Лего буст самоделки с инструкциями

This project is a LEGO-based reimplementation of an existing Arduino candy sorter project. Building with LEGO block-units made this a challenge, but programming and debugging the LEGO Boost via the app is much easier compared to Arduino.

The sorter goes through a loop of movements and events to sort candy:

1. the swivelling plate picks up one candy by moving the hole under the feeder tube
2. It turns to move that candy under the color sensor.
3. The color sensor sees the color, and a slide rotates so that the candy will fall in the correct color zone or bucket.
4. The plate turns to bring the candy to the drop location, where the floor ends and the slide begins.
5. The slide turns back to its initial position

Throughout this build, colors don’t matter. We used bricks from our spare collection, with no record of which LEGO set they once belonged to. The notable exception being the LEGO Boost main block, external motor and external color sensor. One exception in terms of color: the region around the color sensor is intentionally white, so the color detection of the candy is not disturbed by the surrounding LEGO bricks.

Let’s get started.

Get the parts

Get the following parts (as seen in the first picture). The slopes should be white, the other parts can be any color. The hole in the small Technic block is not a regular hole, rather one that doesn’t allow the axle to turn (as seen here on bricklink ) That will be crucial later.

Assemble the parts

Assemble the parts (second picture). This plate will be swinging back and forth to transport candy from the supply to the color sensor, to the sorting ramp, and then back to its starting position to pick up the next piece of candy. Only the wheel part sticks out on the top. We didn’t have a wheel attachment with height one. In the final machine, it didn’t look like the wheel was actually doing anything, so you can probably do without. I just wanted to make sure the swivelling plate doesn’t touch the floor when it turns.

Get the parts

N.B. the bevel gear pictured is a 12-tooth version. This part was introduced in 1995. An earlier 14-tooth version as introduced in 1980 would work just fine. Whatever version you use, you’ll need a matching gear later in the build.

The holes in the 1×6 Technics brick aren’t used in the build, so you can use a regular brick instead.

The length of the axle we used was 10 studs. A bit shorter may be enough. (Cfr. second picture)

Assemble the parts

As seen in the third picture.

Join both pieces together

As seen in the fourth picture. The swivelling plate doesn’t need to touch the grey Technic rectangle. The axle should extend a bit beyond the swivelling plate. The axle will rest in a hole in the floor of the complete build.

Get parts

get an axle and another bevel gear. The blue piece is there as a reference for the length of the axle (but will be used in the next step). Remember to match the bevel gear type to the earlier one.

Assemble and get more parts

The grey axle goes through the middle hole, just enough to slide through the bevel gear. Make sure it doesn’t touch the perpendicular black axle.

The spacer goes onto the grey axle, and the length 3 pins go on either side. Assemble the next four blocks and get a 16 tooth gear.

Assemble

Join the new part on the previous one. The new part sits at spacer distance from the old part, connected by the length 3 pins and the axle. Slide the gear onto the grey axle where it protrudes from the new part.

This step is optional, as it was purely decorative. I created two minifigs that look a bit like my children, gave them a tablet in their hands (a decorated 1×2 tile with buttons and dials). I mounted them on a small plate attached on top of the long black axle so they turn back and forth as the sorter is working.

We displayed and demoed the sorter at the CoderDojo Belgium Coolest Projects fair in 2018. Decoration makes for entertained viewers!

Build the structure

With assorted (and mostly regular) bricks, we’re building the structure that will hold the mechanism up and provide the floor for the candy mover. The black block pictured will be one of the legs on which the structure stands. Only one special block is used here: a simple 1×2 brick with one hole. This is where the axle from the previous part will pivot. The hole is only one unit deep, underneath is a regular brick.

Attach the previous part

The third picture shows how the previous part is attached to the new one. You can see the first leg extending «down».

You’ll see that the swivelling plate can turn freely around the black axle, and the 16-tooth gear can drive that motion via the perpendicular bevel gear.

Build

We extend the large standing structure of the sorter, starting with another leg. We used two short yellow plates on top of a black 2×10 plate to provide support for the slide assembly (which you will build later). Three plates have the same thickness as a standard brick, so that simplifies the overall construction.

