Estimated reading time: 14 minutes
Lathes are dangerous! Add safety guarding such as a chuck shield, chip shield for the cross slide, and covers on the lead screw. Also, don’t overlook the backsplash, tools falling off the headstock into the chuck, or the tailstock falling on your feet!
Like any machine with exposed moving or rotating parts, a lathe is no exception. It requires some safety considerations, such as installing lathe guards. Operating a lathe involves inherent risks because the rotating parts and sharp cutting tools can cause severe injuries if proper safety measures are not in place. To mitigate these hazards and ensure a safe working environment, lathe guards are indispensable. In this article, I will explore lathe guards’ importance, benefits, regulations surrounding their usage, and considerations for using a lathe safely.
What is a Lathe, and What Are the Risks?
A lathe is a versatile machine tool used in machining operations to shape and cut various materials. The primary function of a lathe is to perform turning operations, where the workpiece rotates, and a stationary tool makes cuts.
While lathes are valuable tools, they also present certain risks that operators should be aware of. One-third of all machine accidents in the valves and fittings industry originate from lathes.1
Common Lathe Risks
- Contact with Rotating Parts: The spinning components of a lathe, such as chucks, spindles, and lead screws, can cause severe injuries if operators connect with them accidentally. Accidental contact can lead to entanglement, resulting in severe lacerations, fractures, or strangulation.
- Flying Debris and Projectiles: As lathes cut and shape materials, they generate hot chips, coolant, or other debris. These flying objects pose a risk to operators and may cause burns and lacerations.
- Tool Ejection: Tools or workpieces can become dislodged or ejected from the lathe during operation, especially if they are improperly secured or have issues with the lathe’s setup. Always ensure everything that you tighten everything in place before starting the machine.
- Noise and Vibration Hazards: Lathes can generate significant noise levels and vibrations during operation, adversely affecting operators’ hearing, causing fatigue, and affecting concentration and balance.
- Inhalation of Hazardous Substances: Some machining processes involve using coolant fluids, lubricants, or cutting oils, which may release hazardous substances or generate airborne particles. Operators may inhale these substances if not adequately protected, leading to respiratory or long-term health problems.
Always Stay Vigilant
Growing up, I vividly remember my mother’s role as a machine operator in a textile mill. She instilled a valuable lesson that has remained ingrained in my mind throughout my life: “Regard every machine as a stray dog and approach it as if it was rabid.” These words of caution emphasized the importance of maintaining a vigilant mindset when operating power equipment like a lathe.
This lesson holds deep significance, particularly when considering the experiences of seasoned professionals like Adam Savage, best known as the former co-host of MythBusters, who openly shared his lathe accident story in a YouTube video. Despite his years of expertise with lathes, he came close to losing a finger due to a momentary lapse of caution. (Refer to the video below)
Adam’s situation is a striking reminder that those who grow complacent or underestimate the risks associated with machinery face the most serious dangers. Such incidents underscore the pivotal role of safety shields and guarding mechanisms in minimizing potential accidents.
How does a CNC Lathe differ from a conventional lathe?
Although I am not focusing on CNC lathes in this article, we can briefly summarize the differences between them and conventional lathes.
Conventional lathes and CNC (Computer Numerical Control) lathes differ in operation and safety features. Operators manually control conventional lathes, while CNC lathes are computer-controlled machines that follow pre-programmed instructions and can move automatically.
CNC lathes prioritize operator protection and accident prevention through specific safety features such as interlocking safety systems and complete enclosures. These enclosed work areas prevent part and tool ejections from collisions or improperly chucked parts.
Introduction to Lathe Guarding
Guarding ensures operator safety and promotes a secure work environment. The primary purpose of lathe guards and shields is to protect operators from the flying debris generated during the machining process or from accidental contact with rotating parts. These guards protect operators by creating physical barriers between them and the machine’s moving components, such as the chuck, spindle, and tooling. By effectively enclosing or shielding these hazardous areas, lathe guards prevent accidents and minimize the potential for injuries.
As the lathe rotates, the workpiece and cutting tools engage, and chips and coolant can be forcefully expelled from the work area. Lathe shields serve as proactive barriers, intercepting these materials and preventing them from reaching the operator. By averting contact with flying debris, guards significantly reduce the risk of burns, eye injuries, skin lacerations, and other related hazards.
Lathe guards actively prevent accidental contact with the machine’s rotating components. Acting as physical barriers, guards effectively block operators from inadvertently reaching into hazardous zones where they could encounter rotating parts. Through their enclosing nature, guards minimize the chances of entanglement or injury from direct contact with moving parts.
Ensuring operators know the purpose and correct usage of lathe guarding is essential. The company or organization must train and educate employees on the significance of guarding in maintaining a safe working environment. By instilling an understanding of the risks associated with conventional lathes and the protective role of guards, operators can develop a safety-conscious mindset and take necessary precautions.
