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Mechanical-Machine Design (Adults)

We have noticed a lack of organization and tracking of milling bits in our lab, and not for lack of trying. Therefore, the inspiration for our project is to create a mechanized organization system for these bits that will allow for easy storage, check-in/out, and usage tracking. If done successfully, this machine will increase accountability and respect for the use of milling bits and lab materials while decreasing the number that get lost and/or broken.


Our Hero Shot




Splitting up the work

We have split the work into 5 categories, and assigned 2 teammates to each category. First names are abreviated as follows:

Abbreviation/Name Individual Site Links
A - Avery To see Avery’s contribustions, please visit this site.
B - Barbara To see Barbara’s contributions, please visit this site.
C - Charlie To see Charlie’s contributions, please visit this site.
N - Nidhie To see Nidhie’s contributions, please visit this site.
S - Scott To see Scott’s contributions, please visit this site.


Over the course of the two-week period, some of the assigned tasks varied a little, and different people wound up working together (or alone) depending on who was available at that particular time.

Respective sections are documented below.

Outer Shell and Windows– Scott Moulton, Charlie Horvath (and Nidhie Dhiman and Barbara Morrow– Front Door)

Ferris-wheel, frame and Core Structure

Wheel mockups and Concepts– Charlie Horvath and Scott Moulton

Scott has led the charge on the design front and began by trying out a few ideas for the ferris wheel and bit holding components. Here were the first two concepts.

Scott_tray_concept1.jpg Scott_tray_concept2.jpg

Then the group pivoted to one of Scott’s earlier ideas, to use magnets to hold them up to the wheel, and simply 3D print. This method was deemed preferable since we could vastly reduce the # of printed components. The bit cases would contain magnets where as the wheel will contain a steel ring. Therefor, the bit the printed frame need only “guide” the bit case into the correct position and from there the magnet can hold it in place. Here are some concepts.


Running with this idea, Scott began to think about how to attach the entire wheel together (frame, steel ring, structure), and came up with a 2 hub-cap designs that would sandwich everything together using either bolts or PVC pipe. Better yet, he added some nice flair to the outside of the front-side cap.

Hub_cap_concept.jpg magnet_wheel_concept_3_27_22

Liking this, Charlie combined the green component with the blue frame to become one piece. The back-side hub cap is still a separate piece. Also, if we are clever about a midprint filament change, we should be able to have that lettering come out with nice contrast. Of course, the other pieces around the perimeter will get the same coloring for the remainder of the print, but that is of course ok.


Next steps will be to actually design these components to-scale.

Wheel Design

After this video was shot, this wheel went through a few more iterations. The biggest changes were to the central printed adapter. As you can see in this split-view of the full-stack, the star adapter no longer sticks out of the front of the hub cover cap. Therefore, a star shaped blind-hole was added to the backside of the hub-cap, rather than a through-hole.


Additionally, with the addition of brass collets to keep everything from sliding along the shaft, the 3 radial bolts were removed. At this point, another drive adapter was printed. From this iteration, we discovered a few things. The entire thing press fits onto the drive-shaft. However, the longevity of that press-fit was called into question and therefore the 3 radial bolts were added back, but only to one side of the printed adapter (the back side). Ironically, the print of the first prototype failed before it could print the area with the 2nd set of bolts.


So overall, the first prototype is closer to the final product than the 2nd. After the 2nd prototype, the height of the star feature was adjusted to reflect the thickness of the acrylic panes we would be using for the wheel/gear. Lastly, per the 2nd prototype fitting a bit too tightly on the driveshaft and in the acrylic cut gears, these tolerances were loosened.

Wheel Production

Based on this design, the spacer wheel and gear were laser cut out of 1/4” acrylic (0.232 nominal) and fit onto the printed drive adapter.


The belt we are planning to use was stolen from an Ender 3. As such, the gear teeth were derived from the official Creality CAD file for the Ender 3. However, upon cutting the gear, it was clear that the teeth were not aligning.


So it turns out that the little gear from the Creality CAD model was drawn with 15 teeth at a 2.78 mm pitch. Upon measuring the actual gear, it clearly had 20 teeth on a tighter tooth pitch. At this point, the belt was looked up and we found an official drawing of the belt.


