Leg for a Wooden Table (incredible Strength)

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Introduction: Leg for a Wooden Table (incredible Strength)

I would like to start this post by thanking instructables for featuring my previous post. Hence I am still here and I am writing another instructable.

In this instructable, I will be teaching you how, incredibly cheaply, you can make a leg for a wooden table that is incredibly sturdy, without the use of any wooden support features and/or metal brackets. The wood needed is only that for the leg and that for the table top, but nothing else!

The concept demonstrated in this instructable is inspired by a type of a fastener called a "barrel nut", which is often used by furniture makers (such as the furniture made by IKEA). This concept is taken to its limits in this instructable.

Assuming you got your 4 in x 4 in posts for the legs, and any wood of your choice for the table top, then this instructable requires merely the following:

(a) A 1/2'' GI pipe nipple for each leg you intend to attach to the table top

(b) An M12 bolt of your choice for each leg you intend to attach to the table top

(c) Only two 1/2'' GI pipe caps, which you will use during the making of each leg but do not need to remain attached to the leg

The cost of all the above combined in Dubai (where I currently live) is 30AED (for a table with four legs!) which is equivalent to $8 US.

Beside the enormous savings and the rigidity, this construction method works very well even with low-quality wooden posts with cracks running along them. The only disadvantage I can think of is the fact that the table top strength becomes the weakest link in the design (more on that in the last step of the instructable, when we stress test the leg made).

So let's begin!

Step 1: Clamp and Mark

The first step is clamping your choice of table top onto the leg's wooden post and following your choice of the M12 bolt, mark the end of the usable thread. Let's call this "the first line".

Now grab your caliper and measure the outer diameter of the GI nipple you purchased for this build, doing so, tighten the locking screw on top of the caliper to prevent the measurement from drifting as you remove the nipple.

The reason for doing so is that we are going to use the caliper's internal jaws to offset "the first line" in the direction pointing towards the table top, resulting in what we choose to call "the second line".

The two lines are parallel, and they represent the deeper and the shallower side of the GI nipple as it passes through the leg's wooden post. From the two lines, it is easy to discern the center for drilling. (in the next step)

Step 2: Drill the GI Nipple's Support Hole

Before drilling, it is also advisable to use a center punch to mark the exact position where the hole is to be drilled.

Once punched, use a 22mm spade drill bit, drilling from below (very important!) and penetrating the wooden post throughout.

Take it easy as you drill, try to go up as straightly as possible.

Once finished drilling, it is the time to drill the bolt's mounting hole. (in the next step)

Step 3: Drill the Bolt's Mounting Hole

Perpendicular to the previous hole, and centered within the leg's face meeting with the table top, we drill a 12mm hole to pass the mounting bolt.

Doing so, it is incredibly important to drill past the cavity created by the previous drilling operation (check the last photo attached to this step).

Now that both of the perpendicular mounting and support holes are created, it is the time to insert the GI nipple which would act as a giant barrel nut. (in the next step)

Step 4: Insert the GI Nipple

Doing so, you need to distribute the thread equally between the right and the left side, by skillfully loosening and tightening the right and left GI caps.

Now that the GI nipple is in place, it is the time to drill it, which is by far the most time consuming part of this build (takes 5-10 minutes, and is the subject of the next step).

[Note that in the video attached to this step, the hole for the bolt is not made, in your case you should have that hole already made so do not doubt yourself]

Step 5: Drill and Tap the GI Nipple

Congratulations! You're not very far from finishing this build, however, this is the time where you need to take a break as it is the most critical, and arguably the step that requires the maximum amount of attention and care.

Before we start, you need to mount your leg post in an upright position, preferably in a vice. It needs to be mounted pretty sturdily as both the drilling and the tapping will happen in this position. Take your time and make sure it is mounted well.

Before you drill, and since the drilling will occur on the round surface of the GI pipe, it is essential to center punch the drilling center using a center punch, or using a center drill first.

Once that is done, get your 10mm drilling bit and tighten it in the chuck of your corded drill.

For the drilling, the best practice is to lubricate the drill bit (not the hole), applying pressure straight down for a maximum of 20 seconds at a time. After each 20-second round of drilling, wipe the drill bit with a cloth and apply a fresh dash of oil (very important!).

As you repeat the above, please be conscious of the progress of your drilling by looking through the mounting hole.

Once both of the upper wall and the lower wall of the GI nipple have been penetrating with the 10mm drill bit, it is the time to thread both holes using an M12 hand tap. The good thing is, all this can be done with the GI nipple in place, in the upright mounted position of the post.

