Updates 4/24-4/26: Assembling the blending apparatus

With our materials available, we were very excited to plunge right into constructing our blender apparatus at the end of last week.

Alessandra drilling the hole in the bottom of the pitcher.

Working on the rod that will be inserted through the ball bearing and the blender blade, connecting the wheel spinning against the bike tire with the blade.

Attempting to sand the rod on the wheel axle for the blender apparatus. It was a lot harder than expected- sparks were flying!

Sanding the piece of metal we used to make our blender blade in order to sharpen it.

Bending the blade.

The finished blender blade!

Using the Dremel tool to make a wedge in the nut on top of the wheel axle.

Using the Dremel...

...the nail was aligned and fit in the wedge!

We heard back from Lyndsey, one representative from GrupoFenix, about the stand. She felt that the group would prefer a stand that could be removed from the bike. Therefore, today we plan on moving forward with that design (with Estuardo's help). We also plan on finishing the blender today by bending the nail around the blade to hold it in place, and then sealing it all up using Epoxy.

4/24 Updates

In class on Monday, we were still awaiting the arrival of our blender apparatus materials, so we continued to make headway by fleshing out our bike stand ideas along with a locking mechanism to secure the blender to the rear rack.

In terms of the bike stand, we are still deciding about the most useful way to proceed. While we were very excited about our plans for the simplified stand (a modification of Jodie Wu’s stand) that we worked on last week, we talked with Estuardo and he offered a different design to consider. His idea involves using the center of the rear wheel as the site of attachment for the stand. The stand resembles an upside down rear rack, which could swing up when the bike needs to be ridden, and could swing down to the ground in order to elevate the wheel when blending. This stand would be permanently attached to the bike, as opposed to the detachable stand design we had been developing.  It would extend wider on one side of the bike in order to clear the gear hub.

There are several pros to Estuardo’s idea. First of all, if the stand is permanently attached, the chance of the user losing a loose stand is eliminated. Secondly, it attaches further back on the bike than ours and Jodie’s designs do, making it less likely that someone will hit their heel on the stand attachment.

However, one con with this approach is that if the stand is connected permanently to the bike, it can obviously only be used with that bike, rather than being able to be used on multiple bikes. Also, we are still a bit unclear of how exactly we could attach the stand to such a small part of the bike (we need to flesh this out a bit more with Estuardo).

We have sent out an email to our community partners in Nicaragua, asking them if they would prefer a bike that is permanently attached or one that is detachable. In the meantime, we will continue to make progress on the blending apparatus, as some of our parts have just arrived!

Updates as of 4/22

Alessandra came to class on Thursday, April 18th with a finished rubber wheel fixture on the axle! Here is a picture of her masterpiece:

Given the fact that we were not yet in possession of the McMaster parts we needed for the rest of the blending apparatus, we switched gears and decided to spend class time working on our bike stand design. During the previous class, there had been some debate between our team, Estuardo, and Professor Banzaert about the best location for the bike to come into contact with the stand. After much consideration, it was decided that the frame of the bike was a better option than the middle of the wheel spokes. That being said, we needed to simplify Jodie Wu's design. After a while of staring at her stand unsure of how to accomplish this, we decided we needed to go back to the drawing board and throw out anything and everything that came to mind. Here is a photo of some of our ideas:

       

Jodie's bike has a lot of parts because it is collapsible and adjustable to fit different bikes. Therefore, it requires a stopper and a relatively complex array of parts for the adjusting mechanism. One idea we had was to use rope along the bottom of the stand as a stopper, taking away one metal part that would have to be manufactured and attached. However, Professor Banzaert pointed out that while this was a good idea in theory, in practice the rope would become dirty and worn over time. After much more thinking, we eventually came up with a way to combine the stopping and adjusting mechanisms using a coupling nut, a U-shaped angle iron piece, and a few other parts. Ali and Alessandra went over a materials list with Professor Banzaert, and we are hoping to get our materials soon, as well as talk our design over with Estuardo, so we can move ahead with our building our stand.