The teeth were redesigned to meet this specification. However, in an effort to not waste any more time or acrylic, a test piece was derived. The section 2 was drawn ‘nominally’, or exactly as the drawing. The teeth in section 1 we’re offset outward by 0.005”. The teeth in section 3 we’re offset inward by 0.005”.

TeethTester_CAD TeethTester

In practice, we all agreed that the nominal teeth worked best.


Then the gear could be re-cut, as well as the main wheel. The main wheel was cut out of thinner material (0.166” nominal), but this was now accounted for in the design.


And the belt works!

CAD of Main Assembly

The core ferris-wheel and connection to the motor was designed in Fusion 360.

Additionally, this design in Fusion 360 became a main assembly file. In some instances, this was as simple as bringing in everyones completed design files (bit holders, bit boxes) and in other instances this involved modeling the components others had made after the fact (e.g. Welded frame, wooden box frame). Here is the nearly complete CAD assembly that includes about 90%+ of the components. Notable exceptions are the electronics and the front door of the design, which includes the iPad holder. Time permitting, these will be included in the CAD assembly eventually since they are both important aspects of the design.

Development continued, including the design/production of the acrylic side panels for the wooden frame and the side door for bit retrieval. The latter was more complicated and took some time to design correctly. We settled on a sliding door over a swinging door because this would allow me to position the limit switch in a hidden position, away from potential accidental finger presses. This is important since the current iteration of our code will begin to move the wheel to the home position when that switch is closed again (after bit retreival and closing of door). Here are some shots of the completed design.


The process of taking these photos made us realize there is an issue of clearance between the bit and the limit switch beneath the door.


This prompted us to move the wheel about a 1/2” further away from the door to provide ample clearance. In practice, this caused two issues.

  1. The barcode was no longer front and center within the iPad’s focal range. This caused issues with the scanning of the bits.
  2. Less critical, the bit was now a bit too far deep in the box and difficult to reach.

As a result, we moved the wheel 1/4” back towards the side door to find a happy medium. This also prompted us to move the homing limit switch so that it would still be in range of the limit-switch-knocker. Luckily, the 0.25” move of the wheel seemed to result in a major change of the camera’s ability to find the barcode. It seems that because the camera sees in a cone shape, a small movement of an object that is relatively far away from the camera, resulted in a big change for the location of the bit on the screen. The reaching distance for the bit was also now more acceptable, so this seems to be the wheel’s final resting place.

During the final assembly, a few things needed to happen on the fly. We had to position the limit switch for homing the wheel. This took some time to workout because we we’re running out of real-estate towards the front-right of the machine. This prompted a redesign of the home bit sleeve. Scott took on the task of redesigning and reprinting this piece. While Scott’s piece was printing, Nidhie and I focused on building out a stable base and arm for the limit switch to rest on. Luckily, Scott was able to send me the file so we were able to workshop ideas both physically, and in CAD. This was really tricky and we went through several iterations before settling on the following design.


Getting the length of these two wooden pieces right took some iteration such that the limit switch would not impend the movement of the wheel and also so that the wheel would stop precisely at 3:00 on the clock and the limit-switch-knocker would be level. These wooden pieces were later painted black which helped retain the asthetic.

One system that needed some last minute tweaking was the acrylic blinder pane. The intention of this pane was to block out nearby bits so that the iPad could focus on just the central-bit. In CAD this seemed perfect. However, in hindsight this is of course a difference between an orthographic view and a perspective view. Upon changing the view settings in the render module of Fusion 360, we are able to tweak the focal length until I can see another bit holder poking out from behind the blinder.


We found out the hard way that the iPad camera sees more like the perspective view than the orthographic view. This occasionally cauased the wrong bits to scan. As a result, we produced one more laser-cut piece to further close in the blinders.


One last big effort during final assembly was to create an electrical panel for the electrical components to mount to. Luckily, we did have some foresight that this would need to occur as a very last step. This was part of the inspiration for dividing the right acrylic panel of the box into two pieces. This allowed us to prove out the side-door and the window portion while waiting on the electrical components to be completed. The electrical components were simply mounted by laser cutting holes in the panel to match those on the components and by using nylon standoffs we were able to lift the components off of the acrylic backing in an electrically safe manner. Models for Arduino Uno were downloaded from grabCAD which allowed easy placement of the holes. Other components were measured and transferred into CAD by hand. Luckily, all of the tolerances worked by simply duplicating the spacing/size of these holes onto the acrylic pane.


