Hey guys! In this Instructable I’ll show you my first ever project using concrete! This round side table used white concrete and walnut for the base. I'll share with you the tips and tricks I learned along the way as well as something I'd do differently the next time I did a project like this.

Keep reading and I’ll show you how I did it!

If you like this instructable be sure to check out my most popular instructables below:

5 Pro Tips for Making Cutting Boards

How to Make an End Grain Butcher Block

How to Make a Slab Flattening Mill

The Ultimate Table Saw Fence

If you like this instructional content you can also find me at:

My Website (full tutorials, plans, videos): https://mwawoodworks.com

My YouTube (all my build videos): https://youtube.com/c/mwawoodworks

My Instagram (behind the scenes stuff): https://instagram.com/mwawoodworks

My Pinterest (things I find inspirational) : https://pinterest.com/mwawoodworks

Supplies

TOOLS AND SUPPLIES IN THIS VIDEO:

►Spectape Two Sided Tape - https://amzn.to/3wleKh4

►Black Type 2 Silicone Caulk - https://amzn.to/3zjHqc0

►3/8” Masonry Drill Bit - https://amzn.to/3zjHqc0

►Mud/Concrete Auger - https://amzn.to/3zjHqc0

►Silicone Caulking Tool - https://amzn.to/3zjHqc0

►Heat Gun - https://amzn.to/3zjHqc0

►Table Saw Ripping Blade – https://amzn.to/3zjHqc0

►Table Saw Dado Blades - https://amzn.to/3zjHqc0

►White Concrete Countertop Mix – https://www.concretecountertopsolutions.com/produ...

►Bright White Integral Pigment – https://www.concretecountertopsolutions.com/produ...

►Z Aqua-Thane M35 Concrete Sealer - https://www.concretecountertopsolutions.com/produ...

Step 1: Creating the Concrete Form

So, like I said this is my first time using concrete in a project and the first thing I need to do is create a form to cast the concrete in. I want to create a 20” round table top and so I’m cutting a 20” round circle out of ¾” melamine on the CNC.

For all of you sans-CNC folk two good options for cutting out a circle like this is to use a router attached to a trammel or you could use a circle cutting jig on the bandsaw. If you don’t follow me on Instagram yet I’ve posted videos of making and using my circle cutting jig at the bandsaw, so check those out if you want to learn more about that method.

The end result is one perfect 20” circle.

Now, for the side wall of the form I went and picked up a piece of PVC base molding at the big orange borg. It cost me all of 8 bucks. I went ahead and cut off the top of the trim to leave me with a nice flat surface.

I then turned it up on edge and basically cut it in half but apparently my camera battery died. The end result is a strip that’s about ¼” thick, which gives it enough flexibility to bend it around this circle form and screw it into place.

A trick I learned is that using a heat gun to soften the pvc will get you across the goal line.

Step 2: Sealing the Form

Next I needed to caulk the seams and I’m using black silicone caulk for this. I’m using black just for visibility sake. You can see it better against the melamine versus a white or clear caulk, but if all you can find is white or clear they will work too. This is why I wanted the high visibility so I can go back and remove all the excess easily.

This excess just peels right off the PVC and melamine and a scotch bright pad works like a magic eraser, cleaning up all the remaining smears.

For a little precaution I also added a ratchet strap. I don’t think this is completely necessary but since I haven’t worked with concrete, I wasn’t sure if the sides would bulge or not, so better safe than sorry.

Step 3: Mixing the Concrete

Alright, now for the main event. For this table top I’ll be using white concrete countertop mix.

Besides the concrete the only other things I will be using is water and this bright white pigment which just mixes in with the concrete to give it an extra pop of crisp clean white.

Because this is a dusty process I laid down some black plastic and began by adding the white pigment. I added some water to mix up the pigment. Now to mix all this up I’m using a concrete or mud mixing auger on my drill and I’m using a corded drill here just because I don’t know how much power is needed to mix this and I didn’t want to run out of juice using my cordless drill.

Then I slowly began adding the concrete a little at a time. By the way, did I mention this is really dusty? I recommend wearing a dust mask even if you’re doing this outside.

I mixed the concrete in making sure to get all the lumpy bits and then continued adding more concrete. I just kept adding concrete a little at a time until it was thoroughly mixed and once I got everything into the bucket and all mixed up to a batter-like consistency it was time to pour.

Step 4: Casting the Table Top

I filled the mold up to the 1 ¼” mark. Now here’s something I’d do differently next time.

