Robot Building for Beginners, Third Edition

APPENDIX B ■ APPENDIX B

Or, take a cylinder and subtract two rectangular boxes (cuboids) and you have a slot for the Lego cross
axle. See Figure B-7.

A cylinder with a perpendicular cylinder removed creates a place for a set screw. Further subtracting a
perpendicular cone tapers the entry hole to make tapping screw threads easier. See Figure B-8.

Figure B-6. Subtracting a primative 3D column creates a tube

Figure B-7. Subtracting primative 3D boxes creates a slot for a Lego cross axle