Phil Thien
03-23-2008, 4:36 PM
I've included a pic of my original sled. It uses two t-slots and aluminum sub-fences that allow me to achieve any desired angle. I use a protractor to set the angles (nothing marked on the board).
It works great, with the only caveat being that it takes quite a while to adjust to an angle because I have to slide the sacrificial fence on the sub-fence. There are six knobs required for all of this. So, time intensive. Also, using a protractor each time gets tedious. Oh, and my kids keep taking my protractors for their homework!
I decided having something similar to the Dubby made sense (http://www.in-lineindustries.com/single_dubby.html). Rockler sells one of these, too. But $200 is too much to spend. But, I'd be able to make some permanent marks for angles, make fast adjustments, etc.
I decided to use an Incra 18" runner, and I made my substrate 17" square. This is a prototype, so I may go larger if I decide to make another one.
Instead of routing a slot for a carriage bolt (which would require removing my one and only router from my router table), I decided I'd use a t-bolt and t-slot. This clever (IIDSSM) alternative allows me to route the t-slot all the way to the edge of the board w/o compromising the strength of the substrate. I used a jig screwed to my router table's lift as shown in one of the photos. I use a 12" radius.
The only thing I'm kinda stuck on, and this is where you come in, is how to handle the pivot. I have a 1/4" hole that I used as the pivot to route my arc, and that will act as the pivot for my fence, too.
I could use a carriage-head bolt from underneath (which would have to be countersunk) into a knob above, but my substrate is only 1/2" thick (with the countersink this may not be thick enough to accommodate the square portion of the carriage-head bolt.
I could use a threaded insert in the substrate, but I SUCK at putting them in (and my experience is that they don't like plywood, they separate the plys).
I could countersink the hole from underneath and use a flat-head screw from the bottom into a knob on top, but when tightening from above the screw would spin in the hole underneath (nothing to grab it).
I have seen on McMaster a flat-head screw that had little bumps or keys in it that would prevent it from spinning in a hole. But I can't find them now. I can't remember what they were called. And I have never used them so I don't know how well they work.
It works great, with the only caveat being that it takes quite a while to adjust to an angle because I have to slide the sacrificial fence on the sub-fence. There are six knobs required for all of this. So, time intensive. Also, using a protractor each time gets tedious. Oh, and my kids keep taking my protractors for their homework!
I decided having something similar to the Dubby made sense (http://www.in-lineindustries.com/single_dubby.html). Rockler sells one of these, too. But $200 is too much to spend. But, I'd be able to make some permanent marks for angles, make fast adjustments, etc.
I decided to use an Incra 18" runner, and I made my substrate 17" square. This is a prototype, so I may go larger if I decide to make another one.
Instead of routing a slot for a carriage bolt (which would require removing my one and only router from my router table), I decided I'd use a t-bolt and t-slot. This clever (IIDSSM) alternative allows me to route the t-slot all the way to the edge of the board w/o compromising the strength of the substrate. I used a jig screwed to my router table's lift as shown in one of the photos. I use a 12" radius.
The only thing I'm kinda stuck on, and this is where you come in, is how to handle the pivot. I have a 1/4" hole that I used as the pivot to route my arc, and that will act as the pivot for my fence, too.
I could use a carriage-head bolt from underneath (which would have to be countersunk) into a knob above, but my substrate is only 1/2" thick (with the countersink this may not be thick enough to accommodate the square portion of the carriage-head bolt.
I could use a threaded insert in the substrate, but I SUCK at putting them in (and my experience is that they don't like plywood, they separate the plys).
I could countersink the hole from underneath and use a flat-head screw from the bottom into a knob on top, but when tightening from above the screw would spin in the hole underneath (nothing to grab it).
I have seen on McMaster a flat-head screw that had little bumps or keys in it that would prevent it from spinning in a hole. But I can't find them now. I can't remember what they were called. And I have never used them so I don't know how well they work.