This is a jig I made from scraps around the machine shop and 80-20 Extrusion components. A plunge router will ride long the top rails with the workpiece held between centers via pointed shafts mounted to roller bearings.
An indexing wheel mounted to the outside will fix the rotation for each fluting "run". The indexing wheel is secured with a 1/4-20 machine screw.
Let's take Humpty Dumpty apart and see how it works then see if we can do better than all the King's Horses and all the King's Men....Here is the "Index" end taken apart. Working from left to right we'll re-asemble.
I needed a sharp pointed centering pin. So I ground down a 1/4-20 machine screw.
It will sit in a countersunk hole on the outside plate-
The inside plate is screwed to the bearing shaft.
Now the two plates are screwed together
The screw head that was ground to a point is back to back (or should I say "Head to Head"?) with the screw that tightens the innnerplate to the shaft.,- leaving a sharp tip for mounting the work piece.
NEXT we mount the bearing in the end plate, then fix the end plate to the jig extrusions and attach the indexing wheel. Let's look at the bearing mount.
The bearing rides in a sleeve. I milled a press fit for the sleeve in the end plate.
In order to capture the bearing I made a second plate that gets bolted to the endplate
The milled cavity had be just right.
An indexing wheel mounted to the outside will fix the rotation for each fluting "run".
First the end plate gets mounted to the Extrusions
The mounting screws for the end plate are not flush and I needed to to extend the index wheel anyway so I made a bushing that separates the wheel from the endplate.That distance turned out to be 1/2 inch.
I mounted a 1/2 in flange nut at the base of the plate also. This is where the indexing wheel is secured for each cut.
Now we fasten the indexing wheel/spacer bushing to the tapped bearing shaft and we're almost ready to go!
The indexing wheel has twelve 1/4 inch holes. A 1/4-20 machine screw tightens the wheel at the base for each cut.
The other end of the jig is constructed the nearly the same- It just doesn't have an indexing wheel mounted to the out side, and the inside bearing shaft is turned to a point to secure the opposite end of the work piece. This photo shows the jig in extrusions about 16 inches long.
Well I turned a leg and now am ready to mount it in the jig. First we attach one end to the mounting plate.
I reattach the mounting plate to the index wheel and end plate.
The rear plate is brought up tight to the other end and tightened in place.
The router is in place. It's base slides along the interior grooves of the extrusions.
I needed to set a stop at the head end. The router base hits the mounting plate- but it just happed to hit exactly where I wanted the stop. As the index wheel rotates, the router base will not engage the mounting plate. I tightened the 1/4-20 screw and t-nut in place. Then set and tightened a similar stop at the other end.
I routed away and she works!
ONE down. Three to go.
Several Weeks Later-I finally turned and then ran all the flutes in the other three legs.
Here are a couple of shots with two legs clamped in place to the front frame pieces.
