Ghost Clip

Partner: Edwin.E

Construction Instructions:

1. Create a constraint box for the central portion of the ghost off of the origin.
   1. Follow with two smaller constraint boxes set equal to each other on the top and bottom for the spikes and curves.
      1. Mark all these boxes for construction as we create them
   2. Make a midpoint line from the origin that stretches the full height of the ghost.
      
       
2. Create a box not for construction, over the main constraint box for the body of the ghost.
   
    
3. Circular Arcs
   1. Create three 3pt arcs in the bottom constraint box and set them all equal to each other.
      1. Each arc should have its curved end touching the bottom of the box, with its open end towards the main body.
         
          
4. Everything from this point forward is going to be only on the left side unless specified.
   
    
5. Triangles
   1. Create a construction line from the origin to the top of the center of the top constraint box to find the midpoint of the top box.
   2. Create 7 anchor points in the top constraint box (4 on bottom, 3 on top). Create lines between these anchor points, and make them all equal.
      
       
6. Create a construction line from the bottom of the arcs upwards to where the mouth will be.
   1. Make a construction line from the other construction line going directly up, and then one perpendicular to that. They should be set equal to each other at 0.6cm
   2. Create a center point arc from where these two construction lines meet that then goes from each end to the other.
   3. Create a vertical line from the endpoint of the arc 2.5cm for the mouth.
      1. Offset this entire thing with caps to create the mouth.
      2. Everything should be offset 0.15cm on both sides with caps.
      3. After this is offset delete the cap going over the midpoint
         
          
7. Create a construction line from the inside line of the mouth where the arc starts straight up to line up the center point of the eye. Create a center point circle from the end of the construction line for the eye.
   
    
8. Mirror the mouth, eye, and triangles to make it all symmetrical. 
   
    

EDITS:

1. Take the mouth outlines from the bottom center point of the arc and the outermost point of the arc before it extends straight up. Create the vertical aspect of the mouth from there. 
   1. Offset the mouth only one direction inside and add caps.
   2. Delete the cap that formed across the centerline, and then mirror the remainder of the mouth over the centerline to create the entire line.
      
       
2. Take the eye measurements 0.5cm from the sides, and 1.1cm from the top of the second triangle. Set the eye dimensions to 0.6cm to put them in the proper place.

How I Designed This:

A partner and I were given a 3D-printed ghost, and we started by takin

g measurements of said ghost. To ensure we had the same measurements, Edwin and I would go back and forth with each measurement taken. We quickly came to the conclusion that the majority of the ghost was symmetrical after figuring out that each triangle at the top was equidistant from each other, along with being the same size.

While we were taking these measurements, we were noting them down on a sketch of the ghost that was being created at the same time. The sketch was at 200% so we could preserve detail given that it would be incredibly difficult to note all the different dimensions on a 3cm by 6.5cm space and be able to read this information later on coherently. 

Once we got what appeared to be an exact replica of the ghost on paper, we transferred it over to Solidworks. Once we were on the software, inputting the dimensions was simple. We drew the shapes using the line, arc, and rectangle tools (both for reference geometry and the final product). 

However, the sketched ghost wasn’t perfectly reflecting the one that we were given to replicate, and we had to start modifying different dimensions. To start, the mouth wasn’t in the right place relative to the sides once we offset it. This was due to the fact that we originally took the measurements from the bottom center and left outermost side, ultimately making the arc different than it should have been. We deleted our mouth and took the mouth measurement from the bottom of the outermost curve of the bottom. The original measurement was 1.3cm for the center, and we shrunk it down to 1.15cm for the bottom part. Even though this doesn’t change the size, it allowed us to put the mouth curves and height in a more precise spot. 

After having a bottom point drawn in, we took the measurement of the side of the mouth to the side of the ghost. With this, we were also able to choose the width and height of the curve more precisely by taking the distance of the bottom point to the wall minus the distance of the vertical stretch to the wall. Once this was fixed we put the old vertical stretch heights back in and then did a singular direction offset with caps. Once we did the offset we deleted the cap that was crossing the centerline and then mirrored the rest of the mouth over the centerline to make it symmetrical.

We also made another rookie mistake, which was basing the measurements of the eyes on the measurements of the mouth. Because of this, we needed to go back and remeasure the eyes relative to the sides and top of the ghost alongside measuring the distance between the eyes which helped us confirm that our distances were correct.

Post Printing

After all the above steps (along with being out for a week with Covid) we printed our ghosts. Even after printing the ghosts, there were a few mishaps and mis-dimensioned parts. The eyes were slightly too small, and the mouth was too tall.

For the eyes, it was more than likely a measurement issue where our rulers weren’t calibrated to each other, which is something we found in the sketching process and presented a challenge early on where we needed to ensure both rulers had marks at the same points. There were points where I’d get 0.4 and Edwin would be 0.5 with his ruler while using the same model. Chances are that we used a ruler that was slightly wider than what 1mm is in reality.

The mouth dimensions was fully a user problem, and looking back it could have been fully prevented. When we measured the ghost originally, we took the length of the vertical stretch as 2.5cm. This dimension was correct, but it includes the arcs at the top of the mouth, which we didn’t account for. This ended up making the mouth an extra ~0.2cm in height.