1. Mechanics / Construction

Submitted by paulstreats on November 30, 2007 - 8:56pm.
 

This section is dedicated to building the chassis, forming the legs, and attatching the servos.

 
  
 Build The Chassis  
  
 

The main chassis is made out of a sheet of flat plastic material (I used plexi glas), The design that I used is in the pictures below. Simply draw the design onto your flat plastic, I scored the design into it with a modelling knife.

 
  
   
  
 
Next you will need to cut the pieces out, you could use a saw such as a coping saw, or use an electric jigsaw or something.
 
Note: You will need two of the connector pieces. 
Try to see if your servo's slide into the gaps in the ends of the body pieces, they dont need to fit all of the way in lengthways. 
  
 
Next you will need to add some holes to bolt your servos onto the body, line your servos up like this:
 
  
  
And then mark out and drill the holes. 
   
  
 You will then need to glue the various body segments together. They will need to fit together like this: 
    
 
If you are using acetone or the paint thinners method, these work by melting the plastic slightly on contact, the acetone/thinners evaporates quickly thereby allowing the plastic to set again. Liberally apply the thinners to both of the surfaces to be joined then press together and hold firmly for about two minutes. Leave to set properly without any tension for a further 5 to 10 minutes.
 
  
 
Making The Legs
 
  
 
First of all center the servos, you can do this electronically if you know how, but i find that just manually centering works well enough.
Your servos should have come with a "horn" attatched. Twist the horn all of the way to the left, then all of the way to the right. The turn it to the position between the two extremes.
 
  
 
Once you have found the approximate center, remove the servo horns by unscrewing the little black screw in the center. While you are doing this you should want to keep hold of the horn and the servo to stop it turning out of position.
 
  
Now we need to make the leg mounts. We will be using the round servo horn and the cross shaped servo horn.  
Place the cross servo horn onto the round servo horn, make some pilot holes to attatch them, if you look at the cross horn you will notice that there are holes already on it, you will need to take one of the pointy screws that came with the servo and screw through the secod hole in from the outer edge of the cross servo horn arm, screw all of the way through to the round hown underneath. Do this on three of the arms. 
  
Next, unscrew the two horns again so they are seperate. drive the screws back halfway through the round servo horn. 
Take a length of rigid metal wire such as a coat hanger(about 30cm / 12") and fold it in half fashion them like this to fit onto your servo horn mount:
  
Put the servo horn mounting screw through the middle hole, then place the cross shaped servo horn over the top and screw together.  
  
 You can now attach the servo mount back onto the servo. 
  
 Repeat this process for the other servo 
  
 Next Shape The legs to look similar to this 
  
  
  
 The legs will catch on carpet, and slip on smooth surfaces, so you will need to coat them with something, I used the Polymorph granules, but only coated them about halfway up so I can easily alter the shape and position of the legs later if I need to. You might also want to put some hot glue onto the very bottom of the legs to make them slightly tackier 
 You might be able to just push some polystyrene onto the legs 
  
 Bolt the servs onto your robot base like this if you havent done so already
  #PICTURE#
 That is the end of the mechanics / construction part, You may want to add some extra holes onto the back part of the robot in order to mount your circuit board, I think I made the dimension Right to be able to fit the prototyping board from the $50 dollar robot onto the back base, Just mark up your screw holes ready.