Attach

Attach the second leg as shown in the second picture.

Build

We extend the raised floor of the structure. This floor is two units thick throughout. Color choice is arbitrary except for the white blocks. In the area around the color sensor, we’ve selected white bricks to avoid influencing the Boost color sensor.

Attach

The second picture shows where to attach the floor extension.

Build around the external motor

The rotating slide will guide the candy to the correct color bucket. The external motor is the first Boost part we’ll integrate. We add a couple of Technic parts to fix the motor to the rest of the structure even better. The axle goes through the first hole, the pin through the second.

The slide attachment

We continue with two double-perforated 1×2 bricks and a double pin of length 3, as shown in the fourth picture. If you only have one double-perforated 1×2 brick, that’s OK. The slide attaches to only one of these.

Build

The slopes are standard two-units-wide, one-unit-high slopes. The black end slopes are six studs long and tapered, which allows the slide to turn closer to the raised floor of the construction.

Two 1×8 plates extend from the main plate by 1 unit, and avoids the slide tilting down too much when it doesn’t make contact with the bottom of the raised floor altogether.

Attach

The slide attaches to the axle using a pivot. We found this 2×2 pivot plate, but the 1×2 versions are more common and would work as well.

Slide and motor get attached to the legs of the structure, and this is where the 2 yellow plates on one of the first legs come in. The long perforated beam we attached to the front of the external motor fits perfectly on those two plates.

Build

The next leg is built from standard Lego bricks. No Technic elements, no plates, no narrow beams, just bricks.

Attach

This leg gives the structure a fourth point of support to stand on.

Extend the floor

More regular bricks to extend the raised floor (third and fourth picture).

We can now turn the structure upright for the first time. It’s far from finished, but you can get a better idea of how it will move and function now.

Build

More regular bricks to form the five parts seen in the first picture.

Assemble

The second, third, and fourth picture show how to assemble the five parts.

Attach

Alignment is critical, so the fifth and sixth picture clarify how to align the new piece with the existing structure.

Pictures seven and eight show the attached piece.

Check

The floor is now large enough to allow the transport swivel plate to swing (and maybe ride) back and forth. You should see basic alignment between the hole in the transport plate and the top of slide. This is where the candy will drop onto the slide.

Before the sorting begins, candy needs to be fed into the sorter at the correct position. To facilitate this, we construct a feeding tube.

Build

We start with a 4×4 square of plates as seen in the first picture. Notice that one 1×2 piece is intentionally missing on the bottom layer. Candy will be moved away in that direction by the swivel plate. An extra plate could potentially jam larger candy pieces.

A layer of round bricks is built on top of that base, and a second layer is constructed (second picture). Both layers can be joined (third picture).

This tube is one of the only pieces of the structure that will be oriented studs-up. We need a 90-degrees attachment to connect it to the structure that way. The fourth picture shows the components for this construction. Note that we used a 1×2 plate with a sidebar, but ended up not using it. Substitute a regular 1×2 plate if you want. These components form the base of the next layer of the tube, as shown in the fifth picture.

Then a third layer can be added (sixth picture). A couple of plates (three 1×2, two 1×4 and one 1×8) are used to even everything out (seventh picture).

Decorate

In the final picture, we add a couple of decorational elements, to clearly point out the candy entry point to the user: a couple of 1×2 dial/control plates, an envelope plate and two 1×2 arrow plates on 1×2 pivots. Decoration is optional, even when it is functional…

Build

We need a wall over the raised floor to mount the feeder tube (at 90 degrees). The wall is one unit thick. For alignment with the feeder tube, we insert two plates between the Technic attachments. A third plate is needed to make this wall exactly 9 units high, but that third plate is already mounted on the structure (can you spot a lonely 1×6 blue plate in our pictures?). We used 1×2 bricks with fixed pins, but 1×2 bricks with a hole and a pin are equivalent.

Assemble

With correct alignment as shown in the second picture, it should now be obvious how the feeder tube attaches to this wall.

