2 mm & 3 mm hex drivers

The 2 mm and 3 mm hex drivers see the most use in this build. We recommend a quality driver in each size.

Driver sizes

These cover the socket screws used in this build: 2 mm for M3 button/flat head screws, 3 mm for M5 button/flat head screws (BHCS/FHCS), and 5 mm for M6 socket head cap screws (SHCS).

Preload the T-nuts

Slide every T-nut into its slot before squaring the frame.

Direction Convention

Top, bottom, left, and right throughout this manual refer to this view.

Mind the placement

The short extrusion carrying the four slide-in T-nuts goes on top.

Counterbores face out

The counterbored ends of the long extrusions face outboard, each counterbore aligned with the short extrusion's end bore.

Square before final tightening

Each M6×20 SHCS drops through the long's counterbore into the short's end hole. Run all 8 in snug, square the frame on a flat surface, then tighten.

Reinforce the frame

One joining plate reinforces each corner. Run an M5×10 BHCS through the plate, start a drop-in T-nut on it loosely, drop the assembly into the closed frame, then tighten.

Feet point down

The bumpers are the machine's feet, mounted under the four corners of the frame.

Use the screws that come with the bumpers

If the bumpers you bought came with their own screws, use those. They're the right size.

Center hardware first

Drop the center M5 square nut and its M5×10 BHCS into the middle counterbore hole first. The idler stacks block access later.

Confirm the idler spins freely

Once installed, check that each idler turns freely.

Flat face toward the screw

Seat each square nut with its flat face pointing toward its screw.

Side pocket hard to seat?

If a side square nut won't drop into place, clear the pocket with a small screwdriver or a pin first. Prints can leave residue in the slot.

Two ways to the frame

The block locks to the frame in two places: the middle M5 screw catches a slide-in T-nut in the extrusion slot, and the bracket bridges block and frame. On the bracket, the longer M5×12 BHCS threads into the block's captive square nut; the M5×10 catches the T-nut in the frame slot.

2 mm gap to the corner plate

Position the block so it sits 2 mm clear of the frame-corner joining plate.

Each idler stack is 18 mm

Idler 8.5 mm, spacer 9 mm, shim 0.5 mm. Use shims and spacers to bring every idler stack to a uniform 18 mm.

Spacer must total 9 mm

The spacer is 9 mm tall. If you can't buy that exact height, stack shorter spacers to total 9 mm.

Long screw into the block

Same screw split as the left bracket: the M5×12 BHCS threads into the block's captive square nut, the M5×10 into the frame-slot T-nut.

Match the left block's gap

Set the right block the same 2 mm clear of the frame-corner plate as the left block. Keep both gaps equal so the idler stations stay symmetric.

Motor A idler — sits lower

This idler carries Motor A's belt. With no spacer, it rides on the lower belt plane.

2 mm gap to the corner plate

Set this block 2 mm clear of the frame-corner plate, the same gap used at every other idler station.

Motor B idler — sits higher

This idler carries Motor B's belt. The 9 mm spacer lifts it onto the upper belt plane.

Match the left block's gap

Set the right block the same 2 mm clear of the frame-corner plate as the left block, so the lower idler stations stay symmetric.

Note the motor wire direction

Check which way the motor's wires face and match the orientation shown. That orientation sets the wiring clearance later.

Only the spacer height matters

Motor A's spacer must be 8 mm tall.

Tighten in a cross pattern

Run all four motor screws in finger-tight first, then tighten opposite corners in pairs. This pulls the motor flat against the bracket instead of tilting it to one side.

Motor A

We refer to the left motor as Motor A.

Note the wire direction

Confirm the motor's wires face the direction shown before fixing the bracket.

Leave the bolts loose

Don't fully tighten the motor mount yet. You'll slide it later to tension the belt.

A taller spacer here

Motor B's spacer must be 12 mm tall.

Right motor — mirror image

Built like the left motor, but mirrored: the cable connector faces right.

Motor B

We refer to the right motor as Motor B.

Mirror

This is the right motor, a mirror of the left. The cable connector faces right.

Leave the bolts loose

Snug only. Final torque comes after belt tensioning.

Two heights

The A and B belts sit at different heights: Motor A's pulley (left) is coplanar with the lower idlers, Motor B's pulley (right) coplanar with the upper idlers. Slide each pulley along its motor shaft into position, then lock it down with the set screw.

Set screws

Tighten one set screw onto the shaft's D-flat first, then tighten the other.

Threadlocker

Apply threadlocker to every set screw. A loose pulley throws off motion accuracy and is the single most common issue users report. Before you do, though, make sure the pulleys and idlers are aligned. You can also hold off on the threadlocker and apply it after the belts are installed.

Build two Y rails

The Y axis uses two identical rails. Assemble both the same way.

Clean and grease the rails

MGN9H rails arrive coated in shipping oil. Wipe it off and pack the carriage with fresh grease before mounting. That's what gives smooth, long-lasting motion. Prep every rail the same way.

Let the T-nuts hang

Thread an M3×10 FHCS into every other hole and let its drop-in T-nut dangle on the screw tip. Lower the whole rail onto the extrusion slot, then tighten to draw the nuts up snug.