I should have made the side walls to the exact size I wanted the top to be and filled it all the way to the top so I could screed the top flat. I ended up having to remove a small hump in the middle with a grinder and a flap disc. It worked just fine and solved the problem but it’s a step I could have avoided.

Once everything was settled in the mold I needed to vibrate the heck out of it get rid of any air bubbles. I’ve seen people use sanders or reciprocating saws or even just shaking it manually, but I found the perfect tool to use was my theragun.

I just added some tape to keep the end from getting dirty and worked the side of the mold for about 30 minutes. I let this thing set up for about 48 hours before I de-molded.

Step 5: Demolding the Table Top

De-molding now will allow all sides of the concrete to get air flow and finish curing.

And you can see how easily the mold separates from the concrete, nothing stuck at all.

And now for the big reveal. I’m super impressed with how smooth even the top is and also how free from bubbles it was. Pretty amazing stuff.

There’s definitely a little sanding work to be done to smooth the edges, but I expected this would be the case given my hack job with the caulk.

All in all I think this was a successful first pour and I’m very happy with those results.

Step 6: Cutting Table Base Blanks

Alright, while the concrete sits for another couple days to fully cure it’s time to work on the table base. I’m going to make the base out of 8/4 black walnut and I begin by cutting leg blanks with my jig saw.

I examine the end gran of the blanks to see if I can get rift sawn material from them. Here I’ll highlight what I mean. Do you see how on each end of the board the grain runs diagonally?

If I use that material I will get a straight grained look on all my leg parts which is what I’m after here.

I’ll cut off both sides to use and save the middle for another project down the road.

To make the base, I mocked everything up in Sketchup and I took my final design and cut out these templates out of ½” plywood on my CNC.

At this point I was still undecided about the final leg design and I cut out a template for a straight edged leg and another template with a sweeping curve on the outside of the leg.

Another way to produce templates like this is to print your design onto sheets of paper and glue those to your plywood and then cut to just outside the line using a bandsaw, jigsaw or table saw and then sand to the lines with a sander.

I then laid my templates onto the stock to see how much I needed and set up my table saw to rip my parts down to rough width.

Step 7: Milling Table Base Blanks

I always like using a dedicated ripping blade, especially when I’m cutting 8/4 hardwood. It’s the most efficient way to get through the material without burning or wearing down the saw blade.

I rip down my board until I have enough material to get all four legs and my stretcher parts.

I then quickly milled everything down straight and square using the jointer and planer. I’m still keeping everything to rough oversized dimensions at this point because this is just the first milling

One all four sides were surfaced I marked the center of each board and double checked that my templates still fit.

I then chopped each one in half at the miter saw to give me four leg blanks and two blanks to cut the stretchers from.

At this point I sticker everything to let them sit and acclimate overnight.

Step 8: Creating Table Base Parts

OK, next day I bring all my blanks down to final dimensions.

First by trimming off some excess width by using the bandsaw. I’ll save these offcuts for something down the road.

I then use the planer to surface all four sides to remove the bandsaw marks and make sure I hit my final thickness of 1 ¼”.

I can now cut my stretcher parts down to final size as well since each individual part would have been too small to go through the planer.

So, my method of template cutting is to fix the template to my stock using strong two-sided tape. I use a product from Spectape. I am careful to place my template to avoid any blemishes or defects in the material if possible to product the cleanest look.

I then like to trim off all the waste as close as I can to the template using my bandsaw. A bandsaw is a really great tool for making these finer detail cuts because I can follow curves and deal with weird angles without needing special jigs to do it safely and quickly. I try to cut anywhere from 1/8 to 1/16 of an inch from the template to give myself the least amount of material to remove with my router.

Step 9: Template Routing

Now at the router I set up the height of my spiral flush trim bit so that the bearing rides against my template like this. I then trim away the excess starting with the sides.

I then use a special wrap around motion to trim the end grain. You don’t want to stick the end grain directly into the router bit because this could wind up in a dangerous kickback and really easily damage the end of your workpiece.

I then repeat the same process with the legs and with the lower stretchers.

Once all the parts are cut out I can move onto joinery.

Step 10: Joinery Pt 1

Next I lay out my parts to mark the leg joint locations. I’m going to use dominos to join everything together.

I can assemble the whole base with just eight dominoes dowels would work here too but I would double up the number of dowels used.

