Tutorial BA: PMI on the Impeller

Source	Ming C. Leu, Wenjin Tao, Amir Ghazanfari and Krishna Kolan, NX 12 for Engineering Design (Missouri University of Science and Technology), section 5.5 (Product and Manufacturing Information).
You learn	the PMI tab: Rapid and Linear, Radial, Centerline, Note; model views; Inherit PMI on a drawing
Part	tutorial AU's impeller, `Impeller_impeller`. The replay runs AH and AU first.
Sizes	the book’s, in inches, typed in millimetres.

Step by step

1. Dimensions along the axis

Open Impeller_impeller and click the PMI tab. Select the impeller’s two end faces and click Rapid Dimension, then MB2: 16.25 in, the cone’s length. Select the large end face and the bore’s floor and click Linear: 16 in, the bore’s depth.

2. Diameters

The book does not say which view the PMI goes into. The diameters are read down the axis, so double-click Right under Model Views to make it the work view. Then click Radial on each of these, with the Diameter method:

the large end’s circular edge, Ø15;
the small end’s circular edge, Ø8;
the bore, Ø4;
the pin hole, Ø0.275.

3. Centerline and note

Double-click Front under Model Views. Select the bore and click Centerline (Supplemental Geometry): its axis appears, a little longer than the bore. Select a blade, click Note, type Five impeller blades and press MB2.

Save the part.

4. The drawing

Press Ctrl+Shift+D and click New Sheet (B, 11 x 17, here at 1:10). Make a Base View looking at the front, a Projected View to its right (the view down the axis), and a Base View in the isometric direction. The front and right views show hidden lines. Set each view’s NX_InheritPMI to Aligned to Drawing (Entire Part), the option the book picks in the View Creation Wizard. Select each view and click Inherit PMI. The front view gets the two lengths, the note and the centerline. The right view gets the four diameters.

The replay

#	In the book (NX)	In FreeCAD NX-Style	Result	Notes
BA1	Open Impeller_impeller (tutorial AU’s part)	File > Open (by script)	same	tutorial AU’s impeller: same solid as the reference: 0 mm³ differ, box within 5.9e-13 mm, 31 faces (31 in the reference)
BA2	File > PMI (check mark on): the PMI tab	the Modeling ribbon’s PMI tab	differs	tab 'PMI'. NX 12 turns the PMI application on from File; NX-Style’s PMI tab is always there
BA3	Rapid: the impeller’s two end surfaces, the linear dimension 16.25	Face4, Face7 selected + ribbon 'PMI › Dimension > Rapid Dimension'; nothing typed; MB2 = OK	same	412.750: 16.2500 in, the end faces 16.2500 in apart (the book’s 16.25)
BA4	Linear: the bore’s depth 16	Face4, Face31 selected + ribbon 'PMI › Dimension > Linear'; nothing typed; MB2 = OK	same	406.400: 16.0000 in from the large end to the bore’s floor (the book’s 16)
BA5	The diameters are read down the axis: Right as the work view	double-click 'Right' under Model Views in the Part Navigator	differs	the book does not say; a PMI goes into the work view, and a drawing view looking down the axis inherits those (Aligned to Drawing)
BA6	Radial: Ø15, the large end	Edge4 selected + ribbon 'PMI › Dimension > Radial'; Method Diameter; MB2 = OK	differs	Ø381.000
BA7	Radial: Ø8, the small end	Edge11 selected + ribbon 'PMI › Dimension > Radial'; Method Diameter; MB2 = OK	differs	Ø203.200
BA8	Radial: Ø4, the bore	Face25 selected + ribbon 'PMI › Dimension > Radial'; Method Diameter; MB2 = OK	differs	Ø101.600
BA9	Radial: Ø0.275, the pin hole	Face26 selected + ribbon 'PMI › Dimension > Radial'; Method Diameter; MB2 = OK	differs	Ø6.985
BA10	The centerline and the note in Front	double-click 'Front' under Model Views	differs	the view the sizes along the axis are in
BA11	Supplemental Geometry > Centerline: the inner surface of the impeller	Face25 selected + ribbon 'PMI › Supplemental Geometry > Centerline'; the bore’s face; MB2 = OK	same	from x = -3.2800 to 15.2800 in on the XC axis: the bore (-2 to 14 in) and 8% past each end
BA12	Note: 'Five impeller blades', its leader on a blade	Face29 selected + ribbon 'PMI › Annotation > Note'; the text typed; MB2 = OK	same	'Five impeller blades', its leader on Face29 (a blade; 0.0e+00 mm from it)
BA13	The trimetric view with the PMI; save the file	Show All PMI, Trimetric; file name given once by script (the system file dialog is not driven); a change, then the Ctrl+S key	same	Impeller_impeller.FCStd rewritten by Ctrl+S: the file holds the change and the part is unmodified afterwards (modified before the key: True); FreeCAD format, not .prt
BA14	File > Drafting	Ctrl+Shift+D	same	TechDrawWorkbench
BA15	Drawing sheet: as in 5.2 (B 11 x 17), here at 1:10	ribbon 'Home › Drawing > New Sheet'; the sheet’s Template, Scale and Projection	differs	ANSIB_Landscape.svg: 431.8 x 279.4 mm (the book’s 17 x 11 in), scale 0.1, Third angle. NX asks for size, scale and projection in one Sheet dialog; FreeCAD’s New Sheet uses the default template and these are the sheet’s properties
BA16	Drawing views (View Creation Wizard): Front, Right and Isometric; Inherit PMI, Aligned to Drawing (Entire Part), Inherit PMI onto Drawing	body selected + ribbon 'Home › View > Base View' (Front, then Isometric), 'Home › View > Projected View' Right; the views' NX_InheritPMI	differs	Right looks down the axis (1.0, 0.0, 0.0), with hidden lines; inherit modes ['Aligned to Drawing (Entire Part)', 'Aligned to Drawing (Entire Part)']. NX’s wizard asks for the PMI option; here it is each view’s NX_InheritPMI property (NX: Settings > Common > PMI)
BA17	Inherit PMI onto Drawing: the PMI and the note on the views	each view selected + ribbon 'Inherit PMI'	differs	front view: lengths [16.0, 16.25] in (the PMI [16.0, 16.25]), the note [['Five impeller blades']], the centerline at y = 151.94158625194856 (the axis: 151.9416); right view: diameters [0.275, 4.0, 8.0, 15.0] in (the PMI [0.275, 4.0, 8.0, 15.0]). Skipped: front [], right []. NX inherits in the wizard; here the Inherit PMI button does it per view

