≤0.002mm Accuracy
Every bar individually inspected and certified
HRC56-58 Hardness
20CrMnTi alloy steel, wear resistant, built to last
Cryo Treated
-196°C treatment eliminates internal stress for long-term stability
Includes Box
Aluminium storage case included with every test bar
UK Stock
In stock now, ready for immediate dispatch
Free UK Delivery
On all spindle test bar orders
Why You Need a Spindle Test Bar
Verify Spindle Health
A crash, bearing wear, or just years of use can knock a spindle out of alignment. A test bar lets you measure taper runout at the spindle nose and at 300mm out — revealing problems before they scrap parts.
Qualify After a Crash
After even a minor spindle collision, you need to verify the taper hasn't been knocked out of true. A test bar and a dial indicator give you a definitive answer in minutes — no guesswork.
Check Head Alignment on 5-Axis Machines
A test bar is essential for verifying swivel head and rotary axis alignment on 5-axis machining centres. Clamp the bar in the spindle, sweep it with an indicator mounted to the table at multiple head angles, and you can quantify B-axis and C-axis geometric errors that directly affect part accuracy. Particularly useful after a head rebuild, crash investigation, or routine geometric verification on Hermle, DMG Mori, and Mazak 5-axis machines.
Machine Acceptance Testing
When buying a used machine or commissioning a new one, a test bar provides an objective spindle and head alignment measurement. Most machine tool dealers and service engineers carry one as standard equipment.
Technical Specifications
| Taper | Diameter | Length | Approx. Weight | Common Machines |
|---|---|---|---|---|
| BT30 | 32mm | 300mm | ~1.8 kg | Small VMCs, drill-tap centres, Brother, Robodrill |
| BT40 | 40mm | 300mm | ~3.4 kg | Medium VMCs, most 40-taper machines, DMG, Doosan, Haas VF |
| BT50 | 50mm | 300mm | ~6.5 kg | Large VMCs & HMCs, heavy milling, 50-taper horizontals |
| HSK50A | D30 | 250mm | ~2.1 kg | High-speed spindles, 5-axis machines, DMG Mori, Hermle |
| HSK63 | 40mm | 300mm | ~3.8 kg | HSK63 spindles, 5-axis, high-speed machining centres |
Material & Heat Treatment
- Material: 20CrMnTi alloy steel — high hardness, wear resistance, and shock resistance
- Heat Treatment: Carburised and hardened to HRC56-58°
- Cryogenic Treatment: Deep-cooled at approximately -196°C to eliminate retained austenite, relieve internal stress, and ensure long-term dimensional stability
- Ageing: Post heat-treatment ageing for shape stability — will not deform under normal use
- Grinding: Precision ground on CNC cylindrical grinders for consistent ≤0.002mm accuracy
Spindle Test Bars in Stock
BT30 Taper
HSK50A Taper
HSK63 Taper
Frequently Asked Questions
What is a spindle test bar used for?
A spindle test bar is inserted into the machine spindle taper and used with a dial indicator to measure spindle runout, head alignment, and axis geometry. For standard machines, it verifies that the spindle taper is concentric with the spindle axis. On 5-axis machines, it's the go-to tool for checking swivel head and rotary axis alignment after a crash or rebuild — sweep the bar at multiple head angles to quantify B-axis and C-axis geometric errors.
Which taper do I need for my machine?
Match the test bar taper to your spindle taper. BT30, BT40, and BT50 are standard on most machining centres. HSK50A and HSK63 are common on high-speed and 5-axis spindles. Check your machine manual if unsure.
How do I use a test bar?
Clean the spindle taper thoroughly. Insert the test bar and clamp it. Mount a dial indicator on the table or spindle housing. Measure runout at the spindle nose and at 300mm out. Compare readings against the machine manufacturer's specification.
What accuracy can I expect?
All our test bars are guaranteed ≤0.002mm concentricity. Each bar is individually ground and inspected before leaving the factory.
Does the bar come with a storage case?
Yes. Every test bar includes a fitted aluminium storage box to protect it from damage and corrosion when not in use.
Can I get a test bar for a different taper or length?
We stock the most common sizes listed above. If you need a different taper or length — such as CAT40, CAT50, HSK100, or a custom length — contact us and we can source it for you.
Need a Different Taper or Length?
We can source CAT40, CAT50, HSK100, and custom-length test bars. Contact us with your requirements.
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