Identification of Hazardous Locations on a Lathe
Identifying specific areas on a lathe that require proper guarding to enhance safety is crucial. The image below shows a well-guarded conventional lathe with an installed chuck guard, lead screw cover, and chip shield.
Hazardous Parts of a Lathe
- The chuck is the main rotating component on a lathe. Lathe operators use it to hold and secure the workpiece during machining operations. Even though there is no specific OSHA requirement for lathe chucks, 1910.212(a)(1) specifies that rotating parts need guarding. Never stick the jaws more than half outside the chuck, remove the chuck key when not in use, and ensure you have correctly secured the chuck into the spindle.
- The lead screw and feed rod are typically located beneath the lathe’s carriage and engage with the carriage’s split nut. As the lead screw rotates, the carriage moves along the lathe bed. Exposed lead screws are an entanglement hazard and must be covered.
- The point of operation on a lathe is where the cutting tool engages with the rotating workpiece and where shaping and material removal occur. Understanding and respecting the point of operation actively contributes to maintaining a safe lathe operation. Guards, such as chip shields, protect against contact with the workpiece, cutting tools, and flying debris.
- The headstock on the left side of conventional lathes contains the drivetrain and spindle. The top of the headstock is often flat, which operators tend to use as a work surface or extra storage. You will often find speed and feed control levers on the front of it. A simple safety upgrade I recommend is adding a simple fence or barrier on top of the headstock to prevent items from vibrating off and into a spinning chuck.
- The spindle on a lathe is a hollow shaft that goes through the headstock and transmits the rotary movement to the chuck. You can mount a chuck or faceplate on one end of the spindle. On the other end, the spindle exits the side of the headstock where long parts stick out. Many times, the safety of this area of a lathe is ignored. Still, it is essential to safeguard this area where entanglement and nip point hazards can exist. Furthermore, take special care when loading long bar stock with long stick-out, ensure it is adequately supported, and use the proper spindle speeds. Check out the video below to see what I mean.
- The tailstock assembly is a movable component that an operator can slide on the bed. The primary purpose of the tailstock is to provide additional support to the workpiece or as a holder for attachments such as live centers and drill chucks. The tailstock is a heavy component, but on slippery bed ways, an operator’s strong tug could pull the tailstock entirely off the machine and onto the floor. A straightforward solution to this safety hazard is to install a bolt or stopper at the end of the bed to prevent the tailstock from sliding off the back.
- The backsplash contains chips and coolant on the backside of a lathe. The bottom is usually tapered, so any chips or coolant ejected are returned to the chip pan. Ensure the backsplash is at least 6 feet tall to prevent ejections or reach-over hazards behind the lathe unless it is against a wall or structure.
Be wary of long bar stock sticking out of the spindle end!
Types of Lathe Guards and Safety Upgrades
Now that we know the areas of a lathe that are of safety concern, we will look at some available solutions to bring your lathe up to safety standards and regulations.
Safety regulations require a chuck shield to prevent entanglement hazards. The most popular chuck shield is polycarbonate and flips up for access to the chuck. Nine times out of ten, you will find a chuck installed on a lathe’s spindle. Other times, it could be a faceplate or collet chuck.
Lathe Chuck Shield
Ferndale Safety’s most popular safety shield for lathe chucks is the model TF pictured here. The shield includes a built-in safety interlock switch to prevent machine operation with the guard open.
One of the features of the model TF is the easy replacement of the polycarbonate window and the fact that it has a built-in safety interlock switch. The switch is essential for two reasons:
- It prevents the lathe from being turned on if the shield is not in place.
- It reminds an operator to remove the key from the chuck as the guard will not close with the key left inserted.
Regarding point 2 above, special spring-loaded keys are available. They can enhance safety; leaving the key inside the chuck becomes impossible without constantly applying downward pressure while turning.
The Lead Screw (or Leadscrew)
The best solution to covering the lead screw on a lathe is self-retracting covers that move with the carriage, such as the model AR from Ferndale Safety.
Lead Screw Cover
Prevent entanglement hazards by covering the fast-rotating lead screws on your lathes.
Another type of lead screw cover is the metal coil or spring cover, but this type is only for smaller toolroom lathes with lead screws up to 24 inches long. In addition, an installer would need to remove the lead screw to install this type of cover, which may be complex depending on the lathe.
Prevent Ejections With Chip Shields
The chip shield is mounted on the carriage or cross-slide, where the bulk of chips, swarf, and coolant is generated. The job of this shield in life is to help protect the operator from flying debris such as hot metal shavings. The model TC, shown below, is a great choice and is available with laminated safety glass that resists pitting and burning.
Lathe carriage chip shields protect the operator from flying chips, coolant, and other debris from the point of operation on a lathe.
While not directly involved with lathe safety, I highly recommend a nice high-powered LED work lamp such as the “Super Bright LED work lamp.” Good lighting will increase the chance of operators using see-through shields, as they often complain that safeguards limit visibility.