Mount

Mounting the wall on the sorter is easy. It attaches to the 1×6 plate next to the 16-tooth gear on one side (third picture). We fix it to the raised floor on the other side as well, using a 2×10 brick (fourth picture). You could use a 1×10 brick, as the wall is only one unit thick. We need enough space so the swivelling plate can freely move underneath.

Build

Another arch extends over the raised floor. It supports the Boost color sensor. Three plates are used to align the sensor as well as possible. One goes on the top side, two on the bottom side. We happened to have a three unit high 2×2 brick, but three separate bricks would be just fine.

Attach

The 2×8 brick on the end supports the far end of this arch. We’ve added a couple of bricks to the raised floor to firmly hold the two arch supports in place (one for the feeder tube and one for the color sensor).

Check alignment

We can now manually swivel the transport plate and check alignment of the transport hole with the feeder tube, the color sensor, and the drop-off point at the top of the slide. You can even test it with a piece of candy (an M&M or Skittle should have the correct size). If the transport plate can not move freely between these three points, you need to retrace your steps, because something went wrong.

Build

Gather the parts as displayed in the first picture. These include two 24-tooth crown gears and an 8-tooth gear (the smallest Technic gear).

Assemble

Insert the short red axle into the A motor, and attach the perforated 2×4 plate with the black axle as seen in the second picture. The assembly with the second perforated 2×4 plate holds the black axle in place (third picture).

The stopper prevents the axle from sliding away, but leaves enough space to allow you to manually slide the crown gear away from the 8-tooth gear to stop automatic movement, or to calibrate the starting position before starting the sorter.

Add a leg

Next we’ll add a leg to the motor block, to support it at the correct height so the whole structure doesn’t topple. Just a couple of regular 8×1 bricks and two plates are enough (picture four and five).

Attach the external cables

Attach both the external motor and the color sensor. It doesn’t matter which cable goes where, since the programming blocks don’t rely on the connection ID. Picture six and seven show the top view of the motor block and the cables coming from the main structure.

Replace batteries

If your Boost block may need new batteries, this is a good time to replace them.

Mount the motor block

We can now mount the motor block. Adjust the crown gears so they grip both the 8-tooth gear on the motor, and the 16-tooth gear on the main structure.

Admire your candy sorter

The sorter is finished! In step 16 we build a base that will hold the sorter and provide four sorting buckets. Then we need to create a Boost program, and the sorter will work! If you want to see the sorter in action as soon as possible, skip step 16 now, and return later if you want.

Build

The first picture shows the 32×32 base plate with all of the parts we use to build the sorting buckets. We foresee spectators on one side, hence we use windows there, so they can see where the sorted candy lands.

The colored translucent pieces on top of that wall are there mainly for decoration, but also they are placed in front of the zone where Skittles of that color will be deposited. The same goes for the translucent blocks in the middle of the base plate.

The side walls are there to hold up the front wall and to avoid spillage. The middle wall is the divider between the green and yellow zone. It features a small 1×2 ridge to avoid Skittles hitting the divider head-on and bouncing back. That’s probably an unlikely corner case, but we found the piece so we used it.

The two other dividers can’t be placed in standard perpendicular Lego fashion. We worked around that by using 2×2 rotary plates on the base, at a distance of 6×4 of each other, and upright 12×4 plates with 90 degree angle attachments at the last position. Details of the 12×4 plates can be seen the second picture.

The third picture shows the blocks on the right side of the base plate. They are meant to align the legs at the same position every time, so that the pivot point of the slide is centered on the base plate. Pictures five and six provide detailed views. If you built the legs of the structure differently, you should change the position of these blocks to match the legs on your sorter.

Admire

Picture six shows the finished base plate as seen from the top.

The final picture shows the sorter as it stands on the base plate.

Create a project

The project uses the left internal (A) motor of the Boost block, the external motor and the color sensor. Combining these elements in a program can be done via the “create a project” function of the Lego Boost app. If you’ve never created your own project, find instructions on the Lego website: https://www.lego.com/en-us/themes/boost/articles/…

Understand what the program needs to do

The main movement is the swiveling candy mover plate, driven by the A motor. Initialize it so the hole aligns with the feeder tube (slide away one of the crown gears to allow free movement, then slide the crown gear in place again). Initialize the slide in the central position.

