I was having a hard time with a temporary (and maybe inaccurate) sled making my final sled that needed to be accurate (chicken or the egg). So, I decided to make my own sled by hand as best I could. If still off maybe I’d have a better chance at getting a more accurate final sled. I have yet to make that final sled because my hand made one seems to work just fine.
Here are some pictures of the build.
I started with creating a simple print out with some circles to aid in positioning things. Taped it to the board then drilled a 1/4" hole dead center in the circle middle.
Then a quick scrap piece of wood became my circle jig that has a 1/4" hole in the middle spaced 9" from the center of the hole to the inside of my router bit (giving me a 18" sled when done).
Then round and round stepping the bit down each pass.
Then using the same 1/4" hole, I placed my 1/4" bit in that hole for aligning my router to the center of the sled.
Then, using the print out circles, I placed my ring upside down so I could center it “exactly” in the middle of the sled/bit. I was careful to keep the same brackets in the same spot just in case they were slightly different.
A center punch helped get holes right where they needed to be.
Then all the holes where drilled or had pilot holes drilled for bolts/screws.
Center hole for router bit clearance was next. Yup, you guessed it - same 1/4" hole (although this one didn’t really need to be centered).
Cleanup time. I used a chamfer bit to router the outside sled edge and inside circle edge. I also heavily rounded all counterbore holes to help them not get caught on previous cuts.
Time to place the bricks. This I could have made a little better/easier but I placed these by eyeballing it with some measurements to make sure they were somewhat symmetric.
Then I opted to put on numerous coats of polyurethane to seal the wood, create a hard surface to prolong sliding life, reduce friction slightly as it glides and creates a smooth surface for saw dust to fall off. Make sure it dries for a few days after your last coat to get it good and hard.
Then everything was installed. Z-axis holes were drilled after everything was mounted.
I’m quite pleased with how it turned out and feel like I did the best I could to get everything centered by using the same 1/4" hole and template. I’m starting to cut some test cuts and I’ll update on how accurate it is. I’m curious about the center hole roll test @Dustcloud has mentioned. Thanks to everyone for your tips and inspiration.
Edit: Also, just for completeness, I sanded the inside edge the ring bearings ride on to remove the bumpy paint. Glides great now. I also sanded the inside router base to help the router go up and down for Z-axis then applied some light grease to the same housing and the Z-axis screw rod. I am using a bungie for positive Z-axis engagement attaching to the handle bolts (without the handles).