Wall thickness
- Machined metal walls: 0.8 mm minimum, 1.5 mm comfortable
- Machined plastic walls: 1.5 mm minimum to resist cutting forces
- Die cast aluminium: 2–4 mm, kept as uniform as possible
- Die cast zinc: from about 1 mm for detailed parts
Resources / Design tips
Design tips that cut cost, not corners
Most of a part's price is fixed by the time the model is finished. These are the decisions that matter.
Six areas to review
Corners and radii
- Every internal corner in a milled pocket carries a radius
- Use the largest radius the design allows — bigger tools cut faster
- Add fillets to castings; sharp corners crack dies
- External sharp edges are fine, but chamfer entry faces
Tolerances
- Default to a general tolerance and call out only critical features
- ±0.02 mm is achievable but costs more than ±0.1 mm
- Group tight features so they can be cut in one set-up
- State datums explicitly rather than implying them
Holes and threads
- Use standard drill and thread sizes wherever possible
- Keep hole depth under 4× diameter to avoid special tooling
- Thread only as deep as the fastener requires
- Consider inserts in soft alloys for repeated assembly
Draft and parting lines
- Apply 1° draft minimum on cast vertical faces
- Increase draft on textured or deep surfaces
- Place the parting line where witness marks are acceptable
- Avoid undercuts unless a slide is genuinely justified
Finishing
- As-machined is the cheapest acceptable finish for most parts
- Bead blast hides tool marks and evens out appearance
- Anodising adds thickness — allow for it on fits
- Mask threads and bearing bores before coating
Send us the model and we will review it.
Send your CAD file, drawing or sample part — an engineer reviews every enquiry and replies with material, tolerance and lead-time options.