The program can now, in an eternal loop,

1. move the plate “a” steps further using the A motor, “a” being just enough to position the candy below the color sensor. Adapt the “a” constant by experimenting.
2. One of the color sensor detection blocks will fire when the candy is in place, setting the “d” variable to the degrees of movement needed from the external motor to swing the slide to the correct zone. In the example, I associate red with -45, yellow with -15, green with 15, and black with 45. You might want to add a detection block for white, setting “d” to 0, to avoid movement when there is no candy.
3. The main loop waits for one second, then reads “d” and stores it in variable “c”. Storing the current value of “d” is needed because the color sensor will see bricks of other colors when plate moves. We need to remember the value associated with the candy color so we can move the slide back to the central position.
4. The external motor then activates, moving the slide “c” degrees.
5. The candy mover plate will now move the plate “b” steps further using the A motor, covering the distance between the color sensor and the drop position above the slide. Adapt the “b” constant by experimenting.
6. The program waits one second, which should be enough for the candy to drop in the correct zone.
7. The candy mover plate moves back “a” + “b” steps. We specify a negative speed to get the motor to turn in the other direction.
8. The slide turns back “c” degrees using the same trick: negative speed with a positive degree value.

Create the program

I think it’s fun to write your own program, but to help you, the included picture shows an example program. Values may need to be tweaked for your specific build.

Have fun!

If you tried this project, we’d like to hear from you! Please send us a message at

Bert de Bruijn <legoboostcandysorter@debruijn.be>.

This instructable and the included pictures are available under the terms of the Creative Commons Attribution-NonCommercial (CC BY-NC) license 4.0 – https://creativecommons.org/licenses/by-nc/4.0/

This project is a LEGO-based reimplementation of an existing Arduino candy sorter project. Building with LEGO block-units made this a challenge, but programming and debugging the LEGO Boost via the app is much easier compared to Arduino.

The sorter goes through a loop of movements and events to sort candy:

1. the swivelling plate picks up one candy by moving the hole under the feeder tube
2. It turns to move that candy under the color sensor.
3. The color sensor sees the color, and a slide rotates so that the candy will fall in the correct color zone or bucket.
4. The plate turns to bring the candy to the drop location, where the floor ends and the slide begins.
5. The slide turns back to its initial position

Throughout this build, colors don’t matter. We used bricks from our spare collection, with no record of which LEGO set they once belonged to. The notable exception being the LEGO Boost main block, external motor and external color sensor. One exception in terms of color: the region around the color sensor is intentionally white, so the color detection of the candy is not disturbed by the surrounding LEGO bricks.

Let’s get started.

Get the parts

Get the following parts (as seen in the first picture). The slopes should be white, the other parts can be any color. The hole in the small Technic block is not a regular hole, rather one that doesn’t allow the axle to turn (as seen here on bricklink ) That will be crucial later.

Assemble the parts

Assemble the parts (second picture). This plate will be swinging back and forth to transport candy from the supply to the color sensor, to the sorting ramp, and then back to its starting position to pick up the next piece of candy. Only the wheel part sticks out on the top. We didn’t have a wheel attachment with height one. In the final machine, it didn’t look like the wheel was actually doing anything, so you can probably do without. I just wanted to make sure the swivelling plate doesn’t touch the floor when it turns.

Get the parts

N.B. the bevel gear pictured is a 12-tooth version. This part was introduced in 1995. An earlier 14-tooth version as introduced in 1980 would work just fine. Whatever version you use, you’ll need a matching gear later in the build.

The holes in the 1×6 Technics brick aren’t used in the build, so you can use a regular brick instead.

The length of the axle we used was 10 studs. A bit shorter may be enough. (Cfr. second picture)

Assemble the parts

As seen in the third picture.

