In regional New Zealand sometimes the only way to get hardwood is to buy slabs via an online auction / forum and dry it yourself. I had this one slab of oak that warped and cracked severely while drying and would be no good as dimensional lumber. I needed a project that would allow the timber to move and utilise its inconvenient size. Once I started working the wood I decided it would be a bar to match a garden bench project I had done earlier. Using bolts as risers I was able to make the slab appear to float above the frame while also accomodating some of the shape. The project isn't quite finished, I still need to touch up the paint and put an oak shelf on the bottom, but there's enough here to recreate this project.
In this instructable I am going to take you through how I built the pictured outdoor bar table with a floating top. I’m going to present the instructable in a slightly different order than the order I made it, reflecting on how I’d do it differently and the most sensible order to write it. At the end I've put down some handy links that I used.
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Step 1: Materials
Dimensions are given in metric then italics for imperial which I have rounded off for simplicity. The cost of materials and tools in NZ is quite different to other places so I won’t convert the cost from NZD to more common euro, usd or etc. All in this cost me less than $300 and based on what I've seen in big box furniture stores I believe a similar item would retail for ten times that price.
Bill of materials:
- Slab of oak (or other wood) - $30 NZD (online auction)
- 20mm, ¾ inch, thick Jarrah or other hardwood for the “butterflies” – I had some scrap, you really only need a piece as big as our hand.
- PVA wood glue. I believe in the US this is called "white" glue.
- Expanding wood glue or resin.
- Your favourite wood finish, I used linseed oil.
- 5* M8 stainless steel bolts, nuts and washers 40mm long, just over ¼ inch thick, and 1½ inches long – a few dollars
- 25mm, 1 inch square steel tubing, wall thickness of 1.6mm, 16 gauge. 4 lengths each of the following 1350mm, 350mm and 850mm, or 53 inches, 14 inches, 34 inches. Purchased from online steel monger I paid $130 including shipping and cutting to size.
- Paint (hammerite), I had some left over from the bench project, a small pot costs $20
- Furniture feet to stop the steel from scratching the floor and water getting in - $10
Step 2: Tools Required
Live edge top
- A variety of chisels and a wood mallet, dovetail chisels are good for getting into the corners.
- Planes. I used a stanley #4 for finishing, a #7 and an electric planner for rough dimensiong
- Circular saw
- Straigtht edge
- Work bench and/or a couple of "2x4"s to keep the timber of the ground while cutting.
- Orbital sander, I bought this special for this project and I'm glad I bought the best I could afford.
- Paint brush or rag for finishing
- Workshop vacuum.
- Something to sharpen and resharpen your tools
- Sand paper
- Drill and spade bit.
- Jig saw and or coping saw.
- Wirefeed welder, I used FCAW which is also called gasless MIG.
- Angle grinder for cleaning up my amateurish welds and splatter.
- Drill and 7mm, ¼ inch, metal drill bits, lubricating oil
- Spanner / wrench
- M8 screw thread tap.
- Paint brush
Step 3: Live Edge Top - Dimensioning.
The first thing I had to do was to get the slab into rough shape and remove the deep chainsaw cut lines. I do enjoy old school had tools, but gave up after 2 days and bought a cheap electric plane. With the electric plane I went up and down the piece turning the piece over constantly checking high points with straight edge and level. It became clear that this surface was never going to be perfectly flat. The slab was an awkward and irregular shape that became thinner at one end, by cutting one of the long edges I could remove some of the cup shape and give the slab a bar or bench dimension. So I placed the slab on three 2x4 timbers so I could cut the piece with a circular saw. The idea here is that resting the slab on the 2x4s one side doesn't fall off half way though the cut taking a big chunk of the good side with it. To cut the slab I went in multiple passes first a shallow pilot cut with each pass I lowered the circular saw deeper into the wood, it took 4 goes in total. I then straightened up the edge with the electric plane. With the long side cut "visually parallel" to the live edge I could then make 90 degree cuts to the edges and the piece began to take on a more furniture like shape.
After some online reading I concluded the bark should be removed since bugs could live in it could flake off one day. I chiseled the bark off which was it was surprisingly difficult compared to what I've seen online, most likely due to the climate the tree was grown in and when the tree was cut down. I also decided at this point in time, that the cut edges should look very precise and square, while the remaining cup shape would emphasize the natural curved edge of the slab, this was the inspiration for the floating effect. To enhance this floating effect I took a deep rabbet on the bottom of the front side and rounded it over with a spoke shave, but you could also do this with a plane or sander.
Step 4: Cut the Butterflies
Butterflies, dutchmen, arikata, inlay what ever you call them.
The butterfly inlays are intended to prevent the crack from opening further. It's surprisingly easy to do. Just note that I got carried away and in the image and the grain is in the wrong direction and I had scrap it. If you imagine the butterfly as the real animal, the grain should be perpendicular to the butterfly's flight path. Cut out the shape with a jigsaw or a coping saw, the shape didb't matter for the aesthetic I was going for so I just focused on making straight edges. After cutting out the body, I filed the edges so they are presentable, a flat faced file is good for keeping the edges flat. The file also generates a lot of saw dust which I kept for the in fill.
Step 5: Carve Out the Inlay
Carving out the recess is simple enough. First trace out the butterfly using a sharp pencil or a knife.
- Cut out a shallow "outline" grove from the inside to the cut line.
- Make a ladder pattern with the chisel parallel to the "waste" of the butterfly, but don't go deeper than the grove
- Chisel out the ladder.
- Repeat steps 1 - 4, making the next outline with the chisel, bevel in. Dont try to go too deep at once.
