I have a few larger slabs of camphor laurel to try large diameter turning and 2 of them had fairly plain grain so I thought on one of them I would try pyrography. This was a big experiment and Im happy with how it turned out considering my limited experience. I now know many areas where I can improve in this area. The wood burner that I used was only a small pen burner with 5 different tips that I got for $10 a few years back.
This instructable will cover 2 main points.
-Large Diameter turning/ turning a platter (steps 1-4)
-Basic Pyrography using a cheap burner (steps 5-13)
Hope it helps or inspires you :)
Step 1: Set Up for Large Diameter Turning
Before mounting the timber on the lathe it needs to be set up correctly. My lathe has a speed dial and 2 belts. For big pieces you need to put the belt on the low setting. This gives the lathe more power at compared to having it running at the same speed on the high belt.
For turnings this big you will need the outboard attachments. For my lathe this was a $100 investment. This comes with a bed extension and extended tool post.
Speed. I go roughly by the rule:
Dia (inch) x rpm = approx 6000 (therefore at 20 inch platter I was running at about 300rpm)
This is also not set in stone. For uneven pieces or other bigger pieces run the lathe slower and eventually build it up. I also tend not to go past 2500rpm on smaller diameter pieces as i don't see the need. It is a good safe standard but also do not go beyond what you are comfortable with.
Attaching the timber. For shaping the back I just used my face plate with 6 screws. The timber was cut round to make the turning easier and allow me to increase speeds quicker
Step 2: Start Turning (shaping the Back)
Start a low speed and work your way up as the platter becomes true and evenly weighted. The tools I use are a bowl gouge and a detail gouge for the shaping and a skew for the bottom.
With the gouges you want to be riding the bevel. This means you want to lower the tool handle so the tools edge is cutting the timber rather than scraping (refer to the picture). Work from the inside to the out side when shaping the outer of the platter.
The skew chisel is used as a scraper to true up the bottom to keep it flat. It is even best to slightly taper it in to prevent rocking. With the lathe off I used a ruler to check that its slightly con caved.
The recess in the bottom is for the 4 jaw chuck to grip to. Depending on your chuck this is usually approx 50-65mm. I used the detail gouge to remove most of the waste then the skew to true it up.
Step 3: Sanding the Back
To get a good finish sanding well is key. I used cloth back abrasives on turnings as I find they last longer than paper backs and also the heat from the friction is not as quickly felt. I normally start at 80 or 120 grit depending on the amount of sanding need and then progress to 240 and 400. This is for jobs that are lacquered. If I oil a job I will then quickly use 600 and 1200 wet and dry as well (bit over the top but I love that natural shine).
Step 4: Turning the Face
When turning platter I prefer having the tail stock applying pressure. The 4 jaw chucks are strong but when you are working that far out from center the leverage can pop it out with too much pressure. This is an additional safety measure that has kept me a lot safer.
With the outboard extension you can not get a tail stock. So I made my own. Its a solid bit of spotted gum that I have cut a tenon in so it slots into the bed. There is a threaded rod with a bolt and a shaped metal washer to clamp to the bed. There is an old live center that had been perfectly positioned by using the head stocks center to mark it out. Its a simple design but has to be done accurately.
By pushing this stock against the timber and locking it off I get adequate pressure.
Start turning the edge with similar tools and techniques. Mark out where you want the hollow to be and use that as a reference for your ratios. Normally I do 1 part rim to 2 parts bowl but for this one I did 1:1 as the rim was the feature.
Work as far as you can with the tail stock then sand that as well. Sanding pressure can also be enough to pop it off the lathe so do what you can while it is still well supported.
Remove the tail stock and then slowly take of the little bit that remains, working it down with the gouge. I found for this working my way out gave me less chance for a dig in.
Step 5: Design
I looked at many maps and got inspired for designs. I found things that I wanted to include such as boats, sharks, compass and palms. With this I created a sketch which then changed a bit but it was enough to start making plans. The main reason this changed was the timber. With the grain of the timber, this is a canvas that can dictate where things go in your design. There were 2 features that affected my design. A section of high figure and a small coloured streak. The figure looked like rough waters so that is where I placed the sharks. I worked around the colour streak and turning it into part of the island. From there I put everything else in, sketching it with pencil.
Step 6: Experiments and Bits
My burner came with 5 different tips so testing their capabilities is important before actually using it on a completed job. There were 2 sharp pointed tools, 1 soft point, 1 angled bit and 1 shading bit. I also tried some scorching with a butane torch but chose not to use it on this job.
Also dont be afraid to stop and experiment as you go. My technique changed heaps as I learnt.
To change bits I used pliers. This allows the burner to stay hot and my fingers to stay unmarked. This burner had a screw thread so it was an easy change.
Step 7: Outlines
Using the soft point tip i started tracing my pencil lines to get my basic outlines. I found this was the best point to start.
The key to this is continuous movement. If you stop it will but darker quickly. The faster you go, the less it burns, therefore light lines. If you move slow you get dark thick lines. I started mid way to get a brown line.
Step 8: Shading
Once again continuous movement and speed is key. Also do not go back and forth in one stroke. The quick stops when you change direction does mark. Try to quickly the tool on and pull it off.
I found working in the direction you want the eye to lead you also made a difference as seen with the boat.
Contrast is also important with working in shades. There is nothing wrong with going all black but just remember you can go darker but not lighter.
With the mountains, I started with a base shade and built it up on one side but continuously going over it until it darkened. By moving across I was able to blend it in. Finally I outlined it to clearly define it.
Step 9: Dotting With a Point
This can end up quite accurate but is very tedious so get comfortable and take your time. Try and keep even pressure. The harder you push, the bigger the dot. With this technique you only get black so shading isnt an option. This was great for the compass and some outlines.
Step 10: Straight Lines
Using the point tool I got straight lines. This was great for the track and for masts and outlining.
The masts and outlining, like other tools, they key is constant movement. It does cut into the timber a bit so finding your grove is easy.
The tracks main challenge was getting an even line. by putting pressure on either the heel or toe of the point created a tapered line. This can be easily corrected by putting pressure the other way.
Step 11: Thick Lines and Odd Shapes
I experimented using the edge of the tool rather than using a tip. this thick line ended up being very suitable for palm leaves.
The coconuts were just done by pressing the little round screw on the side into the timber.
Dont just be limited to the tips they give you. Be creative.
Step 12: Mistakes
Mistakes are hard to remove. I accidentally hit open space (pic 1). I sanded most of it out but there is still a faint line.
Another spot I slipped I was able to cover up by adding waves (pic 2). This is better as it doesnt create hollow from sanding and if done will it can look completely intentional. It also tests your creativity.
Step 13: Finish
Lightly sand and erase all pencil marks. Make it as crisp as possible.
I used lacquer to seal it well with out smudging the charred marks. Between coats, cut it back to remove dust that is caught up. I did 3 coats and that gave me a great finish.
Good luck turning and burning :)