A fabricated frame or guard is only as good as the shafts, bushes, pulleys and gears that bolt onto it. When those turned parts arrive late, oversize or in the wrong material, the whole assembly waits. This guide explains what to put on the drawing and in the purchase order when you place CNC turning and gear cutting job work alongside a fabrication order, so that the parts fit first time and can be checked against clear criteria.
A machinist works from the drawing, not from the conversation that produced it. A good package for turned parts and gears includes:
Dimension from functional datums, such as a bearing seat or a mounting face, rather than from the end of the bar. This helps the machinist hold what matters and helps the inspector measure it the same way.
Write the material as a recognised grade, for example EN8, EN19, EN24, EN353, 20MnCr5, SS304, SS316 or a named bronze grade, rather than "MS" or "steel". If an equivalent grade is acceptable, say so on the drawing. Ask for a material test certificate where the part carries a significant load.
Heat treatment needs equally clear notes. Specify the process (through hardening, case carburising, induction hardening or nitriding), the required hardness with the scale (for example HRC or HB), and, for surface treatments, the effective case depth and where it applies. State whether features such as threads, keyways and centres must stay soft. Sequence matters too: a part hardened after finish machining will distort slightly, so precise bores and bearing seats are often ground after hardening. If your drawing leaves the sequence open, ask the supplier how they plan to manage it.
Put close tolerances only where function needs them. For most dimensions, a general tolerance note such as ISO 2768-m (medium) is enough and keeps cost down. For bearing seats, bores and locating diameters, use ISO 286 fit designations, for example H7 for a bore and a suitable shaft tolerance such as g6, h6, k6 or m6 depending on whether you want a running, sliding or press fit. Quoting the fit, not just a number, tells the machinist the intent and lets the inspector use the right gauge.
Add geometric tolerances where they matter: runout of a gear seat relative to bearing journals, perpendicularity of a shoulder that locates a bearing, or concentricity between two diameters. Specify surface finish as Ra values on the surfaces that need them, for example Ra 3.2 on general turned faces and finer values on bearing, seal and sliding surfaces. Leaving surface finish off the drawing invites inconsistent results between batches.
A gear cannot be quoted or cut from a sketch of its outline. The gear data block on the drawing should list everything in the table below. If the gear meshes with an existing gear, send the mating gear data or a sample as well.
| Gear data item | Why it matters |
|---|---|
| Gear type (spur, helical, bevel, worm, rack, sprocket) | Decides the cutting method and tooling |
| Module (or diametral pitch for imperial gears) | Sets tooth size; must match the mating gear |
| Number of teeth | Fixes the gear ratio and pitch diameter |
| Pressure angle (20 degrees is most common) | Must match the mating gear for correct meshing |
| Helix angle and hand (for helical gears) | Left-hand and right-hand gears are not interchangeable |
| Face width | Affects load capacity and blank length |
| Profile shift coefficient, if any | Changes tooth thickness and centre distance |
| Tip and root diameters | Used to prepare and check the blank |
| Accuracy grade and the standard it refers to | Defines allowed pitch, profile and runout errors |
| Tooth thickness check (span over teeth or over pins) | Gives a measurable acceptance value for backlash |
| Centre distance and mating gear details | Lets the supplier confirm the pair will mesh |
| Bore, keyway or spline, and hub details | Connects the gear to its shaft |
For sprockets, give the chain number, pitch and roller diameter instead. For worm sets, give the number of starts, lead and the worm wheel throat diameter.
Decide what evidence you need before the order is placed, because it affects price and planning. Typical items are:
Ask for these documents to travel with the goods or by email before dispatch, so the parts can go straight to assembly without being held at incoming inspection.
Many problems appear where a machined part meets a fabricated one. A shaft bearing housing welded to a frame will move as the weld cools, so bores in fabricated parts are often finish-machined after welding. Mark which features are machined after fabrication and which are cut or drilled before. Specify mounting hole positions on both parts from the same datum and agree whether the fabricator or the machinist owns the final fit.
Placing turned parts, gears and the fabricated structure as one package can reduce this risk, because one supplier is responsible for the fit between them. At Vidhee Eng. Works, CNC turning and gear cutting can be arranged with fabricated assemblies, so the frame, brackets and machined parts are coordinated under one order. This is part of a wider approach to engineering and manufacturing outsourcing for OEMs who prefer a single point of contact.
Vidhee Eng. Works has worked from Navsari, Gujarat since 2004 under an ISO 9001:2015 certified quality management system, supplying fabricated assemblies across India and for export. If your next assembly needs shafts, bushes or gears to go with the fabrication, send us your drawings with material, heat treatment and gear data, and we will review them and come back with any questions before quoting.
Send your drawing, material and quantity to Vidhee Eng. Works, Navsari, and get a clear quotation with a delivery date.
No. Our in-house work covers CNC fiber laser cutting, CNC press brake bending, welding, CAD drafting and deburring. CNC turning and gear cutting can be arranged with fabricated assemblies, so shafts, bushes, pulleys and gears are coordinated with the frame or enclosure under one order and one point of contact.
At minimum, give the gear type, module, number of teeth, pressure angle, face width and material, plus the bore and keyway or spline. For helical gears add helix angle and hand. Accuracy grade, heat treatment and a tooth thickness check such as span measurement help the quote match your real needs. A sample of the old or mating gear also helps.
A general tolerance note such as ISO 2768-m is a sensible default for dimensions that do not affect function. It avoids leaving dimensions with no tolerance and stops the machinist from guessing. Then apply ISO 286 fits, such as H7 bores or k6 shafts, and geometric tolerances only on the features that locate bearings, gears or mating parts.
Yes, a sample can be the starting point, but worn parts hide the original sizes, especially on gear teeth and bearing seats. Share what you know about the mating parts, material and hardness, and approve a prepared drawing before machining starts. That drawing then becomes the reference for future orders and for inspection.
Share your material, thickness and quantity — we’ll review it and come back with a quote and a delivery date, not just a price.