In the book (NX)

In FreeCAD NX-Style

Result

Notes

BA1

Open Impeller_impeller (tutorial AU’s part)

File > Open (by script)

same

tutorial AU’s impeller: same solid as the reference: 0 mm³ differ, box within 5.9e-13 mm, 31 faces (31 in the reference)

BA2

File > PMI (check mark on): the PMI tab

the Modeling ribbon’s PMI tab

differs

tab 'PMI'. NX 12 turns the PMI application on from File; NX-Style’s PMI tab is always there

BA3

Rapid: the impeller’s two end surfaces, the linear dimension 16.25

Face4, Face7 selected + ribbon 'PMI › Dimension > Rapid Dimension'; nothing typed; MB2 = OK

same

412.750: 16.2500 in, the end faces 16.2500 in apart (the book’s 16.25)

BA4

Linear: the bore’s depth 16

Face4, Face31 selected + ribbon 'PMI › Dimension > Linear'; nothing typed; MB2 = OK

same

406.400: 16.0000 in from the large end to the bore’s floor (the book’s 16)

BA5

The diameters are read down the axis: Right as the work view

double-click 'Right' under Model Views in the Part Navigator

differs

the book does not say; a PMI goes into the work view, and a drawing view looking down the axis inherits those (Aligned to Drawing)

BA6

Radial: Ø15, the large end

Edge4 selected + ribbon 'PMI › Dimension > Radial'; Method Diameter; MB2 = OK

differs

Ø381.000

BA7

Radial: Ø8, the small end

Edge11 selected + ribbon 'PMI › Dimension > Radial'; Method Diameter; MB2 = OK

differs

Ø203.200

BA8

Radial: Ø4, the bore

Face25 selected + ribbon 'PMI › Dimension > Radial'; Method Diameter; MB2 = OK

differs

Ø101.600

BA9

Radial: Ø0.275, the pin hole

Face26 selected + ribbon 'PMI › Dimension > Radial'; Method Diameter; MB2 = OK

differs

Ø6.985

BA10

The centerline and the note in Front

double-click 'Front' under Model Views

differs

the view the sizes along the axis are in

BA11

Supplemental Geometry > Centerline: the inner surface of the impeller

Face25 selected + ribbon 'PMI › Supplemental Geometry > Centerline'; the bore’s face; MB2 = OK

same

from x = -3.2800 to 15.2800 in on the XC axis: the bore (-2 to 14 in) and 8% past each end

