ConstructionEssentially it comprises:
- a base 10" x 17" made from 18mm plywood (preferably baltic birch 3/4")
- a clamp plate 8" x 17" made again from 18mm plywood
- a hardwood fence, in my case an oak scrap, glued onto the clamp plate
- 8 off 3/8" captive T nuts
- 4 off 10mm (3/8") washers
- 2 off 3/8" star knobs
- 2 off self adjusting toggle clamps
- 8 off M5 x 40 long countersunk head socket screws with nuts and washers(or equivalent imperial).
The hardwood fence is glued to the top plate and cut away to clear the star knobs when they are in the forward position.
Drill 2 columns of 4 holes (8 in total) for the T-nuts in the base plate. These start 3-3/8" from the front of the longest edge of the base plate on 15" centres. The remaining 3 pairs of holes are drilled inline with the first two on 1-1/4" centres.
Next counterbore these holes on the underside of the base plate with a Forstner bit to clear the head of the T-nuts. Then the T-Nuts are inserted from the underside and hammered home.
|Underside of base plate showing the|
counterbores for the heads of the T-nuts
The two slots in the clamp plate are routed to line up with the base plate holes again on 15" centres as clearance for the threaded shafts on the star knobs.
|Top view of the full assembly|
Note there is no workpiece shown here
In the article Tim suggested using captive T-nuts on the underside with screws holding the clamps from the top but I didn't have any small T-Nuts so used the method above.
A hole is then drilled to hang the jig up.
|Section through the jig|
(photos below taken from the article while viewing it on an ipad)
|Photo of jig in action|