Final Testing

Track Pieces

Coming back from Thanksgiving break, Melaney brought in cardboard shipping tubes that she found very cheap at the dollar store. She already took the time to put fun colored scrap-booking paper and a sealant over them. The pieces are pictured in Figure A below. This seemed like a promising option to use as track pieces so we tested them.

We compared the weight of these pieces to the rain gutter (which could be held with three neodymium magnets) and it came in lighter. Knowing that it was lighter it would be able to be supported by the magnets and could possibly only require two. They were easy to cut in half to make half pipes unlike all of the other materials we tried. We wanted to make sure that they were durable so we dropped one on the ground from five different heights. The heights ranged from only half a foot off the ground all the way to our shoulder height. It handled each drop well and had no visual damage. We also attempted to replicate the amount of force a toddler could apply to the tube to crush it. We determine that it would require more force than a two year-old could apply, but we realized that a toddler stepping on the piece would most likely bend it. Since the piece would not be indestructible we compared that con to the price and ability to replace the piece. The cardboard is very cheap and the process of adding paper and sealant is simple enough that our client could do it if need be. Because of this, we determined that it passed the test and we would use cardboard shipping tubes as our track pieces.

Securely Attach the Magnets

Once we decided on the track pieces we needed a way to attach the magnets where they would be secure and have some form of protection. We decided that since our pieces were curved it would be easiest to 3-D print something rather than try to mold something to the correct shape.

Kevin went to the Machine Shop and worked with Griff who helped us to create our connection pieces. He was easily able to make the curved edged that would match that of the tube and able to make a hole in one side for the magnet to sit in. The first one that we printed left a small amount of the magnet exposed when it was placed in (this can be viewed in Figure B. below). We determine that leaving a little out would be fine but when we place the track piece on the connector it was not able to sit flat on the piece when both were pushed flush against the wall. We knew that this would create an issue and not allow the magnet to fully connect to the board which we need in order to hold up the piece.

We then made another connector piece with a slight change to the design. When we talked with Griff he told us that he lined up the inner edge of the curved piece with the outer edge of the tube, we discovered that it would be better to line up the outer edge of the curved piece with the outer edge of the tube. Griff also thought of adding the lip at the bottom of the piece in order to help combat any leverage that would occur from the magnet not sitting completely flush. The depth of the lip is the same as the depth of the exposed part of the magnet. The design for this updated piece can be seen below in Figure D as well as the piece after it printed in Figure E.

Proving the Connector Pieces and Track Pieces will Work

Once we made the final design of the connector we tested it by lining it up with the track and placing it against the whiteboard. The piece was going to work well for us. The piece was made as lightweight as possible so it wouldn't affect the magnet but we tested the strength by attempting to crush it in our hands and we were unable to.

Then our next biggest issue was making sure that the magnet and the piece stay glued on and don't come off. We glued the magnets into two of the connectors and the connectors on to one track allowing the glue to dry for about 30 minutes. Then we attached it to the whiteboard and everything held. The track could handle the weight of the vehicles that we had purchased at the moment. We also were easily able to pull the track off the whiteboard which was a concern if the kids would be able to do it, but the tube provides so much leverage it won't be a problem for them. At one point one magnet came out as the tube was pulled off the board. After testing this again but letting the glue dry for 8 hours the magnets no longer came out, but it was good to see that most likely the magnet would come out on the board and the children will not be able to pull the magnets off the board by themselves.

Finally, we had determined that our track pieces will work and they have a way to connect to the board. We began to fabricate the rest of the pieces of our project after this test.

Frame

During the break we had Bill in the Machine Shop help us put the sheet metal on an MDF board that we were able to get from the shop for free. This board is very thick and will provide stability. We tested that the sheet metal stayed to the board and could not be pried free. This was determined to work so we decided to also do it to the other side, as testing from the Shepherd of the Hill School taught us that the more surface area available for the children to play with the better. Coming back from break Alex brought a plan for the frame. He had sketched out dimensions with the plan of sliding the MDF board in grooves in the side supports. He had three different options for how to give the frame angled supports. We went to Bill in the Machine Shop to test these ideas. Bill told us that the frame was going to be sturdy enough and confirmed that the third option would be the best. Those plans can be viewed in Figure F below.

After confirmation from the testing we did on the frame, the connectors, and the track pieces we continued with finalizing our detailed design and began fabricating the whole system. For more information on our finalized design please view the "Detailed Design" tab. For more information on the fabrication of the system please view the "Design Fabrication" tab.