Hole Layout Using a Single Datum (Plates + Center Punching)

Accurate hole placement in FRC depends on using a consistent datum and properly marking drill locations before cutting. 

 

 Using a Datum for Hole Layout 

 A datum is a fixed reference edge used to measure all features from. 

 For plates, the best datum is usually: 

 

 A straight factory edge of the material 

 

 All hole locations should be measured from this same edge: 

 

 Measure X distance from the datum 

 Measure Y distance from the datum 

 Do not switch reference edges between holes 

 

 Using one datum ensures: 

 

 Holes stay aligned in a grid 

 Parts match CAD layouts 

 Errors do not accumulate across measurements 

 

 

 Marking Hole Locations 

 Once measurements are made: 

 

 Mark each hole location clearly with a pencil or scribe 

 Use a combination square or speed square to ensure straight layout lines when needed 

 Double-check critical dimensions before punching or drilling 

 

 

 Center Punching 

 A center punch is used to lock in the exact drill location before drilling. 

 Why it is used: 

 

 Prevents the drill bit from “walking” (sliding off the mark) 

 Improves accuracy on metal surfaces 

 Creates a small indentation that guides the drill bit 

 

 How to use it: 

 

 Place the punch directly on the marked point 

 Hold it steady and perpendicular to the surface 

 Strike firmly with a hammer to create a visible dent 

 

 

 Best Practice Workflow 

 

 Choose a single datum edge 

 Measure all hole positions from that datum 

 Mark each point clearly 

 Use a center punch on every hole location 

 Drill carefully, keeping the bit centered in the punch mark 

 

 

 Key Idea 

 Good hole accuracy comes from consistent measurement from the same datum and center punching every mark before drilling.