Join both pieces together

As seen in the fourth picture. The swivelling plate doesn’t need to touch the grey Technic rectangle. The axle should extend a bit beyond the swivelling plate. The axle will rest in a hole in the floor of the complete build.

Get parts

get an axle and another bevel gear. The blue piece is there as a reference for the length of the axle (but will be used in the next step). Remember to match the bevel gear type to the earlier one.

Assemble and get more parts

The grey axle goes through the middle hole, just enough to slide through the bevel gear. Make sure it doesn’t touch the perpendicular black axle.

The spacer goes onto the grey axle, and the length 3 pins go on either side. Assemble the next four blocks and get a 16 tooth gear.

Assemble

Join the new part on the previous one. The new part sits at spacer distance from the old part, connected by the length 3 pins and the axle. Slide the gear onto the grey axle where it protrudes from the new part.

This step is optional, as it was purely decorative. I created two minifigs that look a bit like my children, gave them a tablet in their hands (a decorated 1×2 tile with buttons and dials). I mounted them on a small plate attached on top of the long black axle so they turn back and forth as the sorter is working.

We displayed and demoed the sorter at the CoderDojo Belgium Coolest Projects fair in 2018. Decoration makes for entertained viewers!

Build the structure

With assorted (and mostly regular) bricks, we’re building the structure that will hold the mechanism up and provide the floor for the candy mover. The black block pictured will be one of the legs on which the structure stands. Only one special block is used here: a simple 1×2 brick with one hole. This is where the axle from the previous part will pivot. The hole is only one unit deep, underneath is a regular brick.

Attach the previous part

The third picture shows how the previous part is attached to the new one. You can see the first leg extending «down».

You’ll see that the swivelling plate can turn freely around the black axle, and the 16-tooth gear can drive that motion via the perpendicular bevel gear.

Build

We extend the large standing structure of the sorter, starting with another leg. We used two short yellow plates on top of a black 2×10 plate to provide support for the slide assembly (which you will build later). Three plates have the same thickness as a standard brick, so that simplifies the overall construction.

Attach

Attach the second leg as shown in the second picture.

Build

We extend the raised floor of the structure. This floor is two units thick throughout. Color choice is arbitrary except for the white blocks. In the area around the color sensor, we’ve selected white bricks to avoid influencing the Boost color sensor.

Attach

The second picture shows where to attach the floor extension.

Build around the external motor

The rotating slide will guide the candy to the correct color bucket. The external motor is the first Boost part we’ll integrate. We add a couple of Technic parts to fix the motor to the rest of the structure even better. The axle goes through the first hole, the pin through the second.

The slide attachment

We continue with two double-perforated 1×2 bricks and a double pin of length 3, as shown in the fourth picture. If you only have one double-perforated 1×2 brick, that’s OK. The slide attaches to only one of these.

Build

The slopes are standard two-units-wide, one-unit-high slopes. The black end slopes are six studs long and tapered, which allows the slide to turn closer to the raised floor of the construction.

Two 1×8 plates extend from the main plate by 1 unit, and avoids the slide tilting down too much when it doesn’t make contact with the bottom of the raised floor altogether.

Attach

The slide attaches to the axle using a pivot. We found this 2×2 pivot plate, but the 1×2 versions are more common and would work as well.

Slide and motor get attached to the legs of the structure, and this is where the 2 yellow plates on one of the first legs come in. The long perforated beam we attached to the front of the external motor fits perfectly on those two plates.

Build

The next leg is built from standard Lego bricks. No Technic elements, no plates, no narrow beams, just bricks.

Attach

This leg gives the structure a fourth point of support to stand on.

Extend the floor

More regular bricks to extend the raised floor (third and fourth picture).

We can now turn the structure upright for the first time. It’s far from finished, but you can get a better idea of how it will move and function now.

Build

More regular bricks to form the five parts seen in the first picture.

Assemble

The second, third, and fourth picture show how to assemble the five parts.

Attach

Alignment is critical, so the fifth and sixth picture clarify how to align the new piece with the existing structure.

Pictures seven and eight show the attached piece.

