How To Repair Tormach 1100m BT30 Spindle Replace Spindle Bearings

This video has a detailed full teardown and replacement of the Tormach BT30 Spindle Bearings.

https://www.youtube.com/watch?v=8EooLj1NlrY

UPPER BEARINGS

The upper bearings are sitting on top of each other. There is no spacer.

These are the markings on what someone claims is the stock upper bearings (unverified)

HP7006C-2RZTN12/P5

In a comment from the above video:

Part number breakdown:

70 Dimension Series Indicates an angular contact ball bearing in the 70 series (ISO 10 dimension series). Outside Diameter: 55 mm, Width: 13 mm

06 Bore Size The bore diameter code. Multiply by 5 to get the millimeter size: 06 \times 5 = 30 mm.

C Contact Angle Indicates a 15° contact angle. This is optimized for high speeds and lower axial loads.

2RZ Sealing Non-contact seals on both sides. These keep grease in and dirt out without adding much friction.

TN12 Cage Material A glass-fiber reinforced PA66 (Polyamide) cage, usually ball-centered.

P5 Tolerance Dimensional

• These are the markings on the upper bearings in the video, which the guy says he already previously replaced from another tormach BT30 spindle that the lower bearings had failed.

• 7006CTN1P5DBA

• 19014

• CSC

• Outer race = -4

• Inner race = -3

Nomenclature Breakdown

Code Meaning Details

70 Bearing Series Extra-light 70 series angular contact ball bearing.

06 Bore Size 06 x 5 = 30 mm inner diameter.

C Contact Angle 15° angle; optimized for high speeds and radial stiffness.

TN1 Cage Material Polyamide (Nylon) cage, reinforced for high-speed stability.

P5 Precision Class ISO Class 5 (ABEC 5); provides high running accuracy.

DB Arrangement Back-to-Back duplex pair; handles axial loads in both directions.

A Preload Light Preload (standard for high-speed/low-heat applications).

REPLACEMENT UPPER BEARINGS

These are the replacement upper bearings. Note that they do not have seals and therefore do not come pre greased.

• NSK brand

• 7008CTRDUL P4Y

• 904

• DD-6336

• D: A=-3, B=-3

• d: A=-6, B=-6

• C: -58

LOWER BEARINGS

The lower bearings have an inner and outer race spacer between them.

HP7008C-2RZTN12/P5 DBA

• These are the markings on the stock lower bearings shown in the video. They have rubber seals.

• HP7008C-2RZTN12/P5 DBA

• TCHH95B8474

• Outer race = -5

• Inner race = -2

• Inner race spacer width = 0.59305in

• Outer race spacer width = 0.59305in

Breakdown of the Part Number:

7008: The dimensional series, representing a bore (inner diameter) of 40mm, an outer diameter of 68mm, and a width of 15mm.

C: Indicates a 15 contact angle, designed to handle high-speed rotation and primarily axial thrust loads.

-2RZ: Features non-contact rubber seals on both sides of the bearing to protect it from dust and debris while maintaining low friction for high-speed operation.

TN12: Indicates a Polyamide (Nylon) cage reinforced with fiberglass, designed for lightweight and high-speed operation.

/P5: The ISO P5 precision class (ABEC-5 equivalent), meaning it is manufactured with stricter dimensional and running tolerances than standard (P0/P6) bearings.

Configuration (The "DBA" Suffix)

​This is the most critical part for installation:

• ​DB: This stands for Back-to-Back mounting (also known as the "O" arrangement).

  • ​Lines of force diverge toward the bearing axis.

  • ​This provides high moment stiffness, meaning the pair is very effective at resisting tilting forces.

• ​A: Indicates the Preload Class.

  • ​A usually signifies a Light Preload. This allows for the highest possible speeds with minimal internal friction.

REPLACEMENT LOWER BEARINGS

These are the replacement lower bearings they used in the video. They do not have a rubber seal

• NSK brand

• 7008CTRDUL P4Y

• 904

• DD-6336

• D: A=-3, B=-3

• d: A=-6, B=-6

• C: -58

  
  

GREASE

2RZ non contact rubber sealed bearings come pre greased. This is not only convenient, but retains the grease better and shields the bearing from debris.

The unsealed bearings that were used in the video require grease.

The YT video recommends using

• KLUBER Lubrication

• ISOFLEX NBU 15

The grease says "Low Temperature". Is this really a low temperature application?

Cleaning bearings prior to greasing.

How much grease to add to bearings?

NSK says that the grease should fill 15% of the free volume within the bearing.