Placement Aid for 30mm and 33mm Mounts

I have a number of projects that involve panel or bulkhead mountings using 30mm and 33mm holes. 

When deciding on hole placement you need to consider clearance for rotation of mounting nuts.   These templates have outer diameters of 45mm and 52mm, with a center hole of 4mm.   

The 4mm hole accomodates the tip of a "Sharpie" marker pen. 45mm should provide clearance for the nut on projects with a 30mm hole.  52mm should provide clearance for nuts on projects with a 33mm hole.

If the template fits in a given location, drilling at the center point will give you hole placement that should allow tightening of the mount nut without interferance. 

Please verify template vs nut sizes prior to use.