RepRapPro Huxley y axis assembly
Contents
Goal
By the end of this stage, your machine will look like this
Tools
You will need the following tools
- Phillips screwdriver
- Adjustable spanner
Step 1: Sled assembly
RP parts Quantity 4 Hardware Quantity Frog 1 LM6UU Linear bearings 4
- 4x3/8" self tapping screw 6
M3 washers 6 Begin by inserting a linear bearing into each bearing holder. The bearing will be an interference fit in the RP part, so may need some persuasion to go in. A good trick is to warm the printed part with a hot air gun, then put the linear bearing on a flat sturdy surface and push the printed part over it. If you need to apply more force, use the adjustable spanner (set to a diameter just larger than the linear bearing outer diameter) and push down on the printed part.
When correctly fitted, the linear bearing should protrude by the same amount from each end of the bearing holder.
Slide 2 linear bearings onto each 270mm long smooth rod. 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.
Now slide the smooth rods into the bar clamps. Using a vernier caliper, measure between the smooth rods. Ensure the distance between the rods is the same at both ends.
You can now fit the laser cut Frog. Before you tighten everything, you should pre-drill a hole in the frog for the Y-axis end stop adjustment screw and install this screw; its really difficult to install later. You can locate this screw by temporarily placing the frog and shafts in place; the correct hole location is in line with the end stop switch mounting hole, moving paralell to the smooth rods.
The frog is attached to the four bearing holders using at least one #4x3/8" self tapping screw (and M3 washer) per bearing holder. Begin by attaching the frog to the 2 bearing holders on one side, ensuring the linear bearings slide freely. From the underside, the fitted frog should now look like this
fitted Frog
It is important that the above assembly slides freely on the smooth rods. Take your time to get this step right as it will help you when commissioning the machine. If the Y axis is too tight, the motor will struggle to accelerate the axis as it should, resulting in missed steps and failed prints.
Step 2: Y motor and idler brackets
RP parts Quantity
1 1 1 1 Hardware Quantity 623 bearing 1 M5 washer 1 M3 x 16mm screw 4 M3 washer 1 M3 nut 1 NEMA 14 stepper motor 1 M3x10mm socket set screw 1 14 Tooth moulded pulley 1 T2.5 Belt 600mm 1 The next stage is to fit the Y axis idler and motor assemblies. Each end is made up of 2 printed parts and some hardware. Each end is in 2 parts to enable printing these components without the need for support material.
Motor end
Fit the 14 tooth pulley to the Y axis stepper motor. This should slide over the front shaft (the one with a flat), and is fixed to the shaft by tightening the M3x10mm socket set screw (Note: the gear has an encapsulated nut, insert the screw and tighten it all the way until it breaks out into the centre hole. Clear out the plastic and then fit it onto the motor). Don't tighten the screw too much with the pulley mounted otherwise you could break the pulley apart. Ensure the teeth face in towards the motor (the Y axis belt will not fit with the pulley the other way around). Screw the motor to the Y motor bracket using the 3 M3x16mm screws, then fit the parts for the Y motor bracket either side of the 626 bearing, and between the serrated washers on the top cross bar.
The Y axis motor end will now look like this
Y axis motor fitted
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 2 printed parts. Fit an M5 washer on the boss printed on the inside of the thicker part of the idler bracket. Before screwing the two printed parts together with the M3 screw, slide the screw through the Y-idler-split-1 printed part, slide the 623 bearing onto the screw and pass the toothed belt around the bearing. Ensure this can move freely over the bearing. If the printed part restricts the belt's movement, remove the belt and file/cut some material away form the offending section of the printed part. Once happy with this, place an M3 washer over the bearing, then the y-idler-split-2 printed part onto the M3 screw, and tighten with the M3 nut. Fit this assembly onto the cross bars in a similar fashion to the Y axis motor end.
Step 3: Y axis belt
RP parts Quantity 2 Hardware Quantity T2.5 PU Belt 600mm 1 M3x16mm screw 4 M3 nut 4 M3 washers 4 Loosely fit the belt clamps to the top face of the Frog using the M3x16mm screws, fitting a washer beneath the head of each screw.
Loosely fitted belt clamps
Now slide the belt under one of the belt clamps and tighten the latter ensuring the belt in centred. Route the belt through each Y axis motor end, around the 14 tooth pulley, under the two 626 bearings, around the 623 bearing in the Y axis idler end 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 Frog to either end of the smooth rods without the belt escaping.
Y axis belt fitted
Y axis belt fitted Slide the Frog to the motor end of its travel, then line up the Y motor bracket so the belt runs freely though its run. Repeat for the idler end. You can now loosen one of the belt clamps, pull the belt tight and fully tighten both belt clamps. The final stage is to manually slide the Frog from end to end, at different speeds, ensuring you have smooth movement. If the belt snags at any point, adjust the belt runs. For example, if the belt tends to one side of the idler bearings, tip the idler bracket over a little so the belt maintains its position centrally over the bearings as the Frog is moved from end to end.
