MODULE M5 · 10.0 HOURS

Bearing and Fastening Part Installation

0% complete

Prototype safety boundary

Low-voltage educational prototype, not a certified machine safety system
Do not use stop circuits created by learners as safety functions or emergency stops
Perform normal stops by software torque release; after planned stops, physically disconnect the 3 insulated power adapters and verify the de-energized state by measurement before maintenance or access
Do not place hands in the operating range while power is applied; test from no-load in a fixture
Wear impact-resistant work goggles during cutting, drilling, and tendon tension testing
In case of abnormal heat, odor, or smoke, do not approach; cut the power supply to the 3 adapters via a pre-designated building panel breaker outside the hazard zone or a certified upstream master disconnect and evacuate. If no upstream disconnect is available outside the hazard zone, do not energize the system. Torque release is not a substitute for power disconnection
Before introducing to environments with human access, a dual-channel, manual reset, EDM, feedback-capable dual contactor must be separately designed and verified under the review of a qualified safety expert

LEARNING OBJECTIVES

Module objectives

Understand mechanical tolerances and installation principles of bearings and shafts for precision robotic hand fabrication.
Master methods to secure fastening strength of engineering plastic parts using heat-set inserts.
Minimize assembly clearance using appropriate torque and fastening specifications.

Tolerance Management of Bearings and Shafts

For smooth movement and rigidity of precision robotic joints, we use iglide® J sleeve bearings (JSM-0810-10) and 8 mm aluminum precision shafts (AWMP-08). Sleeve bearings are designed to adjust their inner diameter when press-fitted into housings, and complying with the recommended housing inner diameter tolerance is key [S17, S18]. If clearance occurs, joint precision drops; if too narrow, friction increases, reducing the current efficiency of the actuator (DYNAMIXEL XM430).

Heat-set Insert Installation

PC-CF (carbon fiber reinforced PC) prints are prone to thread wear due to material characteristics when metal screws are directly fastened. To prevent this, brass heat-set inserts (HTBI-M3-BR) are used [S21]. Inserts are inserted into 4.0 mm pilot holes and heated to melt surrounding resin for fastening, maintaining high mechanical strength even after repetitive disassembly/reassembly [S21]. If the insert tilts, the alignment of the assembled link becomes misaligned, so maintaining perpendicularity is essential.

WORKED EXAMPLES

Worked examples

Example 1: Housing inner diameter check - The outer diameter of iglide® JSM-0810-10 bearing is 10 mm. Therefore, the housing bore must be designed to 10 mm, and if the pilot hole 4.0 mm is not maintained during insert insertion, the insert may spin or the housing may be damaged [S17, S21].
Example 2: M3 screw assembly - M3x10 cap screws are fastened using a 2.5 mm hex wrench, and since excessive torque can cause cracks in the resin around the insert, fix it with minimum force at the 'point where it no longer turns' [S20].

LAB PROTOCOL

Robotic Hand Joint Precision Assembly

1
1. Verify the 4.0 mm pilot hole in the PC-CF print housing is clean and align the insert vertically.
2
2. Heat the soldering iron to an appropriate temperature and slowly press the insert vertically to press-fit parallel to the housing surface.
3
3. Press-fit iglide® bearing into the bore, insert 8 mm aluminum shaft, and check clearance and resistance.
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4. Complete fastening between links using M3 screws and verify that friction is uniform by moving the joint.

Safety check

Soldering iron is high temperature, so beware of burns and place on stand immediately after heating.
Ventilate thoroughly so as not to inhale fine dust generated during insert press-fitting.
Proceed with work while wearing goggles.
In case of abnormal heat, odor, or smoke, do not approach; cut power supply to the 3 adapters via a pre-designated building panel breaker outside the hazard zone or a certified upstream master disconnect and evacuate. If no upstream disconnect is available outside the hazard zone, do not energize the system. Torque release is not a substitute for power disconnection. Maintenance/access must only be performed after planned stops, physical disconnection, and verifying the de-energized state by measurement

Lab deliverables

Friction test logs per joint
Photos verifying vertical alignment of inserts
Records of degrees of freedom and clearance of assembled links

ASSIGNMENT

Assembly Tolerance and Fastening Force Analysis Report

Deliverables

Joint assembly sequence and torque management planTechniques for solving clearance issues (using shims or modifying tolerances)Preliminary grip test data for assembled robotic hand links

Rubric

Is the verticality of insert insertion clearly described?
Did you correctly explain the concept of bearing and shaft tolerance?
Were safety rules followed during the assembly phase?

KNOWLEDGE CHECK

Knowledge check

1Why does the inner diameter of an iglide® J bearing adjust after being press-fitted into a housing?Inner diameter automatically increases due to elasticity of bearing material during press-fit.It is designed so the bearing inner diameter is precisely adjusted to the tolerance of the housing bore during the press-fit process.The inner diameter before press-fit is always manufactured smaller than standard.

2What is the appropriate pilot hole size when using brass heat-set inserts in PC-CF prints?3.5 mm4.0 mm4.4 mm

FIELD CHECK

Completion criteria

Verify uniform friction resistance of 5 assembled finger joints and submit measurement records.
Visual and dimensional inspection to ensure all inserts are flush with the PC-CF housing.
Pledge to follow safety rules during assembly and submit work log.

MODULE SOURCES

Module sources

iglide J JSM-0810-10 Sleeve Bearingigus.com · technical_documentation
drylin R Metric Aluminum Precision Shaft AWMPigus.com · technical_documentation
Socket Head Cap Screws Technical Datain.misumi-ec.com · technical_documentation
M3 Heat-Fix Threaded Inserts HTBI-M3-BRaccu-components.com · datasheet