Here is the materials list for the bike stand (w

e’re planning on using metal from the shop as well as the following materials from McMaster):

1. 2, Grade 5 Zinc-Plated Steel Coupling Nut 5/8"-11 Thread Size, 2-1/8" Length, 13/16" Width, #90977A205

2. 2, ASTM A193 B7 Alloy Steel Fully Thrd Stud Plain Finish, 5/8"-11 Thread, 4" Length, #98750A216

3. 1, Zinc-Plated Steel Acorn Nut 10-24 Thread Size, 3/8" Width, 13/32" Height, #91875A120

4. 1, ASTM A193 Grade B7 Alloy Steel Threaded Rod Plain Finish, 3/8"-24 Thread, 2' Length, #98957A805

Updates from 4/18

Last class, we received some of our materials that we needed to construct our bike-powered blender. We worked on assembling the wheel axle that we are using for our blending apparatus. After experimenting with several different types of wrenches, and with the three of us working on loosening the nut, we were finally able to take apart the axle! We obtained the longer bolt from one axle and inserted it into a well-greased axle (so there will be more space to attach a rubber wheel that will spin against the tire’s wheel). Alessandra was able to use Epoxy glue to glue the rubber tubing together, which she then wrapped tightly around the bolt to form a wheel that will touch the bike’s rear wheel and spin, powering the blender. In addition to putting together the wheel axle and rubber attachment, we also attached the bike rack to our bike. This was a bit more difficult than expected, and involved using a different set of nuts and bolts than the ones provided in the bike rack kit. Now that we have our wheel axle/rubber wheel attachment and the bike rack on our rack, we will continue today with attaching the blender to the axle and mounting the entire apparatus on the bike rack.

Taking apart the axle using a clamp, a wrench, and a lot of (wo)manpower!

Ali working on attaching the rear rack

Updates from 4/8

In Monday’s class, we confronted a number of challenges that we are currently facing in designing our bike blender. Our current areas of concern are in obtaining the correct materials for the blender apparatus as well as designing an effective stand. In terms of our stand, we would like to strike a balance between strength and simplicity. While we like the stability of Jodie Wu’s design, we want to reduce the number of parts that each joint requires. We also collected a number of wheel axles for our blender apparatus and attempted to disassemble them (in order to better understand the inner parts), which proved to be quite a challenge without the correct wrenches. We realized that in order to move forward with the construction of the bike blender, it would be really useful to have a bike toolkit so that we can take apart the wheel axle, remove the parts, and obtain the nuts and bolts that would have the most utility for our apparatus (we need a longer bolt so that we can attach the rubber wheel that will spin with the bike wheel).

We were also able to communicate with a Grupo Fenix representative on Monday. After our discussion, we were able to obtain images of the bike blender that is currently implemented in Nicaragua.  The images of the current bicycle stand reveal that the stand is permanently fixed to the bicycle with screws attaching the stand to the frame of the bicycle.  It appears that the screws are necessary to stabilize the bicycle and make it safe for someone to ride it while it is stationary.  After seeing these images, the problem with the current design is much clearer.  We need to design a stand that can be easily removed from the bicycle, but is still safe and stable for stationary riding.  

"Crit Modge" (aka Critical Module)

Critical Module: 

One of our biggest concerns with our current bicycle-powered blender designs is that it is unclear what our detachable, back-wheel stand will be able to support. We need to design a stand that will be stable and adaptable to the potentially wide diversity of bike designs present in Nicaragua. Thus, for our critical module, we measured 20 bikes on campus to get a better idea of what our stand design should be able to support. Our hope was that the bikes present on Wellesley’s campus would be more diverse than the array of bikes that would typically be found in Nicaragua, and therefore our stand design could safely support those found in Nicaragua. To do this, we measured the circumference of the chain stay (where the stand will attach), the distance from the middle of the rear wheel to the top of the rear rack, and the width between the left and right chain stays that straddle the wheel on 20 bikes around the Wellesley College campus.

We then took the average value and standard deviation for each of these measurements, which is summarized in the graph below:

Figure 1. Bike measurements from Wellesley College for critical module. The value for the chain stay circumference, represented as a mean + standard deviation, was 6.5 + .8 cm. The value for the distance from the rear rack to the middle of the rear wheel, represented as a mean + standard deviation, was 8.5 + 1.8 cm. The mean value (+ standard deviation) for the width between the left and right chain stays was 9.6 + .5 cm.

Based on these measurements, we can conclude that our bike stand should have clamps that can attach to the chain stays with a circumference of anywhere between about 5.5 cm to 7.5 cm. Furthermore, the mechanism by which we clamp the stand to the chain stays should be able to accommodate a width of about 9 to 10 cm. In terms of the blender attachment, the length of the wheel and axle attachment to the blender should be between 7 to 10 cm. Our critical module measurements demonstrated to us that we will need to design a stand that can make slight adjustments to different types of bikes, though accounting for these deviations should be doable with the design we are considering. We now have a much better understanding of standard bike dimensions which will be particularly useful as we move forward into the construction phase of our project.

