10. Machine Week

For this week, we were put in groups where we assigned to create a machine. Evan Park, Richard Shan, and I created an automated ouija board which connects to an OpenAI API to give a response from a spoken input. Extensive documentation of this project and the process of creating it can be found on the group site.

Week Reflection

This week (or really 2.5 weeks) I learned a lot about how gantry systems work, including how they are assembled, how they function, how to create one, and how to program it using a CNC Shield and Arduino Uno through GRBL. I also expanded my knowledge of Raspberry Pis, including its application in programming and automating systems. Additionally, I strengthened my skills through practice using different machines in the lab such as the laser cutter, the ShopBot CNC machine, and the 3D printers.

Below is the portion of documentation from the group site which includes processes that myself and Evan Park collabarated on:

Fusion 360

To start out creating the box, we designed a file in Fusion360 that will assemble the box that will hold our gantry and the rest of our electronic components. The top of the box will also have the Ouija Board engraved on top. We designed it in Fusion360 so that we could use parameters to change the size of the box if needed. We added a small panel for a button that we would use to activate the microphone that would pick up our speech and turn it into text for ChatGPT. We also added a hole for a USB for debugging and a hole to put your finger in and push the top off.

This is the file we created and a photo of the parameters

We then exported this file as a DXF.

Laser Cut Tests

We decided that we wanted to laser cut our design on cardboard first to make sure everything fit as we wanted.

After the first cut, we realized that we had not made the sides longs enough for each screw to fit in so we mades the sides longer by increasing the two parallel sides by 2 times the material thickness. We fixed this issue then laser cut again. This time the box was assembled with no problems. Mr.Dubik also suggested that we add joints to our design so we went into Fusion and added joints We then laser cut this file to test our joints. Now that our tests looked good, we started to create the toolpath for our file in Aspire.

Aspire

We then took our DXF file into Aspire. We took a tape measurer and found that the length and width were 96’’ and 48’’ respectivly and with calipers we measured that the width was .46’‘. This was our Job Setup in Aspire

Once our job was setup, we imported the vector for our box. We then started to create our toolpaths. There was a problem that not every vector was connected so we used the join tool to join them together.

Then we added dogbones by using the filet tool and specified our tool radius and went along each finger joint and added dog bones so that they would fit when we milled them. We then used a profile toolpath. We started the profile toolpath by adding all the tabs we needed for our mill.

We used a 3/8’’ compression bit because they prevent chipping the top or bottom of our wood and they are overall suitable for our job. We also decided to add ramping to prevent harming our bit. This is a photo of our settings for our toolpath. Then we clicked calculate at the bottom. This gave us a preview of what the toolpath would do if we used the “Preview Toolpath” tool and ran the simulation. This is what the cut would look like according to the simulation Since everything looked good, we sent the file over to the ShopBot to mill.

ShopBot

We were milling a wood that had already been milled before so we had to organize our file so it went around the already milled out parts on the wood.

Once organized, we downloaded the toolpath and ran an aircut on the ShopBot software to make sure everything looked good and then ran the full cut.

MILLING VIDEO

Post Mill

There were a few issues that we found out after we milled. The first issue was that we had milled the magnet holder on the box the wrong way.

This meant that we would have to re-mill the long sides after we flipped the long sides horizontally on Fusion360. This is us milling the long sides again, the process was the same as last time.

We were working around an already milled plywood so we had to rearrange our file so that it would fit on the wood. I used the same process as before to mill out the file but, while the file was milling, I realized that the tabs weren’t present. This was most likely due to my cut depth being too deep for the wood. This made the wood shift a little when the pocket toolpaths started. I stopped the ShopBot and put brads in each of the cut out pieces so that they wouldn’t move for the pocket toolpaths. Unfortunately, I stopped the cut a little late so one of the sides were a little bit scuffed but it didn’t cause any issues so we kept the piece.

Also, we realized we had not given a sufficent offset for the joints: We needed to sand them down so that they would fit together.

Then we glued the magnets using hot glue onto the pieces so that they would snap the cover on the top whenever we put them together.

We also engraved our Ouija design onto our lid, modifying a design found online: We converted this image to an svg using CorelDraw’s Quick Trace tool, removed some of the unnecessary responses such as “good bye”, and added in some punctuation so as to make the ghoul a little more literate. We would also lasercut a design that we would use to cover the magnet we were moving on an 1/8’’ plywood. SVG OF SUN (GET LATER) Now our box was ready to be assembled.

Assembly

Assembly of Box

Now it was time to assemble our pieces to create our box.

The first thing I did was screw the magnet holders onto the sides of the boxes. I did this by using a measuring tape to figure out the center of the magnet holder on the other side, marking it with a pen, and then screwing a screw into that mark. I did two screws for each magnet holder.