The cable management was still in process at the time of this photo’s taking, but this offers a good picture into how the various electronics were mounted. Duct tape was then used to manage the tangle of cables and keep them away from the movement of the wheel. One final hiccup was finding that the limit switch wires needed to be longer in order to reach the homing limit switch safely, in a way that cleared the movement of the wheel and other components. This was fixed by simply extending these wires and heat-shrinking the connections.

Powering Up NEMA17 Motor– Nidhie Dhiman and Barbara Morrow

On April 6th, Nidhie Dhiman and Barbara Morrow worked to get one NEMA17 Stepper Motor working. We used a 12V power supply (adapter) with an L298N Motor Driver attached to the NEMA17 Stepper Motor. Since none of us had ever worked with an L298 Motor Driver, we needed to do research before we began.

The first website called ““SKR Pro V1.1 - TMC2208 UART v3.0 (BigTreeTech)” was useful in understanding the rationale behind the wiring we would use for the NEMA17 Stepper Motor. However, this wound up not be an ideal site in the end because a CNC Shield is not being used in our Bit Organizing Machine as it is in this video.

This site– “MC2209 and TMC 5160: Guide for MKS Gen L and SKR V1.3” – was also viewed; this too wound up not being great because the guy in the video was really only comparing the different motor drivers that could be used in conjunction with NEMA17 Stepper Motors being replaced in the mechanics of a 3D printer.

This site showed that we needed a GRBL file when using NEMA17 stepper motors. We followed this link, and we were eventually sent to this github site that contained the source code for the .h files and an extensive collection of C files. In addition to this, we found “GCode Sender” site that may be helpful in developing coordinates in the code for our milling bits storage concept.

“This final site” was incredibly helpful in how to wire the NEMA17 Stepper Motor to the L298N Motor Driver. Although this video showed how to connect two small DC motors to the L298N Motor Driver, we were able to determine the proper connection of just one NEMA17 Stepper Motor. This site actually contained a diagram of how the NEMA17 Stepper Motor should be connected. After wiring it, we eventally got the NEMA17 Stepper Motor to respond. The motor would vibrate for a short period (the central axis spattering back and forth in a “confused” motion), and then eventually “die out”, stopping the vibration altogether.

After several attempts to remedy this, we realized that the motor responded better when one member held her fingers under the IN1, IN2, IN3, and IN4. She seemingly was completing the circuit whenever she touched the ends of the IN1 and IN4 pins with her finger. We found the headers and repositioned them back onto the L298N Motor Driver to the left of the IN1 pin (the ENA pin) and to the right of the IN4 pin (the ENB pin).

After this, we plugged it all in again with the 12V power adapter, and the motor continued to spastically vibrate and “die out”. During a conversation with Dr. Adam Harris, and as he questioned us about the 12V power adapter, we realized that we were using an AC 12V power adapter, and we were trying to use it with a DC motor. We searched the 12V power supplies, and Nidhie Dhiman was able to find only one that was a DC 12V power adapter. We plugged in the new adapter, and instantly, the NEMA17 Stepper Motor began fucntioning beautifully as expected the Stepper One Revolution Arduino file.

The follwing video shows the work we did to get the NEMA 17 Stepper Motor to function properly with a L298N Motor Driver.


Universal Bit Holders and Magnetic Attachment– Barbara Morrow

For our universal bit holder and magnetic attachment, we decided to utilize a design similar to commercial bit holders that we have seen in the Charlotte Latin School Fab Lab.


However, we needed to customize the bit containers to the size of our “wheel design”, and we wanted to place a 3mm x 1 mm neobdynium magnet in the bottom of the bit holders so that they would not slip out of the wheel as it rotated.

The first thing we did was measure the internal dimensions of a bit tray that is intended to hold the bit container.

Internal1 Internal2

Designing the Bit Box/Container (In Fusion 360)

The following table shows the steps (and description) of how the bit holders were designed (in Fusion 360).