As noted before, having a walkway behind the lathe requires additional guarding to prevent injury to passersby. Instead of modifying existing backsplash shields or building complex structures on the lathe, you can use a mobile shield such as Ferndale Safety’s movable backsplash shield.
Other Lathe Safety Guards & Accessories
In addition to the guarding solutions mentioned above, we can add other things to increase the efficiency and safety of conventional lathes, such as:
- A foot pedal to stop the machine, or if one already exists, ensure it is adjusted correctly.
- If you have a collet closer attachment to the spindle, consider getting a guard like the model FER-HL-CC.
- Install an emergency stop button located within the operator’s easy reach.
Guarding Standards and Regulations
Suppose you made it this far; congratulations! That’s a lot of information; hopefully, you learned something new. But what about the regulations, you might ask? According to OSHA, things such as chucks must have additional guarding and are mandatory. And in my opinion, other stuff like headstock fences are significant safety enhancements even though they are not mandatory.
According to OSHA, “All machines consist of three fundamental areas: the point of operation, the power transmission device, and the operating controls. Despite all machines having the same basic components, their safeguarding needs widely differ due to varying physical characteristics and operator involvement.”5
The three significant areas of concern are: The work-holding device (chuck), The point of operation (tool post and cross slide), and the power transmission device (lead screw.)
The most critical OSHA regulation for lathes is 29 CFR 1910.212(a)(1): “Types of guarding. One or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips, and sparks. Examples of guarding methods are – barrier guards, two-hand tripping devices, electronic safety devices, etc.”
The standard ANSI B11.6-2001 (R2020) titled “Safety Requirements for Manual Turning Machines with or without Auto Control” aims to eliminate or control hazards to personnel associated with manual turning machines. ANSI B11.6.21 specifies that manual lathes shall be safeguarded with a chuck guard.
For CNC lathes and turning centers: ANSI B11.22-2002 (R2020) titled “Safety requirements for turning centers and automatic, numerically controlled turning machines.”
In 2018, 58% of work-related amputations involved machinery such as lathes. Of all amputations in the same year, 1,660 cases involved machinery used for metal or woodworking.
Benefits of Using Lathe Guards
Using lathe guards provides various benefits for a safer and more efficient work environment. They serve as a crucial line of defense against potential accidents, ensuring the safety of operators and those in the vicinity. The risk of injuries is significantly reduced as lathe guards act as physical barriers, preventing operators from accidental contact with rotating parts, flying chips, or other hazardous elements. By adding a shield at the point of operation, you actively minimize the likelihood of cuts, burns, or eye and face injuries.
Using lathe guards ensures compliance with safety standards. Actively incorporating guarding demonstrates a commitment to safety and adherence to industry regulations. Many occupational safety standards and guidelines mandate using guarding to protect machine operators. By adhering to these standards, businesses create a safer working environment, avoiding penalties and legal issues.
A fully safeguarded lathe has a minimum operational impact. It enhances the enjoyability of use because hot chips are better contained instead of flying toward the operator and causing burns.
General Lathe Safety Guidelines
In addition to the safeguards, here are some general safety guidelines for using a lathe in point form.
- While operating an engine lathe, never wear long sleeves, gloves, jewelry, etc.
- An emergency stop system should be in place and easily reached by the operator.
- Always wear appropriate PPE
- Don’t store the chuck key inside the chuck when not in use.
- Keep the floor and area clean of chips and tripping and slipping hazards.
- Do not use your hands to clean chips and swarf. Use a chip hook.
- Retsch, T. (2011) Lathes. Available at: https://www.iloencyclopaedia.org/part-xiii-12343/metal-processing-and-metal-working-industry/item/679-lathes (Accessed: May 19, 2023).
- Department of Health, State of New Jersey. (June 13, 2017). Fatal Occupational Injuries Surveillance (FOIS) Investigation Report, “Machinist Dies After Being Pulled Into Engine Lathe” at https://www.nj.gov/health/workplacehealthandsafety/documents/fatal-injuries/16nj05.pdf
- Canadian Centre for Occupational Health and Safety, Government of Canada, OSH Answers Fact Sheets, Metalworking Machines – Lathes at https://www.ccohs.ca/oshanswers/safety_haz/metalworking/lathes.pdf (Accessed 2023-05-18)
- Occupational Safety and Health Administration, U.S. Department of Labor, (January 26, 1979), Letter Dated June 9, 1978, to Donald Shay Concerning the Guarding of Lathe Chucks and the Appropriate Standard at https://www.osha.gov/laws-regs/standardinterpretations/1979-01-26
- Occupational Safety and Health Administration, U.S. Department of Labor, Machine Guarding eTool, Machine Guarding: Introduction at https://www.osha.gov/etools/machine-guarding/introduction (Accessed 2023-05-21)