OpenFlexure microscope

Print the parts and review the intended use

The OpenFlexure microscope is for research, teaching and schools. Building it from the open design does not make it a certified medical device, and any diagnosis must be done by qualified professionals.

This is the first stage of building the OpenFlexure Microscope v7 high-resolution version.

Credit: OpenFlexure Microscope v7.0.0-beta5 by the OpenFlexure Project (Richard Bowman et al.), licensed CERN-OHL-S-2.0. Source and official build guide: openflexure.org and build.openflexure.org/openflexure-microscope/v7.0.0-beta5. Adapted by TwinWorks; not endorsed by the OpenFlexure Project.

Print all parts before starting assembly. Print the optics module in black and the condenser in a dark opaque filament. For this stage, prepare only the main body, stand and 16 M3 nuts: 12 for the main body and 4 for the stand. Keep the main body and stand separate throughout this procedure.

Remove the brims

Peel the brims carefully from the main body and stand using a utility knife, not a scalpel. Cut the main body's custom brim free before peeling it away. Support the print and keep your fingers out of the blade's path.

Cut the main body's printing ties

Use the utility knife to cut the 6 ties inside the actuator columns of the main body and the 4 ties on its rear legs. Trim all 10 ties flush. Cut only the temporary ties, leaving the surrounding printed structure intact.

Embed the 4 stage nuts

Place the 4 M3 nuts in the stage side slots of the main body, one nut per slot. For each nut, pass a temporary M3x10 screw through the corresponding hole and engage the nut. Use a 2.5 mm ball-end Allen key to tighten the screw gradually, pulling the nut into its recess. Stop when the nut is seated, then unscrew and remove the temporary screw. Repeat for all 4 nuts.

Embed the 2 illumination-platform nuts

Place the 2 M3 nuts in the two nut recesses of the main body's illumination platform. Leave the third hole without a nut. Pull each nut into its recess with a temporary M3x10 screw and a 2.5 mm ball-end Allen key. Stop when seated, then remove the temporary screw.

Embed the 2 X motor-mount nuts

Place the 2 M3 nuts in the X motor-mount recesses of the main body. Pull each nut into its recess with a temporary M3x10 screw and a 2.5 mm ball-end Allen key. Stop when seated, then remove the temporary screw. Do not fit the motor during this stage.

Embed the 2 Y motor-mount nuts

Place the 2 M3 nuts in the Y motor-mount recesses of the main body. Pull each nut into its recess with a temporary M3x10 screw and a 2.5 mm ball-end Allen key. Stop when seated, then remove the temporary screw. Do not fit the motor during this stage.

Embed the 2 Z motor-mount nuts

Place the 2 M3 nuts in the Z motor-mount recesses of the main body. Pull each nut into its recess with a temporary M3x10 screw and a 2.5 mm ball-end Allen key. Stop when seated, then remove the temporary screw. Check that the main body now contains 12 nuts: 4 at the stage, 2 at the illumination platform and 2 at each of the X, Y and Z motor mounts.

Remove the stand's printing supports

Rock the printing supports back and forth to break them away from the stand. Remove the detached material and clear the mounting-lug nut recesses without damaging the lugs.

Embed the 4 stand nuts

Place the 4 M3 nuts under the mounting lugs of the stand, one nut per lug. Pull each nut into its recess using a temporary M3x10 screw and a 2.5 mm ball-end Allen key. Stop when seated, then remove the temporary screw.

Check that all 4 nuts are retained and the lugs are undamaged. The main body and stand are now prepared, with 16 embedded nuts in total. Keep them separate for the next assembly stage.

Prepare for actuator assembly

Start after preparing the main body. Assemble the X actuator first, then Y, then Z. Centre all three after fitting their feet.

For each actuator, set out one large gear, one M3x25 hex bolt, one brass M3 nut, two M3 washers, one Viton band and the matching lettered foot. Use the steel nut only as a temporary assembly aid and remove it after bedding the bolt.

This is the second stage of the OpenFlexure Microscope v7 high-resolution build, OpenFlexure Project, CERN-OHL-S-2.0.

