How make corner 4x4 posts with 1 1/2 groove to attach 2x6 boards for raised garden bed garden boxes?

Question

I'm in the process of building some raised garden beds out of cedar and I'm using 4x4 as corner posts and I want to put a 1 1/2" slots in the 4x4 posts to secure the ends of 2x6's into the corners. I will then use lag bolts to attach the 2x6's to the 4x4's. This way the 2x6's ends won't curl up as this commonly happens after been exposed to the elements. My problem is a have a basic router and table saw and can't decide on the easiest way to make the groove's in the 4x4's. Is there a router bit that will cut 1 1/2' wide and 3/4 deep? Or is there a dado blade that I should be buying to attach to my table saw (assuming my table saw will let me). An additional challenge I face with this grove is that I only want it to go up 18 inches of the 24 inches of the 4x4 and need help on how to do this.

Thank you for your responses!

Answer 1

I am going to make some assumption here due to not having a picture or drawing to go from.

1. The groove is to be started at one end of the 4X4, not in from the ends.

2. The groove will be along the edge of the 4X4, at one or more corners.



If so, you can use the table saw or a hand-held circular saw and rip from the bottom of the 4X4 up to the highest point of the groove at whatever depth you want the 2X material to sit; I would recommend flush. This would be 1 1/2 inches from the edge of the 4X4 and at least 1/2 the width of the 4X4 (1 3/4"). Scribe a line along one side of the 4X4 at 1 1/2" and on the other face at 1 3/4" the length you intend to cut out. Mark a square line at that point across the sides that will be up during the cutting or place a stop block at that distance from the blades cutting edge.

When you make the saw cuts there will be a small section the the blade cannot reach unless you overcut. That can be removed using a wood chisel after the main portion has been removed.

Saw setup: Set the blade height to 1 3/4" above the table and the fence at 1 1/2" from the blade. Make all the cuts needed at this setting on all the 4X4 posts first. After these cuts are made lower the blade to 1 3/8" and move the fence to 1 3/4" from the blade. Make all the cuts on each 4X4 at this setting. Cut across the square mark you made earlier, using a circular saw if you have one. This can be dangerous on a table saw and I highly recommend not using it for this application. You should now be able to remove the main portions of the cutouts from the 4X4 posts and, using a wood chisel and hammer, remove the remaining portion of 4X4 to achieve a smooth surface for the 2X boards.



Good luck and enjoy!

Answer 2

We made ours using gravel boards, which you get from a timber merchant. Gravel boards are long planks of wood about 2metres by 15cm (6ins) which you can cut to the length you want. They come pre-treated against rot and last a good long time. We put strong stakes in the corners and screwed the planks to these. 6 years ago, they're still going strong, much cheaper than the plastic kind and you can make them to your own size requirements.

Answer 3

1

Answer 4

use your table saw, that'll be fine