If you fly rubber and find that your motor is either too strong (and you want a slightly weaker motor) or too weak (and you want a slightly stronger motor, maybe you don’t know intuitively what is the next increment. I encountered this and decided to develop a chart or table to help me.

This assumes two things: 1) you won’t be using a rubber stripper and 2) you have the 5 sizes of rubber available (1/16″, 3/32″, 1/8″, 3/16″. & 1/4″). With these sizes of rubber, you will be able to combine them into nearly every 1/32″ increment.

The information is arranged in vertical columns. Find the desired motor in the left-most column. Then move across that row and each cell in that row offers a combination that creates that total. Each column has a certain dimension of rubber as the Primary and then what secondary dimensions will need to be added.

The example that started me down this path was a motor that was 2 loops of 3/16″. I thought it was maybe too strong, but what would be the next smaller size? With this chart, I can see that 2 loops of 1/8″ plus 1 loop of 3/32″ is the next smaller increment – of one more step would be 1 loop of 3/16″ plus 1 loop of 1/8″.

Increment | 1/16″ | 3/32″ | 1/8″ | 3/16″ | 1/4″ |
---|---|---|---|---|---|

1/16 | 1/16 | ||||

3/32 | 3/32 | ||||

1/8 | (2x 1/16) | 1/8 | |||

5/32 | |||||

3/16 | (3x 1/16) | (2x 3/32) | 1/8+1/16 | 3/16 | |

7/32 | 3/32+1/8 | 1/8+3/32 | |||

1/4 | (4x 1/16) | (2x 3/32)+1/6 | (2x 1/8) | 3/16+1/16 | 1/4 |

9/32 | (3x 3/32) | 3/16+3/32 | |||

5/16 | (5x 1/16) | (2x 3/32)+1/8 | (2x 1/8)+1/16 | 3/16+1/8 | 1/4+1/16 |

11/32 | (3x 3/32)+1/6 | (2x 1/8)+3/32 | 1/4+3/32 | ||

3/8 | (6x 1/16) | (4x 3/32) | (3x 1/8) | (2x 3/16) | 1/4+1/8 |

13/32 | (3x 3/32)+1/8 | ||||

7/16 | (7x 1/16) | (4x 3/32)+1/6 | (3x 1/8)+1/16 | (2x 3/16)+1/16 | 1/4+3/16 |

15/32 | (5x 3/32) | (3x 1/8)+3/32 | (2x 3/16)+3/32 | ||

1/2 | (8x 1/16) | (4x 3/32)+1/8 | (4x 1/8) | (2x 3/16)+1/8 | (2x 1/4) |

17/32 | (5x 3/32)+1/6 | ||||

9/16 | (9x 1/16) | (6x 3/32) | (4x 1/8)+1/16 | (3x 3/16) | (2x 1/4)+1/16 |

19/32 | (5x 3/32)+1/8 | (4x 1/8)+3/32 | (2x 1/4)+3/32 | ||

5/8 | (10x 1/16) | (6x 3/32)+1/6 | (5x 1/8) | (3x 3/16)+1/16 | (2x 1/4)+1/8 |

21/32 | (7x 3/32) | (3x 3/16)+3/32 | |||

11/16 | (11x 1/16) | (6x 3/32)+1/8 | (5x 1/8)+1/16 | (3x 3/16)+1/8 | (2x 1/4)+3/16 |

23/32 | (7x 3/32)+1/6 | (5x 1/8)+3/32 | |||

3/4 | (12x 1/16) | (8x 3/32) | (6x 1/8) | (4x 3/16) | (3x 1/4) |

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