Braxton Kyle Bensel

Click on the Gantt Chart to download it!

For my Decision Matrix, I used five different qualities to rank the three modules I discussed in Assignment 4. I looked at

Cost

The cost evaluates how much each module will cost. Module 2 will be the most costly due to the springs present but even those aren't really that expensive (it's just expensive comparatively.) All in all, these modules shouldn't be too costly.

Ease of Use

Ease of Use evaluates how simple it is for the user to use the module. This mostly relates to how the module will have to be installed with regards to the rail. Module 1 and 2 will require a bit more adjustment by the user, while the third module should simply slide onto the rail at the start of assembly.

Ease of Assembly

Ease of Assembly looks at how difficult the module will be to assemble. Module 1 will be pretty difficult to assemble because it has to be put on the rail and then held onto the rail while the connecting bar is attached on both sides. Module 2 is also fairly difficult as the springs will need to be fastened fairly uniformly without issues or the module could easily fail.

Coolness

Coolness looks at how much I like the module and how cool I think it is. Like before, I'm including coolness because it is an important choice to me, but it's not that influencial on the decision this time. Honestly all of the designs are cool to me, but Module 3 is a bit less stunning than the others.

Ease of Obtaining

Ease of Obtaining looks at how obscure the parts are for each of the different modules. The only one that was moderately more difficult was Module 2, which required obtaining torsion springs. Both other modules just require miscellaneous hardware.

With this Decision Matrix, it is clear that the right decision is Module 3.

A bolt is needed to secure the two baseplates with one another.

Functional Requirements	Design Parameters	Analysis	References	Risks	Countermeasures
The plates must freely rotate.	Clearance Hole for both plates.	With a clearance hole for both plates, both freely rotate.	My knowledge :)	May not have as much structural integrity as desired.	Guarantee the bolt is tightened enough to prevent flexing without preventing rotation.
	Clearance Hole for one plate.	If only one plate has a clearance hole, the bolt will only freely rotate in one.	My knowledge :)	May bind more than desired if alignment is poor.	Guarantee that bolt hole sizes are correct.
The bolt must not shear.	Bearing Stress Analysis for bolt shear	Bearing Stress = Compressive Load / Characteristic Area	Solids	Bearing Stress might be more than the max allowable stress.	Guarantee bolt is strong enough.
The plate must not fail	Stress Analysis of Plate	P=σ*A	Solids	Stress might be greater than allowable stress.	Guarantee bolt is strong enough.

Now lets get into the actual math.

From this, I've sourced this bolt from McMaster-Carr : Bolt
I've also established that the minimum thickness for the plate should be around 1/8 of an inch.

Click on this image to download the model!




Overall, not much changed from my initial model (as I sort of went ahead and did a lot of the guesstimating for the bolt sizes and plate sizes. A lot of the dimensions are limited by the available parts. For example, I could have made the base plate 1/8" thick, but my sourced bearings were 1/4" thick. I decided to keep the plate thickness at 1/4" so that the whole bearing is covered by the plate which should increase the stability considerably. It also makes affixing the bearing a lot simpler rather than having to add some spacer. I dropped the center bolt to a #3 because of my calculations, which gives a bit more room in that area and should be considerably lighter than the #10 bolt that was originally there.