Photo Description
Fusion1 Make a square with dimensions of 14.25mm x 14.25mm.
Fusion2 Extrude 62.5mm from the front to the back.
Fusion3 Make the new 3D feature a shell (with a 1 mm shell diameter).
Fusion4 This is what the bit holder looked like after it was shelled.
Fusion5 Add an offset plane to the bottom of the bit container. Make a (center) circle with a diameter of 3 mm.
Fusion6 Make the center circle a “hole”. This then completes the design for the bottom of the bit box/container.
Fusion7 To begin making the bit lid, start by making another square with the dimensions of 14.25mm x 14.25mm.
Fusion8 Extrude the base rectangle 10mm from front to back. Make the new 3D cube a shell with a diameter of 1mm.
Fusion9 Create an offset plane on the bottom of the cap. Determine the points needed to form an isosceles right triangle by measuring out lines that are 2.75mm in length from each side of the right angle.
Fusion10 Using the pre-determined points, make a “T-shape” on the bottom (offset) plane. Extrude this “T-shape” 20mm.
Fusion11 Repeat the last two steps for each of the for corners. (Or, select all of the faces of the extruded “T-shape” and select “Mirror” using both the X and Y axes until all four corners contain the “T-shape”.)
Fusion12 The original four “T-shapes” in each right angle needed to be re-designed because the opening in the middle was too large–preventing them from gripping and holding tightly onto the bit. This shows the new “curved” design of the “T-shapes” in the right angles.
Fusion13 This shows the final cap design with bit grips working well.

The following images show the final designs as they were and after they had been 3D printed using Prusa printers in the Charlotte Latin School Fab Lab.

Base1 CapV1

After the base and the cap were done being 3D printed, they were joined together. However the cap was very loose, and the original cap could not hold onto a bit.

Combine2 Combine1 Combine3
This shows the two pieces (bit box/container)– base and cap together after 3D printed. This shows the first designed cap placed on top of the bit box/container base. This shows the assembled bit box/container base and cap placed in one of the bit trays.

The bit box/container base fit perfectly into the bit tray (as seen in the image below on the left). However, when the cap is placed on the base, and the two pieces are turned upside down, the cap falls off (shown in the image on the right). The bit box/container cap was then redesigned (as mentioned above). The following two images show the bit box/container base and cap as they were placed into the wheel.

InWheel1 InWheel2

Once the cap was re-designed (image below on the left), and 3D printed again, we took a desktop milling bit and placed it in it (image below on the right). The bit was held snuggly, but after a few times of testing the cap with the bit, one of the internal “T-shapes” broke.

BitCompare CapV2

The following two images show the newly assembled bit box/container that wound up being much better than tthe first. When the bit is held by the four curved “T-shapes”, it causes the sides to push out slightly. This puts pressure on the inside of the bit box/container, and the cap stays on. However, when we handled both verion 1 and version 2 of the bit box/container cap, both of them broke. We decided to try printing them in the Formlabs (Prusa) Resin 3D printer in the Charlotte Latin School Fab Lab. The following images show us using the resin 3D printer.

Resin0 Resin1
Bit Box Cap After Resin Printing Top Version of Bit Box Cap After Resin Printing
Resin2 Resin3
Pulling Bit Box Cap Out Of Resin 3D Printer Putting The Bit Box Cap Into The Resin Wash

Arduino and Electronics Controls– Avery Horvath (assisted by Barbara Morrow)

After Avery Horvath had designed the code and wired the two Arduino Uno’s with the NEMA17 Stepper Motor (with driver), Barbara made the following drawing of her circuitry.


Avery and Barbara then began soldering the electronics for the Wheel-O-Bits.

The following table and images show some of the steps of soldering the circuitry of the “Wheel-O-Bits”.

Image Description
Limit1 This shows our soldering midway through the process. We needed to stop at this point and retrieve the limit switch (on the piece of wood) to ensure it worked before moving forward with the soldering. We initially were planning to solder the wired directly onto the Arduino pins, but we wound making a change to that plan later on.
Perf1 This image shows our idea of trying to use a perforated board (in lieu of the breadboard we had been using). We attempted to use male header pins with it, but we realized (sadly a few wires into it) that we did not account for the “space” between pins 7 and 8. The male header pins did not fit into Ports B and D in the Arduino Uno. We tried modifying this by removing a pin, but the space between pins 7 and 8 was not the same width as the space between other pins.
Perf2 Avery was able to bend the male headers so that they would indeed fit through the perf board. In doing this, we were able to quickly run diagnostic tests as we soldered the remaining components, and we were not having to re-wire between tests and adding other components/wires.
Working1 This shows the first test we ran with the LCD after wiring the pins and components that would be operated by Arduino 1.
Working2 Although this image shows the LCD positioned upside down, this shows all of our soldering complete (outside of wiring the three wires with/to the two limit switches).