X: bed the bolt into the large gear

Bed the M3x25 hex bolt into the X large gear using the printed nut spinner, a steel nut and the gear holder tool. Draw the bolt head into its seat in the gear, then unscrew and remove the temporary steel tool nut.

X: seat the brass nut

Drop the brass M3 nut through the front hole of the X actuator column. Tap it flat in its seat.

X: fit the washers and insert the drive bolt

Thread both M3 washers onto the M3x25 hex bolt with their curved sides facing each other. Push the bolt and X large gear into the top of the actuator. Turn the gear to screw the bolt into the brass M3 nut until the nut lifts. If the nut turns, hold it with the nut tool.

X: oil the screw thread

Lift the X large gear and put 1 drop of light oil on the M3x25 bolt thread. Lower the gear again.

Do not skip this: running the screw without oil will damage it.

X: assemble the band tool and hold the column

Assemble the band tool by inserting its two arms into the band tool cover.

Rotate the X large gear until the screw thread shows through the column hole. Insert the nut tool to hold the column while fitting the band and foot.

X: fit the Viton band and foot

This is the trickiest part of the build.

1. Loop the X Viton band through the X lettered foot and hook it onto the band tool.
2. Put the foot onto the actuator with the letter facing out.
3. Push the band tool in until the band clicks into place, then remove the band tool.
4. Seat the foot flush and remove the nut tool holding the column.

Y: bed the bolt into the large gear

Bed the M3x25 hex bolt into the Y large gear using the printed nut spinner, a steel nut and the gear holder tool. Draw the bolt head into its seat in the gear, then unscrew and remove the temporary steel tool nut.

Y: seat the brass nut

Drop the brass M3 nut through the front hole of the Y actuator column. Tap it flat in its seat.

Y: fit the washers and insert the drive bolt

Thread both M3 washers onto the M3x25 hex bolt with their curved sides facing each other. Push the bolt and Y large gear into the top of the actuator. Turn the gear to screw the bolt into the brass M3 nut until the nut lifts. If the nut turns, hold it with the nut tool.

Y: oil the screw thread

Lift the Y large gear and put 1 drop of light oil on the M3x25 bolt thread. Lower the gear again.

Do not skip this: running the screw without oil will damage it.

Y: hold the column for band fitting

Reuse the assembled band tool. Rotate the Y large gear until the screw thread shows through the column hole. Insert the nut tool to hold the column while fitting the band and foot.

Y: fit the Viton band and foot

This is the trickiest part of the build.

1. Loop the Y Viton band through the Y lettered foot and hook it onto the band tool.
2. Put the foot onto the actuator with the letter facing out.
3. Push the band tool in until the band clicks into place, then remove the band tool.
4. Seat the foot flush and remove the nut tool holding the column.

Z: bed the bolt into the large gear

Bed the M3x25 hex bolt into the Z large gear using the printed nut spinner, a steel nut and the gear holder tool. Draw the bolt head into its seat in the gear, then unscrew and remove the temporary steel tool nut.

Z: seat the brass nut

Drop the brass M3 nut through the front hole of the Z actuator column. Tap it flat in its seat.

Z: fit the washers and insert the drive bolt

Thread both M3 washers onto the M3x25 hex bolt with their curved sides facing each other. Push the bolt and Z large gear into the top of the actuator. Turn the gear to screw the bolt into the brass M3 nut until the nut lifts. If the nut turns, hold it with the nut tool.

Z: oil the screw thread

Lift the Z large gear and put 1 drop of light oil on the M3x25 bolt thread. Lower the gear again.

Do not skip this: running the screw without oil will damage it.

Z: hold the column for band fitting

Reuse the assembled band tool. Rotate the Z large gear until the screw thread shows through the column hole. Insert the nut tool to hold the column while fitting the band and foot.

Z: fit the Viton band and foot

This is the trickiest part of the build.

1. Loop the Z Viton band through the Z lettered foot and hook it onto the band tool.
2. Put the foot onto the actuator with the letter facing out.
3. Push the band tool in until the band clicks into place, then remove the band tool.
4. Seat the foot flush and remove the nut tool holding the column.