    

Updated Schedule:

Bike Blender

- make a physical prototype (Jambo): start on 4/8, continue work on 4/11

- implement blender on bike(s): by 4/18

- test blender and revise costs: 4/18 or 4/21

Bike Stand

- draw design and communicate with Estuardo about constructing a bike stand 4/8

- provide this design and materials list to Grupo Fenix 4/8

Bike Anatomy:

Source: http://www.andhiniedewi.com/2010/10/bike-anatomy.html

The blender attachment will sit atop a rear rack (over the rear wheel).  The rack will attach to the 5-sprocket block on the rear hub.  The bicycle stand will attach to the chain stay above the frame of the bicycle.  The variation that we are most concerned with is the difference in the circumference of the chain stay, the width between the left and right chain stay and the distance from the rear rack to top of the tire.

Communications with Grupo Fenix:

Last week, we were able to have a conversation with a member of the staff of Grupo Fenix. In this conversation, we had a number of our initial questions answered about the project, which are summarized in our previous post. Today, we will hopefully be talking to members of the youth group that has worked on the bicycle powered blender. The questions we plan on asking are as follows:

1. What are the biggest problems with your current design?

2. Do you have photos/other documentation of the design?

3. What design specifications/elements are most important to you?

4. Is it very difficult or expensive to purchase a rear rack for a bicycle?

5. Are there a wide variety of bikes in Nicaragua? What factors vary the most?

Project goals, specification, and progress thus far

Problem Statement:

To design, construct, and share a bicycle blender apparatus and detachable bike stand that renders the bike rideable when not in use for blending.

Our community partner for this bicycle blender project is Grupo Fenix, focused in Sabana Grande, Nicaragua. Sabana Grande is a rural village approximately 200 km outside Managua with  approximately 500 residents. The community relies heavily on wood for cooking and suffers from deforestation and poverty. Currently, a youth group involved with Grupo Fenix has developed a design for the bicycle-powered blender. Their current design relies on a platform in which the bike attachment only has one wheel. A method of securing the blender to the bicycle while retaining complete function is necessary to make the bicycle successfully have multiple purposes. The bicycle powered blender is a method of income generation for residents, as residents will make smoothies and

Based on the current design and the community with whom we are forming a partnership, we would like to build a simple blender apparatus and a stand, made from local materials, that supports the back wheel while in use for blending.

Project Specifications:

Measurable outcomes that the project should accomplish

• Create a blending attachment that can fit on 80% of Nicaraguan bicycles and does not inhibit the bike from being ridden (includes stand for back wheel and blending apparatus)
• design review will be followed by multiple rounds of testing and improvement
• Design a universal bike stand (training stand) easily made from local materials and provide this design to Grupo Fenix
• transportable but supportable
• consult estuardo about our stand design
• Test bicycle-powered blender design on campus using at least 5 different bikes
• Blender will blend fruits and beans

Pugh Chart:

	Making a blender	Pre-constructed blender (S)	Metal Stand	Wood Stand
Cost	+	S	S	+
Construction feasibility	-	S	S	+
Use of local materials		S	S	S
Durability	-	S	S	-
Aesthetically pleasing	-	S	S	-

Documentation/ Updates:

In class on Monday, we sketched a couple of designs for stationary bike stands we were considering as a method of securing the back wheel while the bicycle was in use for blending. We also outlined the basic mechanism for a blending apparatus that could be connected to the bike.

During class, we received a lot of feedback about possible improvements and points of clarification for the designs. After each group had examined our designs, we reevaluated our plan of action. We realized that the stand had to be a lot more flexible (in terms of supporting a wide variety of bikes), which would mainly come from attaching the stand to the bike frame rather than the bike wheel. We took inspiration from Jodie Wu’s bike stand, as it would be a much more viable solution to creating a stand that would fit a diverse array of bikes. By the end of the class, we created a styrofoam prototype of the stand. 

In other news, we recently talked with our community partner from Grupo Fenix. We have discovered that the blender is mainly being used for blending fruits and beans. The youth group actually has a design for a metal bike stand, though it is not durable and needs considerable improvement. We have also learned that the community has recently acquired welding capabilities, which would allow us to use metal in our construction process. Additionally, our community partner was interested in a design that could be made without using a store-bought blender (and rather a pitcher with an attached blade) in the interests of cost. Our next steps will be to design and carry out a critical module and to develop a materials list for the blending apparatus.