App Integration and User Experience– Nidhie Dhiman

We found a great open-source website for asset management. Nidhie Dhiman took the task of working through the software as her main job, along with working with Barbara to get the stepper motor working, the bits box designed and anything else that would come up.

We began by setting up a free account in Reftab. They offer a lot in their free version. We worked with the assumption we would begin this project as a proof of concept and didn’t need to add everything in the Bantam library as an asset to begin with. So, their free verion with a total of 50 assets worked perfectly for this project.

With this same version, we are able to customize information required for the assets, run reports, create “loanees” to use the assets and much, much more! Even if we decide to pay for this later on in the lab, the monthly cost is the equivalent of saving 2 bits, so it’s well worth the investment in our opinion.

Once the account was set up, we decided it would be best to speak with Zack Budikowski, who manages our materials and machines in the lab. Nidhie asked him for a listing of our most common bits for PCB milling (to make sure we accounted for them all) and if possible to pull purchase information so we can track when we purchased and added them to the system. Should we choose to keep just the trial version, we also talked about instructors just back-filling and resetting the assets in the software when a new bit was needed.

Another exciting piece for Zack was that moving forward, we can set up and capture data for how long a bit was used. This way, we can eventually track the lifespan of the bit and see how quickly we are using them up.

In order to better understand the software and what it provides, Nidhie set up a brief meeting with one of the creators. When they met, they discussed how the software works, the types of reports we could run and most importantly for our group, how to incorporate our students into the system. One of our main goals when we discussed the software as a team, was that we didn’t want to have to have students set up separate accounts to use the sytem. He was able to help us understand how to set them up as “loanees” on the back end so they would not have to.

Once the call was completed, we were able to confirm we were using the software correctly. We used the “Asset” tab to log our bits since this allowed for idividual tracking/coding of each one, and then quickly set up a few sample items into the Assets category so we could practice with user inputs and the app. After setting up assets, we needed to add some “Loanees” to the list. We colleagues and a few test students from my classes/Fab Academy.

Test Loans were then performed on a few of the bits in the system. The image below shows the checkout of one of the bits on the main assets page. At this point, we had checked a few assets in and out to make sure the sytem captured everything.

Overdue Asset emails are automatically sent by the sytem to anyone who has not turnd in an asset by the end of the (24 hours). we purposely left one asset open to test the email system and at 12:02am, I received the following email reminding me to turn in my asset.

Once we were done with adding the assets we wanted to use into the system, we set up the barcode labels. We planned on using these labels on the sides of the boxes to make check-out/ check-in quicker and easier. You can actually customize the labels to the size and information needed. For our purposes, we changed the size to the built-in Avery label size for return address labels. we didn’t use the actual labels because the size was too big for our boxes, but the print size of the barcode fit perfectly. So, we quickly cut the barcodes out and adhered them to the boxes.

In our original idea, we discussed making returning the bits boxes foolproof. We were planning to put the barcode on each side of the boxes. That way, no matter what orientation the box was returned, the barcode was scannable. However, the design of the box was so precise and fit into the holder very snugly. So, for this version, we opted to put the barcode just on one side and made note of it in the workflow.

Designing and Laser Cutting iPAD Case– Nidhie Dhiman and Barbara Morrow

For our Universal Bit Holder/Organizer, Nidhie Dhiman and Barbara Morrow sat together and designed the iPAD case that would be placed into the front “door”/face of the entire device. Since Nidhie Dhiman had created the checkout system using Reftab software, we needed to make sure that the iPAD would be mounted at an optimal height. The camera on the iPAD needs to be able to scan a bar code on the sides of the bit box bases, and we had to make precise measurements. As Nidhie made and called out measurements, we drew out a rough sketch of the iPAD holder in the Notability app on my iPAD (shown below), and we used Corel Draw to design it.


The following table shows how Nidhie and Barbara Morrow collaborated together to design the iPAD case.

