Apart from putting finish on guitars, the binding process has been my biggest frustration. My guitars have big arches on the top and backs, both laterally and longitudinally and cutting channels around the upper/lower bouts and waist areas has been very frustrating involving lots of cuts altering both depth and width.
I use a Makita laminate trimmer, which is light enough hand held and comes with a side following attachment that lets me use ordinary router bits rather than those with guide bearings. This has the power, but the base area is too big to follow just the edge (hence the bout/waist problems). The solution is to put a raised area on the base close to the cutting edge of the bit with a very small surface area to follow just the edge. This, however, makes the trimmer very unstable hand held.
Having done some research, Don Williams adaptation of the Harry Fleischman jig was the perfect solution to give me stability. I want to have the trimmer moving round the guitar as I think this gives me better control in areas such as the bottom and top of the guitar where purflings have to be mitred. I set myself the goal of producing the binding and purfling ledge in width and depth with just one pass of the cutter.
Getting to the end of making Don's Jig (thanks for the great info on your website Don!!) I realised that I would not have freedom of motion in all of the directions I required. Don's jig can only adjust the angle the trimmer meets the guitar via the movement from the main Lazy Suzy bearing, so if you are, say, going round the lower bout into the waist area then the trimmer stays more or less at the same tangential angle to the perpendicular sides. The round donut on the base means this keeps the trimmer on the top but it bridges longish lengths in places. With the more common arching used on guitars this wouldn't be a problem, but with the degree of arching I have on my guitars the bridging of the donut would not give me a uniform depth binding channel in these critical areas. Hence I needed the trimmer to swivel, to keep the small "follower" on the top/back edge and the routing bit and guide perpendicular to the sides at all times.
I have had to do a modification to Don's design to enable this by putting another smaller Lazy Suzan bearing in the part of the jig that holds the trimmer. The follower is a small donut bandsawed from a food chopping board, with a 13mm hole drilled in centre, epoxied to the base. The beauty of it for me is that I can use just the one router bit to cut the binding/purfling channels and adjust the depth and width of cut on the trimmer. I have set it up for a 11mm double flute (I have found this wide enough for all of the binding/purfling combinations I use) and this drops through a 13mm hole drilled in the new base plate.
Lazy Suzy bearing with the centre hole big enough to take my Makita laminate trimmer.
The knob that holds the Makita side guide follower needs thinning slightly to fit in the centre of the Lazy Susan bearing and still be adjustable.
The new base plate is fitted to the Makita holder.
A mounting plate for the trimmer is made from Birch ply with the centre hole matching that of the Lazy Suzy bearing and attached to the binding jij sliding arm. The four holes match with the Lazy Susan bearing plates.
This is how rhe Lazy Suzy will attach.
The Makita base plate isattached to bottom plate of the Lazy Susan bearing with nuts/bolts/ washers. In my first version I used half of a rubber tap washer as the bearing to ride on the guitar top/back and this is shown in this picture. This didn't work out too well.
So I replaced this with a donut bandsawed from food chopping board, with 13mm hole drilled in centre, epoxied to the base.
The Makita laminate trimmer is put into it's holder.
The height and depth of cut set as normal using the laminate trimmer.
And here it is in action.