Parallel (3D)

Click the faces you want machined — the eye cants on a lifting block, a domed top, a sloped ramp — and they light up blue. Every other face on the part still counts when the tool comes down, so passes stop short of anything you didn't pick instead of cutting into it. Pick nothing and the whole part is fair game.

The tool is placed against the actual surface for ball, bullnose and flat end mills, so a 1/4" ball reaches into every fillet it fits and rides over every edge without dipping. Surfaces are re-sampled finely for the toolpath rather than using the screen display, so the finish matches the model.

Set the pass angle, the stepover (the dialog shows the scallop height a ball leaves on a flat), and whether passes zig-zag or all run one way. Add perpendicular passes for a cross-cut finish, and keep only up-hill or down-hill cuts if your material prefers one.

A fixed stepover spreads out on a wall: passes a few hundredths apart in plan can be far apart up the slope. Turn on machine steep areas and Parallel adds passes in between wherever neighbouring passes differ in height by more than your maximum steep stepdown, never closer than the minimum steep stepover. The flats keep your normal stepover.

Multiple depths repeats the passes at heights stepped down to the finished surface, stopping at Top, either one whole depth at a time or every depth of a pass before the next. Passes normally finish one side of an island or pocket before crossing to the other; turn on simple ordering for plain row-by-row order.

Limit cutting to a slope range (flat areas only, walls only, or anything between), bound the passes by the picked faces' outline or box, or pick your own closed loops — with the tool centred on, inside or outside the boundary plus any extra offset. Top and Bottom heights cap the cut, and stock to leave works radially and axially for a semi-finish pass.

Short moves between passes stay down and follow the surface at cutting feed; longer ones lift just the safe distance over the highest point in between, or go fully to Clearance if you prefer. Turn on fillets to round the corners where a stay-down link meets a pass, so the machine doesn't stop dead at every row change.

Links clear the stock that's actually still there, not just the finished part. Before it finishes, JetCad simulates the earlier operations in the setup, so every rapid stays above the terraces and fillet stock a roughing end mill left behind, and the tool feeds up out of material before it rapids anywhere.

Smoothing turns long runs of tiny moves into fewer, longer ones within your tolerance. A move is never allowed to dip below the surface, so smoothing can only leave material, never cut too deep. Feed optimization slows the cutter for a set distance around corners sharper than your maximum directional change or bends tighter than the reduced feed radius, optionally only in valleys. The reduced feed is a plain feed edit, so changing it doesn't regenerate the toolpath. With a box or loop boundary, contact point boundary limits where the tool touches the part rather than where its centre goes, so a ball can finish right up to the edge of a sloped area.

Turn on rest machining to finish only where a bigger cutter left material — the fillets and wall corners it couldn't reach. Point it at an earlier Parallel or Scallop operation (any stock that operation left counts too) or type in a reference tool diameter and corner radius, and set ignore stock less than to skip hairline differences.

A third source, the stock the earlier operations left, reads the simulated in-process stock instead of a cutter shape: the pass cuts only where material still stands above the model under the cutter. It catches the strips a bigger cutter's row spacing skipped along a wall and the terraces a rough left, and skips everything already at size.