Image Description
CorelDraw1 The iPAD used was a 7th generation iPAD with dimensions of 9.8” × 6.8” × 0.29”. A box was drawn with dimensions of 8” x 11.5”, and a second box with dimesions of 6.25” x 8.25” was placed in the exact center of the larger box. The two boxes created a “frame” that would serve as the outer covering of the iPAD “case”. We decided to use slot-fit sides, and to place the vertical slots exactly 1” from each corner, we used a 1” x 1” colored box as a spacer for slots that were 1.185” x 0.25”. (We planned to use clear acrylic that was 0.23” thick). Once the slots were placed, one vertical side piece was created so that it had rounded “tabs” that would fit into the previously created verticla slots. The rounded tabs were created by making an oval with the same (long) diameter as the height of the slots, and this oval was placed on the outer edge of a 0.6” x 10” rectangle. The segment delete tool in Corel Draw was used to remove the overlapping lines. A small (gray) spacer was created to make sure each verticla slot was the exact same distance from the outer edge, and a turquoise long spacer was created to make sure they were consistently parallel to each other.
CorelDraw2 Similarly to how the vertical slots were created, the 1” x 1” green “spacer” box was used to place the horizontal slots. We now used a pink “spacer” box to ensure the horizontal slots were the same distance from the inner part of the front “frame”.
CorelDraw3 To make a horizontal side piece, a 6.26” x 0.839” rectangle was placed on the bottom horizontal portion of the “frame”. The two slots were copied and pasted and the same pink spacer was again used to ensure they were equidistant from the bottom line.
CorelDraw4 Ovals with the same long length as the slots were again placed on the outer part of the horizontal piece rectangle, and the segment delete tool was used to remove the overlapping areas. The copied and pasted rectangular slots were also deleted.each side piece was duplicated, and all lines were made hairline for laser cutting. It was at this point that we performed a test cut of the iPAD case on coardboard, and we realized that the bottom side pieces were too short.
CorelDraw5 This shows how we modified the bottom side pieces to make them the correct length so they would come into contact with the vertical side pieces.
CorelDraw8 This shows the final design of the iPAD case. After laser cutting it a second time on cardboard, we realized that we neglected to do two things: 1) We forgot to allow access to the power button on the bottom of the iPAD’s front screen; and 2) we realized tha the iPAD was sitting slightly too low inside the case. We decided to add a 2” circle to th center of the inside bottom (the inner horizontal line) and use the segment delete tool to remove the overlap. To remedy the low-position of the iPAD, we used the cutout pieces from the slots to “lift” the iPAD inside the case 0.24”. Coincidentally, this also provided space for the iPAD’s charge cord which we also had not accounted for. Finally, we removed the top horizontal slots because this would allow curators to remove the iPAD easily by sliding it upward.
As we performed this test cut, we realized that there were lines that had been “doubled up” in Corel Draw. This caused the laser cutter to make two passes over the same lines, and this can sometimes result in the cardboard catching on fire. Thankfully, this did not happen. We were able to remove the doubled-up lines when we modified the design in Corel Draw.

Designing and Laser cutting Front Door

Once again, Nidhie Dhiman and Barbara Morrow worked together to design the front door of our Wheel-O-Bits, and this piece was also intended to be cut out of clear acrylic with a 0.23” thickness. The iPAD cases needed to be positioned and adhered to the front face so that the iPAD camera would line up with the barcodes on the bit base bases. In order for curators of the Wheel-O-Bits to be able to access and re-stock the bits, we needed to place hinges on the front. We found three hinges in the Charlotte Latin Schoo Fab Lab and used callipers to measure their outer dimensions and screw holes. We also decided to place the hinges on the right side of the box to allow more support for the weight of the iPAD and its case.

