Best method to enlarge diameter of sub mounting hole in MDF?

[boriskov]

Hi all,

I have a sidemount box that I have ordered from eBay that I'll need to enlarge the diameter of the mounting hole to fit a JL 10TW3-D4.

The box has a recessed mount and looks like this -



Ignoring the fact that it's already been carpeted (I'll deal with that), my rough calculations show that I'll need to increase the internal diameter of the actual cut out by about 8mm which is a 4mm increase to the radius. The larger diameter hole, depending on how I choose to mount the sub, may need its diameter to be increased by 14mm or a 7mm to the radius. Not huge numbers.

Obviously a router is the right tool for the job. I can't quite get my head around the different bits or whether it's easiest to cut out a blank to fill the hole and then re-route using a circle jig?

I have access to a plunge router but was going to pick up one of these as it's a lot smaller for detailed jobs and comes with a circle jig -

Ryobi 350W Trim Router Kit I/N 6210408 | Bunnings Warehouse

Working with wood is not my forte, anybody keen to offer up some advice?

Cheers,

Jake

[ozynigma]

Not great with wood and routers myself either. Suggest screwing a temporary piece under the hole to give you a working platform. Then set the router up to do a circle and cut out the top recess then enlarge bottom hole. Use a square edged router bit.

[boriskov]

Not great with wood and routers myself either. Suggest screwing a temporary piece under the hole to give you a working platform. Then set the router up to do a circle and cut out the top recess then enlarge bottom hole. Use a square edged router bit.

Thanks, I figured I'd need to make up something like this?



That little Ryobi trim router should be small and nibble enough for the tight working space. It comes with a circle jig too which is a bonus.