Straight side toward the motor

The left and right joints are mirrored. Mount each one with its straight side facing the motor.

Tighten in a cross pattern

Thread all four screws in first, then tighten opposite corners in pairs. This seats the joint flat on the slider.

Preload the X-beam T-nuts

Slide the two M5 T-nuts in, one from each end.

Check the X beam slides smoothly

The X beam should glide freely along the Y rails. If it binds, realign the Y rails until it runs smoothly, then tighten them from the center bolt outward.

Be patient

Don't expect to get it in one pass. Snug a few screws, slide the X beam to feel the resistance, then nudge the Y rails and try again. It can take a few minutes of back-and-forth before the beam glides smoothly.

X rail

Mount this rail just like the Y rails: let the T-nuts hang loose, lower the rail into the slot, then tighten.

Check both axes move freely

The X rail is now mounted on the X beam. Confirm its carriage slides smoothly along the X rail, and that the whole beam still travels freely along the Y rails. If either binds, realign that rail and retighten from the center out.

Motor B idler — sits higher

This idler carries Motor B's belt on the left joint. The 9 mm spacer lifts it above the others, keeping its belt on the upper plane.

Use the correct hole

The idler mounts in the top hole of the left joint. Take care not to use the wrong one.

Motor A idler — sits lower

Use the toothed idler here, not the smooth one.

It carries Motor A's belt and, with no spacer, rides on the lower belt plane.

Install in the right position

Before tightening, confirm the idler is seated in the correct position on the joint.

Motor A idler — sits lower

This idler carries Motor A's belt on the right joint, in the top hole. With no spacer, it rides on the lower belt plane.

Install in the right position

Before tightening, confirm the idler is seated in the correct position on the joint.

Motor B idler — sits higher

Use the toothed idler here, not the smooth one.

It carries Motor B's belt and, with the 9 mm spacer, rides on the upper belt plane.

Check all four idlers

All four idlers are now mounted on the XY joints. Recheck that each one sits in its correct location.

Install belt A

The Motor A belt is a single open length with both ends clamped to the X carriage. It must stay flat in one plane and never twist along the way. The teeth grip the toothed pulleys; the smooth back rides on the smooth idlers.

The clamp self-locks

Feed each belt end into the clamp's bottom slot, loop it around the post, and fold it back against itself so the teeth mesh. That teeth-on-teeth grip holds the belt with no extra fasteners.

Tension by sliding the motor

Leave Motor A's two M5 screws loose, clamp both belt ends into the clamp, then slide the motor to pull the belt tight.

Clamp the belt before mounting

Make sure the Motor A belt is seated in the clamp's bottom slot before you fix the clamp to the X carriage.

Match the Motor B belt length

Before fitting the Motor A belt into its clamp, cut the Motor B belt to match it. Both must be the same length.

Install belt B

Route the Motor B belt on the upper idler plane. It must not cross belt A. Clamp both ends to the X carriage, the same way as belt A.

Check the belts

With both belts installed, push the carriage by hand through its full travel in every direction. It should move smoothly with the same, even resistance throughout. That resistance is just the motors. Confirm there's no sticking, no interference, no twisted belts, and no odd noises, with the two belts on their separate planes.

Threadlocker

If the pulley set screws have no threadlocker yet, apply it now that the belts run smoothly.

Belt tension

Equal tension on both belts is essential for a CoreXY motion system. Even a slight difference between the two will skew the gantry's motion. You can adjust a motor's position to fine-tune the tension of its belt.

Pluck the belts

For a quick check, move the X carriage fully to the motor side and pluck the indicated belts with a finger. The two should feel and sound about the same. Matching pitch means roughly equal tension.

75 Hz at 220 mm

For a precise check, measure each belt with a tuning app on your phone while the X carriage is parked at the marked position. Pluck the belts and aim for 75 Hz. If both read the same frequency, the tension is correct.

Fit the stylus tip

The solenoid ships with a nut on its bottom end. Remove that nut, then thread the stylus tip on in its place.

Solenoid mount holes

Two M3 holes, 15 mm apart.

10 hole pairs for height tuning

The mount has 10 pairs of holes, spaced 1 mm apart. Pick a pair now, and you can later raise or lower the stylus in 1 mm steps.

Route the power leads

As indicated, feed the solenoid's +/− leads into the rectangular hole on the mount side, then run them up and out through the rectangular hole at the top.

Ground the solenoid

Clamp the ground wire's bare copper between the solenoid housing and the mount, then tighten a screw to pin it. This grounds the solenoid. Run the ground wire out through the other rectangular hole below to join the power leads.

Mount the solenoid to the clamp

Six screws hold the solenoid assembly to the clamp. To adjust the stylus height later, undo them and refit at a different hole pair.

Make two

You need two identical cross-beams for the bed.

Seat the bed on the beams

Lay the two cross-beams parallel, slotted faces up, then lower the bed's hanging T-nuts into the slots and tighten.

Install the phone bed

Stand the frame on end first. It's far easier to work vertically. Then slide each beam's T-nuts into the slots on the frame's underside.

