Patent Application
20160184953
An embodiment of this device is a digital camera mounted on an arm that is fixed in position relative to a lathe hollowing apparatus. The camera looks down onto the cutter at the end of the hollowing apparatus. An image is taken of the cutter and is stored in a computing device. The cutter image is isolated from the surrounding background and superimposed over the live video-feed from the camera on a monitor. The operator can then see exactly where the cutter is inside the vessel at all times. Additionally, a line can be drawn by the computing device at a specified wall thickness away from the cutter to indicate to the operator how close the image of the cutter can come to the edge of the vessel to create that desired wall thickness. Similarly, when doing spindle turning and attempting to duplicate a previously turned object, this device can be used to visually see the desired shape of the object superimposed over the piece of wood currently being turned. In this configuration, the camera is positioned at a fixed point over the center-line of the lathe focused down onto the turning.
The first application of the invention is shown in
The camera 5 must first be calibrated so the scale of the cutter 7 is known. This will allow display of dimensions on the monitor during operation of the device. The calibration target card 12 is held near the vertical level of the cutter during this operation. The calibration target card 12 has a pattern printed on it of a predetermined dimension. The software identifies the platter on the card and can calculate the size of each pixel at the current distance to the cutter 7 from the camera 5.
In an alternative implementation of the invention, the user is required to enter the distance from the camera 5 to the cutter 7. This will give the software enough information, along with the known viewing angle of the camera 5, to calculate the size of each pixel as they relate to the real world near the cutter 7.
Under user control, the software next will capture an image of the cutter 7, while the cutter 7 is not inserted into the vessel 2, and determine its peripheral shape as viewed from the camera 5. Because the background image of the floor of the workshop below the cutter 7 is likely not clean and uniform in color, some assistance by the user is required to help the software find the cutter in the image. A target region is drawn on the screen 11 which restricts the area the software needs to look to find the cutter. The user is required to hold a solid colored card or object below the cutter to more clearly show the software which pixels are part of the cutter 7 and which ones are part of the background.
In an alternative implementation, the software could record the camera images as the operator moves a card or other object under the cutter 7 and determine which pixels are fixed and which pixels are changing colors. After a short time, the software will know which pixels are part of the cutter 7 and which pixels are not.
In order to know the distance the cutter 7 is from the exterior surface of the vessel 2, the software provides additional assistance in the form of a line 16 on the screen 11 around the image of the cutter 17 that is the distance from the cutter 7 which the operator has entered as a desired wall thickness into the computing device 10. The distance this line is drawn from the cutter image 17 is calculated based on the calibration done earlier to determine the scale of each pixel at the cutter 7 distance from the camera 5. Now the operator can move the captive hollowing rig 3 and camera assembly 4 and 5 such that the wall thickness line 16 comes up to the edge of the live video feed of the vessel 18 exterior. At that point, the desired wall thickness is reached.
The second application of the invention is shown in
That image of the original turning 19 and optional edges which were detected are displayed as a semi-transparent overlay over the video feed. When a new wood blank 13 is inserted into the lathe, as shown in
Additionally, the software in the invention allows the user to interactively erase the background of the overlay by selecting colors on the screen which are not part of the original turning, using a mouse or remote control. In this way, the position of the tool and the uncut wood is not obstructed by the overlay and the operator can have a clear view of the work being done.
This is a nonprovisional application of a provisional application No. 62/022,789, filed 2014 Jul. 10 When woodturning on a lathe by hand, it is difficult to know the dimensions of what is being turned or the wall thickness of a hollow vessel without stopping the lathe and using some sort of caliper device to measure the turning. When creating a deep vessel or one with a small opening, it can be difficult to fabricate a caliper with the proper dimensions to fit into and measure the wall thickness at each point along the surface of the vessel. Over time, several attempts have been made to create an apparatus that assists the woodturner in these tasks. To increase productivity, such a device would not require the lathe operator to turn off the lathe to use said device. One attempt at solving the hollowing issue is to attach a feeler arm to the hollowing tool that ends at a point within a given distance from the cutter. This is awkward and is hard to adjust for different positions around the surface of the vessel. The most common modern solution to the problem is to mount a laser pointer to the end of an arm affixed to the cutting bar so the laser is pointing down perpendicular to the plane of freedom of the hollowing tool bar. The laser is oriented so that the laser light points to a position in space beside the cutter, at a distance which corresponds with the desired wall thickness. When using such a device, the cutter, which is inside the vessel, is moved toward the wall of the vessel until the laser dot falls off of the side of the vessel. This method is useful but not very accurate and requires continual adjustment of the laser so that it is oriented on the side of the cutter perpendicular to the surface of the vessel. No equivalent commonly used method exists that allows live measurement of both position and diameter of details while duplicating on a lathe without turning off the lathe and holding a template or caliper up against the turning.
| Number | Date | Country | |
|---|---|---|---|
| 62022789 | Jul 2014 | US |
