A drawing the shop can actually quote
Dimensions with tolerances, material, surface finish, thread callouts and which datum features matter. A 3D model alone is not a specification — it carries no tolerance information.
What we can help you buy on 1688
CNC machining parts
Last updated
A machined part is made to a drawing. If the drawing is incomplete the shop will fill the gaps with whatever is cheapest, and it will be entitled to.
So the first part of this process is getting the drawing to a state where there is nothing left to guess.
Request a quote for cnc machining parts
What we check before you pay
Which tolerances you actually need
Tight tolerances on every dimension multiply the price. We look for the features that matter functionally and let the rest run at general tolerance, which is usually the single biggest cost lever.
Material grade and its certificate
Aluminium 6061 and 6063 are not interchangeable, and neither are 304 and 316. We ask for the mill certificate and check it names the grade on the drawing.
Surface finish and treatment
Anodising, plating, passivation and bead blasting each change dimensions slightly and need to be specified before machining, not after.
First article before the run
One part, measured against every toleranced dimension on the drawing, with a report. It is the cheapest insurance in this category and we recommend it on every new part.
Inspection equipment the shop actually has
A shop that cannot measure a tolerance cannot hold it. We ask what they have — callipers, height gauge, CMM — and match the part to the capability.
How an order runs
- Send the drawing A dimensioned drawing with tolerances and material, in PDF plus a STEP file if you have one. If you only have a sample, we can dimension it.
- Drawing review before quoting We tell you what is missing or ambiguous, and where a tolerance is costing more than it is worth.
- Shops matched to the part Quoted from shops whose equipment and measuring capability fit the part, not simply whoever is cheapest.
- Quote and approval Machining, material, treatment, first article, our service fee, inspection and freight, itemised.
- First article inspection One part measured against the drawing with a written report before the balance runs. You approve it before production continues.
- Production inspection and shipping Sampled parts from the run measured against the same dimensions, then packed and shipped.