BMS Spindle Service

+48 505 909 717
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+48 505 909 717
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+48 505 909 717

On-Site Taper Grinding
of Spindles in Machine Tools – SK / BT / ISO

On-site spindle taper grinding – precise taper restoration at the customer’s location, with minimal cost and zero machine downtime.

BMS Spindle Service CNC offers mobile grinding of SK, BT, and ISO tapers (sizes 30 / 40 / 50) without the need to disassemble the spindle, directly on the machine.

Our experienced mobile service operates across Europe, delivering spindle taper grinding within 24 hours. We restore the full contact surface of the taper and reduce runout to as low as 2 microns (0.002 mm), restoring OEM-level tool clamping precision.

Why On-Site Taper Grinding Is Best
for Maintaining Production Continuity

The CNC spindle taper is a critical interface between the tool and the machine – its geometry directly affects machining precision, stability, and safety. Wear or damage results in off-center tool holding, which negatively impacts the cutting process. Even minor taper deviations can cause serious issues:

  • Weak tool holding – leads to reduced accuracy and poor part quality, and in extreme cases, tool dislodgement.
  • Vibrations and excessive tool wear – increased instability during machining shortens tool life and may damage the machine, raising production costs.

Mobile spindle taper grinding restores ideal clamping geometry – improving tool holding force, reducing runout, and ensuring full stability of the machining process. This service quickly eliminates the above issues while maintaining the highest CNC precision and minimizing downtime.

Spindle taper grinding on CNC machine without disassembly at customer site

Process of Mobile
Spindle Taper Regrinding

Each mobile spindle taper grinding service follows a proven five-step process. This allows us to fully restore the spindle taper geometry to OEM standards without disassembly. Below we present the step-by-step process carried out directly at the customer’s site:

1. Inspection and Diagnosis

We begin with a thorough assessment of the taper condition inside the spindle using precision measuring tools. We check axial and radial runout, inspect the taper surface for wear or damage, and evaluate the quality of tool contact. Based on these readings, technicians diagnose the issue and plan the grinding scope to restore the taper to nominal geometry.

2. Preparation for Grinding

Before machining begins, we prepare the machine tool and spindle. The spindle is locked in position and the area is protected from grinding dust (e.g., guides are shielded). The taper surface is thoroughly cleaned of coolant, rust, or contaminants to ensure ideal grinding conditions. Then we install the grinding attachment—a specialized tool that allows precise grinding inside the spindle. This tool is aligned and calibrated so that its axis matches the taper axis, ensuring OEM-compliant geometry.

3. Taper Grinding

The core regeneration process involves precision taper grinding inside the spindle using a portable grinder. Our technician removes a minimal material layer to correct taper shape and eliminate damage. The process is slow and controlled to prevent spindle overheating. Using modern grinding technology and continuous monitoring, we restore surface smoothness and taper angle to OEM standards. This removes runout and surface irregularities, ensuring full contact between the taper and tool holder. All work is done without removing the spindle, reducing downtime and avoiding assembly errors.

4. Measurement and Verification

After grinding, we perform a detailed check of taper geometry. We re-measure runout with high-precision dial indicators and evaluate the surface quality (e.g., using contact dye tests). We verify if concentricity and taper angle are within OEM tolerances—typically runout is reduced to about 0.002 mm. Tool fit is also checked: after grinding, the holder should achieve maximum contact surface to ensure optimal clamping force. If all parameters are correct, the service is finalized.

5. Final Testing

We finish with operational tests to confirm spindle performance post-regeneration. We run the spindle and check its behavior under load—looking for absence of vibration, noise, or overheating. If needed, we test tool clamping and perform trial runs or rotations. Since the grinding was done in-situ, no spindle reinstallation or realignment is required. After tests, the machine is ready for production. The whole mobile regeneration is typically completed within one day, minimizing downtime and restoring full machine capacity quickly.

Spindle taper grinding process in CNC machine
►
Taper Toolholder Restoration SK/BT/ISO in CNC Machine

Most common spindle taper issues
and how to fix them

Spindle taper runout

Excessive runout causes vibrations, reduces tool life and machining accuracy.

Solution – Mobile taper grinding reduces runout to as low as 2 μm and restores axis alignment.

Taper surface wear

Scratches and irregularities weaken contact between the tool holder and spindle.

Solution – Taper regrinding restores smoothness and OEM contact geometry.

Unstable tool clamping

Looseness in the taper reduces machining accuracy and may cause tool ejection.

Solution – Taper grinding ensures full contact surface and secure tool clamping.

Frequently
Asked Questions

The entire service (from inspection to final testing) is usually completed within one working day. The grinding process itself typically takes a few hours, but including preparation and final checks, the machine is offline for no more than several hours. Thanks to our mobile service, we can often perform the work within 24 hours of request, minimizing production downtime.
No, spindle disassembly is not required. The entire regeneration process takes place directly on the machine. Our special grinding attachment allows us to restore the taper geometry without removing the spindle. This offers major advantages—no disassembly means a faster repair, no need for reinstallation or alignment, and a reduced risk of damage during handling.
After precision grinding, the spindle regains near-original factory parameters. Taper runout is reduced to as little as 0.002 mm, improving machining accuracy and surface finish. Tools are held more securely, enhancing rigidity and process stability, eliminating vibration and reducing tool wear. In practice, your machine operates as accurately as with a new spindle—but at a fraction of the replacement cost.
Yes. Our mobile team serves customers throughout Europe. Regardless of your plant’s location, we can arrive with the necessary grinding equipment. We operate 7 days a week and offer 24-hour response time – in urgent cases, we act immediately to restore your spindle taper. Pricing and scheduling are arranged individually, and in many cases, we can arrive within 24 hours of your request.

Mobile Taper Grinding SK / BT / ISO
to OEM Standard

Use our mobile taper grinding service to restore full geometry and clamping force without taking the machine out of production. We work on-site with top quality standards.

  • Restoration of SK, BT, ISO tapers (30 / 40 / 50) to OEM specification

  • In-situ grinding – no spindle removal required

  • Precision up to 0.002 mm – verified by measurements

  • Mobile service – 24h response, available 24/7

Contact us and order the service. We will ensure perfect clamping and top CNC machining quality.

CONTACT

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