Image Description
CorelDraw6 To ensure that the slots on the bottom of the side pieces on the iPAD case were correctly aligned with the position on the front door, we went back to the iPAD case design file in Corel Draw and grouped them. For the area of the front door, we made a rectangle with dimensions of 19.437” x 21.93”. This allowed the front door to lay flush with the upper surface of the Wheel-O-Bits box. Nidhie and Barbara carefully measured where we wanted the iPAD case placed on the front door by taping the iPAD case together and marking its position on the door with tape. We then measured the distance from the bottom and the right side of the door. We made yellow and green spacer rectangles to correctly align the iPAD case’s bottom slots.
CorelDraw7 Using the dimesions of the hinges, we created a small rectangle with three screw holes. We grouped the four items and copied and pasted it twice so that there were three in all. We placed the first hinge in the center of the right vertical side by sliding it along the right-side line until the “midpoint” alert appeared. Since the hinges really just needed to be placed in nearly equal distances, we again utilized a recagngular spacer to ensure the top and bottom hinges were the same distance from their horizontal lines.
CorelDraw9 This shows the final design for the front door. We removed the rectangles around the hinges (leaving just the screw holes). We thought about rastering the hinge positions in addition to vectoring the screw holes, but we realized this would not look as asthetically “clean”.
This shows us test-cutting the front door case on cardboard. We found that the iPAD case we previously designed fit perfectly in the front door, and its position was also perfect.

Nidhie and Barbara used Weld-On #16 Thickened Acrylic Glue to glue all of the pieces together. We were so excited about how nice it looked and how well the designs fit together.

Success1 Success2
Success Picture #1– It works! Success Picture #2– Great team work!

Adding Neopixel Strand to Wheel-O-Bits– Nidhie Dhiman and Barbara Morrow

Using Nidhie Dhiman’s SAMD11 and ATTiny 412 PCB’s we decided to add 28 (WS2812) Intelligent Control LED Integrated Light Sources to the upper front area of the “Wheel-O-Bits” Asset Management System. Since Nidhie had used this for her Outputs Week, we felt we could easily do this. While it did take less than an hour to get the Neopixels finctioning as planned, we did run into a couple of problems.

When we tried to upload Nidhie’s code, it contained a loop, and we were not sure how to go about removing the loop.

One of Barbara Morrow’s students (J.R.) had found and shared LED Strip Effects Generator, which is a quick and easy way of generating Arduino code for a strip of LED’s. We were able to use this site to generate the following code:

#include <Adafruit_NeoPixel.h>

class Strip
  uint8_t   effect;
  uint8_t   effects;
  uint16_t  effStep;
  unsigned long effStart;
  Adafruit_NeoPixel strip;
  Strip(uint16_t leds, uint8_t pin, uint8_t toteffects, uint16_t striptype) : strip(leds, pin, striptype) {
    effect = -1;
    effects = toteffects;
  void Reset(){
    effStep = 0;
    effect = (effect + 1) % effects;
    effStart = millis();

struct Loop
  uint8_t currentChild;
  uint8_t childs;
  bool timeBased;
  uint16_t cycles;
  uint16_t currentTime;
  Loop(uint8_t totchilds, bool timebased, uint16_t tottime) {currentTime=0;currentChild=0;childs=totchilds;timeBased=timebased;cycles=tottime;}

Strip strip_0(28, 2, 28, NEO_RGB + NEO_KHZ800);
struct Loop strip0loop0(0, false, 1);


void setup() {

  //Your setup here:


void loop() {

  //Your code here:


void strips_loop() {
  if(strip0_loop0() & 0x01);

uint8_t strip0_loop0() {
  uint8_t ret = 0x00;
  switch(strip0loop0.currentChild) {
  if(ret & 0x02) {
    ret &= 0xfd;
    if(strip0loop0.currentChild + 1 >= strip0loop0.childs) {
      strip0loop0.currentChild = 0;
      if(++strip0loop0.currentTime >= strip0loop0.cycles) {strip0loop0.currentTime = 0; ret |= 0x02;}
    else {
  return ret;

However, this code did not work.

Future Development Opportunities
Re-design bit box caps with thicker grip at their bases
Mill PCB’s with microcontrollers that would reduce down to one board
Generate a design that can house more bits
Shorten bit boxes to reduce outer mass
Prevent user from removing bit prior to checking it out
Adapt outer casing for wall-mounting to create a lower profile
Add more lighting effects with enhanced lighting (lights chasing the wheel)

Bill of Materials (BOM)

