I just wanted to let the community know that I completed my first autonomous robot project and used something for the body which I haven't seen used yet. Strong-Ties are cheap (58 cents each (US)) and worked rather well for us. My blog captures a complete parts list, links, lessons learned, source code and a few videos. If interested, please visit http://techdiy.tv and let me know what you think.
Interesting little robot. It seems like you are developing an eye toward "what can I use for robotics" when it comes to looking at things; while the use of metal tie plates for robotics isn't new, it does take a certain amount of insight until you get that "aha!" moment, then you start looking at everything like that (hmm - can I use that watermelon for a robot part? /joking - or am I?).
Regarding your tip about lubricating drill bits with oil: Yes, this is paramount. In fact, there exist special purpose oils just for the task called "cutting lubricants". On a per ounce basis, though, they don't come cheap. The best oil to use, one recommended by tons of old-time machinists stretching back decades or more - is common bacon grease! It doesn't matter if it is rancid or not. Save it up, put it in a small jar and stick it in your fridge (maybe with a warning sticker). Dab it out as needed. Best part: As it warms up, you get the wonderful smell of bacon suffusing your shop - what could be better?
/note: If you're a vegetarian or vegan, then you might be SOL on the bacon grease...
When the BOT passes the door, it seems confused and makes a ( IMHO unnessesary ) turn.
Instead of using POTs to syncronize motorspeeds, you better use encoders.
TechDIY.tv has moved to http://michaelwittmer.com/
I will be rebuilding the autonomous bot again for my son so it will be covered on the new site. We gave the 1st one to my dad/my son's grandfather as a present. For now, you can see the original here if interested: http://wp.me/p46r1I-3T