Help: Attaching chunky legs to farmhouse table.

[Mechelle]

Looking for advise. I am hoping for suggestions on best way to attach legs to table. Background: A few years ago I built a 4 x 8 farmhouse table in 2 sections of 4 x 4 each. Rustic looking using 4x4s for the legs. I was fairly new to building things that major and used pocket hole screws to attach everything. The reason it was made in two sections was becaus the table would serve a dual purpose. In November and December serve as dining room table for family coming in for holidays and the rest of the year sections would be separated for quilting and craft table. It turned out pretty good and the table is sturdy as hell, will probably be around long after I am gone (providing it doesn't get destroyed in a fire or something of that nature). However, I have noticed the 4x4 legs have cracks in them now, which, after doing a lot of research is to be expected due to wood expansion (didn't know about that then). 

Recently I decided to build another dining room table. This one will be a solid 6 ft in length. I purchased some beautiful chunky rolled farmhouse table legs with a 5x5 inch shank. Before I start building I wanted to make sure I did as much research as possible on the best ways to build to avoid cracking. I understand how to attach the apron to the table top using fastners. I have ordered good steel figure 8 fasteners that I will make a countersink with my forstner bit in the apron and attach to the top. I also read it wouldn't hurt to use 1 pocket hole screw in the center at the short ends and that will still allow expansion without cracking. What I am at a lost for is the best way to attach the table legs themselves to the table, so that the legs won't eventually crack. I have watched video after video and the only one that specifically showed the table leg attachment (other than just saying "next you attach the table leg and you're finished) was one guy ran a bolt through the brace that caddy-cornered into the corner and center of the leg. That didn't seem like it would make a good hold, to me. So any suggestions? If I pocket hole from the ends of the apron into the shank of the legs will that cause splitting later on? Do I glue the leg to the table top? It just seems the legs, as heavy as they are, should be attached to the top, themselves, somehow. The legs do not have the predrilled bolts in them. They are flat on top. I really want to do a good job on this and get all my ducks in a row before starting. I included a photo of the legs. Any suggestions would be greatly appreciated. Thanks.

[Matt Tennessen]

I'm guessing the video you watched had either a wooden or prefabricated metal corner bracket. Those typically work on knockdown tables by using the bolt to pull the leg towards the bracket, thus bracing it tightly against the walls of he apron. A substantial mortise and tenon would be my preferred method but depending upon your skill set or available tools that might not be a possibility. This Youtube video might be helpful for you. 

PS, don't attach the legs into the table top, just the aprons. 

[wdwerker]

I have made wooden corner brackets instead of using the metal ones but the legs attach to the aprons and the aprons attach to the top. Mortice and tenon, Dominos or dowels from the aprons to the leg are a good idea.  Making the legs removable is a good idea on a large table, even if multiple screws have to be removed. 

Another way to mount the tabletop to the apron is " Z clips" or furniture buttons that fit into a mortice in the aprons. Your top will change width across the grain but the length won't change enough to matter. 

[wtnhighlander]

The problem with the thick legs is that the interior moisture content is difficult to determine. Also, thicker material can create more force as it collects water and swells. My best suggestion is to do what you can to stabilize the moisture in the legs. @wdwerker often mentions taking a daily measurement of the object's weight, until it stops changing. Requires time, but should be a good indicator.

Then seal EVERY SQUARE MICRON of all surfaces to help slow moisture transfer. You won't stop it, but you can buy yourself some tolerance for short-term swings.

Assuming the need to use knock-down brackets as shown above, be sure to drill correctly sized pilot holes for the lag bolts. 

All these actions will minimize the chances of the legs cracking or splitting.