|Forum topic by Viktor||posted 03-03-2013 09:19 AM||50800 views||16 times favorited||7 replies|
03-03-2013 09:19 AM
This is just a variation of a very common router surfacing jig, except instead of flat surface it creates convex or concave one.
The bridge that supports the router has curved beams (R= 194 cm) which I cut using oversized circle cutting jig. The frame is made from Bosch 45mm T-slot aluminum extrusions and brackets that are very handy for building various temporary contraptions.
For concave side just flip the router jig (I reattached the router base with screws).
I found it is much easier to make passes along aluminum extrusions than working across. The bridge has to be twice as long as the width of the work piece (my was too short, so I attached the router off center and worked from the opposite sides).
I used 35 mm diameter surfacing bit. It works fine on the convex surface. On the concave side the router has to be tilted like so:
When tilted, flat bottom bit produces shallow elliptical grove rather than rectangular one. In this case passes must be made along the work piece, not across, to have seamless transition.
If the rail was circular (a large ring around work piece), one could produce spherical (bowl/dome) shape.