Projects – Circle Cutting Router Base – Part 1

To progress my plans to build a router table I need to cut a circular hole to clamp the body of the router in.

The diameter of the hole required is quite a bit bigger than that of any of my spade bits, forstner bits or hole saws, but smaller than my router can cut using the trammel in circle cutting mode.

I looked at a variety of circle cutting bases in books including Router Jigs and Techniques and Jigs & Fixtures for the Table Saw & Router, and some online such as this one.

I decided perspex is a better material for such things than ply or MDF, so I bought a selection of thicknesses (4mm, 6mm, 8mm and 10mm) of Lexan from a seller on eBay.

Selection of Lexan

There’s the potential for another Catch-22 situation with some of the circle cutting bases, as many of the instructions I’ve found involve using a router table to cut the slots used to allow adjustment of the hole size.

Thinking about this gave me a great excuse to procrastinate, but eventually I resolved to beat this blockage by starting with a simpler design and I settled on a basic offset base with pre drilled holes and a rolled pin as the pivot.

(I reasoned that even if the pre drilled points weren’t in the right place I could always drill another slightly off the pre-existing line of holes, and even if I later built a fancier circle cutting base I could still use the old one as an offset base).

My router has two bases – one plunge and one fixed, with the plunge base having a larger diameter and one flat edge and the fixed base being smaller and completely circular.

Each has a 6mm clear plastic base on it, but having removed them I realised that the mounting screws are located in the same places, so I decided to use the larger plunge base as the template.

Draper router bases

As this will double as an offset base I won’t want it flexing or breaking, so I decided to use the 8mm Lexan in the hope that it would be sturdy enough.

I dimly recall using perspex at school, so I knew I could leave the protective film on both sides until the last moment and use it for marking out the shape.

I used the 63mm hose adaptor from my vacuum extractor as a template for the curve at the narrow end.

Lexan with offset base marked out

I set my bandsaw to its low speed and used a 14 TPI 1/2” blade from TuffSaws to cut the shape.

I was expecting to have to swap to 1/4” blade, but was impressed by how tightly the 1/2” blade could cut if I gave it some relief cuts every so often.

I then tidied a few of the rough edges up a bit with a file.

I figured using a flush cutting bit and the original router base as a template would neaten up the curves, but I was a bit scared of damaging it, so I sandwiched a scrap piece of ply between them with double sided sticky tape to ensure only the bearing went anywhere near the original base and jacked the whole lot up on bench cookies:

Trimming the offset base

I’d locked myself in the garage as my daughter had a friend over and I wanted to ensure they stayed out and safe.

When I tried to unlock the door to get a snack, the key broke off in the lock and I was forced to cut the lock off with the metal cutting saw blade in my Stanley knife!

Escape kit

The circle cutting router base will be continued (and concluded) in Part 2.

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This entry was posted in Circle cutting router base, Jigs Fixtures & Appliances, Projects, Tools and tagged , , , , , , , , , , , , , , . Bookmark the permalink.

3 Responses to Projects – Circle Cutting Router Base – Part 1

  1. Pingback: Projects – Router table – Part 3 | Aggravated Wood Butchery

  2. Pingback: 2013 Workshop projects | Aggravated Wood Butchery

  3. Pingback: Projects – Circle Cutting Router Base – Part 2 | Aggravated Wood Butchery

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