- Once sufficiently deep focus on flattening out the base.
You could use a router or drill to cut out the waste faster, but personally I don't get good results this way. Next Place the butterfly over the gap and tap in place with a mallet. Ideally place a scrap of wood larger than the butterfly between the mallet to even out the pressure and prevent dents from the hammering.
Step 6: Fill the Crack
The crack in the slab was quite significant, so I started the in fill with an expanding glue and left overnight. I sanded down the over flow and using an engineers scribe I scratched out the surface glue to create a space to fill in. I regret doing this as some of the expanding glue is still visible if you look closely in the right places. A better alternative would be pre-filling with resin and then making the filler with saw dust and resin.
I made a make shift wood filler by mixing the red saw dust from the butterflies with PVA glue. Once it was a tooth paste consistency I squeezed it into the cracks flattening the top of with a paint scraper. I then sprinkled a little more red saw dust over the crack so the surface of the in-fill would adsorb some finish in the same way the inlay did. This improvised wood filler did stain the surrounding mood but that was removed easily removed with sanding. I also used some oak saw dust and glue to fill in some minor cracks away from the main seam. I used the oak saw dust filler to fill in a couple of mistakes around a butterfly but on reflection I should have used the jarrah filler.
Step 7: Sand, Sand and More Sanding
Now it was the time complete the slab. I started with the plane getting the butterflies and the oak to the same level. Unfortunately the piece of oak I had was pretty gnarly and I got a lot of tear out since the grain changed direction often despite frequently sharpening my plane iron. This meant I had some serious sanding to do. I started off with an "angry" 40 grit and sanded for what felt like a life time. Eventually I moved to 60 grit. One of the things about random orbital sanders is they leave a characteristic chain-shaped scratches in the wood, especially if you angle the sander. So I frequently stopped looked for spots that needed attention marked them with a pencil and restarted. Moving on to 80 was a happy moment and I was able to progress to 120 then 180 quickly. Since this piece is going outside I didn't see the need to go any higher in grit, but you should do what pleases you. I finished the surface with a rag dipped in linseed oil.
Step 8: Start on the Metal Frame.
The first thing you should do before welding is clean up all the saw dust.
I laid out all the metal on the flattest part of the floor. I held things in place with clamps and 90 degree magnets, check for square tack welded the frame in place check for square then finished up the welds. I then cleaned up the welds with a grinder. Next I placed the next side of the frame on top to ensure the same dimension and welded it up like I did the first. Next I connected the two frames together with the short pieces. This last step is a little tricky since I prefer to weld it all together with the frame standing. Welding the frame this way means I don't get an rock or wobble in the frame. This method does however require a lot of clamps and angle magnets and works well if you clamp one of the frames against a work bench. I checked for level and square over and over again. tack welded everything in place rechecked for level and square then finished the weld.
I generally use scrap wood pieces to make sure the edges are not only square but flush. I also find it good to put the shop vac on blow and clamp it nearby to ventilate the weld smoke. Just run the vac for a while to get any wood dust out of the system.
Once the frame was in place I tested the frame for strength by sitting on it since that slab is heavy! Then I asked the wife to join me on the frame. It's plenty strong. Not bad second time welding... Also note I welded the cross beams not at the sides but slightly in from the sides. I believe this adds to the floating effect.
Step 9: Paint and Drill Holes for Risers
Next I went over the frame with some hammerite paint. I like this paint for it's hard wearing quality, the trick is to really slap it on thick. I then drilled a few holes for the risers which are just bolts. I drilled the riser holes away from the front of the frame so you don't immediately see them when the slab is on top. Always use lubricant when drilling on metal otherwise you'll loose the temper (soften) the drill bit. I then made a thread for the bolt with a screw thread tap. To tap a thread you wind 180 degrees clockwise, wind back 90 degrees to break of the filament then repeat until done. Once the holes were completely threaded I screwed in a bolt with a washer and a nut until the bolt touched the bottom of the of the steel. The idea is these bolts act as risers, but we dont want the structure held up by 1.6mm (1/16 of an inch) of steel thread so the bolt is tightened onto the washer to distribute the weight. More about the bolts next.
Step 10: Adjust the Risers
With the bolts tightened all the way down I place the slab on the frame. The slab should sit on at least three bolts. I wound the bolts upwards to make the slab level and that so all the board was stabilised by all 5 risers. The trick here is to doing this right designate at least one bolt as "locked in position" otherwise you end up going around in circles. Next I marked where all the bolts contacted the wood, took the slab of and drilled a small recess for the bolts to rest in. I then replaced the slab on top and tightened the nuts down against the frame.
And we're done. I still need to touch up the paint and I've put in the furntiure guards on the bottom and the top of the frame. The top ones stand out a little and I need to paint those white. The slab doesn't slide around thanks to the recess holes I drilled and also allows for movement in the wood. I will, however, secure the slab with some steel cable given the frequency of earthquakes down here. All in all I'm very happy with how it came out. I'm only an amateur maker so I'd appreciate any future advice / critiques.
Step 11: Helpful Information
Jay Bates advice on flattening https://www.youtube.com/watch?v=PwLY-zbqA2g&t=173s
Matthew Cremona's advice on butterlfy keys: https://www.youtube.com/watch?v=hvzu6fWFskA
Welding a steel frame instructable by FabianG8: https://www.instructables.com/id/Steel-Bar/#C0SF87UIX6FVETA
Live edge slab instructable by ChrisReddy: https://www.instructables.com/id/Live-Edge-Maple-Slab-Outdoor-Table/
Also lookup instructable author Brian https://www.instructables.com/member/buildalongwithbrian/