Check

The floor is now large enough to allow the transport swivel plate to swing (and maybe ride) back and forth. You should see basic alignment between the hole in the transport plate and the top of slide. This is where the candy will drop onto the slide.

Before the sorting begins, candy needs to be fed into the sorter at the correct position. To facilitate this, we construct a feeding tube.

Build

We start with a 4×4 square of plates as seen in the first picture. Notice that one 1×2 piece is intentionally missing on the bottom layer. Candy will be moved away in that direction by the swivel plate. An extra plate could potentially jam larger candy pieces.

A layer of round bricks is built on top of that base, and a second layer is constructed (second picture). Both layers can be joined (third picture).

This tube is one of the only pieces of the structure that will be oriented studs-up. We need a 90-degrees attachment to connect it to the structure that way. The fourth picture shows the components for this construction. Note that we used a 1×2 plate with a sidebar, but ended up not using it. Substitute a regular 1×2 plate if you want. These components form the base of the next layer of the tube, as shown in the fifth picture.

Then a third layer can be added (sixth picture). A couple of plates (three 1×2, two 1×4 and one 1×8) are used to even everything out (seventh picture).

Decorate

In the final picture, we add a couple of decorational elements, to clearly point out the candy entry point to the user: a couple of 1×2 dial/control plates, an envelope plate and two 1×2 arrow plates on 1×2 pivots. Decoration is optional, even when it is functional…

Build

We need a wall over the raised floor to mount the feeder tube (at 90 degrees). The wall is one unit thick. For alignment with the feeder tube, we insert two plates between the Technic attachments. A third plate is needed to make this wall exactly 9 units high, but that third plate is already mounted on the structure (can you spot a lonely 1×6 blue plate in our pictures?). We used 1×2 bricks with fixed pins, but 1×2 bricks with a hole and a pin are equivalent.

Assemble

With correct alignment as shown in the second picture, it should now be obvious how the feeder tube attaches to this wall.

Mount

Mounting the wall on the sorter is easy. It attaches to the 1×6 plate next to the 16-tooth gear on one side (third picture). We fix it to the raised floor on the other side as well, using a 2×10 brick (fourth picture). You could use a 1×10 brick, as the wall is only one unit thick. We need enough space so the swivelling plate can freely move underneath.

Build

Another arch extends over the raised floor. It supports the Boost color sensor. Three plates are used to align the sensor as well as possible. One goes on the top side, two on the bottom side. We happened to have a three unit high 2×2 brick, but three separate bricks would be just fine.

Attach

The 2×8 brick on the end supports the far end of this arch. We’ve added a couple of bricks to the raised floor to firmly hold the two arch supports in place (one for the feeder tube and one for the color sensor).

Check alignment

We can now manually swivel the transport plate and check alignment of the transport hole with the feeder tube, the color sensor, and the drop-off point at the top of the slide. You can even test it with a piece of candy (an M&M or Skittle should have the correct size). If the transport plate can not move freely between these three points, you need to retrace your steps, because something went wrong.

Build

Gather the parts as displayed in the first picture. These include two 24-tooth crown gears and an 8-tooth gear (the smallest Technic gear).

Assemble

Insert the short red axle into the A motor, and attach the perforated 2×4 plate with the black axle as seen in the second picture. The assembly with the second perforated 2×4 plate holds the black axle in place (third picture).

The stopper prevents the axle from sliding away, but leaves enough space to allow you to manually slide the crown gear away from the 8-tooth gear to stop automatic movement, or to calibrate the starting position before starting the sorter.

Add a leg

Next we’ll add a leg to the motor block, to support it at the correct height so the whole structure doesn’t topple. Just a couple of regular 8×1 bricks and two plates are enough (picture four and five).

Attach the external cables

Attach both the external motor and the color sensor. It doesn’t matter which cable goes where, since the programming blocks don’t rely on the connection ID. Picture six and seven show the top view of the motor block and the cables coming from the main structure.

Replace batteries

If your Boost block may need new batteries, this is a good time to replace them.

