2nd May 2021 To trammel? Or not to trammel?

 *

Sunday 42F overcast and raining. Not sure what I should be doing today. I have become so used to dry weather.

A router trammel [radius bar] should be taking shape by now. The router's own fence bars can be used if fixed onto the end of a suitable board. To allow some adjustment. Though studs can be substituted for the fence bars. 

I'll need a range from 2 to 2.15m radii. It is vital that the whole set-up is rigid yet moves freely in an arc. Judder is the enemy. Proper support for the full plywood arc and the trammel centre point are also important. The whole arrangement needs quite some space. The arcs are 1.5m long. The radius bar plus router and centre support more than 2.2 meters overall.

I used to clamp the arcs down, for cutting, but countersunk screws into the "bench" are safer. They do not impede the progress of the router. Like clamps so easily can. Nor is there the risk of a slip in arc position during clamping.

A panel pin makes a poor centre. A screw being much more rigid and secure in use. A sacrificial working surface is an expensive luxury. Avoided by fixing packing pieces under the arc being cut.

Before lunch I had found a much stiffer length of alloy tubing than the builders' straight edges. I made a piece of sturdy, aluminium angle into an adapter for the long fence bars from another tool. 

If I make the centre pin 2m from the face of the angle I can make quick adjustments for radius from that reference point. Which will save me having to measure right back to the centre pin over 2 meters away every time.

Now I can use the little Makita router for cutting the plywood arcs. It's small size is a pleasure to use compared with the bulk of the full size routers. Though there is one oddity with the Makita router: Corrosion must have formed under the rubber sleeve of one of the supplied, base adapters. It looks like a hideous disease! I have never had any other tool looking like this.

*