Self-Centering Round Object Clamp – Adjustable & Customizable (Silicon Wafer Holder)

This is a self-centering, spring-loaded clamp for round, flat objects — originally designed to safely hold a 200mm silicon wafer (2-6mm thick), but equally useful for discs, lids, glass panes, or any other round item you need to grip securely without damaging it. Three spring-tensioned arms, each riding on ball bearings, automatically center and clamp the object as they're drawn inward, so it works across a range of diameters without manual adjustment. The main body houses the bearing/spring mechanism, and a 3-part base gives it a stable footing.

A detailed assembly guide is included as a PDF attachment!
(It was created with Bambu Studio's Assembly Group Manager, which was sometimes a bit tricky to use — so please excuse the assembly PDF if it's not perfectly polished.)

Stückliste (Bill of Materials):

3x Extension Spring, 5x20.5mm
6x Metal Rod, 4x100mm
3x Metal Rod, 3x25mm
6x Ball Bearing 623ZZ (3x10x4mm)
1x Ball Bearing 607ZZ (7x22x7mm)
6x Socket Head Cap Screw M2x4 (Strap assembly)
3x Socket Head Cap Screw M2x6 (Strap assembly)
1x Socket Head Cap Screw M2x6-8 if needed + M2 washer (Base assembly)
7x Heat Set Insert M2
1x Heat Set Insert M5

Note: Heat-set inserts and the screws used to secure the tension bands are not shown in the 3D model/renders. The same applies to the tension springs — they are not modeled either. All of these parts are visible and installed in the photos of the assembled unit.

Two versions (base + gripping jaws):

Both the base and the gripping jaws are available in two versions: one plain, and one with small recesses on the gripping/contact surfaces. The recessed version lets you glue in a soft, damping material at the contact points for extra grip and to protect the clamped object.

Main screw / assembly note:

The main screw is an M5x25 — the length can be varied to suit your build. During assembly, screw the M5 into the Connector Screw part first, then insert that assembly into the bearing.

Print Settings

• Printer brand:

  Bambu Lab

• Rafts:

  Yes

• Supports:

  Yes

• Resolution:

  when printing the Base_Bottom, you should activate variable layerhight, to geht a better resolution

• Notes:

  Tolerances:

  Fit tolerances depend on your printer's calibration — check them for your setup, as the fit may come out slightly loose depending on your machine.

Notes:

Tip (M5 screw handle):

Tip: you can print a small handle for the M5 socket head screw — designs for these are freely available online — which makes turning it noticeably easier.

Spring hooks note:

The gripping jaws and the linear rail's end cap each have small hooks molded in for anchoring the tension springs. These need to be pressed into place first, then assembled.

Customization / scalability

The whole design is fully customizable — by using longer (or shorter) rods, a longer main screw, and longer bands, you can scale the holder up or down to fit different sizes beyond the original 200mm wafer, making it adaptable to whatever round object you need to clamp.

Material note (Tensioning Strips):

The tensioning strips are best printed in TPU for flexibility, though PLA will most likely work as well.