible of the remainder.

Hand-turn the Y motor by holding the hub of the 14-tooth pulley between your fingers. You will be able to feel the clicks as the motor's rotor magnets run past the ends of its stator coils. Make sure everything on the Y axis stays in line and runs freely right from one end to the other and back.

Next step

X axis assembly