Robotics/Physical Construction/Construction Techniques

Working with Metals

Measuring and Marking

• Do: Measure twice, cut once. Putting it back on is MUCH more difficult than taking it off.
• Do Not: Measure with a micrometer, mark with chalk, cut with a torch. Accuracy is important in moving parts.

Cutting and Sawing

• Sawing sheet metal requires a saw with a fine-tooth blade. As a general rule of thumb at least three teeth should touch the material being cut.
• The teeth should be aimed away from the handle.
• Only apply pressure when pushing the saw away from you, not when pulling back.
• A miter box can be very handy to make straight or 45° cuts. Use a metal box as wooden boxes wear out very fast.

Drilling

• Use a punch to make a small indentation where you want to drill the hole.
• Use a slower speed to drill the hole than you would use for wood.
• Use clamps when working with sheet metal. Don't hold it with your hands as metal is very sharp when cut.
• Large holes can be made by drilling a hole and using a file thread or small metal saw to cut the hole. Finish with a half round file.
• A groove can be cut by drilling two holes at the outer edges and using file thread or small saw to connect both holes.

Filing

• Files exist in different shapes and different roughness.
• Filing straight: Hold the file diagonal on the surface, apply pressure and move the file upwards while moving from left to right.

Bending

Place the sheet metal between 2 wooden boards in a vice. Let the line where you want the material to bend match up with the border of the boards. Use a hammer to bend the metal.

Working with Plastics

Cutting

Thin plastics can be cut with a sharp utility knife, thicker material can be sawed. When sawing plastic, care must be taken to not melt it.

Drilling

Drilling plastic requires a slow speed drill. Special drills for plastics are much better as metal drill can cause the material to crack.

Large holes and grooves can be made the same way as in metal.

Bending

Use a heat gun (paint stripper) to heat up the plastic, bend it and let it cool down. Bending can be done by hand.

Further reading

• "the #1 rule of machining: Always properly secure the workpiece." -- David Cook[1]