BA12

Note: 'Five impeller blades', its leader on a blade

Face29 selected + ribbon 'PMI › Annotation > Note'; the text typed; MB2 = OK

same

'Five impeller blades', its leader on Face29 (a blade; 0.0e+00 mm from it)

BA13

The trimetric view with the PMI; save the file

Show All PMI, Trimetric; file name given once by script (the system file dialog is not driven); a change, then the Ctrl+S key

same

Impeller_impeller.FCStd rewritten by Ctrl+S: the file holds the change and the part is unmodified afterwards (modified before the key: True); FreeCAD format, not .prt

BA14

File > Drafting

Ctrl+Shift+D

same

TechDrawWorkbench

BA15

Drawing sheet: as in 5.2 (B 11 x 17), here at 1:10

ribbon 'Home › Drawing > New Sheet'; the sheet’s Template, Scale and Projection

differs

ANSIB_Landscape.svg: 431.8 x 279.4 mm (the book’s 17 x 11 in), scale 0.1, Third angle. NX asks for size, scale and projection in one Sheet dialog; FreeCAD’s New Sheet uses the default template and these are the sheet’s properties

BA16

Drawing views (View Creation Wizard): Front, Right and Isometric; Inherit PMI, Aligned to Drawing (Entire Part), Inherit PMI onto Drawing

body selected + ribbon 'Home › View > Base View' (Front, then Isometric), 'Home › View > Projected View' Right; the views' NX_InheritPMI

differs

Right looks down the axis (1.0, 0.0, 0.0), with hidden lines; inherit modes ['Aligned to Drawing (Entire Part)', 'Aligned to Drawing (Entire Part)']. NX’s wizard asks for the PMI option; here it is each view’s NX_InheritPMI property (NX: Settings > Common > PMI)

BA17

Inherit PMI onto Drawing: the PMI and the note on the views

each view selected + ribbon 'Inherit PMI'

differs

front view: lengths [16.0, 16.25] in (the PMI [16.0, 16.25]), the note [['Five impeller blades']], the centerline at y = 151.94158625194856 (the axis: 151.9416); right view: diameters [0.275, 4.0, 8.0, 15.0] in (the PMI [0.275, 4.0, 8.0, 15.0]). Skipped: front [], right []. NX inherits in the wizard; here the Inherit PMI button does it per view

Result	Means
same	The book’s NX steps work as written.
differs	It works, but the FreeCAD way is different; the notes say how.
limit	The book’s way fails in FreeCAD itself; a workaround follows in the next steps.
missing	FreeCAD has no such function; a stand-in follows.
skipped	Not replayed; the notes give the reason.
FAILED	Did not work.

Result

Means

same

The book’s NX steps work as written.

differs

It works, but the FreeCAD way is different; the notes say how.

limit

The book’s way fails in FreeCAD itself; a workaround follows in the next steps.

missing

FreeCAD has no such function; a stand-in follows.

skipped

Not replayed; the notes give the reason.

FAILED

Did not work.

Each PMI is compared with the impeller the Part API builds from the book’s sizes. The lengths must be the distances between its end faces and the bore’s floor, the diameters its circles and cylinders. The centerline must lie on the X axis and run from the bore’s floor to its mouth, plus the overrun. The note’s leader must end on the blade. On the drawing, each inherited dimension must carry the PMI’s value, and the centerline must lie on the axis as the front view shows it.

What differs from NX

NX 12 switches the PMI application on from File. NX-Style’s PMI tab is always there.
NX places a PMI with a click in the graphics window. Here it is placed beside its face, in the work view’s plane.
NX’s Inherit PMI option is in the View Creation Wizard. Here it is each view’s NX_InheritPMI property, and the Inherit PMI button brings the PMI onto the view.
The book’s axial view shows the Ø8 end as a dashed hidden circle. Here, too, the view draws hidden lines, and the dimension goes on the dashed circle.
A note inherited onto the drawing goes above the view, without its leader, as in the book’s figure.
The book’s drawing view of the PMI is isometric. Inherit PMI places dimensions on edges seen square, so here the PMI goes on the front view and the view down the axis. The isometric view shows the part only.