Item Number/Amount Needed Cost
Unpolished (Mill) 1008-1010 Steel Square Tube, 1” Square Tube, 0.083” Wall Thickness, 0.0834” Inner Diameter, 4’ Length 1 ~$19.44
2 in. x 2 in. x 8 ft. Furring Strip Board Lumber 1 ~$3.96
Heavy Duty Nut & Bolt Assortment Kit, 172 Pieces, Includes 9 Most Common Sizes 1 ~$24.99
Sutemribor 320 Pieces M3 Stainless Steel Button Head Hex Socket Head Cap Bolts Screws Nuts Assortment Kit + Wrench 1 ~$16.99
Zeberoxyz 2PCS Set GT2 Synchronous Wheel 20&60 Teeth 8mm Bore Aluminum Timing Pulley with 2PCS Length 200mm Width 6mm Belt (20-60T-8B-6) 1 ~$12.89
ETHCOOL 200 Pcs Small Magnets 3mmx2mm Little Magnets Mighty Tiny Magnets 1 ~$9.99
Amazon Basics PLA 3D Printer Filament 1 (or 2 multiple colors if desired) ~$25.61
Baltic Birch Plywood - 1/4” thick, 24” x 30” 1 (out of pack of 3) ~$17.99/3
Acrylic Plexiglass Sheet 1/4” x 24” x 36” - Clear 1 ~$49.50
Acrylic Black Sheet, 24” x 36”, 1/4” (any color) 2 ~$89.99
Hicello 2Pcs Glass Doors Hinge, Wall-mount Stainless Steel Shower Door Clamp, Glass Hinge Clamps Clip for 5-8mm Thick Glass 1 ~$5.99
Apple iPad with Retina Display - 4th Generation - MD510LL/A (16GB, Wi-Fi) - Black (Renewed) 1 ~$119.95
Defender Security U 9941 (Keyed Different) Drawer and Cabinet Lock – Secure Important Files and Drawers, 5/8”, Diecast Stainless Steel, Fits on 5/16” Max Panel Thickness 1 ~$7.09
ELEGOO UNO R3 Board ATmega328P with USB Cable(Arduino-Compatible) for Arduino 2 ~$18.99
ELEGOO 120pcs Multicolored Dupont Wire 40pin Male to Female, 40pin Male to Male, 40pin Female to Female Breadboard Jumper Wires Ribbon Cables Kit 1 ~$9.99
STEPPERONLINE Nema 17 Bipolar 42Ncm( 1.5A 42x42x39mm 4 Wires with 1m Cable & Connector for 3D Printer CNC DIY (1 Pack) 1 ~$9.99
SparkFun 16x2 SerLCD - RGB Text (Qwiic) - Red/Green/Blue Text on Black Display 3.3v Logic and Power 1 ~$21.50
2Pack L298N Motor Drive Controller Board Module Dual H Bridge DC Stepper 1 (out of two) ~$14.99 (for 2)
Cylewet 5Pcs KY-040 Rotary Encoder Module with 15×16.5 mm with Knob Cap for Arduino (Pack of 5) CYT1062 2 (out of 5) ~$9.29 (for five)
BTF-LIGHTING WS2812B RGB 5050SMD Individual Addressable 16.4FT 60Pixels/m 300Pixels Flexible Black PCB Full Color LED Pixel Strip 1 (need ~24 LED’s) ~$31.99 (for 300 LED strip
Multi Plug Outlet, Outlet expanders, POWSAV USB Wall Charger with 3 USB Ports(Smart 3.0A Total) and 3-Outlet Extender with 3 Way Splitter 1 ~$13.99
12V 2A Power Supply Adapter, SANSUN 120VAC to 12VDC Transformer with 5.5x2.1mm DC Output Jack, 12 Volt 2 Amp Power Supply for LED Module LED Strip Light (1pcs) 1 ~$7.99
HTVRONT Orange Permanent Vinyl, 12 Pack Orange Vinyl for Cricut - 10 Orange Vinyl Sheets 12” x 12” & 2 Transfer Tape Sheets 1 (need 2 sheets) ~$8.49 (for 10 sheets)
100 Pieces Hinged Screw Cover Caps Plastic Screw Caps Fold Screw Snap Covers Washer Flip Tops (Black,S) 1 ~$6.49

We also used two limit switches that we pulled off of an old 3D printer, and a small piece of 2” x4” scrap wood to build attach the limit switch. To hold the vertical acrylic pieces into place, we used a small amount of PS Weld-On 16 Acrylic Plastic Cement. Charlie and Avery had an old rotary adapter at home, and we used it to operate the LCD.

Links to Files: Stepper Motor Code





Last update: June 17, 2022