Micro-joints and tabs in laser cutting: why, how big and where to put them

What micro-joints prevent

• Parts falling: the CypCut manual says micro-joints keep parts from falling out of the plate skeleton; CypNest adds warping.
• Tip-up collisions: a small part cut free can tilt on the slats and the head runs into it — the second reason CypCut gives.
• Damage and lost parts: OSH Cut says parts without joints can fall into the machine and be damaged, or tip up and put the machine at risk.
• Not every part needs them: OSH Cut and 247TailorSteel both say large parts resting on the slats usually do not, while small and narrow parts do.

How big

Adding them in CypCut and CypNest

• By hand: click Micro Joint, then click the contour where each joint goes — on the compensated path too. A new length does not change joints already placed (CypCut manual §3.3).
• Auto MicroJoint: by count (10 puts ten joints on every selected part) or by distance (100 puts one every 100 mm).
• Explode MicroJoint splits the contour into segments you can edit one by one, each with its own lead; Clear MicroJoint removes them.
• From CypCut V731 the head flies over a joint without lifting or slowing down (FlyCut), so joints cost little machine time.
• CypNest adds batch tools: Modify Microjoint changes lengths in bulk, Microjoint at long side filters by edge length, Microjoint in Cross holds co-edged parts at their intersections, and Add Microjoint by line places joints across a row of parts.
• Bridges are the related tool: CypCut's Bridge joins neighbouring parts with a strip of a width you set, so they cut as one group with fewer pierces — the manual warns the group's continuous cut adds heat. On plasma, SheetCAM's holding tabs do the job: set the tab length on the operation's Cut path tab and place tabs with the Holding tab tool.

Where to put them

• At the start of the cut: 247TailorSteel always places a joint where the cut path starts, and Kinetic PrimeCut builds a joint as a negative overcut — the cut stops short of the lead-in and the lead-out is dropped.
• Away from fits and show faces: a joint leaves a nub, or a small notch when the lead-in sits slightly inside the part, the undercut style OSH Cut uses on almost every job.
• On straight edges a file can reach, not in tight inside corners.
• Around the part on long, thin parts so they cannot twist out; one or two often hold a compact part (estimate — check on the first sheet).

Removal is where joints cost money. Every part has to be broken out and usually filed or ground: 247TailorSteel tells customers to file or grind the joints themselves, and LaserBoost removes them only for an extra charge. Zorocut's quote has no line for joints, so if you clean them up for the customer, add the time to the setup or as handling in the price calculator.