The dust settled from the last couple of small projects, and I have finally continued work on the Longworth chuck. I struggled with what to use for the rubber grabbers, and was planning to order some rubber stoppers for test tubes but kept putting off buying them for some stupid reason. Then I was with my wife at Walmart one day and I ran across some replacement feet for folding chairs. My brain fires off the thought, so I grabbed them asthey should work great for this project.
I cut some sections of a dowel on the table saw, then drilled them on the lathe with a 3-jaw chuck. After that I used a chunk of dowel and put each rubber foot on the lathe to drill a hole and inserted a bolt. There is the perfect amount of tension when tightened with a wing nut – they snug up quite nicely.
I then used a 1/8″ piece of hard board/Masonite to make a circle cutting jig. While I already had one, this one allowed me to slot the pivot point slightly giving the 1/4″ spiral up cut bit a bit of slop. Holding the jig close on the first pass, and pushed away on the second pass allowed for a nearly perfect amount of play. If it was too tight or too loose it would bind once assembled .
We had previously drilled holes into the top layer with a little bit of play in them. This allowed the drill bit to be reused as the pivot point. A comfortably snug fit, yet easily moved. Notice there are 4 short slots and 4 long ones, and that the slots go all the way through both boards. All went well with this, minus the hand and arm cramping while holding the router. The boards are sitting on double stacked bench cookies to keep the attached metal chuck from touching the bench. Just watch the bench cookies, you don’t want to route a groove through them.
Once all the routing was complete, I unscrewed the top board, flipped it over and inserted the center pin. Then the top board got rotated until the outer points of the arcs lined up, long to long and short to short. The rubber feet were then inserted into the assemblies in each hole. We put washers on both sides of the board so it will slide a bit easier.
Its not quite done yet, but the picture below is proof that it will work. Finger hole still need to be drilled in it as it’s annoying and painful to rotate. It also needs a bit more sanding on the grooves to remove the sharp edges and fuzzies from the routing process. Then it will be time to true it all up on the lathe to make the outside concentric and round off the edges as I sure don’t want to catch that on my hand or arm accidentally. A bit of finish and a coat of wax for good measure and it will be done!