Beware that as you tap, the tap will show a lot of resistance (a sign of tapping the upper wall), then no resistance, then a lot of resistance again (a sign of reaching and tapping the lower wall). Work your way carefully until you have threaded both the upper and the lower wall of the GI pipe, and the tap is showing no resistance for the second time (this happens as the manual tap's handle get's closer and closer to the post).

Once that is accomplished, you have successfully passed the hardest part of this build. All is left is to attach the leg's post to the table top, in the next step.

Step 6: Drill the Table Top and Attach the Leg

Wow, you've been a long way! The good news is that you are 3 minutes away from seeing your post attached to the table top, all is needed is to drill the table top at the point where you want to attach the leg, then using your M12 bolt to join the table top with the fabricated leg's post.

Doing so, and in case you wanted the M12 bolt to be flushed with the surface of the table, then bare in mind that tightening the bolt will compress the wood, hence bore the hole but while leaving at least 1mm of the bolt protruding. This way, when you tighten the bolt to full strength, it will be flushed with the table's surface.

Immediately after assembly, the strength of this joint should be evident. However, if you need a proof of how strong it is, please feel free to move to the next (and the final) step of this instructable, where we would be trying our best to destroy it.

Step 7: Test It!

It is important to note that if it wasn't for the countersunk feature of the socket cap bolt, this leg would have been much stronger. In fact, letting the bolt sit on the table top, with a thick washer would have made it indestructible, but while compromising looks.

As we reach the end of this instructable, please feel free to improve on our work and/or to throw in your ideas and suggestions. We believe this is an excellent and a truly viable build technique which we wanted to share with the community. Thank you!

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    45 Comments

    Nice instructable - cheaper than buying store barrels and certainly a way to make giant ones that will be very strong and very affordable.

    You could eliminate the end caps from the pipe and simply use an unthreaded section of pipe to create a home made barrel. You might also consider tapping the pipe outside of the wood so you can clean the cutting oil off rather than risk staining the wood from the cutting oil. (Also, if you broke the tap while tapping in the wood, you'd end up destroying the leg to get the pipe and broken tap back out.)

    Could also just drill part way through the leg and insert a section of pipe (the barrel) that is 1" shorter than the width of the leg. Then, one end is already plugged by 1/2" of wood and the opposite (hole side) can be plugged by a dowel to hide the barrel entirely (after it's assembles so you can position the barrel to receive the table bolt.

    If you do not have a leg made from the center of a tree where the grain is circular, in other words, with the grain biased in a single direction - make sure the pipe is inserted perpendicular to the grain for greatest strength.

    Great advice on making the pipe flush to the surface, or embedded with a plug!

    I want to challenge you on your grain direction advice though.

    From what I have experienced, wood most often splits across the grain, so I would want to position the pipe parallel to, rather than across (perpendicular to) the grain for greatest strength.
    (so that any natural splitting that occurs will be 90 degrees to the pipe)

    Doug! Absolutely great feedback! I am working on the next instructable in this series and would try to take the concept to a better level. I am thinking along the same direction as your comment. Shorter barrel nut leaving 6 millimeters from each side so a laser cut circle of wood can be plunged to hide the barrel nut entirely. I am also thinking of a thread locking mechanism and an aligning mechanism. Keep up with giving great feedback!

    to give a hidden finish drill table top hole a little larger for 1/4 inch and put a plug of material in it to hide the bolt head

    Good idea.

    If you need 10 minutes to drill that hole in the pipe and or you need to drill from the bottom up in the wood to keep from burning it you need to get some new drills. :) No way that a drill bit should get hot enough to burn wood. Not even close.

    Even a sharp bit, if of large enough diameter and operated at a speed too high or with an advance speed too low, can burn wood.

    And what is your point? You really have to abuse any bit to get it to burn wood. I doubt any sharp bit you can use in a corded or cordless hand drip is going to burn wood. A person almost would have to want to burn the wood to get any bit to do so.

    If in that project the bits are burning the wood then they are dull. My comment was written to add to the utility of that particular project. The man was evidently using very dull bits and commented in his instructable as if it was normal to take so long to drill through a piece of pipe and that drilling down would burn the wood. Both false.

    You are right, my bits were a bit dull. However going so deep without removing the chips will eventually lead to the chips clogging the drilling. You can either use a vacuum from the top for extraction or flip the piece upside down every now and then to clear up the hole. Thanks for reading.

    The addition of cutting/tap oil would help immensely in drilling through the pipe.

    On the other hand, any shape bit appropriate for the job at hand and operated at a correct speed will do the job quickly and without burning the wood. Again, no way that a drill bit should get hot enough to burn wood. Not even close.