Starrett S828
Starrett S828 Wiggler/Center Finder Instruction Manual
Model: S828 | Brand: Starrett
1. Introduction
The Starrett S828 Wiggler/Center Finder is a precision tool designed for accurately locating a spindle relative to a workpiece in machining operations. This set includes the main wiggler unit and three interchangeable attachments, allowing for versatile application in various measurement tasks. It is an essential tool for establishing precise working centers and features.

Figure 1: The Starrett S828 Wiggler/Center Finder with its complete set of attachments.
2. Components Included
Your Starrett S828 Wiggler/Center Finder set includes the following components:
- One (1) Starrett S828 Wiggler/Center Finder Main Unit
- One (1) Ball Contact 828B (0.250" / 6.35mm diameter)
- One (1) Disc Contact 828C (0.100" / 2.54mm diameter)
- One (1) Pointed Contact (PT09186)

Figure 2: All components of the Starrett S828 set, as received.
3. Setup and Assembly
The Starrett S828 Wiggler/Center Finder is designed for quick and easy setup. Follow these steps to prepare your tool for use:
- Unpacking: Carefully remove all components from the packaging. Inspect for any signs of damage during transit.
- Attachment Installation: Select the desired attachment (Ball Contact, Disc Contact, or Pointed Contact). Snap the chosen attachment into the chuck of the main wiggler unit. It is not necessary to remove the collet nut for this process.
- Securing the Attachment: The attachment is clamped by a ball swivel-joint, which allows for adjustment to an angular position or true concentricity. Ensure the attachment is securely seated before use.
- Mounting: Insert the main wiggler unit into the spindle of your milling machine or other appropriate machine tool. Ensure it is held firmly and runs true.

Figure 3: The interchangeable attachments are easily installed into the main unit.
4. Operating Instructions
The Starrett S828 Wiggler/Center Finder is used to precisely locate the spindle relative to a workpiece. This is crucial for accurately making part features such as bolt hole locations.
General Operation Principles:
- Spindle Speed: For optimal performance and safety, operate the machine spindle at approximately 1000 RPM when using the wiggler.
- Concentricity: The spring tension on the ball of the point guides the contact to concentricity, allowing the work to be brought into perfect alignment with the machine spindle.
Using the Attachments:
Each attachment serves a specific purpose:
- Ball Contact 828B:
This attachment (ball diameter 0.250" or 6.35mm) is primarily used for locating work by bringing the contact against the workpiece. It is effective for quickly and accurately locating working centers or edges. When touching an edge, observe the point where the contact "wobbles" and then suddenly "snaps" into true concentricity. This indicates the edge has been found.
- Disc Contact 828C:
Featuring a small disc at the end (0.100" / 2.54mm diameter), this attachment is designed for use in more confined areas, such as narrow slots or shallow holes, where the larger ball contact may not fit. Its operation is similar to the ball contact for edge finding and centering.
- Pointed Contact (PT09186):
The pointed contact is ideal for centering the spindle over layout lines or a center punch mark. To use, turn on the spindle, gently bring the pointed tip close to the mark, and allow it to self-center. Once centered, turn off the spindle and visually align the tip with your layout mark for precise positioning.

Figure 4: Overview of the Wiggler/Center Finder features and various attachments.
5. Maintenance
Proper maintenance will ensure the longevity and accuracy of your Starrett S828 Wiggler/Center Finder.
- Cleaning: After each use, wipe down the wiggler and its attachments with a clean, soft cloth to remove any dust, chips, or oil residue. For stubborn grime, use a mild cleaning solution and dry thoroughly.
- Lubrication: Periodically apply a light coat of precision tool oil to the moving parts, especially the ball swivel-joint, to ensure smooth operation and prevent corrosion.
- Storage: Store the wiggler and its attachments in a clean, dry environment, preferably in a protective case or drawer to prevent damage and contamination. Avoid storing in areas with high humidity or extreme temperature fluctuations.
- Inspection: Regularly inspect the attachments for wear or damage. Ensure the ball contacts are securely attached and the pointed contact is not blunted.
6. Troubleshooting
This section addresses common issues you might encounter with your Starrett S828 Wiggler/Center Finder.
| Problem | Possible Cause | Solution |
|---|---|---|
| Attachment wobbles excessively or does not snap to concentricity. | Attachment not fully seated in the chuck; debris in the chuck; worn ball swivel-joint. | Ensure attachment is fully snapped in. Clean the chuck and attachment base. If wear is suspected, contact Starrett support. |
| Ball contact becomes loose or detaches. | Excessive force during use; manufacturing defect; wear over time. | Avoid applying excessive side force. If the ball detaches, it may indicate a need for replacement. Contact Starrett support for assistance. |
| Inaccurate readings or difficulty finding edges/centers. | Incorrect spindle RPM; dirty contact surface; damaged attachment tip. | Verify spindle speed is around 1000 RPM. Clean the contact tip and workpiece surface. Inspect the attachment tip for damage and replace if necessary. |
7. Specifications
Key specifications for the Starrett S828 Wiggler/Center Finder:
- Model Number: S828
- Product Dimensions: 5.5 x 1.3 x 1.1 inches (139.7 x 33.02 x 27.94 mm)
- Item Weight: 2.72 ounces (77.11 grams)
- Manufacturer: Starrett
- Included Attachments: Ball Contact 828B, Disc Contact 828C, Pointed Contact PT09186
- Ball Contact Diameter: 0.250 inches (6.35 mm)
- Disc Contact Diameter: 0.100 inches (2.54 mm)
8. Warranty and Support
For detailed warranty information regarding your Starrett S828 Wiggler/Center Finder, please refer to the documentation provided with your purchase or visit the official Starrett website. Starrett products are known for their quality and durability.
If you require technical assistance, have questions about product operation, or need to inquire about repairs or replacement parts, please contact Starrett customer support directly. Contact information can typically be found on the manufacturer's website or in the product packaging.
You can visit the official Starrett store for more information: Starrett Official Store
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