Position the phone

Place a phone on the bed, pushed into the top-left corner. Move the X carriage around and check the stylus tip can reach every part of the screen.

Set the solenoid height

Set the solenoid's mounting height so the stylus tip just makes stable contact with the screen. Too low, and the solenoid can't pull in fully: the magnetic force is then too weak to hold the tip down, so the tip springs back and both long-press and swipe fail. Too high, and the tip can't reach the screen or the contact patch is too small. Fine-tune until the tip makes stable contact with the screen.

Fit the T-nuts

Leave them loose for the next step.

Mount the control board holder

Mount it on the top extrusion's outer face.

Fasten the control board

Four screw–nut pairs. The lower two nuts are obscured and not drawn.

Fit the T-nuts

Two M5 FHCS into hammer T-nuts. Leave them loose for the next step.

Mount the tube holder

Mount it on the top extrusion beside the control board. Its 4 mm socket anchors the fixed end of the Teflon tube.

Rough length

Make the tube about 400 mm, long enough to reach from the tube holder to the X carriage at its farthest position.

Anchor the solenoid leads

Cable-tie the solenoid leads to the tube holder, so the solenoid's travel can't shake the wire at the control-board terminals. Constant shaking works the contact loose, and the solenoid stops tapping the screen.

PTFE vs FEP

Either tube works here: PTFE (milky white) or FEP (clear). The Ø4 tube's stiffness is enough to hold the wire bundle's shape.

Spiral-wrap the tube

Spiral-wrap the solenoid wires to the Teflon tube along its length. The wires don't go inside. The tube just stiffens the bundle so it holds a clear path past the belts and motors.

1/4-20, not metric

The socket screw and hex nut that the gooseneck mounts on are 1/4-20, the imperial tripod thread (≈ 6.35 mm). Don't substitute an M6.

Imperial Tools

SHCS 1/4-20 takes a 3/16" hex key; hex nut 1/4-20 takes a 7/16" (or metric 11mm) open-end wrench. Needle-nose pliers you already have will also do the job. There's no need to buy tools just for this.

Thread on the gooseneck

Spin the gooseneck's female end onto the stud, snug against the hex nut. The free male end takes the camera next.

Thread on the camera

Thread the camera's 1/4-20 female socket onto the gooseneck's male stud until it bottoms on the stud collar. The camera now hangs off the neck tip.

Use the lower slot

Mount the corner bracket on the lower slot of the right extrusion's outer face.

Orient the camera

Bend the gooseneck so the camera points squarely at the phone screen, and align the sensor's long edge with the phone's long edge.

Lock it down

Make sure the camera is held firm. It shouldn't drift or wobble.

Route the USB cable

Secure the camera's USB cable along the gooseneck to keep it clear of the belt.

Power off first

Never plug in or remove a driver while the board is powered.

Mind the orientation

Match each driver's pin labels to the board silkscreen before pressing it home. A reversed TMC2209 can burn out on power-up.

Rule of thumb

Colored to colored, black to black.

Heatsink

TMC2209 driver modules typically include a heatsink that can be stuck onto the top of the driver chip.

Connections

The board uses standard GRBL axis outputs, remapped as follows: the X-axis motor driver drives Motor B, the Y1-axis motor driver drives Motor A, and the Spindle output drives the solenoid (in place of a spindle).

No polarity

The Spindle output (to the solenoid) is not polarity-sensitive. Either lead can go to either terminal.

Motor cable connectors

Motor side: 6-pin PH2.0 (2.0 mm pitch), with two pins empty and only four used. Board side: 4-pin XH2.54 (2.54 mm pitch).

Extend the leads

The solenoid's stock leads don't reach the control board. Splice extra hookup wire onto both the 12 V and GND leads.

Keep the stock leads under 50 mm

Cut the solenoid's stock leads back to 50 mm or less before splicing, so the joints sit clear of where the cable bends most. A joint that flexes with every gesture fatigues and snaps.

Stagger the splices

Solder each joint and cover it with heat-shrink. Offset the two splices about 10 mm so the insulated joints don't sit side by side.

Ground the stylus

The stylus rides on the solenoid's iron core, and the core is tied to the housing through the metal return spring, so grounding the housing grounds the core, and the tip with it. Give it a real ground reference. Do not use the control board's GND.

Why it matters

A capacitive screen senses a touch through capacitive coupling to ground. A finger works because the body is a large conductor tied to earth; the arm's stylus couples to earth too weakly, so a tap shifts the screen's charge distribution only slightly, and the phone registers the touch unreliably. Tie the stylus to a solid ground to restore that coupling and steady the touch.

How to ground it

Connect the housing to the power supply's common ground. The simplest option is to clip the wire to bare metal on a desktop PC chassis that is grounded through a three-prong outlet. The chassis reaches earth through the mains, giving a stable reference.

Three wires

Three wires run from the solenoid: positive (+), negative (−), and ground. Use spiral wrap to bind all three wires together with the Teflon tube into one bundle, and run it up to the control board holder, then connect + and − to the control board's Spindle terminal and the ground wire to the power supply's common ground.