This instructable shows how to transform an oak log from discarded scrap wood to beautiful butcher block!
Tools you will need:
Oak log (or some other hardwood)
Butcher block conditioning oils
Step 1: Harvesting and Processing the Wood
This part is best done with a band saw, but I didn't have one of those so I used a saws-all with a 9" blade.
The goal here is to cut off pieces of wood from the log that will be manageable sizes for the table saw. My table saw is limited can't cut wood thicker than 3.5", so I tried to make cross cuts in the log that were no thicker than that. I ended up with slices that were around 3 inches thick, 7 inches wide, and around 8-10 inches long.
Next I cut the pieces of wood on to my table saw.
Now, at first the pieces I was working with were awkward and irregularly shaped from the rough cutting, but after several cuts on the table saw they began to take shape.
The trick was to start with a single cut with the table saw and use the fence to make it as straight as possible, then use that cut face as a reference for an opposing cut. I kept going back and forth between the faces till the cuts were lining up parallel and adjacent faces were perpendicular. This process resulted in a final "block" about 1.5" thick, 1.5" wide, and 3" long. You can see the progression from large rough shapes to small, rectangular, blocks in the image.
It is important that you end up with blocks that are consistent in size and shape. Differences in shape between blocks (as well as blocks with corners/edges that aren't quite square) will result in gaps when assembled. Gaps are home for food/particulates and inevitable contamination of the butcher block. Repeat the process till you have plenty of blocks to create the size board you want. The one I made was about 9" square and required around 20 blocks to make it.
NOTE: You need to make sure you are using a log that has been aged -- essentially you need the wood in it to be dried out. Green lumber will warp over time as it dries which will ruin the look of the butcher block. Depending on the size of the log it can take months or longer for the wood to dry after being cut from the tree. If you get a log that has already been sitting for awhile you are more likely to have wood that has already dried. Otherwise you'll need to find a way to dry it in a backyard kiln of some kind (the construction of which is a whole other instructable unto itself).
Step 2: Assembling the Cutting Board
With all the blocks cut, you can assemble them together.
First, picture a brick wall. Imagine how each brick is placed... they are always staggered between rows. That means that while no bricks in adjacent rows will be in-line with each other, bricks separated by a row will often line up. We get this same look in the butcher block by first creating "rows" of the individual blocks you've made. Do this by gluing the blocks end-to-end and clamping them together.
SUGGESTION: Gluing is not precise and can result in slight mis-alignments or shifting of the blocks. To account for this, make your rows longer than you need. Give yourself extra room to do a trim cut once the cutting board is assembled to bring it back to a nice, square, shape.
I would suggest using Tight-bond glue in this step. It has been shown to be stronger than the surrounding wood when cured (ie you break wood before breaking the adhesive) and is non-foaming. While I like gorilla glue for many things, in this case I didn't want to have a glue that could foam up and create voids/gaps where contaminants could be trapped. Additionally, my experience is that gorilla glue doesn't tend to be as hard (ie chip/cut resistant) as tight-bond once cured.
Now, with several rows bonded and cured, you just need to lay them up together to form the shape of the butcher block. Remember to off-set them from each other. You can decide by how much (I tried to offset each row by half the width of a block). Apply glue and clamp.
Finally, you just need to cut the block to shape. Trim off the excess material and and overhangs with a table saw. You should be left with the general shape of you board. Now you just need to finish it.
Since the wood being used was harvested from a log, there were knots and voids in some of the blocks I had cut (you can see a couple in the images posted). I could have kept cutting until I was left with enough blocks without any such defects ... but I liked the look of these imperfections so I kept those blocks. The problem with doing this is you can't leave that hole open or it will get contaminated from the food being cut on the board. The solution to this was to use some 2-part epoxy to fill the voids. I poured in the epoxy until it started to overflow on to the top of the assembled block. The excess epoxy was sanded away as the rest of the block was shaped and finished.
Step 3: Finishing the Cutting Board
Time to break out the sander
I used a belt sander and went from 40 grit to 150 grit. Afterwards I use another power/orbital sander to continue sanding up to 330 grit.
While still rough-sanding the block I used the belt sander to grind the radiused edges into the board. I wanted the board to be totally smooth to the touch so I didn't want any hard edges. Admittedly this shaping of the edges may have been easier with a router, however, I didn't have one so I went with the belt sander.
Once the board was sanded smooth, the final touch was to use butcher block conditioning oils. These oils are either mineral oil or in some cases a gel/wax that is buffed into the wood. Either way, the effect of the conditioning oil is to:
1) highlight the grains and bring out the color and contrast in the wood
2) prevent the wood from cracking or pulling apart in use
2) season the wood and seal it from contamination by blocking up the pores of the butcher block.
Seasoning a butcher block is the only real way to seal it that is food safe. Using polyurethane or other typical wood sealing treatments will leave you with a surface treatment that will crack, break away, or be worn away with time. This will expose wood pores to absorb grease/bacteria from the food. The conditioning oils are re-applied on a regular basis and over the life time of the butcher block create a barrier that protects the wood.
The rule of thumb is:
Treat the butcher block 1 time a day for the first week, 2 times a week for the first month, and once a month for the lifetime of the block.
With that, the block is ready for use. Enjoy!