30-31.1.12

Monday and Tuesday have been relatively uneventful. I now have the correction plates for the design screwup in the drive plates fully fabbed and have started installing them.

I had fun today (Tuesday) teaching myself to power tap. I saw Mr. Van Dyke power tapping PVC over the weekend and was captivated. After asking him about it, and doing some reading at home, I decided to try it with a larger tap (1/4-20) and soft (6061) material. While I was relatively shy at first and wasn't making it all the way through the .125" plate, I did eventually get the hang of the basic idea. The process of power tapping consists of using a drill press or mill as a framework for tapping instead of attempting to line things up by hand, as well as doing so under the power of the drill or milling machine motor. The way this is done is by placing the tap in the drill chuck and hand-tightening it; the reason for hand-tightening only is that it causes the chuck to act as an artificial torque-clutch slipping before breaking the tap. Then (with copious amounts of cutting fluid) one spins the tap up to speed by turning the drill press on, brings the tip down to just above the surface, quickly shuts off the drill press (or mill) and plunges the tap into the hole, letting it coast through (the whole process is done with very little pressure). Overall, I'm excited to keep improving my tapping skills.

Last night and today I did some work on my own time on the materials of Project ÜberTank, and discovered that this program will require a good bit of funding to manufacture at the level required for an FRC robot. The shear amount of tread required for a robot that is 37"x27" is quite large and rather expensive. A preliminary run-through of the parts and materials on McMaster-Carr ended with a total price for just the tread being close to a thousand dollars. While I was slightly deterred at first, Ms. Lindborg told me to go forward and not let money stop me. Whether this is a true commitment from the power that controls team money to go through with it, or simply her curious as to what I am capable of, is something I do not know. Time will tell, I suppose...

The current BoM (Bill of Materials) for a single linkage:

• 3.25" 6061 aluminum round-stock of a 0.25" diameter (McMaster #8974k31)
• 1.5" W1 water-hardened tool steel of a 0.125" diameter (McMaster #8890k18)
• (2) 1" long nylon spacers of a 0.5" o.d. (Outside Diameter) and a 0.25" i.d. (Inside Diameter) (McMaster #94639A506)
• (1) 0.75" long nylon spacer of a 0.25" o.d. and a 0.14" i.d. (McMaster #94639A305)
• 2" latex tubing of a 0.75" o.d. and a 0.5" i.d. (McMaster #5234K85)
• (2) self-locking retainer clips for a 0.125" shaft (McMaster #98430A116)

With these parts/materials the cost for one 1.25" link is $5.71, and with a rough estimate based on the size of our robot the number of links needed will be approximately 165 links. Do the math and you get well over $900. This number of links does not account for the lot size of parts on McMaster-Carr (it will not be possible to buy the exact number of parts/amount of material needed), nor does it consider spare parts or extra material for manufacture error.

On top of all this comes nearly every significant problem that we had with the first "standard" tank drive (machining the Drive Plates, et cetera...), as well as the necessity to fabricate some sort of sprocket system for holding/powering the tread.

While I have not given up (yet), this is proving to be an incredibly costly and in-depth project. We will see what more is to come.