How to spec a CNC turned part (and get an accurate quote)
The six things to include on a drawing or enquiry so a machine shop can quote quickly and accurately, without a dozen back-and-forth emails.
A good enquiry gets a fast, accurate quote. A vague one gets questions, or worse, an optimistic price that changes later. Here is what to include.
1. Material and grade
Not just “steel”. Specify mild steel, EN8, SS304 or SS316, or describe the environment and let us advise.
2. Critical dimensions and tolerances
Mark which diameters and lengths are critical, and their tolerance. A part where every dimension is toleranced to ±0.01 mm costs far more than one with two critical features and the rest general. Tell us what actually matters.
3. Threads
State the thread callout (e.g. M20 × 2.5, ½"-BSW), the class of fit, and whether it is cut or rolled. For studs, give the length schedule.
4. Surface finish
Sealing faces and valve balls need a fine finish (low Ra) and possibly polishing or lapping. If a surface just needs to look clean, say so, it is cheaper.
5. Quantity and schedule
One prototype, or 500 a month? Quantity drives price and lead time. An honest timeframe helps us plan.
6. A drawing or sample
A PDF drawing, a 3D model, or even a photo of a worn part with key dimensions lets us quote confidently. We reverse-engineer from samples routinely.
Send those six things and you will usually have a firm quote and lead time in a day.
Have a part that fits this?
Tell us the material and spec, we’ll quote it.
Keep reading
MS vs SS316: choosing the right steel for your turned part
Mild steel or stainless? The right choice depends on corrosion, strength, cost and finish. A practical guide for buyers speccing machined components.
ReferenceThread standards explained: metric, BSW, UNC and Acme
Metric, Whitworth, Unified, Acme, a plain-English tour of the thread standards you will meet on studs and fasteners, and when each is used.
Have a drawing or a part to match?
Send us your specification, sample or worn part. We’ll reverse-engineer it, quote quickly and machine it to precision, from a single prototype to volume production.