Merc90HPnewbie for one was wondering about installing his temp and water pressure guages on his fiberglass dash. Others probably have faced the same challenge. - use a high speed router. Some call it a cutout tool. It's bigger than a dremel tool and runs at about 20,000 RPM.<br /><br />It's a compact handheld tool with bits that look a lot like a drill bit.<br />Roto zip is the popular brand, available at most hardware stores. That brand is high priced, about $80, I think.<br /><br />Harbor Freight (harborfreight.com) sells one for about $30 (unless you find it on sale - a frequent occurance). <br /><br />The only bits that I know of are the Roto-zip brand... a pack of the basic bits is about $8. I used the most basic bit on my dash... solid hard fiberglass, about 5/16" thick. No sweat. The hole for my tach was a bit under 3 3/8". I first marked my hole a bit small, cutting the opening in one piece, then 'nudged around the edges until my tach slipped in snuggly. Friction Fit.<br /><br />I did drill a pilot hole, just to get my bit started into the fb... once cutting, your only moving the tool horizontally, resting it on it's plastic base to keep it steady.<br /><br />I am an electrician and I use this tool for cutting fine cabinetry, lathe- and -plaster... even tile (with limited success). Those last two surfaces require tougher more exotic bits, but with the basic bit I have cut outlines in 1/2" wooden composite siding. <br /><br />For fiberglass, you get a neat accurate cut. <br />The noise is much like a loud dentist drill, and it generates some very fine dust... ear and eye protection are recommended, and maybe a dust mask as well. Don't apply too much sideways pressure, trying to hurry the job. Just let it cut and you guide it smoothly in circle.
