It’s been a little while since the first entry. Hopefully, things will start moving a little faster. Maybe.
Not a lot done, but I’ve finished one of the more difficult parts of the build. The bearing mounts that will hold the cutterhead.
I started with 2 blocks of aluminum, 1”x3”x5”.
I first drilled 2 holes in each, so that I could bolt them to my CNC router. The first thing I did was route the pockets for the bearings. I started a little under size, then snuck up on the size until I could just push them in with my fingers, but too tight to pull them out. After I got the size figured out, I trimmed the perimeter to the final size.
Then, it was a lot of work on the drill press, drilling a lot of 3” deep holes.
I first drilled the 4 mounting holes 3/16” diameter. I then attached the steel base plates to the aluminum with double sided tape, and used the drill press to mark the hole locations in the steel plates. Then drill and tap the steel for the 1/4-20 threads, and enlarge all the 3/16” holes to 1/4”
I countersunk the center holes, and then flipped the block upside down and enlarged the bottom 2/3 of the holes to 5/16” for a little clearance.
I then enlarged the outer holes to 5/16” for clearance.
After what seemed like 4-5 hours at the drill press, I was finally done drilling the aluminum.
Next step was to cut the 45° corners on the table saw. I left them square until the drilling was done to make the drilling easier.
I set up a stop block on my cutoff sled, and cut all 4 corners off. Cutting aluminum on the table saw with the blade at 45° throws chips everywhere.
The last step was to counterbore the outer mounting holes on the beveled edges.
I clamped the blocks to a fixture block mounted to my CNC router, then used a probing routine to find the center of each hole. I used a 3/8” 2 flute spiral bit to counterbore the hole to .65”, to allow a little clearance around the 5/8” washers.
Final step was about an hour of wet sanding to give them a finished look. They’re not perfect, but not too bad. I was able to get almost all of the milling marks off. There’s just one bad spot. I tend to pay a lot of attention to detail at the start of my projects, and not so much at the end when I just want them finished. But I really want to try and make this look as good as possible.
So right now, the steel base plates are drilled and tapped to accept the bearing blocks. When the side rails are ready, I need to drill the mounting holes in the steel base plate, and transfer the holes to the side rails. Then I’ll epoxy and screw the base plates to the rails, giving me a solid mounting point for the bearing blocks. Much better than a small piece of baltic birch.
Tomorrow I start working on the LVL side rails.
Here’s a CAD screenshot showing the bearing block, mounting plate and hardware.
And here are the finished bearing blocks. Right now, the back block is closed on the back side, but I may open it up, so that I can get the bearing out if I need to change it.