The Hardinge Tool Room Lathe is the most common lathe we see in production environments. Most were made between the mid-1940’s and early 1980’s yet many of these lathes still have decades of service life left in them.
The most common retrofit to these machines is to bring them into alignment with modern safety standards. This is where many people run into trouble. These beautiful vintage machines are popular for a reason, they’re a joy to use! It breaks my heart to see well-intentioned safety contractors turning these easy-to-use machines into awkward production-slowing annoyances.
In this article I’ll discuss how we can bring these machines into alignment with modern safety standards. And we’ll learn how to do this while also retaining their delightfully efficient traditional controls.
Table of contents
Identifying a Hardinge Lathe
The easiest way to identify any machine is by it’s nameplate. For Hardinge Lathes, these nameplates are often found on the front of the left cabinet or on the cover of the electrical cabinet (left side of the machine). See image below.
Alternatively, if all markings have worn off the machine, here are some hints that would suggest your lathe is a Hardinge:
- The machine is the traditional “‘Hardinge Gray” color.
- The “ways” or “bed” of the machine (the smooth horizontal surface) has a continuous flat dovetail. This looks like a large flat top that is angled under on the sides. This feature isn’t completely unique to the Hardinge but it’s definitely not common on other machines. See photo below.
- You see references in documentation (or on the machine) to a model name like “Precision”, “Super Precision”, “HLV-H”, or “HLV-M”.
How Hardinge Lathes are Traditionally Controlled
For most production processes, these machines can be run and cycled by an operator using just a few large levers. The functions of these levers vary from model to model depending on the purpose of the model (e.g. threading, turning, multi-step process, etc.) but typically include:
- Collet Open/Close (1)
- Spindle Forward/Neutral/Reverse (2)
- Spindle High/Neutral/Low (3)
- Quick-Acting Handle (5)
- Power Feed Clutch (4)
An experienced operator can perform multiple operations on a part in just a few seconds. This makes these machines pleasant to use as an operator and also highly efficient and profitable for a manufacturing business.
Are Traditional Hardinge Lathe Controls Safe?
Like all good things, these traditional controls come with some tradeoffs. In the case of safety, here are some examples:
- there are as many as 6 different ways for the machine to transition from ‘stopped’ to ‘running’. NONE of them are labeled as ‘start’.
- After a power outage, when the machine is first turned on, or when resetting the original e-stop-like button, the machine will restart if the levers are in the wrong position. This is an explicit violation requirements for the controls of a machine in a modern workplace.
- Many of the original labels may no longer be legible.
- If not maintained, the levers get sloppy and it can be hard to differentiate by feel between say forward and neutral.
- Most of the original machines came with a spindle brake that was automatically applied whenever the spindle turned off. Unfortunately, this brake relies on a piece of cork that wore out on most machines decades ago and hasn’t been services/replaced.
- While the mechanical parts of the machine are still robust after decades in service, the electrical systems (e.g. contactors, switches, etc.) are decades beyond their useful life. This makes them prone to unexpected and intermittent failures.
(machine guards are another important part of lathe safety – but we’ll cover that in another article)
Why Common Safety Retrofits Can Have Negative Outcomes
Most safety retrofits to old machinery are simple; you just replace the original starter with a premade on/off/e-stop panel. One common example of an undesirable change on these lathes is to replace the forward/reverse lever with momentary push buttons mounted above the machine. Or, to add an aftermarket e-stop without considering the rest of the control system.
In both cases, that is a big mistake. These machines are also well known to machinists and any changes to their standard operation is bound to have the following effects:
- The changes can confuse and frustrate even the most experienced machine operators. There is no competing with decades of muscle memory and a common understanding
- cycle times will increase and profitability will decrease
- Operators will try to remove the retrofit to restore original operation themselves. This typically bypasses the new retrofit and gets people into a bad situation
- Operators may start to equate “safety” on machines with negative outcomes, which can significantly effect safety
- The addition of an aftermarket e-stop may not account for all the ways these machines can turn on. This means that resetting an e-stop could start the machine – a big no no).
How Do I Make The Traditional Lever Controls Safe?
MAKESafe Tools has developed an electronic control system for this exact purpose – retrofitting Hardinge Lathes. With this system, you can retain the convenience of the traditional controls and bring the overall operation up to modern safety standards. On your lathe, our system will:
- Prevent unintended startups after loss of power or an emergency stop (e.g. anti-restart)
- Provide an ANSI, NFPA, and OSHA-compliant e-stop function to the machine
- Automatically apply braking to the spindle on every machine cycle or e-stop
- Install easily by maintenance personnel onto existing machines
- Integrate easily with aftermarket machine guards and interlocks
- Provide modern and resettable protection against short circuits and motor overloads.
- Meet any safety performance level required by the customer
If you’d like to learn more, please contact us!
Here is an example of one such installation:
