Contents of the Robot Arm folder.

Back to front page.

The 3-axis robot arm was designed because I always wanted to build such a thing. The plans were  intended to be sold to individuals who felt the same way and schools and other educational establishments who wanted to use them for teaching everything from electronics to mechanical construction. The Mechanical part of the plans show how to build a machine with an A3 size bed (the x and y axes) plus a lift of 6 inches (the Z axis). All the materials are stock aluminium or steel. The motors used are NEMA type 23. The electronics are very simple and include circuits to drive these motors, although there are now better ways of doing this. (Links to web sits with more modern electronics are included.) The whole principle of how to drive the motors with a computer is given in detail, including an interface for an Amstrad PCW computer. Yes, you did not read that wrong… It was designed in the days before I could afford a PC. However, there is now some amazing free software that you can download from the web that will control these types of machine, and again, links are give. I’ve since built a bigger version and use it as a CNC machine, controlling a Router, to cut shapes and carve in wood. The machine described in the plans would have enough power to drive a mini drill (Dremel type thingies), or hold a pen and be used as a plotter. As with all the plans, they give you the opportunity to get a basic machine working and then modify it to suit your use. It’s a brilliant educational tool for schools and far more use in everyday life than learning that King Harold lost his left eye in 1066.

 47 pages. First produced in 1991 

Changes that I would make if I were to do it today. 

Since I designed the machine linear bearings have dropped in price and you can find bargains on e-bay. It would work far smoother using linear bearings for all the slidey bits rather than the brass bushes described.

The bits about programming are useful for academic purposes, but if you go to: 

You can download a brilliant piece of free software to control a 3 axes machine.

It will output step and direction signals through a PC Parallel printer port that can be fed into a driver circuit to operate the motors. 

The electronics mentioned in the plans will work. (But check the voltage outputs from the PC printer port, and heed the warnings on the software site about the possibility of blowing up your PC !!!. Use a separate parallel port card, to minimise any potential danger.) 

However, better chips have been developed for driving stepper motors, and I would recommend you take a look at:

The site is a haven of knowledge for all things to do with home made CNCs. Look in their index for “Hardware” and “Stepper drivers” for some up to date ideas.

 The pages are as follows:

Page 0  Copyright notice                 
Page 1  Front cover                      
Page 2  Index                            
Page 3  Introduction                     
Page 4  General description              
Page 5  General description              
Page 6  Stepper motors                   
Page 7  Stepper motors                   
Page 8  Mechanical construction          
Page 9  Mechanical construction          
Page 10 Mechanical construction          
Page 11 Electronics                      
Page 12 Electronics                      
Page 13 Electronics                      
Page 14 Mechanical parts list            
Page 15 Nuts and bolts                   
Page 16 Electronic parts                 
Page 17 Programming                      
Page 18 Programming                      
Page 19 Programming                      
Page 20 Programming                      
Page 21 Programming                      
Page 22 Programming                      
Page 23 Programming                      
Page 24 Programming                      
Page 25 Addresses                        
Page 26 Appendix  1                      
Page 27 Main frame                       
Page 28 Support pillar                   
Page 29 Support pillar                   
Page 30 Support pillar                   
Page 31 Support pillar                   
Page 32 Y carriage                       
Page 33 Support brackets and capstans    
Page 34 X slide supports                 
Page 35 Z and X carriage                 
Page 36 Slides                           
Page 37 Finger pieces and solenoid pull  
Page 38 Z carriage base and motor spacer 
Page 39 Power supply circuit             
Page 40 Solenoid driver circuit          
Page 41 Input buffer circuit             
Page 42 Stepper motor driver circuit     
Page 43 IN/OUT port for Amstrad          
Page 44 Photos                           
Page 45 Photos                          

Back to front page.