This is the manual of Studio 1.0.2, an earlier version. The manual of the latest version
Documentation 1.0.2 Technical manual
Fits, runout and inspection methods
How Studio cuts a size to a fit, how it allows for the cutter's runout, and how it measures a part with the touch probe. The twin's numbers here are estimates from its physical models; Studio claims no positioning accuracy for the machine.
Fits (ISO 286)
A size can carry a fit: a hole's diameter ("d": "Ø12 H7"), a shaft's ("fit": "g6" on an outside contour), a slot's width, or a rectangle's X and Y sizes. Studio takes the fit's limit deviations from the ISO 286-2 tables for the size, or the limit deviations as you write them ("tol": "+0.015/0", in millimetres).
Cutting to the middle of the zone
The wall is roughed with an allowance, then finished in a pass of its own to the middle of the fit's zone. Fits of grade IT6 and finer get a spring pass: the finishing lap again, at size, to take off what the tool's deflection left. The closed loop adds spring passes where the twin's estimate of the deflection asks for them.
The answer says, for each fit, the zone, the diameter it was cut to, and why.
Common fits
| Name | Pair | Use |
|---|---|---|
sliding | H7/g6 | Turns or slides, small clearance |
locating | H7/h6 | The closest clearance fit: put together by hand |
transition | H7/k6 | A little clearance or a little interference: locating, light press |
press | H7/p6 | Interference: pressed in |
A pair names both parts: the hole takes the first, the shaft the second.
The cutter's runout
A cutter that runs out cuts a hole larger than itself. The twin models the runout of the tool in its holder as an envelope. For a size with a fit, Studio moves the finishing path inwards for a hole, outwards for a shaft, by that envelope, so that the size the twin estimates is still the middle of the zone. A reamed hole is not changed: it is the reamer's size.
The envelope is the twin's estimate for its model of the tool and holder. Measure the first part.
Measuring with the touch probe
A touch and its compensation
Each touch is a sequence of probing moves (G38):
- a protected move to near the surface, which stops if the probe triggers on the way;
- a fast probe to the surface;
- a move back until the probe releases, then a little further;
- a slow probe to the surface: only this one's trigger point is used;
- a move back to where it started.
The trigger point is the ball's centre. Studio adds the ball's effective radius in the touch's direction. The effective radius and the probe's lobing come from its calibration on a ring gauge of a known diameter.
Holes, bosses, walls and floors
- Holes and bosses: four or eight touches round the wall at one depth. Studio fits a circle to the ball's centres by least squares, then adds the effective radius.
- Walls: touches square to the wall, at points along it.
- Floors and tops: touches straight down.
- Positions are given in the program's coordinates, from the work zero.
General tolerances (ISO 2768-1)
A size without its own tolerance takes the general tolerance of the class asked for (f, m, c, v), from ISO 2768-1's table for its size range: linear sizes, and the heights and angles of chamfers.
When the twin's grid is coarse for a tolerance, the twin's estimate for that check is said to be too coarse to judge; the measured value is judged all the same.
Form checks (ISO 2768-2, first step)
The class H, K or L after the ISO 2768-1 class (for example "mK") adds form checks, judged by ISO 2768-2's tables:
| Check | Touches | Table |
|---|---|---|
| Flatness | A floor on a 3 × 3 grid; the spread of the points from their plane | 1 |
| Straightness | A long wall, 3 to 8 points along it; the spread from their line | 1 |
| Perpendicularity | A wall at a second depth; its lean over the wall's height, against the machine's Z | 2 |
| Circularity | A hole or boss at 8 points; the spread of the radii | 4 (the diameter's tolerance) |
Two touches on a wall can only be told apart when they are far enough from each other. A wall too short for that, for example under a chamfer of its edge, is listed with the reason instead of a value.
A probe calibrated only on its effective radius has lobing of its own. It shows in the circularity: the report says how large the twin's probe model takes it to be.
Chamfers and V grooves
- A chamfer is touched twice down its slope, at 0.3 and 0.7 of its width from the outline. The line through the two ball centres runs parallel to the slope: it gives the chamfer's width, depth and angle.
- A V groove (an engraving or a V-carving) is touched twice on each flank. The two lines give the groove's depth at its apex, its width at the top, its included angle and its offset from the line it was cut along.
- A thread is not measured. Its crests are the straight bore, and the twin's probe meets only the cells' tops; the answer says so.
What the twin's estimate means
The twin cuts its simulated workpiece with the same program, then runs the same touches on it with the same probe model. Its estimate is what that calculation gives. It shows the program's own effect on each size, as far as the twin models it: the tool's deflection, its runout, the cutting forces.
The estimate is not the machine's measuring uncertainty. The report says nothing about how precisely the machine measures or positions.
Limits
- The probe measures what it touches. A feature narrower than the ball, or a surface the ball cannot reach square, is not measured; the answer says why.
- The twin's workpiece is a grid. Its estimates are only as fine as that grid; where it is too coarse for a tolerance, the twin's estimate is not judged.
- Form checks are a first step of ISO 2768-2: flatness, straightness, perpendicularity and circularity. Symmetry and parallelism are not checked yet.