Mount the motor block

We can now mount the motor block. Adjust the crown gears so they grip both the 8-tooth gear on the motor, and the 16-tooth gear on the main structure.

Admire your candy sorter

The sorter is finished! In step 16 we build a base that will hold the sorter and provide four sorting buckets. Then we need to create a Boost program, and the sorter will work! If you want to see the sorter in action as soon as possible, skip step 16 now, and return later if you want.

Build

The first picture shows the 32×32 base plate with all of the parts we use to build the sorting buckets. We foresee spectators on one side, hence we use windows there, so they can see where the sorted candy lands.

The colored translucent pieces on top of that wall are there mainly for decoration, but also they are placed in front of the zone where Skittles of that color will be deposited. The same goes for the translucent blocks in the middle of the base plate.

The side walls are there to hold up the front wall and to avoid spillage. The middle wall is the divider between the green and yellow zone. It features a small 1×2 ridge to avoid Skittles hitting the divider head-on and bouncing back. That’s probably an unlikely corner case, but we found the piece so we used it.

The two other dividers can’t be placed in standard perpendicular Lego fashion. We worked around that by using 2×2 rotary plates on the base, at a distance of 6×4 of each other, and upright 12×4 plates with 90 degree angle attachments at the last position. Details of the 12×4 plates can be seen the second picture.

The third picture shows the blocks on the right side of the base plate. They are meant to align the legs at the same position every time, so that the pivot point of the slide is centered on the base plate. Pictures five and six provide detailed views. If you built the legs of the structure differently, you should change the position of these blocks to match the legs on your sorter.

Admire

Picture six shows the finished base plate as seen from the top.

The final picture shows the sorter as it stands on the base plate.

Create a project

The project uses the left internal (A) motor of the Boost block, the external motor and the color sensor. Combining these elements in a program can be done via the “create a project” function of the Lego Boost app. If you’ve never created your own project, find instructions on the Lego website: https://www.lego.com/en-us/themes/boost/articles/…

Understand what the program needs to do

The main movement is the swiveling candy mover plate, driven by the A motor. Initialize it so the hole aligns with the feeder tube (slide away one of the crown gears to allow free movement, then slide the crown gear in place again). Initialize the slide in the central position.

The program can now, in an eternal loop,

1. move the plate “a” steps further using the A motor, “a” being just enough to position the candy below the color sensor. Adapt the “a” constant by experimenting.
2. One of the color sensor detection blocks will fire when the candy is in place, setting the “d” variable to the degrees of movement needed from the external motor to swing the slide to the correct zone. In the example, I associate red with -45, yellow with -15, green with 15, and black with 45. You might want to add a detection block for white, setting “d” to 0, to avoid movement when there is no candy.
3. The main loop waits for one second, then reads “d” and stores it in variable “c”. Storing the current value of “d” is needed because the color sensor will see bricks of other colors when plate moves. We need to remember the value associated with the candy color so we can move the slide back to the central position.
4. The external motor then activates, moving the slide “c” degrees.
5. The candy mover plate will now move the plate “b” steps further using the A motor, covering the distance between the color sensor and the drop position above the slide. Adapt the “b” constant by experimenting.
6. The program waits one second, which should be enough for the candy to drop in the correct zone.
7. The candy mover plate moves back “a” + “b” steps. We specify a negative speed to get the motor to turn in the other direction.
8. The slide turns back “c” degrees using the same trick: negative speed with a positive degree value.

Create the program

I think it’s fun to write your own program, but to help you, the included picture shows an example program. Values may need to be tweaked for your specific build.

Have fun!

If you tried this project, we’d like to hear from you! Please send us a message at

Bert de Bruijn <legoboostcandysorter@debruijn.be>.

This instructable and the included pictures are available under the terms of the Creative Commons Attribution-NonCommercial (CC BY-NC) license 4.0 – https://creativecommons.org/licenses/by-nc/4.0/

For the 2019 Coderdojo Belgium Coolest Projects fair, we built a LEGO Boost variant of Yoshihito Isogawa’s Mindstorms pipe cleaner bending robot. He only published a Youtube video of his EV3 robot, so we didn’t have any building instructions to start from. Building from scratch took several iterations before achieving a working robot, but we’re thankful that we could borrow some of Mr. Isogawa’s brilliant ideas nonetheless.

