Intro: Camera Assisted Bowl Coring
When I started looking into wood coring systems, or center saver systems, the biggest warning I saw was that some systems had a steep learning curve. That didn't scare me away so I went ahead a purchased McNaughton coring system because it had more versatility in what you could remove. I quickly ran into the steep learning curve I had read about and got really frustrated quickly. With some practice I was able to get two bowls out of one blank but I wanted a more dependable way of doing it where I could better predict where the cutter was going and know if I was off track. There is a laser mount that can be purchased that is supposed to show you where the tip is but that still wouldn't help me predict where I was headed. I had run across a video on Youtube by Zentient1 that showed how to use an aftermarket back up camera to aid in hollowing. I figured that if it can work for hollowing it should be transferable to coring!
Step 1: Equipment
- I selected a system on Amazon.com the had a 7" monitor. To be able to see what you are doing while working bigger is better.
- A 12v power supply, I selected a power supply for an old router. I cut off the end that plugged into the router and wired it to the camera system.
- A PVC reducing T joint, 1 1/4" ID reducing to 3/4" going up
- Assorted 3/4" PVC pipes and fittings (these I had on hand from previous projects)
- Longer bolts to replace the short set screws that came with the hollowing system
- A method for mounting the T joint on the lathe to modify the internal diameter
Step 2: Modifying the T Joint
First, see if the hollowing handle is able to slide into the T joint. If it fits you are lucky and can go right to cutting the joint to length. If you are like me and the shoulder inside the joint is too tight you simply need to mount the joint in your lathe chuck and use a scraper to remove a little bit of material. Once you can slide the coring handle in you are set. A tight fit is better than a loose one.
Next transfer the length of the hollowing handle's mounting portion to the T joint. Cut off the extra and file the edges to remove any sharp edges. Measure the center to center distance for the two mounting holes and transfer that distance to the T joint. Select a drill bit that is just bigger than the bolts you will be using. I placed a shim under the T joint while drilling to insure I was drilling perpendicular to the axis of the handle. The hole on the other side of the joint can be larger because it will be a clearance fit.
Now it is time to slide the T joint onto the handle and add all of the fasteners. I had to enlarge some of the holes to get them to line up better as well as sand down the surface to give me just a little bit more travel for the bolts I used. Now that the joint is in place you are ready to start assembling the rest of the camera mount.
Step 3: Initial Setup of the System
Initially I used several lengths of PVC that I already had cut to determine how high and how long I wanted the arm to be. I aimed to have the center of the cutting tip in the middle of the screen and I wanted the camera to be close enough to allow for a large path profile on the screen. I ended up using 3/4" T joints on the vertical elbow as well as for the camera mount. The T joints allow for the cords to be easily run through them and simple mounting of the camera. I initially zip tied the camera in place and once I was happy with where it was focused I marked the mounting hole locations. From there it was simple to remove the camera and drill the mounting holes.
Step 4: Screen Overlay Setup
Now comes the part where you can predict where the cutting tool is going to travel. I used a large sheet a paper and simply outlined the shape of the blade. I then rotated the tool following the same profile and marked that section in red. The black is where the tool is and the red is where it will want to go as it cuts.
Place the sheet of paper on the bed of your lathe and hold the cutting blade in place. Looking at the screen you should be able to line up the outline on the paper with the actual tool profile. I cut out a section from a clear sheet protector and taped that to the monitor. Then using a marker, or whatever you want to use, draw the outline of the tool on the monitor cover. I used dotted lines to indicate the predicted path of the tool.
A separate over screen will be needed for each size cutting tool. When changing between blades it is easier to adjust where the over screen is taped on the monitor then it is to adjust where the camera is pointed in order to get the images to line up.
Step 5: Final Results
Yes, while coring the PVC does vibrate a lot. Once you get the PVC pipes where you want them you will want to glue them in place so they can't vibrate apart. During coring the vibration isn't a huge problem because all you need to do is stop cutting and you get a clear picture of where you are. I think I might also adjust where the tip of the cutting tool is in relation to the center of the screen to get more of the bowl in view.
Apart from the vibration I believe this system will be an excellent way to use a coring system with more confidence, more bowls per bowl blank and hopefully result in fewer bowls with the bottoms cut through!
Thanks for checking out my Instructable, for more information about my work you can visit me on Facebook, Etsy.com or YouTube, just look for StonecreekTurnings.