29/03/2014
The question of whether a turntable possesses lateral rotation is a fundamental one, particularly when considering their application in automotive maintenance, such as wheel alignment. A turntable, by its very design, is engineered to facilitate rotational movement. However, the specific nature of this rotation, and whether it includes a lateral component, depends on the type of turntable and its intended function. In the context of vehicle servicing, particularly for wheel alignment, turntables are crucial for allowing the wheels to be steered independently and accurately. This article will delve into the mechanics of turntables used for this purpose, drawing inspiration from a DIY approach, and explore the concept of lateral rotation in this specific application.
Understanding Turntable Mechanics
At its core, a turntable is a device that allows for smooth, controlled rotation. Traditional turntables, like those found in hi-fi systems, are designed for a single, precise rotational axis. However, in automotive applications, the term "turntable" often refers to a specialised plate that sits beneath a vehicle's wheel, enabling it to pivot. The primary function here is to simulate the steering of the front wheels, allowing technicians to measure and adjust camber, caster, and toe angles accurately. The lateral rotation in this context refers to the movement of the wheel and tyre assembly as the steering angle changes, which is precisely what the turntable facilitates.
DIY Turntables for Wheel Alignment
The information provided about constructing DIY turntables using Lazy Susan bearings is an excellent illustration of the principles involved. Let's break down the components and their significance:
- Lazy Susan Bearings: These are the heart of the turntable, providing the low-friction rotational capability. The choice of bearings with a 1000lbs capacity is a wise one, ensuring they can comfortably support the weight of most passenger vehicles. The smoothness of these bearings is paramount for accurate alignment readings.
- Aluminium Plates: Two pieces of 1/2" aluminium plate serve as the robust surfaces between which the Lazy Susan bearings are sandwiched. Aluminium is a good choice due to its strength-to-weight ratio and resistance to corrosion.
- Degree Markings: The precise marking of degrees is absolutely critical for a wheel alignment turntable. This allows the technician to set the wheels to a known starting point (zero degrees) and then measure the degree of steering angle applied. The plan to use a V-groove router bit to incise these lines is a practical approach to ensure the markings are durable and won't easily wear off.
- Locking Pins: The inclusion of locking pins to set the turntable at zero degrees is a vital feature. This ensures that before any measurements are taken, the turntable is in a precise, known position, eliminating any potential for error introduced by a slightly misaligned turntable.
The Role of Lateral Rotation in Alignment
When performing a wheel alignment, the technician needs to assess how the wheels behave when steered. This is where the concept of lateral rotation becomes essential. The turntable allows the wheel to pivot, and the degree markings enable the technician to quantify this movement. For instance, when checking the steering axis inclination (SAI) or caster, the wheels are turned to specific angles, and the turntable's ability to rotate smoothly and accurately is what makes these measurements possible. The accuracy of the turntable directly impacts the accuracy of the alignment results.
Comparing DIY vs. Commercial Turntables
While DIY turntables can be effective, it's useful to consider how they compare to commercially available units:
| Feature | DIY Turntable (as described) | Commercial Turntable |
|---|---|---|
| Bearings | Lazy Susan bearings (high load capacity) | Precision-engineered roller bearings or ball bearings |
| Construction | Aluminium plates, bolted or riveted assembly | Machined steel or heavy-duty composite materials |
| Degree Markings | Manually marked (router bit) | Laser-etched or precision-machined |
| Locking Mechanism | Drilled locking pins | Integrated locking pins, hydraulic locks, or pneumatic locks |
| Durability | Dependent on build quality and materials | Generally very high, designed for professional use |
| Cost | Potentially lower if materials are sourced economically | Can be significantly higher |
| Calibration | Requires careful initial setup and periodic checks | Often pre-calibrated, with recommended recalibration intervals |
Key Considerations for Longevity and Accuracy
For any turntable, whether DIY or commercial, several factors contribute to its longevity and the precision of its readings. Regular cleaning is essential to remove dirt and grit that can interfere with the bearings. Lubrication, according to the bearing manufacturer's recommendations, will also extend their life and maintain smooth operation. For the DIY turntables, ensuring the locking pins engage securely and that the degree markings remain clear and legible is vital. The stability of the base on which the turntables are placed is also a crucial element; uneven surfaces can lead to inaccurate measurements.
Frequently Asked Questions
Q: Does a turntable have lateral rotation?
A: Yes, the type of turntable used for wheel alignment is specifically designed to allow for lateral (or rotational) movement of the wheel, enabling the measurement of steering angles.
Q: What is the purpose of degree markings on a wheel alignment turntable?
A: The degree markings are essential for accurately setting the wheels to specific steering angles for measurement and adjustment of alignment parameters like caster and camber.
Q: Are Lazy Susan bearings suitable for automotive turntables?
A: Yes, if they have a sufficient load rating (like the 1000lbs mentioned) and are of good quality, they can provide the necessary rotational capability for DIY alignment turntables.
Q: How can I ensure my DIY turntable is accurate?
A: Ensure the turntables are perfectly level, the degree markings are precise, and the locking pins engage firmly at the zero position. Regular checks for wear and tear are also recommended.
Q: What is the primary advantage of a professional alignment system over DIY?
A: Professional systems typically use more precise components, offer advanced calibration, and are built to withstand heavy, continuous use, ensuring higher levels of accuracy and repeatability.
Conclusion
In summary, the turntables constructed as described, utilising Lazy Susan bearings and precise degree markings, are indeed designed to facilitate the lateral rotation of a vehicle's wheel. This rotational capability is fundamental to the process of wheel alignment. The DIY approach highlights the core mechanical principles, demonstrating that with careful construction and attention to detail, effective tools can be created for automotive maintenance. The effectiveness of such a tool hinges on the quality of its components, the precision of its markings, and the user's understanding of its function. While professional equipment offers greater convenience and potentially higher accuracy, the ingenuity behind a well-made DIY turntable is commendable and serves its purpose admirably.
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