Week 4: Initial Bender Idea, Shop Access

I have created a basic Solidworks model of what our Hossfeld-type bender may look like. It consists of an arm that has a pin that rotates about a center pivot, a base with a pin and the aforementioned center pivot, and a die that sits on the center pivot and allows material to be bent across/around it.

The dimensions of the bender, and more specifically the die, will largely depend upon dimensions determined by the track improvement team for the next generation track.

The first prototype will most likely be created out of wood (plywood or hardwood) with a metal band on the edge of the die and metal pins, though this is still being debated. The final build should be made of mostly or entirely metal. The intent is to make use of material currently sitting in the shop to fabricate these benders before purchasing more material.

Week 3: Research and Ideas

Some research was done into stock benders, and most affordable methods appear to require force generated by the user to bend the stock.

One method appears to utilize a moment arm, and to force stock to bend about a pin at a pivot point, with force being applied at two points away from the fulcrum.

An alternative method appears to utilize a hydraulic ram/press with a mold or die to force material into shape.

A third method may utilize a scissor jack with a mold or die on one side to force material into shape.

Dies cast to particular specs appear to be expensive, so fabrication of molds in-house will be investigated.

The most pressing issue with the designs above is that they do not actively measure how much material has been bent.

A fourth method may work similarly to the first, but utilize a pawl on a large pivot pin and two ratchets (one to advance the pawl, one to hold the pawl in place while the other is moved) to allow for measured material advancement through the bender.

Rough sketches:

 

Week 2: Looking Back and Looking Forward

As is mentioned in the team's post this week, there are a number of things that can be done going forward, including determining working fabrication tools, contacting individuals, and looking at what work has been done on the project in the past. Here, I will address a few of those points in more detail below.

In the shop where the project is currently being housed, there are many hand tools and power tools available, but several tools do not appear to be in working order:
1) Such is the case for the band saws (one has a broken shaft (?), the other has a broken guide or some other ailment), and we are looking at having one fixed in the near future.
2) The lathe in the back of the room has apparently been unused for a year or more, and nobody is sure if it works or not. Tests will have to be carried out to determine its usability.
3) There is a mill against one of the walls, but with no power cord nearby, I could not see if it ran last week. Will look into it more this week.

Between last week and now, I have contacted two people who have worked with the Spartan Superway project before, Kyle Meininger and Kenny Strickland. Kyle runs SJSU's central workshop, and has helped fabricate parts for the project in the past. He gave me a tour of the shop, and offered to review or aid any fabrication methods or designs we may create. Kenny worked on the small-scale track during the 2015-2016 year, and he was able to give me some general information about it first-hand, and several points which I will detail below.

1) Methods for track change at stations presented a major problem. Barcodes were dirtied, the bogie passed by too fast to read it, or the physical support for the barcode reader mounted to the bogie broke. Magnets for one reason or another did not seem to work either.
2) Some designs were needlessly over-machined, such as curvature when creating blocks to hold the wheels to the bogies. Simplifications could be made to the design.
3) Due to the thin width of the top rail, bogies were not always forced to travel in the expected paths which provided them the space to fall of the track, especially at some of corners.
4) Bogies would occasionally stop for seemingly no reason after traveling several loops successfully. Teams were unsure whether it was a software issue or hardware issue.
5) Very little tolerance for error was incorporated into the design. For example, the vertical height between the top guide rail and side tracks that the bogie wheels rolled on mandated very specific heights and widths, which were not always met. Additionally, a change to the design of the front ends of the bogies made it such that there were clearance issues when approaching track changes.

Lastly, I will investigate access to fabrication capabilities beyond the project's shop. This will include several workshops on the SJSU campus, the Tech Shop one block away from campus, and possibly several individuals that have their own private workshops.

I will look to add pictures in the coming days to highlight several of the issues above.
See the week 3 post by the team for the images.