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To fortify or not fortify my lathe: that is the question I often ponder. At one point or another most woodturners will push their lathe a bit, causing the lathe to shimmy and shake. When this happens, it not only raises safety concerns, but it also indicates that the lathe is under a good deal of stress that could potentially accelerate wear. There are varying opinions on how to best remedy this:
Many turners will add mass, such as bags of sand, to the lathe to provide some additional resistance to vibration. Most modern wood lathes provide some accommodation for this, like a location in the frame where a shelf can be placed to position some incremental ballast.
Some turners take a more extreme approach and actually bolt their lathe down to the shop floor, delivering maximum stabilization if done properly.
Some woodturners believe their lathe is structurally designed to handle a specific load, and that any enhancement that allows the machine to spin additional mass is likely to place stress on the lathe that will accelerate its wear.
I believe there is no simple one-size-fits-all answer to the question of whether or not to fortify. All lathes are designed differently and can handle different loads. This inherently means there is no universal law about how much additional weight can be added, even as a percentage of overall lathe weight.
As a general rule, I operate my lathe without any additional weight. But on a couple occasions, when I was turning something that was at the upper limits of the lathe’s capacity, I added some weight. It definitely helped to stabilize the machine, particularly during the roughing stages.
Weight added to the bottom shelf helped a little. When I moved it up and set it on the bed itself, it helped a lot more. So I understand the benefits, but when I do this it makes me wonder about the additional strain that it would place on the lathe itself.
Should the lathe’s shake and shimmy act as a governor, telling me I’m beyond the lathe’s capabilities? Or is it telling me to take action and stabilize the machine? That led me on a discovery quest to get perspectives from some serious wood turners, as well as lathe manufacturers.
Professional bowl turner Mark Stinson is known for turning massive 20” bowls (Ambrosia maple shown above) and avoids adding weight to his lathe.
“I think I have a different view on this topic than many,” he says. “While I agree that adding weight can help, I’m not convinced it’s a good idea. A lathe’s organic weight is based upon its construction. Thinner stock, possibly smaller spindle and bearings. So, if you force a lathe to remain more stable than it wants to be for the task, I believe, you risk stressing the integrity of the machine. This is only a theory of mine. But if you take a lathe that weighs 800# and a lathe the weighs 400#, adding 400# to the lighter lathe doesn’t make it as robust and durable as a lathe that weighs that total mass organically. You can bolt the thing to the core of the earth, but you may still be stressing the welds, spindle, bearings, bed, etc., and it will not eliminate the vibration that can occur between the bed and the sliding headstock, or the bed and the banjo.”
Avid wood turner John Lucas built a box for his Powermatic lathe that holds 250 pounds of pea gravel (pictured at the top of the article).
“I have always added ballast to my lathes,” he says. “I put the weight as low as I can. This setup works pretty well but then I don’t turn a lot of big stuff. I turn a fair amount of smaller out of balance or off-center pieces and it helps quite a bit. I have every confidence that I’m operating within the lathe’s natural limitations, and that the added ballast simply stabilizes the tool and provides me with a better turning experience.”
For turners who might consider taking things a step further and bolting their lathe down to the floor, Canadian turner Lewis Golden shared his experience. His 20” swing General Lathe is bolted into 6” of mesh-enforced concrete using ½” x 5” galvanized wedge anchors (pictured above).
“I have roughed in pieces on the outboard that’s were larger than 20 inches in diameter,” Golden says. “The machine was built at the factory to be fastened down and I believe that there is no more solid fashion, (excluding modifying the machine), to limit movement than anchoring it using the factory drilled base. This has never presented any problems whatsoever and it has not been unbolted since I bought it new 21 years ago.”
I also spoke with a couple individuals who design lathes to get their perspective. Benjamin Helshoj, designer of the Revo Lathe series for Laguna Tools, says it’s a complicated, multi-variable question.
“We do not provide any specific guidelines to our lathe customers,” he says. “I believe that it is ok to add some weight to slightly extend the capabilities of a lathe, but there is a point at which it will mask problems and potentially cause damage to the machine. In that vein, I believe that bolting a lathe to a floor is potentially a bad idea, depending on the design of the machine, as it can muffle the lathe when it is trying to tell you something important. It would be like disabling a smoke detector that is sounding an alarm so that you can get back to sleep.”
Brent English, founder of Robust Tools LLC, weighed in as well.
“I think adding weight or bolting a lathe to the floor will certainly make the lathe more stable, and may improve the experience at the lathe for the turner,” English says. ”It’s important not to impart a twist on the lathe bed as that will negatively affect alignment. But I think if you’re adding weight and/or bolting the lathe to the floor to mitigate a weak or light weight lathe you may be setting yourself up for a false sense of security. If the lathe is shaking, that’s nature’s way of telling you to slow down and/or get things more balanced. The wood will fail before the lathe will, and failed wood flying off the lathe is not to be trifled with.”