I then screwed each side of the box together by screwing it on the edges and also screwed it on the bottom to hold the box together

Gantry

For this project, we wanted a 2D axis gantry system which could be programmed using G-Code.

Mechanics and Wiring

First, we set up the CNC Shield and Arduino to connect to the stepper motors using this video and a few others as reference. To sum up the process, we attached the CNC Shield to an Arduino Uno, attached stepper drivers to the CNC Shield, used ribbon cables to connect stepper motors to the CNC Shield, and connected power to the Arduino through some stripped wires. Eventually, we exchanged these stripped wires for jumper cables as these are more reliable.

I plugged the Arduino into my computer and uploaded the GRBL library to the Uno. From here, we downloaded the Universal G-Code Controller, and we followed the setup directions there to get it connected. Finally, after much trial and error, we were able to move the stepper motors. We went back to Arduino IDE, opened Serial Monitor, and tested a line of G-Code, which also moved the motors. However, later on I realized that one of the motors (connected to the z-axis) did not move as far as the one connected to the x-axis when sent the same distance. I then tried connecting it to the y-axis instead, but this made both motors move, which also didn’t seem right. After switching out many of the components, trying to figure out what the problem was, I later found out that it moves in a way called CoreXY, which uses both the stepper motors to move, even only in one direction. The only time CoreXY only uses one stepper motor is to move in 45 degree angle, as each motor moves two axes equally. It follows the basic equations shown below with A and B being how much each of the stepper motors are moved:

3D Printing Parts for the Installation

Many of the 3D printed parts we used in this build we got from Sand Table video. Below is a table of which designs we got and how many we used.

Part	Image	Quantity
X-Carriage Mounts		2
Idle Mounts		1
Belt Grip		1
Magnet Mount		1
Motor Bases		2
Wire Loops		2

*Note that one of the motor bases must be mirrored horizantally in Prusa or other slicing software before print.

Although we got downloaded many of the 3D files from the Jack Hollingsworth Instructables site (which got these files from the Sand Table video by DIY Machines), we wanted to make at least some of these ourselves. To hold the CNC Shield and the Arduino Uno, I created a simple box with holes in the sides for various cables and wires. I also created the part which would hold the magnet. This part originally fit directly onto the top of the mount and went straight up, before we realized that it would not fit there as the screws used to hold the belt grip would intrude on its space. After this, I recreated this with an offset, however I forgot to turn the slot which the part sticking out went into and we neglected to think about how it went right through the path of the belt, but these things turned out fine. Additionally, either my meausrements were off or I was too cautious, but the holder was about an inch short.

We eventually just printed a small cylindar to fit inside the magnet holder which we hot glued the magnet on the top of. One of the box’s holes was slightly off, but this could be easily fixed by using a soldering iron to melt away some filament, thereby extending the hole.

Assembling the Gantry

The gantry for this machine is based on one for a sand table by DIY Machines. Their video is really good for following the assembly of the gantry machine but we will still outline what we did.

We started by attaching the X carrages onto the X rails by using M38 screws for the carrage. We then attached the smooth idlers using M520 screws.

We then attacked the motors to our motor cases using M3*12 screws.

I then attached the X rails to the idler supports and motor mounts using M312 bolts. I was suggested to start using heat inserts for my screws and I used a certain tool to push the heat inserts vertically into my 3D printed motor mount. We would later attach a teethed idler onto it using M520 screws.

It ended up making the hole clogged with PLA and making a bolt impossible to go through. I had to take a hot air blower and heat the hole until I could push the heat insert out and then take an exactoknife and take material out of the hole until I could push the bolt through and put the nut at the end of it to hold it in. I decided to give up on the heat inserts after this.

We then put everything in the box at this point.

I then attached the Y axis by using M3*12 bolts.

We then attaches the magnet carriawge mount using M3*8 bolts onto the Y axis.

We then ran our belt around the mount going around each motor connecting everything using one belt

We then wood screwed our Arduino and motor mounts into the box. To make sure the motor mounts were squared, we used a triamgular ruler to measure each side and make sure everything was at a 90 degree angle. We then hot glued the Rasberry Pi to the side of the box near the outlet hole. We also attached the magnet holder to the magnet holder carriage mount using M3*8 screws.

We then installed some wire loops with wood screws for wiring organization.

Our box was ready to be programmed and run.

Installing the Gantry

To install the gantry system into the box (which we only did after we got all the programming working with the motors properly), we screwed some what kind of screws into the holes in the 3D printed parts at the ends of the x and y axes. We used a triangular ruler to make sure these were fairly straight and symmetrical. Additionally, we screwed down the wire holders and the box for the CNC Shield and Arduino.

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Last update: May 7, 2024