Group Meeting Minutes 4/30

Agenda

1. Assembly
2. String Gap Measurements
3. Assigning work for Report 4

Attendance

Hannah, Marie, Jonny, and Kelsey were present. The others had scheduling conflicts and will help more with the report and presentation.

Minutes

All teams finished production and have taken measurements.
Sleeves turned out and ready for assembly.

Summary of team accomplishments:

Team	Accomplished	To do this week	Issues Foreseen
IJ1	Production run complete       Measurements complete       Report charts complete		None
IJ2	Production run complete      Measurements complete      Report charts complete		None
IJ3	Production run complete      Measurements complete	Report charts	None
TF	Production run complete       Measurements complete      Report charts		None

Meeting Accomplishments

• All good yoyos were assembled, string gaps were measured.
• Jordan to create string gap chart for Report 4.
• All team to email about alternative design section

Goals:

• Presentation preparation
• Begin to add more material
• Will finalize at group meeting next Friday
• Hannah and Noa to practice and receive group feedback before 5/14 presentation

Final Assembly

Our group met today for 2 hours to assemble all of our yo-yos!

First, Kelsey and Marie attached the two halves of the body and string. Once the good parts were prepared, Hannah measured string gap widths, Jonny skillfully snapped in the pre-assembled IJ2 and TF pieces to the IJ3 caps, Marie acted as quality control on Jonny's pieces, carefully fixing the delicate thermoformed trapezoids, and Kelsey completed final assembly by inserting the shims and attaching the cap assemblies to the completed bodies. When string gap measurements were complete, Hannah took Kelsey's place as the final assembly station.

Our assembly line looked something like this (panorama courtesy of Kelsey's photography skills):

Hannah meticulously measuring string gaps:

 Close ups of our final product:

After 2 hours of hard work (and Jonny asking for worker's injury compensation for his sore wrists), here are all our yo-yos!

Assembly Beginnings

Three of four groups have completed their production runs!

IJ2's production run looked like this...

All 110 parts laid out in the lab:



A closeup on our final parts:



Joanna proudly smiling for the camera with her new injection molded necklace:



Then we met on 4/25 for our typical group meeting to begin assembling all the IJ2 and TF parts. We also had 2 caps (IJ1 still needs to complete their production run on 4/29), so we made one completed yo-yo to test, and the results were great!

The final product looks like this (the final cap color will eventually match the body):



And this:



Then several group members tried their hand at yo-yoing:

While Noa succeeded at showing off some impressive tricks, Jonny mastered sideways yo-yoing....

At least we know we can count on Noa to prove our yo-yo works when it comes to presentations!

We are looking forward to assembling the rest of our parts on Wednesday 4/31.

-Hannah

Group Meeting Minutes 4/25

Agenda

1. Begin Assembling TF and IJ2
2. Progress
3. Assembly Plans
4. Blog post, Gantt chart update reminders
5. Presentation Planning
6. Final goals

Minutes

General Updates

• Shims arrived - fit perfectly!
• Extra appointments canceled
• All final appointments scheduled

Assembly Process:

• Need to turn out inside of sleeves for assembly
• Pull out string from loop side to avoid tangling
• Use pin gauges to check spacing - should standardize spacing
• Made 5 test yoyos
• Decided on 0.022" spacing between the 2 halves (1.5x the string width)

Summary of team accomplishments:

Team	Accomplished	To do this week	Issues Foreseen
IJ1	Production run complete       Measurements complete	Assembly!	None
IJ2	Production run complete      Measurements complete	Assembly!	None
IJ3	Molds complete       Optimization done	Production Run - both will occur Tuesday 4/29	Timing - cutting it close
TF	Production run complete       Measurements complete	Assembly!	None

Meeting Accomplishments

• All TF and IJ2 parts snapped together
• Assembly procedure discussed
• Plans finalized

Goals:

• Production runs completed by 4/29
• "Assembly Party" 4/30 5-6 PM in lab (all but Joanna and Jordan are free)
• Presentation preparation
• File in our google drive - to be worked on individually
• Hannah and Noa to present
• Section division of work
• Design: Joanna
• Process Optimization: Jordan
• Process Capability (info to come): Marie
• Lessons Learned (to be discussed upon assembly): Hannah & team
• Each team member to contribute to each section individually as needed

Group Meeting Minutes 4/18

Agenda

1. Progress
2. Team successes/needs
3. Timing planning
4. Blog post, Gantt chart update reminders
5. Presentation Planning and 
6. Future goals

Minutes

Color Notes:

• IJ1 and IJ3 will match "winner" sample part
• IJ2 is Green 2
• TF is white

Summary of team accomplishments:

Team	Accomplished	To do this week	Issues Foreseen
IJ1	Mold complete       Optimization complete       Production run ready - to be scheduled for Tuesday 4/29 from 10-12	Production run	None      (Help may be needed for production run)
IJ2	Production run complete (110 parts); parts are to spec      Measurements complete	Help support other teams as best as possible - come in to be backup for production appointments	None
IJ3	Molds complete	Process Optimization      Production Run - both will occur Tuesday 4/22 from 3-5	Timing - falling a little bit behind and may need help
TF	Production run complete	Parts to be punched       Measure parts	None

Meeting Accomplishments

• Schedule modified for remaining production runs
• Members encouraged to help teams still working to complete part production
• Shims ordered - email sent to Dave

Goals:

• Production runs completed by 4/29
• Fix Gantt chart again when progress observed after next lab
• Start assembling the top portion in lab on Tuesday 4/29
• "Assembly Party" 4/30 2-6 PM in lab (people can come and go as they are free)
• Presentation preparation
• File in our google drive - to be worked on individually
• Hannah and TBD to present
• Section division of work
• Design: Joanna
• Process Optimization: Jordan
• Process Capability (info to come): Marie
• Lessons Learned (to be discussed upon assembly): Hannah & team
• Each team member 

Group Meeting Minutes 4/8

Agenda

1. Progress
2. Team successes/needs
3. Timing planning
4. Blog post, Gantt chart update reminders
5. Future goals

Minutes

Action Plan to fix cap and body fit

• IJ2 and TF can do production run because they will fit together - Tuesday 4/15
• IJ1 and IJ3 need to redo molds such that they snap fit together

IJ1 Fixes

• Air on the side of smaller outer radius
• Rescale by 2% based off of original molds that were made
• Will remachine on Tuesday

IJ3 Fixes

• Base off the SolidWorks model
• Only go in to Mastercam and change the diameter that snap fits with the body
• Will remachine on Tuesday (likely earlier if possible - maybe Friday morning)

Summary of team accomplishments:

Team	Accomplished	To do this week	Issues Foreseen
IJ1	Rescale molds in Mastercam, export GCode      New molds machined	Remachine molds again to accommodate desired snap fit (Tues 4/15)      Process Optimization      Report 3      Production Run scheduling	Sizing of fit with cap
IJ2	Report 3 finished	Production Run (Tuesday 4/15 appointment)	None unless changes need to be made to accommodate other parts
IJ3	Process optimization finished, flash issue resolved	Remachine mold to optimize fit with body - only change is outer diameter       Report 3       Production Run scheduling	Sizing of fit with body
TF	Drilled out alignment holes for better center punching (making parts concentric)          Finished report	Production Run (Tuesday 4/15 in lab)	None unless changes need to be made to accommodate other parts

Meeting Accomplishments

• Schedule established for production runs - timeline adjusted

Goals:

• Complete prototype and Report 3 components by next Friday (4/11) in case any other issues need to be dealt with - on track to accomplish
• Production runs completed by 4/18
• Fix Gantt chart when progress observed after next lab
• "Assembly Party" 4/18 at 4 PM in lab
• Presentation preparation: done through google docs
• Joanna to create outline presentation
• To be emailed out and worked on individually
• Will come together to finalize in ~2-3 weeks

Shrinkage Measurement after IJ1 Round 1

The body mold ended up shrinking too much to fit in with the rest of the parts. Therefore, we measured the shrinkage so that we can scale up the model and create more space for the part to shrink to the correct size.

Cavity Mold Outer Diameter (in):

2.4765

2.4735

2.4785

2.4745

Average: 2.4760in

Injection Molded Pieces Outer Diameter (in) [2 per part, 4 parts]:

2.4395

2.429

2.427

2.4265

2.430

2.429

2.435

2.4285

Average: 2.4305in

Therefore the average shrinkage was: (2.4305-2.4760)/2.4760=6.9%

We will make the according changes in the Mastercam and remachine the mold.

Injection Molding the Body: Round 1

Noa & Jordan

4/1/14

Injection Molding the Body: Mold Version 1

Today we ran our first trial of injection molded bodies. As seen in Figure 1, we did multiple trials to fine tune the injection mold parameters. A picture of our parameter sheet is seen in Figure 2.

Figure 1: This shows the progression of runs varying the injection parameters

Figure 2: Our parameter sheet showing the evolution of parameters with our final parameters used.

We learned a few interesting things while running our first run of injection molded Yoyo bodies. First, we noticed that the shrinkage of the part during cooling was more than we expected. The layers that are supposed to fit within the body do not: the inner diameter of our body was 2.05 in and it should have been ~2.13 in. This means that we will have to scale up our molds and re-machine them. We will be going into lab tomorrow to measure the final diameters after the plastic has had time to cool and cure.

Figure 3: These are five injection molds of our final set of injection parameters

We also noticed that at the weld line, there is a small air bubble (Figure 3). This is problematic, as it means that we need to drill a small hole as a vent to 4llow the air to escape. Once we have our new mold, we will increase the speed and pressure of the injection mold to create a burn mark at the air bubble. This will show us exactly where to drill the vent hole.

Figure 4: An injection molded body showing a trapped air bubble.

New Thermoform Mold

The mold for the thermoform part of the yoyo needed to be redesigned because webbing occurred between the protrusions of the pinwheel piece (as seen below).

                Webbing occurred despite many variations in the thermoforming parameters, so it was concluded that a new mold needed to be machined. The new mold was a draw-down mold as opposed to a draping mold. Changing the thermoforming method eliminated all of the webbing in the thermoform part, but jeopardized some of the sharpness of the geometry. The two molds can be seen below (the original mold on the left and the new mold on the right).

 

                When the mold was changed to a draw-down mold, the dimensions of the trapezoids in the mold were increased back to dimensions of the full size part because the size of the pockets was the maximum size of the final part. Shrinkage in the part after forming created clearance for the thermoform part to fit through an injected molded part to be stacked on top of it.

The part was molded in both white and clear 0.03” thick plastic to compare materials. Parameters were optimized so the sharpness of the geometry was not lost due to the change in thermoform method.

The new thermoformed part next to the old thermoformed part.

Body Mold Machining

3/18/14

Pinwheel Yoyo Body Molds