The Frame

Recently, I decided to try to make my robot's frame by improvising with parts harvested from a broken bicycle I had been keeping in my garage.  Though I had not settled on an exact plan for the robot, I figured that, during the process of dismantling the bicycle, I would get ideas for how to use the parts.  Initially, my idea had been to utilize mainly the plastic components from the bicycle in order to make the robot as light as possible and avoid having to invest in welding equipment, but, as I continued to remove all of the magnificent metal parts from the bicycle frame, I decided that there was merit in further researching my options for working with metal.  

After some research on the topic, I came across information on using a method of metal joining called brazing.  Brazing, which is not really welding and not soldering, is an ideal method of joining metals that are not alike (such as two different types of steel with different melting points) because it does not require you to melt any of the base metals.  Rather, brazing utilizes an added filler metal that will melt at a lower temperature than the base metals (such as brass), flow into the narrow space between the base metals and form a solid joint upon cooling.  

There are several useful information resources on brazing available on the web these days.  For ideas on how to start brazing on a small budget a good starting point would be the societyofrobots.com's page on brazing.  For more detailed information on brazing you may want to consider purchasing a technical manual on the subject such as the Haynes Welding Manual.   

My final robot frame design utilizing bicycle spokes and chain links.

My brazing arrangement is about as bare-bones as you can get.  It consists of a Bernzomatic "Cutting, Welding, and Brazing Torch Kit," a pair of welding goggles, a pliers, some bricks, and Lincoln Electric flux coated brazing rods.  All of my brazing is done outside on the patio. 

All of the frame parts after they've been cut along side the tools used (note the legs have already been assembled). 

I found that lumps of clay were very useful for holding the parts together while I was brazing. 

Once I felt comfortable with the idea of using brazing to assemble a metal frame for my robot, I then set about creating a robot design using bicycle parts that was both light weight and strong.   Using SketchUp and the dimensions of my assorted bicycle parts, I eventually came up with a design that utilizes the bicycles spokes and chain links to create a suitable frame.   Thus far, I have managed to measure and cut all of the frame component and assemble about thirty percent.  I will post additional information as the project advances. 

Boiling parts of the robot in water to dissolve residual flux.