Ⅰ. Function Overview

When a single part is long and the nesting result includes multiple short remnants, Loop Nesting can be used to automatically cutoff the long part and nest it into the remnants. After cutting, the short parts can be welded together to improve tube material utilization.
Starting from TubesT version 1.47, Loop Nesting is supported. This feature not only helps achieve higher material utilization but also automatically marks part names and welding position symbols, facilitating assembly.

Note: 《》, 【】 in blue font are jumpable tutorial links. Clicking the link allows you to view the detailed parameter description and usage method corresponding to the function.

Ⅱ. Usage Instructions

• Enabling Permissions

• • Loop Nesting is an exclusive feature of the Steel Structure Package. If the nesting interface does not show the Loop Nesting option, you need to claim or enable the permission first.

• Parameter Explanation

• • Available Tube Type: Currently, there are no restrictions on tube types. It supports tubes with cross-sections such as circle tubes, rectangular tubes, L shapes, U shapes, H-beams, and T shapes. 

• • Joint Type: This refers to the shape of the joint when a part is cut off.
    • In the software, hover the mouse over the small question mark to view the corresponding joint stylesand the meanings of common parameters.

• • Min Tube End: The shortest allowable length for cutoff parts (a.k.a. remnant ends).  When set to 600mm, all remnant ends will strictly maintain ≥600mm length.Minimum hole-to-cutoff distance.

• • Weld Position: Range of allowable cutting positions.

    • Example 1:  0 < Weld Position < 0.35
      → Cutoff is permitted within 35% of the part length from either end, avoiding centerline segmentation.
    • Example 1:  0 < Weld Position < 0.5
      → Cutoff is permitted within 50% of the part length from either end, including centerline segmentation.

• • Hole Gap: Minimum hole-to-cutoff distance.

    • Welding near bolt holes or other apertures is prohibited to avoid interference with subsequent assembly operations. Therefore, all cutoff locations must maintain a specified minimum clearance distance from any hole edge.
    • When set to 20mm, all cutoffs must maintain ≥20mm clearance from hole edges.

→ The diagram below illustrates: : A non-perforated part with 600mm minimum remnant length under "0 < Weld Position < 0.35" constraint. Green highlights indicate the allowable cutoff range.

A larger allowable cutoff range enables more variations of short-part lengths, allowing matching with more remnant types, thereby potentially improving material efficiency.

• • Single-part Cutoff Count: By default, each part is cut once. For multiple cuts, use the 【Manual Cutoff 】function.

• • Total Cutoff Parts：Determines welding frequency and directly impacts welding costs.

• • Loss Ratio：Specifies the permitted excess material usage beyond theoretical optimum during nesting. Primarily balances part cutoff quantity and material utilization efficiency.

    • → Setting to 0%， enforces actual tube consumption = theoretical optimum (most material-efficient mode)

    • → Setting to 2%，triggers two-stage optimization:

      • When actual loss >2%: Continuously improves material utilization to cap loss at 2%.

      • When actual loss <2%: Minimizes cutoff counts while maintaining identical tube consumption. 

• • Cut-off Factor: Version 1.61 enhances loop nesting material utilization, delivering superior nesting results. The legacy 【Loss Ratio】 parameter is now replaced with 【Cut-off Factor】.
    •  When unchecked, the system prioritizes maximum material savings without restricting total cutoff counts.
    •  When setting to 2，the system limits the total number of segmented parts to no more than twice the quantity of nesting tubes (i.e., Total Cutoffs ≤ Tubes Used × 2).  This constraint ensures a balance between material utilization and segmentation frequency, preventing excessive cutoffs that could increase welding workload.

• • Root Gap: The intentional space reserved between joint root faces prior to welding, also called assembly gap. Ensures full root penetration during initial welding passes. In software, setting this value shortens remnant ends while maintaining final part length after weld filler deposition.

Ⅲ、Demonstration

Loop Nesting automatically assigns part numbers and welding position markers to segmented components (a.k.a. joints/remnant ends), ensuring clear identification for subsequent assembly processes.

• • • Example: A parent part named "H-beam" will generate two sub-parts labeled "H-beam-P1-1" and "H-beam-P1-2" after cutoff. 
    • Pre-existing text markings on parts will be overwritten by Loop Nesting-generated labels.
    • Precision alignment markers are engraved at joint interfaces – mating these markers during assembly reconstructs the complete part.

Note: The current Loop Nesting function supports calculation for a maximum of 100 tubes per batch.