Centre the X actuator

Rotate the X large gear until the inner column's hole lines up with the outer slot. Stop at this alignment to leave the X actuator centred.

Centre the Y actuator

Rotate the Y large gear until the inner column's hole lines up with the outer slot. Stop at this alignment to leave the Y actuator centred.

Centre the Z actuator

Rotate the Z large gear until the inner column's hole lines up with the outer slot. Stop at this alignment to leave the Z actuator centred.

Inspect the black optics module

Inspect the black optics module, including the lens seat, camera mounting face, RMS thread and top nut trap. Remove loose debris before assembly.

Keep the Pi Camera protected from static discharge throughout assembly.

Press in the achromatic lens

Orient the 12.7 mm achromatic lens with its more curved side down. Use the lens tool to press it into the optics module until seated.

Remove the Pi Camera's original lens

Using its lens-removal tool, unscrew the Pi Camera v2's original lens, approximately four turns. Remove and discard the lens.

Position the camera on the optics module

Fit the Pi Camera v2 to the back of the optics module. Align the sensor with the optical opening and the fixing holes with the mounting points.

Fit the camera cover

Place the Pi camera cover over the back of the camera, aligning its two screw holes with the optics module's mounting points.

Secure the camera and cover

Fit the two No.2 self-tapping screws through the camera cover. Tighten with a #1 Pozidriv screwdriver to secure the camera to the optics module. Do not overtighten.

Fit the RMS objective

Hold the RMS objective straight and screw it into the optics module without tilting it.

Insert the mounting nut

Put the M3 nut into the top nut trap of the optics module.

Start the mounting screw

Turn the M3x10 mounting screw into the nut a couple of turns, leaving about 5 mm of thread showing. Leave it loose for mounting.

Check and connect the camera ribbon cable

Check that the 200 mm camera ribbon cable is Type B: the exposed contacts must be on opposite sides at its two ends.

Open the camera connector latch, insert the cable with its contacts toward the board, then close the latch to secure it.

Mount the assembled optics module

Pass the assembled optics module up through the bottom of the main body. Put its mounting screw through the keyhole on the Z actuator.

Reach the screw with the Allen key through the teardrop hole. Slide the module up as far as it goes, then tighten the mounting screw.

Secure the main body to the stand

Put the main body on the stand, with the body's lugs resting on the stand's lugs. Align the fixing holes.

Fit and tighten the four M3x10 body-to-stand screws using the Allen key.

Fit the condenser lens

Hold the condenser arm and orient the PMMA condenser lens with its flat side down. Use the lens tool to click the lens into the arm.

Fit the illumination thumbscrew

Fit the M3x25 bolt through the illumination thumbscrew. Fit the M3 nut into the dovetail slot, then screw the bolt into the nut loosely. Leave the thumbscrew loose enough for the condenser arm to slide into the illumination dovetail later.

Make the diffuser

Cut a 14 mm diameter diffuser disc from 0.5 mm polypropylene. Use the condenser board spacer as a guide to pierce two screw holes in the disc.

Fit the diffuser and illumination PCB

Stack the diffuser, condenser board spacer and illumination PCB in that order on the condenser arm, aligning the screw holes. Fix the stack with two No.2 self-tapping screws.

Make the LED cable

Use one red and one black 30 cm female-female jumper wire to make the LED cable. Fit the two wires into a 2-pin DuPont housing at each end, retaining the female contacts.

Connect the LED cable

Connect the red and black LED cable wires to the illumination PCB with the red wire connected to +.

Fit the condenser lid

Fit the condenser lid over the illumination assembly and secure it with two No.2 screws.

Mount the illumination dovetail

Position the illumination dovetail above the Z actuator. Fit two washers, one under each of the two M3x10 screws, and secure the dovetail to the body.

Route the LED cable

Route the red and black LED cable wires down the illumination dovetail's cable guide, then down the body's guide between the Z and Y gears.

Slide in and secure the condenser arm

Slide the condenser arm into the illumination dovetail until the arm is about 5 mm above the stage. Hand-tighten the illumination thumbscrew to hold the arm in position.