As always, every challenge has many possible solutions. We present solutions that were possible using our collection of spare LEGO parts. Your mileage, and your parts collection, may vary.

Please note that this instructable was documented by taking the robot apart. Building from scratch is far less linear than taking the final build apart…

We build the robot on two 8×16 stud, regular height plates. One is just for holding the Boost motor block, the other one holds the mechanism itself.

Every step will include pictures of the components used. Small details can make a large difference sometimes, so make sure to zoom in if you’re not sure which type of Lego part we’re using. Please don’t ask where we got a specific part, as these all come from the «spare part» box, with no record of which set they once belonged to.

In the first picture, you can see the Technic parts on the left, and the regular parts on the right. This will not be a large build, as you can see. The Boost main motor block and the Boost external motor are in the middle. We didn’t use the Boost color sensor in this build. The second picture shows all axles we used, with a couple of Technic beams for length reference. We tried to use the minimum length required for the specific purpose of each axle.

Using perforated bricks (mainly 1×6), we construct side walls to mount the feeder wheels between. The total height is a full number of regular bricks, but we split one into three plates, to push the two feeder wheels onto each other. That is also the reason why we have the perpendicular beam: without that beam the forces on the wheels push the wall apart.

On one row you can see two grey pins. The external Boost motor will connect to those, and the wheel axle driven directly by the motor goes in between the two connectors.

We chose Lego wheels that have a compressible rubber tire on a central rim. This allows for pressure to be exerted by pressing the wheels together a bit. The pipe cleaner will be fed between the two wheels, one wheel will be motor-driven, and the other wheel will be driven by its firm contact with the first wheel.

We use 180 degree axle and pin connectors as alignment tubes. The three rear alignment tubes are centered by pins on one side, and by axles on the other side. The axles protrude from the wall on the other side, which allows us to fixate them in a permanent direction. The only part that has three fixed axle attachments in a row was the grey egg-shaped part in the last picture. You could reduce the construction to two alignment pieces, and use a piece with two fixed axle attachments instead. Note that using pins on both sides would allow the alignment tubes to rotate. Also note that the space between the walls is one unit wider than the black tube parts. This is why we add half-unit spacers on both sides.

The wheel on the longest axle is the one driven by the motor, so it is positioned between the grey pins that will keep the motor in place later. It doesn’t need additional stoppers, as the connection in the motor is rigid enough. The other wheel is on the shorter axle, and is kept in place by two half stoppers on either side of the walls.

The alignment tubes are mounted in the dark grey brick in the example. You can see the egg-shaped fixating piece on one side, keeping the alignment tubes oriented correctly.

For the type of wheels we chose, the one plate below/two plates above positioning of the dark grey brick aligns the tubes with the contact surface between the wheels.

In this step, we assemble various items that go into the main front beam. The first is the front alignment tube. It consists of two axles, an alignment tube identical to the ones we used at the back, and a single-ended connector that keeps the pipe cleaner precisely centered. This one goes into the central hole of the main beam. In the previous step we already added a piece that prevents rotation in that position.This is crucial for the alignment tube.

Secondly, we assemble the benders. One bender arm consists of 4×2 elbow beam, a connector, and a small rim. We make two arms.These go one long axles, and into holes two steps away from the central hole.

At the bottom of the bender axles, 24-tooth gears are attached. The short axles from the previous step get 8-tooth gears, and a matching bevel gear for the transmission axle. Note that the 1:3 gear reduction provides extra force for the bender arms. Two 16-tooth gears cover the same distance, but didn’t bend the pipe cleaners reliably during testing.

Once the robot is finished, it is time to fire up the Boost app. Start experimenting with the feeder speed, the bender arm range, etcetera. We created programs to bend a 5 point star, a heart, a circle, a plus sign, and a diamond shape. We used pipe cleaners of 6 mm diameter and 30 cm length.

Have fun and good luck!