Context

Cost spikes are usually designed in. The geometry that drives chatter, tool changes, and scrap is visible long before quoting.

Most cost spikes trace back to DFM misses in deep pockets, corner radii, and thread specs. A short geometry audit catches those risks before quoting.

The Trap

The trap is assuming machining cost scales linearly with size. It does not. Deep pockets, tiny radii, and excessive thread depth can multiply cycle time and risk.

The Geppetto Take

We run a short DFM gate before quoting. If a feature violates a basic rule, we flag it before it becomes a cost explosion.

Evidence / Data

  • Internal radii smaller than tool reach push L:D ratios into chatter zones.
  • Thread depth beyond 1.5xD adds torque risk with little strength gain.
  • Thin walls and deep cavities amplify deflection and scrap risk.

Control Actions

  • Standardize internal radii to match available tooling.
  • Cap thread depth to functional minimum.
  • Stage deep cavities and require coolant clearance.
  • Use tolerance tiers to avoid blanket tight specs.

Checklist

  • Internal radius >= tool diameter for depth.
  • Thread engagement <= 1.5xD unless justified.
  • Deep cavities have chip evacuation plan.
  • Thin walls supported or redesigned.

What to Send

Send the tolerance map, deep feature list, and any non-negotiable geometry.

FAQ

Which DFM rule saves the most cost?

Relaxing internal radii and thread depth typically yields the biggest gains.

Can we keep tight features if needed?

Yes, but cost and lead time will rise accordingly.

What if we do not change the design?

We will quote it, but the risk and cycle time will be visible.

CTA

Send a screenshot for a chaos-check.