Tarmac Cutter Blades are the most simple tool. They can be created from Iron, Gold or Diamond, with matching durabilities. They can be crafted into various thickness, dictating how much of a road should be cut off when they process.
First, you must craft the blade. Follow the recipe below for the material of your choice, then combine multiple of the same blade type to dictate thickness; either 1, 2, 4 or 8. Two blades of 1 thickness create a blade of 2 thickness, two blades of 2 thickness create a blade of 4, and so on.
Once you have a blade appropriate to your needs, simply place it in a Tarmac Cutter and follow the instructions for that machine. Blades will need occasional replacement as their durability breaks.
5x Iron Ingot
4x Iron Nugget
5x Gold Ingot
4x Gold Nugget
4x Diamond Shard (crafted from one solitary diamond)
Combing two identical blades will create a thicker blade of the same material, up to a thickness of 8.