Label the motors and check actuator centring

Label the cables of the three 28BYJ-48 stepper motors X, Y and Z to match their intended axes. Re-check that all three actuators are centred before fitting the motors.

Push the small gears onto the motor shafts

Fit the three small gears, one to each of the three labelled motors. Keep each gear's flange toward the motor and align the flats in the gear bore with the flats on the motor shaft. Push each gear onto its shaft.

Secure each small gear with two No.2 screws

Secure the three small gears with the six No.2 self-tapping screws, two screws per gear. Keep the gear flange toward the motor and the shaft flats aligned while tightening.

Route the X cable and seat the X motor

Feed the X motor cable through the wall channel. Seat the X motor on its mounting lugs with its small gear meshed with the large gear.

Fit the X cable tidy cap and mounting screws

Add the X cable tidy cap over the seated motor. Fit and tighten the two M3x10 screws to secure the motor and cap.

Route the Y cable and seat the Y motor

Feed the Y motor cable through the wall channel. Seat the Y motor on its mounting lugs with its small gear meshed with the large gear.

Fit the Y cable tidy cap and mounting screws

Add the Y cable tidy cap over the seated motor. Fit and tighten the two M3x10 screws to secure the motor and cap.

Route the Z cable and seat the Z motor

Route the Z motor cable down the slot to the left of the Z actuator. Seat the Z motor on its mounting lugs with its small gear meshed with the large gear.

Fit the Z cable tidy cap and mounting screws

Add the Z cable tidy cap over the seated motor. Fit and tighten the two M3x10 screws to secure the motor and cap.

Secure the X and Y cable tidy caps

Secure both cable tidy caps, X and Y, with the two No.2 self-tapping screws, one screw per cap.

Fit the two sample clips to the stage

Take the two M3x10 screws and put one through the hole in each of the two sample clips. Position the clips at the stage clip holes and screw them to the stage with the Allen key.

Flash the Raspbian-OpenFlexure image

Flash the Raspbian-OpenFlexure image onto the microSD card. Select the intended card before starting: flashing erases its contents.

Keep the electronics unpowered during assembly.

Insert the microSD card

Insert the flashed microSD card into the microSD slot on the Raspberry Pi 4.

Prepare the Sangaboard firmware

If the Sangaboard did not come pre-flashed, flash its firmware before fitting it. If it came pre-flashed, continue to the next step.

Insert the two M3 retaining nuts

Put one M3 nut into the stand's front slot.

Put the other M3 nut into the slot in the electronics drawer near the Sangaboard power connector. Seat both nuts in their slots before fitting the boards.

Fit the Raspberry Pi 4 in the drawer

Press the Raspberry Pi 4 into the electronics drawer, aligning its ports with the drawer openings.

Secure it with two No.2 self-tapping screws.

Connect the camera ribbon cable

Connect the camera ribbon cable to the camera port on the Raspberry Pi 4. Open the connector latch, seat the ribbon squarely with its contacts facing the connector contacts, then close the latch.

Fit the GPIO stacking header

Fit the stacking header onto the GPIO header of the Raspberry Pi 4. Align both rows of pins before pressing it evenly into place.

Mount and secure the Sangaboard

Pass the camera ribbon cable through the slot in the Sangaboard. Align the board with the stacking header and press it evenly onto the header without trapping the ribbon.

Secure the Sangaboard with two No.2 screws.

Connect the X, Y and Z motor cables

Plug the X motor cable plug, Y motor cable plug and Z motor cable plug into the corresponding labelled X, Y and Z ports on the Sangaboard. Match each cable to its axis label and seat each plug fully.

Connect the LED cable

Connect the red and black LED leads to the CC header on the Sangaboard.

Slide in and secure the electronics drawer

Arrange the connected cables clear of the drawer edges. Slide the electronics drawer into the stand without pinching or pulling any wires.

Secure it with two M3x10 screws, engaging the M3 nuts fitted earlier.

Connect power and continue with software setup

Connect power through the Sangaboard's USB-C socket.

Then follow the OpenFlexure software setup linked from the OpenFlexure Microscope v7 high-resolution build guide (OpenFlexure Project, CERN-OHL-S-2.0).