Thread: How to Tighten a Corner Radius?

I'm progressing my table build and today cut out the insert hole in the table top. I'm guessing that my method was the bog standard usual way. I cut out some MDF the size of the inner hole on the table saw, making it exactly 20mm smaller than the insert, because my rabbet bits all have a 10mm shoulder outside the bearing. Then set up my MDF template and attached battens flush with it on the underside of the table. Cut out and flush trimmed the inner hole, and used the rabbet bit for the shoulder.

The problem with this is that shoulder's corner radius is obviously the same as the rabbet bit at 16mm, and I'd like to reduce that to give me more room to put in the threaded inserts to hold down router top plate, and I have not worked out how I can achieve that. I don't have any short bits with bottom bearings, but they must be available in a roughly 20mm diameter. With that I'd have to stick some battens flush with the shoulder's edge and wide enough to support the router base, and thick enough for the bearing to run against while at the correct depth.

It has occurred to me while typing this that I could use my small trim router but it has a square base, and I'd be nervous about getting the guide battens the perfect distance from the cut out. Or I could use my big router (Bosch 1600CE) which I also have the fixed base for which is round. I've made a tapered centralizer tool for it. I think I have talked myself into using the Bosch with fixed base, but I would appreciate any thoughts or advice, and especially on setting up the battens?

Incidentally, while I have only owned the Bosch 1600CS for a coupe of weeks now, I am really starting to like it. My favourite feature is the micrometre depth adjustment that is calibrated in millimetres and has no apparent backlash, so I can get spot on depth of cut just like using the metal lathe and milling machines that I am used to. This is contrast to the TRA001 that I have been using for the last two years at my Menz Shed, which only has Imperial depth calibration and is a pain in the butt. The Bosch also handles beautifully with both fixed and plunge bases and is comfortable and secure.

Router Table Cutout.jpg