I love the weathered look of old wood, and wanted to experiment with etching a design into the uneven surface of a slightly asymmetrical log, using a rotary jig on the laser cutter. For this project, I chose an interesting looking log that had been sitting around my shop waiting for the right project to come along. It had a crack and noticeable scar running down one side, which had different colours and hardnesses of wood in it. I thought that this feature would provide some interesting results.
Because my log was longer than I needed it to be, I was able to use the extra length to make a stack of coasters. The scar running down the side of the log, naturally lent itself to making coasters that can be easily lined up in a stack when not in use.
Step 1: Materials and Equipment:
- peeled and dry log that will fit on the rotary jig (not too long, not to big...)
- 2 - 1/8" plywood circles (diameter slightly bigger than the larger end of your log)
- 2 - 1"+ deck screws
- drill and drill bit
- screw driver
- design file for etching the full width of your finished design x the full length (my design went 3 times around the log and stretched over a width of approximately 6").
- laser cutter
- rotary jig
- chop saw
Notes about your design: When you create your design file (I worked in CorelDRAW), you will need to decide how much of your design will overlap as it rotates (if any), the length of the log that your design will stretch over, and how many rotations around the log you want your design to run. This will give you the information you need to determine your design file dimensions. I used a simple vine pattern that I repeated and stretched on an angle over the running circumference, which was equal to three rotations of my log, by the width of the area I wanted to etch (approx. 6").
Step 2: Project #1 - Making the Coasters
The coaster making part of this project didn't get its fair share of photos, but it was a pretty simple process that I will describe here.
If you are cutting coasters from the same log, like me, you will need to make the coasters first, so that you have enough to hang onto when you are cutting the slices off the other end of your log.
- Pick a dry, fairly symmetrical log (easier and safer to cut even slices), that has a diameter you think will be good for coasters. My coasters are about 3" in diameter, and I would probably make them a bit bigger next time, maybe 4", since they are small for some mugs.
- Roughly clean off any bark or loose bits that might fly off during the cutting.
- Decide on the thickness of your coasters. Depending on the kind of wood you are using, 1/2" will make them solid enough, but not too thick - my log was a softwood, probably spruce.
- Lay your log down on the chop saw table, clamping it firmly against the fence so that it will not move or rotate.
- Put on your safety glasses and ear protection, and trim off enough of the log to get a nice flat surface for the first side of your first coaster.
- Clamp a block of wood to the chop saw fence, starting 1/2" from the blade (I've included a photo from my bike rack project to give you a better an idea of what I mean). This block gives you something to butt your log up against to keep the thickness of your coasters even.
- Un-clamp the log and butt it up against the block. Re-clamp the log in position, snugly against the back fence so it will not move or rotate on you, and cut your first coaster slice.
- Repeat this last step until you have enough coasters, but still have enough log left to etch!
- Set the remaining log aside and sand the edges of your coasters to remove any rough edges that might splinter.
Stack them up, and admire, you are all finished making the coasters!
Step 3: Project #2 - Etching With Inconsistent Materials
In this next project, keep in mind that you are not working with the relatively consistent, stock material that is conventionally used on the laser cutter, and will have less control of your final product than usual. Each piece (log) will have its own individual properties and they will affect your results.
As the laser moves over the uneven surface of your log, the focus on the surface will be somewhat inconsistent. The results of the cut will be affected, not only by the specific surface topography of the log and the general symmetry of the log, but by any changes in the properties of the wood (harder and softer).
Depending on the amount of variability you introduce with your material selection, using the same design file and cut settings can give quite different results. For me, this is where the magic happens!
Step 4: Preparing the Log for the Rotary Jig (project #2)
To get the log to rotate evenly and stay centred on the jig rollers, it needed to be made more symmetrical.
The solution I came up with, was to use two circles cut out of birch ply, that were just bigger than the largest end of my log. The whole end of the log, fit within the edges of the plywood circle on either end. I was lucky enough to find some in the scrap bin :).
Once you have your circles cut out, eyeball the approximate centre point of one end of your log and drill a small pilot hole. Repeat this on the other end of your log and do the same for the plywood circles.
Centre one plywood circle on one end of the log by lining up the holes and screw it securely to the log. Repeat on the other end (don't over tighten, since you are screwing into the end grain).
Step 5: Etching Your Log
Place your log on the rotary jig, adjusting the rollers so that the plywood circles run in the middle of them.
When setting up your focus etc., make sure you pay close attention to any particularly high areas on your log that might possibly run into the head of the laser head! I would highly recommend taking this part slow.
Once you are ready, send your design file to print, and see what happens!
Keep a close eye on things as your log rotates, to make sure the uneven weight does not shift it off the rollers.
Step 6: Magic!
I was very happy with the results. So far, I have just been admiring the results and the variations in colour and cut lines in contrast to the weathered wood, and haven't decided what I will incorporate this into yet, possibly a lamp base!
Please share photos of your experiments and projects!