Follow-Up- 12/12

December 12, 2013

Deliverable: Final Report

Our bike stand project is done and done; the final report is submitted, we showed off our design at an engineering open house, and I believe the only thing left to do is complete a survey about the class.

Our final design did not work, which is a bummer. We splayed the two frames out to the side and incorporated support triangles onto each of the four corners. Although we could screw in the top of the hypotenuse to the design, we had to epoxy the bottom corners, so we should have realized this plan wouldn't work.

When we tried out the design, our bike stand fell apart at the seams (no thanks to you, epoxy!).

Problems abound. First, it takes two people to mount the bike on the stand. One person has to lift the bike, while the other has to position each side of the bike stand and simultaneously make sure that no gears or brake wires are caught in the bike stand. Second, during our process of prototype refinement, we didn’t foresee the extent to which stress concentration points would affect the usability of the bike stand, which resulted in the bike stand tipping to the side almost immediately after the rider got on. Third, the chainstay support doesn’t completely support both sides of the chainstays. The weight is distributed unequally which causes the bike to tip back and forth. Fourth, the screws that come up from the bottom create an uneven surface- the screw heads create a slight but significant decrease in stability. In short, it was unrealistic to expect screws to be a practical mechanism to adjust for different bike sizes, and perhaps more importantly, to remain tight against the pressure of riding the bike on the stand.

If you'd like to read our final report, here's the link. Even though we didn't produce a working bike stand for our partners in Nicaragua, we made good progress on designing a better bike stand. I hope that engineers in the future will be able to use our report to help eliminate some options that don't work, or see what we have and improve.

If you have any questions we'd be more than happy to answer them in the comments. Other than that, thanks for reading! 

Fail Early, Fail Later, Fail Always- 12/8

December 8, 2013

Deliverable: Project documentation and prototype refinement. 

We got our welded model on Thursday, and to the chagrin of everyone involved, our bike stand can hold a bike quite well and even support the weight of bike + rider, but once the person starts pedaling, what we want to happen fails in several places. First, the two sides of the bike do not assume equal weight of the bike, and inevitably the bike stand, with bike and rider on top, starts to tip towards one side. Second, because the bike is tipping, the wheel, which should be comfortably suspended and spinning between the two sides, tilts far enough to one side that it catches the posts of the bike stand, preventing the wheel from spinning.

Although our final project is due on Monday, we're going to spend the class period (a) adding to the design, and (b) finalizing our project report. For the design, we're going to try to add triangles to the bottom of each of the four corners in the hopes of added stability. That will cause the legs to splay away from the bike, so we will have to cut leg posts about 10". As for the report, if we can fix our design we'll base our report off of the new final design. If not, the theme of our report will be "We tried really hard," and hopefully our documentation will help future groups perfect the design.

Waiting... 12/2

December 2, 2013

Deliverable: Rough draft of final report

Our welded model isn't quite welded yet. We're on high alert for when it's ready for us to test- we'll get an email sometime before Thursday, and then we'll test the bike stand. Unfortunately for us our timeline prevents us from building a second welded model, so what we get for Thursday is our final product. Luckily for us, it's a pretty slim design, and I have high hopes that it'll work.

Today we're working to produce a rough draft of our final report, for Amy to read over at the end of today. We have until next Monday (12/9) to edit.