Lift and Drag Measurement: Post 2

Fellow Basement Scientists,

The last installment brought about the development of the lift and draft measurement mechanism. However, we still needed to build the device hold it.

Before designing our anchor contraption, we must understand all of what it is meant to do. It must let the anchor screw rotate but not move, and anchor the springs while allowing their length to be adjusted. The first is easy, just drill a hole and stick the screw through it. The second is more difficult. My idea was to have instead of a hold, a slot. The spring would then be attached to a long screw which could more back and forth through the slot and tightened in place. Ok, lets build it.

As usual, I have available wood and decided to use it since it is easily shaped. I also decided it would be best to make two identical sides with the levers in the middle, for stability’s sake. Again, it is important to know for which dimensions accuracy is important and which are not. Here is what I determined.

-Length between two sides: Doesn’t matter, just smaller than the length of my screws
-Position of hole for anchor screw: Not important, just so that there is enough room on the board for the spring screw slots.
-Position and length of spring screw slots: I positioned these off of the hole for the anchor screw. They must be as perpendicular to the corresponding lever as possible and at the position of the spring. Length is not too critical, just long enough for the extent of spring stretch.
-Quality of box construction: This box should be strong and stable for consistent data.

A little preview so you can understand what I am talking about.

Alright, I took a 1×5 and cut two pieces about about 8 inches long and stacked them on top each other to make sure they had equal dimensions. Given the size of the lever mechanism, this one board would not work, but needed another placed lengthwise perpendicular to make room for the other slot for the spring screw. I cut two more similar pieces and placed them in what would be their final position. Holding the lever mechanism up to these pieces, I estimated the locations of the hole for the anchor screw and spring screw slots. Clamping the two sides together, I drilled a hole for the anchor screw. Making the slots now requires a little more precision.

I put the anchor screw through the lever and into the board to simulate its final position. With it in place, I then marked on the board where the spring screw slots must be. This may be breaking some rules, but to make the slots I used the drill press and bit as a router. As basement scientists, you can only use what you have, and for me it is the only thing that would do the trick. To make the slot straight, I clamped a board to the drill press table to act as a guide rail.

Right now, we got all our slots and holes and the four pieces making up the two sides. We need to connect the two sides. I took my 1×5 and ripped a 12in section in two using a table saw. These two pieces will serve to connect the halves, one across the very bottom and another shorter section a little above it. Drill your pilot holes, get your 2″ wood screws and we have our measurement contraption!

Congratulations, We have our measurement mechanism. Hooray for basement science! We wont know if it really works until we start using it. I imagine there will be some debugging at the end of all the construction.

Next, we must determine the spring coefficient of our springs.

Best Regards,
Ben Washington

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