Based on my own experience, and after getting input from several knowledgeable sources, I feel comfortable adding some weight to my lathes. I will occasionally add a couple sandbags, particularly when turning on a midi or midsized machine, but I rarely feel the need to do this on my 24” lathe.
Given some of the massive chunks of wood that I turn, weighing over 100 pounds in some cases, I wouldn’t feel comfortable bolting a lathe to the shop floor without first having a conversation with the manufacturer about the potential risks. If you are operating within the limitations and design of the lathe, then bolting it down might be an option, but with the “smoke alarm disabled” you are left to your own instincts as to what the lathe can handle.
Turning, a term that resonates throughout the industry, a technique that has paved the way for modern machining and has become the cornerstone of mechanical engineering.
With a single point cutting tool and a rotating workpiece, it opens up a world of precision cuts and intricately shaped components.
This article will unravel the ins and outs of turning, laying bare the parameters, operations, types, and equipment involved. Get ready to explore the world of turning, where raw materials are shaped into engineered perfection.
What is Turning?
Turning is a type of machining operation that involves a cutting tool removing material from a workpiece while it rotates around an axis. This operation is performed on a turning machine or lathe, a specialized tool that accommodates various geometries and materials.
With turning, operators can achieve a good surface finish and manufacture parts with high tolerances. It’s a process that allows for the creation of internal and external surfaces, even contoured ones, with unparalleled precision.
The Dawn of Turning: A Historical Perspective
Tracing the origins of turning takes us back centuries, to when manual lathes were used to shape wood and metals. The transformation of the process came with the introduction of Computer Numerical Control (CNC) technology in the mid-20th century, revolutionizing the industry.
Turning evolved from a manually controlled process to an automated one, enabling the production of intricate and accurate diameter components, limited only by the specifications of the machine and operator skill.
What is the Working Principle of Turning?
Turning operates on a simple yet effective principle:
What are the Stages of Turning?
The turning process unfolds in a series of carefully calibrated stages, which we will explore below.
First, the workpiece is mounted onto the lathe. This is often achieved by fixing the workpiece between two centers or securing it in a chuck, allowing it to rotate around a fixed axis.
Next, the single point cutting tool is positioned perpendicular to the workpiece surface. The tool’s cutting edge angle, rake angle, and relief angle, which determine the quality of the cut, are adjusted as per the desired outcome.
Once the setup is complete, the lathe machine is started, and the workpiece begins to rotate. The cutting tool moves in a longitudinal direction along the rotating workpiece, removing material in the form of chips.
The last stage involves checking the workpiece for any imperfections and making necessary corrections. The final part is then measured for dimensional accuracy and surface finish, which may require additional turning operations such as finish turning or sizing.
What are the Different Types of Turning?
Turning is not a monolithic process, but rather a collection of methods, each with its unique characteristics and applications. Here are some of the most common types:
Turning Techniques and Methods
Different turning techniques have been developed to suit the needs of various applications. These include:
Parting off, also known as cut off, involves cutting a piece off a part that is being turned.
Grooving is a turning operation where grooves are made on the surface of a workpiece.
Facing is the process of cutting along the end face of a workpiece, generally to make it flat or to cut it to a specific length.
Knurling doesn’t involve cutting but rather pressing a pattern onto the surface of a workpiece. It is often used to create a serrated pattern for better grip or aesthetic appeal.
Reaming removes a small amount of material from an existing hole to improve its dimensional accuracy and surface finish.
Turning, as an essential machining operation, employs a range of equipment for different purposes. Here are some of the critical tools involved:
A lathe machine, also known as a turning machine, is the central equipment in the turning process. Different types of lathes are used for various turning operations, such as turret lathes, special-purpose lathes, and CNC lathes.
A single point cutting tool, typically made of high-speed steel or carbide, is used in the turning process. The tool’s characteristics, such as the cutting edge angle and tool life, play a significant role in the turning process’s success.
A chuck is a device used to hold the workpiece in place while it rotates.
A tailstock supports the end of the workpiece when it is being turned between centers.
The feed mechanism, usually controlled by a lead screw, controls the speed at which the tool moves along the workpiece.
Parameters in Turning
Several parameters influence the turning process. Understanding these can help optimize the process and achieve the desired results. Some of the main parameters include:
The cutting speed, often expressed in meters per minute or feet per minute, refers to the speed at which the cutting tool or the workpiece moves during the cutting process. It’s a paramount factor that influences the quality of the cut, tool life, and overall productivity of the turning operation.
There are numerous factors to consider when setting the cutting speed, such as:
Another pivotal parameter in turning is the depth of cut, which is the distance the cutting tool penetrates into the workpiece. This factor can have a significant impact on the production rate, surface finish, and tool life.
To highlight a few considerations related to the depth of cut:
The feed rate in turning refers to the distance the tool travels along the workpiece in one revolution of the workpiece. Like other parameters, it can significantly influence the quality of the finish, the life of the tool, and the speed of production.
