The groove you'll be routing will be 1/2" wide "same as the thickness of the plywood" and 3/8" deep. We want this groove to be slightly deeper than the 1/4" over hang you'll be cutting the plywood, which will give it some breathing space. You'll need to pickup a 1/2" Straight Cutting router bit.
NOTE: When you buy your router bits you have to remember what size shank or chuck you have on your router. Most higher quality routers have both the 1/4" and 1/2" chuck but the lower end models will only have the 1/4" chuck. Be aware of this before you buy your router bits!! The reason for the two thicknesses is that a 1/2" chuck will allow for a much stronger router bit that can take on those big jobs that need to cut deep grooves in thick hardwood stock; such as this!
The 3/8" groove depth will allow for some extra space when you put the table border and plywood together during gluing; you wont be gluing the plywood just the table border!
The image below shows a cut view of the side board with the inside groove/slot for the 1/2" Birch Plywood base. You will be routing out the dark brown area.
The first thing we want to do before we even set the boards on the router table is rip a quick groove on the LONG side boards using the table saw to remove some extra wood from the board and give the router an easier job at cutting the groove. Whenever you can take some extra material from a board to give another tool an easier job and relieve the stress on the tool, it's much better for THAT tool and will help it last longer. The rip/groove cut in the long side board removes some extra material that the router doesn't have to deal with and puts a lot less stress and load on the motor of the router; intern giving it a longer life span.
Setup your table saw to the following settings:
Set the blade height to 3/8" as shown above.
Set the width of the cut to 1 - 7/16" wide as shown above
CRITICAL: These settings and the cuts will only be used on the LONG SIDE BOARDS, since you can cut them straight across and the groove wont show on the outside. If you were to cut the Short side board you'd end up leaving an ugly groove hole showing on the corner of the table. Not good!
Once you have these setting ready on the table saw go ahead and laydown the LONG SIDE BOARD on the table saw but DON'T CUT THE BOARD YET!!!
CRITICAL: Make sure you have the word OUTSIDE showing on the top side of the board face so you can read it and the word TOP on the edge of the board facing you and not the RIP FENCE/RAIL side! If this is not correct you will end up cutting a groove on the wrong side of the board! See image below!
When you have the board laid out correctly go ahead and rip the groove along the length of the board. Do this for both LONG SIDE BOARDS!
Now we can move on to the router and cut the main groove on each of the four boards. You will be using TWO methods when routing the boards for the main table border.
1. Straight router cut along the LONG SIDE BOARDS, on top of the rip cut you just made!
2. Precision cut along the inner portion of the SHORT SIDE BOARDS, but not through from end to end. You will be dropping the board on top of the router bit about 1/2" from the edge of the board, then cut along the board but STOPPING about 1/2" before you get to the other end of the board! Don't worry, I will explain this in more detail!!
CRITICAL: The reason for this precision route is because a full groove cut along the side of the SHORT SIDE BOARDS would produce an ugly open notch in the corner of your table, which is what we don't want.
This is something you DO NOT want so to avoid this you will have to make a controlled router cut on the SHORT SIDE BOARDS. What I mean by this is, "when you route the board you will DROP THE BOARD on the spinning router bit 1/2" from the edge, let it sink into the wood, THEN start pushing the wood piece till you get to 1/2" of the opposite edge, intern pulling up of the board and removing it from the spinning router bit before it cuts through the edge of the board! I know, this sounds difficult and confusing but I will explain soon!
Let's start with the LONG SIDE BOARDS and setup the router table with the correct router bit and height. You need a 1/2" square end bit, set to a height of 1/8" for the first pass. We are going to cut the board in [3] passes using 1/8" increments; this will give us our final groove depth of 3/8".
The distance of the edge of the router bit to the face plate is 1 - 1/4"! This means you will have a distance of one and a quarter inch from the bottom of the board to the start of the groove!
Below is what the router table setup should look like before you make your first router pass!
NOTE: DO NOT ADJUST THE TABLE SETTINGS, YOU WILL USE THEM AGAIN FOR THE SHORT SIDE BOARDS!
Now we can move onto the more difficult cuts of the SHORT SIDE BOARDS! When routing these two boards you are going to have to pay special attention to what you are doing to prevent the router from cutting through to the end of the board or your fingers!!
WARNING: The next step is dangerous and if you are not familiar with this procedure or you have never done any woodworking I recommend you get someone to help with this step. I present the next step only to those who know what to do and I take no responsibility for any injury or damage that may occur to those who follow these steps without the proper knowledge or skill. CONTINUE AT YOUR OWN RISK!
CRITICAL: This type of cutting is dangerous and if not done correctly you can injure yourself or mess up your material. Make sure you are very comfortable with doing this type of cut before you continue and be certain you know exactly how you will perform the cut. Remember that you will be placing the board ON TOP of an already spinning router bit so you need to be extremely careful and aware of what you are doing!!! If you just aren't comfortable enough to do this type of cut you can always do the same cuts as the LONG SIDE BOARDS and have notches show up in the corners! With this method you will at least have your table to play on!
NOTE: If you can't perform this step you can always place the board face up on the table and route the groove using the router manually and routing the top of the board instead of using the router table. I will show this method once in a separate blog at the end, showing all the optional methods.
Lower the router bit back down to a height of 1/8", it would be too much of a cut to try and do the whole 3/8" cut in one shot! DON'T TRY IT BECAUSE THE BOARD WILL END UP JUMPING AND GET RUINED!
Again, set the board as shown in the image below:
Now, with the router turned on, pick up the board and move it above and past the spinning router bit but don't let the board touch the bit. When you are about 1/2" past the router bit go ahead and lower the board onto the spinning bit while pressing straight down and against the router fence till the board comes to a stop.
WARNING: KEEP YOUR FINGERS AWAY FROM THE EDGE OF THE BOARD AND THE SPINNING ROUTER BIT!!!!
With the router still spinning start pushing the board along the table to start cutting the groove. Keep moving the board at a relatively quick pace trying not to stop or you will end up burning the wood where the router bit is spinning in one spot! As you get to the end of the board slow down and stop pushing at about 1/2" from the edge! Make sure you have a strong hold on the board and AGAIN, KEEP FINGERS AWAY FROM EDGE AND THE SPINNING BIT! Once you have stopped the board at the 1/2" measurement from the edge, go ahead and stop the router or pick up the board!! Pick the board up and blowout all the sawdust trapped in the groove. After you have cleaned out the groove, raise the bit another 1/8" and run the board through another pass! Perform the pass exactly the same way you did the first pass! When you get the edge again slow down and stop 1/2" before the edge of the board. Clean out the groove again and raise the bit one last time another 1/8" for the total 3/8" height! After this last pass your board should look like the image below:
Below are all four boards after they've been routed!
That does it for the LONG AND SHORT side boards, we can now move onto the inner Birch Plywood base board.
On to the next post!
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