Sawdust on the Floor

Well, everything is set up on the arched top mirror we’re building, so I guess it’s time to get back to work. Oh, by the way thanks for coming back. The next step is to actually create the arched top. I chose to use my 3 HP plunge router equipped with a 1/2″ straight bit to cut the arch profile. To swing an arc with this I needed to modify the base of my router. I had a piece of 3/8″ Lexan that measured 24″ long, by 6″ wide. I scribed a center line down the length of the Lexan. I then removed the original base off of the router and replaced it with this piece of Lexan, making sure that the center line of the router and the center line of the Lexan router base were the at the same point. While I made mine, you can purchase one from several manufacturers if you prefer.

Now I measured back 16″ from the inside edge of the router bit, along the center line of this new base. At this point I drilled a 1/4″ hole in the Lexan along the center line. This created a pivot point for the router to swing from.

Before I began that portion of the task, I reattached a horizontal reference board. I wanted it back on for stability, of the arch and also to provide stability for my router. Instead of the same 4/4 Oak piece, I used a piece of stock that was built up to equal the 6/4 segment pieces. I also added a piece of this built up lumber along the center line of the layout board.

Finally,  it’s time to turn the router on and have some fun. I really enjoyed this part of the project, but to be honest it was one of the more tense portions. I didn’t want Murphy’s Law to sneak in at this state and turn several days of work into a pile of scrap. But here we go. You want to position the router so that the inside edge of the bit is on the line for the outer edge of the arch, and the center line of the router and the center line of the layout board are the same. Whew.

The idea is that you want to install a nail into the layout board through the hole you drilled in the modified router base. Your router now will act somewhat like the beam compass, only it will be removing wood. Starting at edge of the arch, slowly rotate the router around the pin, making several passes to remove all of the wood. Too large of a bite will result in either burning or tear out, so go slow. When you get all the way through the segments, you will have a nice smooth edge. As you can see the location of the nail/pin and the hole in the modified base are very critical, take your time setting them up.

One of the things I found out as I was doing this. The Lexan base that I had installed offered very little horizontal support to the router, in fact none at all. That is one of the reasons that I changed the horizontal reference board to the same thickness as the segment pieces. This is the same reason that I added the built up pieces to the center line of the layout board.

The other thing I realized half way through routing out the outer edge of the arch, is that I had placed all of the hold down screws outside of the segments which made sense at the time. The problem is that I was routing these pieces away, and if I continued there would be nothing holding down the arch. And that would not have been a good thing. So, I installed hold-down screws from the bottom of the layout board into the segments themselves.

After I had the outer ring of the arch completed. I simply removed the nail from the layout board, and reset it 2 1/2″ further down the center line. Once again, I made several passes with the plunge router, taking my time to allow the router and the bit to do the work. I treated the horizontal reference board as a sacrificial piece, continuing the arch into it.

One other thing that I did while doing all of this routing was to have my dust collection system going. I happen to have a floor mounted dust collection port that I placed as close as possible to the work. It didn’t get all of the cast offs, but enough so that I wasn’t ankle deep in saw dust. Believe me I have forgotten to use it before and ended up with a large mess to clean up when I was done.

Ok, now it was time to build the bottom portion of the mirror. The two stiles were easy to make. They were simply two pieces of 6/4 Oak, 2 1/2″ wide and 32″ long. I ran both pieces across the Jointer and the thickness planer, just as I had the pieces that formed up the segments of the arch. Once I was happy with the pieces I cut a #20 Biscuit slot into the end that would join up to the arch.

After some thought, I decided to leave the arch secured to the layout board. In fact I modified the layout board one more time. I removed the horizontal reference board from the layout board, after drawing vertical lines that were perpendicular to it. These lines were for the vertical stiles that were to be installed. After removing the horizontal piece, I cut it into two pieces length wise, and used these as reference pieces along the vertical lines. I screwed these into the layout board along the inside lines of the vertical stiles. These gave me an added place to clamp the stiles in place.

I applied glue and the # 20 Biscuits into the ends of the stiles and glued them onto the arch. To clamp this joint tight, while the glue dried, I installed a long pipe clamp from the bottom of the stile to the top of the layout board. To keep the pieces flat, I also clamped the stiles to the vertical reference pieces. I also added a couple of bar clamps along the end of the layout board. OK, I added quite a few clamps. I am one of those guys who figures you can never use too many clamps.

I let this piece set up over night, before continuing. The remaining two pieces, the bottom rail and the center rail were also cut from 6/4 Oak. Both pieces are 2 1/2″ wide, the length should be 31″ inches. but I subscribe to the theory that it’s better to mark the piece, rather then rely on measurements. After carefully removing the mirror from the layout out board, I did a dry fit of the bottom rail. Only after checking that it and the vertical stiles were at 90 degrees to each other, did I mark the final length of the piece. Instead of biscuits, I choose to use Kreg Pocket screws to connect the rails and stiles.

Once the bottom piece was in place, I turned my attention to the center rail, which was cut using the same process as the bottom rail. I again choose to use Pocket screws to attach the rail to the stiles.

Finally, I had the mirror frame done. Now I had to sand and dress it up. I proceeded to sand the entire top and bottom of the mirror to a 180 Grit . After that I once again turned to my plunge router and a 3/8″ round over bit. I carefully eased the outer edge of the entire mirror. Because there is the potential for the router to tilt, when you are routing such a small area ( 2 1/2″), I temporarily installed some 6/4 scrap along the inner edges of the mirror, to give the router a wider base.

There are only a couple of operations left to perform, prepare the mirror frame back for the mirror and fabricate and install the muntons to the mirror face. The muntons are going to take some time to get through, so I think those will wait till next time, however, I think we can still get the back of the mirror ready for the mirror.

Some of the design decisions I made is that the bottom mirror will be a single piece, with the decorative muntons applied to the face of the mirror. The same will hold true for the top, a single piece with applied muntons. The mirror I planned to use is just over 3/8″ of an inch in thickness. To secure the mirror itself to the mirror frame, I chose to use simple glass clamps that I got from the local woodworking store.

The glass clamps will actually set proud of the back of the mirror, and that was OK with me. I was really concerned about trying to bolt the mirror flat to the wall. What if the wall wasn’t totally flat? Would I crack the mirror or warp the frame, if I tried to force it flat? My solution to mounting the mirror, when I get to that, is to drill evenly spaced holes in the rails and arch. Through which I will use long wood screws and flat washers on the back to make up the distance the clamps hold the mirror off the wall. More on that later, I promise.

To cut the 3/8″ rabbit into the back of the mirror, I turned to the plunge router again. This time I equipped it with a rabbit bit, equipped with a selectable bearing. I installed the bearing that would produce a 3/8 x 3/8 Rabbit. Once again I installed the extra 6/4 pieces outside of the mirror frame to provide extra stability to the router, while I worked on the narrow rails and stiles. I made several passes, so that I didn’t burn the wood or over work the router.

The router works great every place but in the corners, there I needed to do a little clean up. I used a square corner chisel to clean up the corners on the bottom of the mirror. For the top, it was the old fashion method if a sharp chisel and a mallet to get the corners cleaned out.

OK, my back is sore, it’s time to quite for now. I think I will just vacuum up the shop and go see what’s for dinner. If you want to help figure out the muntons, please come back for part 3. I will welcome the company.