Following marking training, we proceeded to hacksawing practice, the most physically demanding and stamina-consuming procedure in bench work. A hand hacksaw consists of a frame and a blade. When installing the blade, cutting teeth must face forward with moderate tightness; overly tight blades tend to snap, while loose ones bend easily and result in deviated cutting paths. Hacksawing imposes strict requirements on posture, force and rhythm: stand firmly with feet apart and lean slightly forward, grip the hacksaw frame tightly with both hands and keep arms straight to push and pull steadily. Apply cutting force only on forward strokes and lift the blade gently without pressure on return strokes, maintaining a steady pace throughout to avoid abrupt speed changes or excessive force.
When I first started hacksawing, I had numerous problems: stiff postures, uneven pushing force and chaotic rhythm led to frequent blade jamming, path deviation, uneven cutting surfaces and even bent saw blades. Meanwhile, repetitive movements caused severe soreness and stiffness in arms and wrists, easily triggering impetuous and slack emotions. Under the instructor’s guidance, I adjusted my standing posture and force application method, slowed down the pace and prioritized stability over speed to keep cutting paths straight. Through constant drills, I gradually became proficient in hacksawing techniques, capable of stable sawing with greatly improved flatness of cutting surfaces and dimensional precision. This practice also tempered my patience and stress resistance, making me realize the truth that fine workmanship comes with slow and careful efforts in bench work.
Filing stood as the core and key procedure of this internship, as well as the decisive step affecting surface quality and dimensional accuracy of workpieces, taking up most of the training hours. Files are classified into rough files, medium files and smooth files: rough files quickly remove excess blank allowance, medium files trim outlines to nominal dimensions, and smooth files perform precision finishing to improve surface finish. Filing demands seamless coordination of both hands, balanced force and steady movements. The file must move horizontally and parallelly without up-and-down swinging, otherwise uneven surfaces and dimensional deviations will occur.
During practical operation, I strictly followed the principle of "rough filing first, precision finishing later and step-by-step processing". I first used rough files to strip surplus materials rapidly, switched to medium files to trim contours once approaching standard dimensions, and finally adopted smooth files for finishing polishing to guarantee flat planes, regular edges and precise sizes. Filing is an extremely concentration-intensive task; slight carelessness in force or angle control will lead to oversize dimensions or inclined planes. During training, impetuosity and unstable hand movements once caused worn edges and uneven surfaces. On one occasion, excessive filing resulted in undersized workpieces that required rework. Through repeated mistakes and revisions, I deeply realized that no carelessness is allowed in bench work, as millimeter-level deviations will impair the service performance of mechanical parts. I calmed down and slowed down operations, measuring dimensions with calipers and try squares after every few filing strokes to adjust postures timely. Eventually, I mastered flat filing, curved surface trimming and chamfer polishing proficiently, and the finished workpieces met training standar
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After mastering basic manual operations, we learned drilling, tapping and external threading, core processes for thread machining of mechanical parts. Before drilling, we double-checked marked central points, aligned the bench drill with punched positioning dimples and clamped workpieces firmly to prevent shaking and offsetting during drilling. We maintained uniform rotational speed, fed drill bits down slowly and retracted bits periodically to discharge metal chips, preventing drill bit overheating and abrasion, oversized holes or misplaced holes. Drilling was followed by tapping and threading: tapping uses taps to machine internal threads in pre-drilled holes, while threading uses dies to cut external threads on cylindrical blanks.
At the beginning of tapping practice, I often suffered from tilted taps, thread stripping and broken threads. The instructor told me that the key to tapping lies in vertical alignment, gentle pressing with slow rotation and timely chip removal. It is necessary to reverse the tap half a turn every full rotation to clear chips and prevent jamming inside threads. After repeated practice following these methods, I fully grasped thread processing skills, producing well-defined threads with proper fit without slipping or skewing defects.
In the final phase of the internship, we moved on to comprehensive assembly, trimming and assessment of finished workpieces. Integrating all previously learned skills, I independently completed the full fabrication of a finished part, covering blank marking, hacksawing blanking, precision filing, drilling and tapping, edge polishing and final assembly debugging. After preliminary machining, I conducted comprehensive inspections on length, width, height,