Cutting the domino mortices went super fast. I set up my domino dock to free up both hands and plunged at my pencil marks.

Since this is a relatively small table I just need one mortice at each joint. If this were anything bigger than say a coffee table, I would think about doubling up my dominoes to be safe.

Step 11: Joinery Pt 2

For the stretchers I’m going to overlap them like and “X” and so that means I need to notch out the center of each one. I’m using a dado stack in my table saw for this because it’s the quickest way to hog away the material. If you wanted to you can use a table saw blade with a flat grind tooth and cut these notches one pass at a time.

I keep cutting, sneaking up on my lines until my stretcher parts fit snugly together.

Now I can begin assembling the stretchers. Since these have inside corners I’m going to tape up the joints so any glue squeeze-out goes onto the tape and I don’t have to clean all that out later.

Then I just add some glue and press them together.

If your joint is snug enough then adding a clamp here is optional. I chose the no-clamp option and these guys get to hang out and dry for the afternoon.

Step 12: Pre-Assembly

OK, the next step is to take the top stretcher and add some holes where the base will be bolted to the top. I marked my locations with a center punch and drilled a 7/8” countersink for the bolt head to sit below the surface.

I then drilled all the way through with a brad point drill bit.

Now is a really good time to go ahead and sand all your parts smooth. This will be much easier to do now then once the whole base is assembled.

I’ll do a final quick once over with the sander after glueup to flush up all the joints, but having the vast majority of the sanding done now will be much less of a headache later.

Now it’s go-time.

For any kind of complex glueup, especially where weird angles are involved I like to do a dry fit first just to make sure there wont be any bad mid-glueup surprises.

Step 13: Table Base Assembly

Once I’m happy

that everything looks right I add glue at the top stretcher and begin adding the legs.

I then go back and wedge in the lower stretcher.

Then I take my curved cutoffs and add them between the clamps and the table base to get nice even clamping across the joints.

Two sided tape is also good for keeping those curved offcuts in place as you add clamps.

And now, we wait.

One final detail to add once the base is out of the clamps is to ease the edges a bit with a block plane.

Step 14: Sealing the Concrete Top

Alright, with the base all glued up its time to head back to the top.

To deal with any inconsistencies along the edge caused by the caulk I used water and 320 grit sand paper. This got rid of any high spots and created a nice smooth round edge.

To seal the top I’m using Aqua Thanes M35 water based concrete sealer. It’s a two part mixture that goes four parts A and one part B.

I don’t need much so I’m using a syringe to measure everything out.

After a thorough and complete mingling together of the molecules, a little molecular hoedown if you will, I applied it with a foam brush on all sides.

I did a total of three coats in two days to make sure this was good and sealed up cause I got little kids with juice boxes roaming around at all times.

Step 15: Joining Top to Base

The last bit of joinery to do is to attach the base to the top. You can see here where I had to grind the high spot off the bottom.

I marked out where I wanted the base to go and double checked that it was centered with a ruler.

I then used an awl to mark the hole locations and then highlighted those with a sharpie so I knew where to drill.

To drill the holes I’m using a masonry bit and I’m using a tape flag as a depth stop. It has an added benefit of sweeping the area clear when you reach the bottom. And a quick vacuum to get up all the dust and there you go, and nice clean hole.

Step 16: Joining Top to Base Pt 2

Next I’m going to add threaded inserts and I’ll secure them with epoxy.

Another fancy trick I learned is to cap off the bottom of the inserts with tape. This prevents the epoxy from filling the inside of the insert.

I just add a dab of epoxy to the hole.

After adding some epoxy to the threads I installed the insert.

And you know it was a success when you see a little schmootz pop out around the edges like this.

Just make sure to clean the schmootz off your hole :-)

Step 17: Finishing the Base

To finish the base I’m using rubio monocoat pure. Its super easy to apply, just rub it in with a white scotchbright applicator.

I love how it warms up the walnut and gives it a nice glow.

After letting it sit for 5-10 minutes I wipe off all the excess oil with a cotton rag and boom, done.

This needs to sit and cure for about 72 hours.

Step 18: Final Assembly

And after letting everything settle down and cure for a couple days it’s time to join these two together.

With a ¼ 20 hex bolt and washer in each hole I ratchet everything down snugly.

No need to tighten with all your strength, you don’t want to pull those inserts out.

And that’s it!

I love how this turned out. The contrast of the walnut and white concrete is awesome and I’m glad I went with the curved legs, it looks really nice with the round top.