Using a computer to turn raw material, including metal, plastic, and wood into complex parts, CNC lathes have a reputation for their precision and are common parts of high-volume manufacturing operations. In addition to reducing human error, CNC lathes create a more productive and efficient workplace, as their speed and accuracy quickly offset the high initial cost. While they require significant skill to operate properly, with the right instruction and practice, anyone can learn basic CNC machining techniques. Ultimately, other than programming, you only need to load the raw materials and then remove the finished product.
Loading the Lathe
Properly setting up a CNC lathe is of utmost importance, as it can drastically reduce the risk of tool damage and wasted raw material. To begin, load the part program into the lathe if it is not already there. On newer machines, you can use a USB drive to transfer programs from a computer to the machine, though with old machines, you many need to use a serial connection to the computer or even a 3.5-inch floppy disk. Next, load the workpiece into the lathe, making sure that the chuck or collet has a tight grip on the workpiece.
You should allow the clamping force of the jaws to hold the material without crushing it, and then finally load the necessary tools into the lathe. This may include boring bars, drills, and insert holders for turning the outside diameters of the raw material. The holders can vary in size and shape and often stay in place via screws in the tool turret. Required tools for the program, as well as for the turret slot in which you should place them, are determined the time of the program's inception.
Setting the Tool Offsets
The next step is setting the tool offsets, so turn on the coolant pump and position the nozzle so that the coolant stream hits the tip of the tool, making sure to repeat this step for each tool. When this is complete, set the tool offsets by slowly bring each tool toward the tool setter on the CNC lathe until you hear a beep, and then record the tool's position in the tool offset screen under the appropriate tool number. The beep signifies that the machine control knows where to find the tip of the tool for precision cutting. You should then repeat this procedure to set the X and Z offsets for each tool, and depending on the program you are using, you may also need to record the tip radius of certain cutting tools in the tool offset screen. You should be able to find the tip radius either marked on the tool or in the documentation for the tool.
Setting the Work Offset
To set the work offset, you should rotate the turret to one of the cutting tools for which you set the tool offset, and then start the spindle and manually jog the cutter so that it faces off the end of the workpiece, leaving a smooth surface. After that, record the tool's position under the Z-axis work offset. Next, run the part program and watch the CNC lathe to make sure that the program functions as intended, making sure you are ready to stop the machine immediately should something go awry. It is important to note that specific the procedure can vary substantially between machines, and as such, you should always consult the user manual for your specific CNC lathe for specific instructions.
How to Buy a CNC Lathe on eBay
To search for a CNC lathe on eBay, you can enter relevant keywords into the search bar located on every eBay page. You can further refine your search results using the advanced search feature to narrow by elements like condition or price, or you can limit the search to show only items sold by top-rated sellers who receive consistently positive feedback ratings. CNC lathes, while considerably more expensive than their manually operated counterparts are, have a reputation for their high output production and reduced defects, and when users arm themselves with the proper knowledge to operate them correctly, they can be useful in a large number of industrial jobs.