Here are some key factors to consider regarding the feed rate:
Other important turning parameters are:
Supported Materials for Turning
Turning is a versatile process that can be used on a wide range of materials. Commonly turned materials include metals like steel, brass, aluminum, titanium, and nickel alloy, as well as plastics such as nylon, polycarbonate, ABS, POM, PP, PMMA, PTFE, PEI, and PEEK.
Some turning operations also extend to wood and other materials, though metals and plastics remain the most common.
Turning is chosen based on the material’s machinability, the complexity of the required features, and the desired surface finish.
More robust materials such as steel and titanium may require more power, specialized tools, or specific cutting force, while softer materials like aluminum and plastic are relatively easy to machine.
Certain materials, due to their unique properties, may produce better surface finishes or allow for more intricate shapes and forms to be machined.
Advantages and Disadvantages of Turning
Like any manufacturing process, turning also comes with its share of advantages and disadvantages.
The advantages of turning include:
On the other hand, the disadvantages are:
Design Tips for Turning
When it comes to designing for turning, there are a few critical points to keep in mind. The following guidelines can help you achieve optimal results:
Softwares used in Turning
With the advent of computer numerical control (CNC) technology, turning operations have become highly automated and precise. CNC lathes are controlled using specialized software that enables complex geometries to be machined accurately and repeatably. Some of the popular software used in turning include AutoCAD, SolidWorks, Mastercam, and Fusion 360. These software tools allow operators to design the part, plan the machining operations, and generate the necessary G-code that controls the movement and operation of the CNC lathe.
Potential Dangers of Turning
Turning, like any other machining operation, presents potential hazards. Accidents can happen due to tool breakage, flying chips, or entanglement with rotating parts. It’s crucial to ensure all safety measures are in place and adhered to, including wearing protective clothing and equipment, regularly maintaining and inspecting the machinery, and providing proper training to operators. It’s also important to maintain a clean and organized workspace to reduce the risk of accidents.
Possible Side Effects in Turning
Turning involves the removal of material from a rotating workpiece using a single point cutting tool. This machining operation can produce several side effects, largely contingent on the operation parameters, the nature of the workpiece material, and the cutting tool characteristics.
A key concern is tool wear, an inevitable occurrence in turning operations, impacted by factors such as cutting speed, feed rate, and the tool’s cutting edge angle. Wear leads to degradation in the tool’s performance, affecting the accuracy and surface finish of the machined component. Moreover, the produced chips, a by-product of removing material, may impose handling and disposal challenges.
Frequently, turning operations require continuous supervision to monitor these side effects. Despite such automation advancements in CNC lathes, an operator’s role in maintaining high tolerances, mitigating tool wear, and ensuring a good surface finish remains essential.
Environmental Impact of Turning
Like other machining processes, turning can have environmental implications. The energy consumption of turning machines, waste generation from the removed material, and the disposal or recycling of spent cutting tools represent significant environmental factors.
Moreover, coolant and lubricants used to mitigate friction, cool the cutting tool, and extend tool life often pose environmental hazards due to their chemical compositions. As the machining industry progresses, eco-friendly alternatives are increasingly being sought, aiming for a more sustainable turning process.
Cost-effectiveness of Turning
The cost-effectiveness of turning is largely dependent on several factors, including machine cost, operator costs, tool life, and maintenance expenses.
The cost of turning services can vary significantly based on factors such as the complexity of the part, material type, tolerances required, and regional labor costs. On average, however, one might expect to pay between $50 and $100 per hour for CNC turning services.
Where to Get Turning Services?
Several organizations offer professional turning services, one notable provider being 3ERP. They specialize in various CNC turning services to a broad array of parts. Turning at 3ERP is carried out on a variety of metals like aluminum, magnesium, steel, stainless steel, brass, copper, bronze, titanium and nickel alloy, as well as plastics like nylon, polycarbonate, ABS, POM, PP, PMMA, PTFE, PEI, and PEEK.
Alternative Technologies to Turning
Although turning is a vital operation for creating cylindrical or tubular components, there exist other technologies capable of generating similar results. Milling, for instance, although fundamentally different in operation, can be used to produce components with cylindrical characteristics and even contoured surfaces.
Furthermore, advancements in additive manufacturing or 3D printing offer an alternative approach for creating complex geometries without the need for subtractive processes like turning.
Conclusion
Turning is an integral component of the machining industry, enabling the creation of intricate components through high precision cuts. Its versatility is showcased in its ability to handle a variety of materials and produce a wide array of shapes and geometries.
While turning brings numerous benefits, it also presents challenges such as tool wear and environmental concerns. As technology progresses, continuous efforts are made to optimize this technique, making it safer, more efficient, and more sustainable. The mesmerizing world of turning will continue to evolve, molding the future of mechanical engineering.
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