enlarging holes in fiberglass or acrylic

[fxst]

I would use a Dremel with a small router bit. Easy to control and always useful.

Pete

[ian]

this is what I am looking at but still has limitations

51mm – 178mm -- actual size will be 2" to 7", or 50.8 to 177.8 mm
6.4mm increments -- it will be 1/4" (= 6.35 mm ) increments

6mm increments is still a sizeable gap. hence why I am asking for widening ideas.

so drill a hole in a piece of thin ply or MDF that is 3-3/4 in (= 95.25 mm) diameter. Then use a straight cutter and guide bush on your router using the 3-3/4" dia hole as a template.