After using this jig you will wonder how you got a tight, highly structural joint before. The cams will provide a very high clamping pressure and if you have prepared the joint properly, it is difficult to find the joint. I joined a AAA Spruce tenor ukulele top a few weeks ago. As we recommend, you should straighten the joint on each side of the plate to align parallel with the grain. After joining this top, I couldn’t find the joint. It was completely invisible!
Parts and material list is as follows:
Minimum 19mm (3/4″) cabinet grade plywood. This will usually be 11 or 13 ply with no voids. You find it most commonly as birch faced cabinet plywood. If you an find a stock of 1″ – go for it. The extra beef is worth it.
Jig Fence (Guitar Jig Only):
19mm (3/4″) Cabinet Grade Plywood. I like to make this fence adjustable to accommodate different widths of wood plates. This means a board approximately 3″ wide x 6/4 or 1-1/2″ in thickness. Use 3/8″ carriage or stove bolts with nice large plastic knobs for easy adjustment. Place flat washers between all movable parts. This means 3 washers per bolt.
Also the fence need to be adjustable to allow for different sized tops and different sized guitars. This is done by slotting the Jig Base and allowing the fence to have free movement for about 3″. Once you fit your top plates into the jig, you can open-up the clamps and adjust the fence to “snug-up” against the plate edge.
Undoubtedly the most critical element of this jig are the lockable cams. These have to be crafted out of 19mm (3/4″) cabinet grade plywood with an off-center pivot and this allows approximately 1-1/2″ of clamping action. Also use large tension knobs on the 5/16″ carriage or stove blots for each of the 3 or 4 cams so you can really tighten them down. Note: The guitar jig has 3 cams and the ukulele jig has 4.
The third movable component on this jig is the Seam Clamp. It is made from (2) layers of 19mm (3/4″) cabinet grade plywood, and has the same knob tightening system as the cam clamps and the jig fence. The fixture also need to be adjustable as to be able to place the fixture over the center of different sized top plates. Again it is done by slotting the Jig Base and allowing for about a 3″ travel. There are (2) tightening knobs – one at each end of the fixture.
HDPE Non-Stick Sheet:
If you want the ultimate in functionality, you can add a 1/8″ to 1/4″ HDPE sheet beneath the Seam Clamp and at the bottom of the Seam Clamp. This will prevent the plates from sticking to the jig. HDPE is know for its non-stick properties. The bottom sheet can be friction fit into a bottom channel (because it cannot be glued) and the sheet that is placed on the bottom of the Seam Clamp can be fastened with small, countersunk screws.
As I always stress, when you make your jigs, molds, templates etc. make them with the same care as with your guitars. Make them in such as was as to show them off. Impress you potential clients with your quality construction and your attention to detail and abilities – even in your work aids, such as this jig.
Our plans for this jig are very detailed and will give you all the dimensions and construction notes you need to make this jig. The hardware package includes the bolts, free-spinning knobs, the HDPE non-stick plastic sheets and rubber feet.