Draft Body

Draft Body

Use the Draft Body command to add and match drafts on both sides of a parting surface and to fill undercut regions with material. You can use this command when you develop models for castings and molded parts.

A double-sided taper on both sides of a datum plane used as a parting object. A double-sided taper makes a part easy to draw out of a mold.

	Parting object Double-sided draft matched on both sides of the parting object Double-sided draft unmatched at parting object

You can match double-sided tapers created on both sides of the parting object. Matching may also be omitted to achieve minimum weight.

A single-sided taper used to fill the undercut region with material.

You can use the Draft command to get similar results, but you cannot match faces at the parting object when you use Draft.

Where do I find it?

Application	Modeling
Command	Draft Body

Create a double-sided draft

This example shows how to create a double-sided draft matched at the parting surface.

1. Choose Home tab→Base group→Draft Body .
2. In the Draft Body dialog box, in the Type group, select Edge from the list.

In the Parting Object group, Select Parting Object is active. 3. Select the datum plane as the parting object.

In the Draw Direction group, Specify Vector is active. 4. Specify the direction in which the draft is to be drawn. 5. In the Stationary Edges group, from the Location list, select Above and Below. 6. Click Select Edges Above Parting and in the graphics window, select the stationary edge above the parting object. 7. Click Select Edges Below Parting and in the graphics window, select the stationary edge below the parting object. 8. In the Draft Angle group, specify the draft angle.

For this example, 10 was entered. 9. In the Match Faces at Parting Object group, from the Match Type list, select From Edges. 10. Click OK or Apply to draft the body.

Draft a body based on an extreme face point

This example shows how to draft a body and control the taper from a point on the face that is furthest from the parting object. The draft updates when you edit the model, so that a different face is furthest from the parting object.

1. Choose Home tab→Base group→Draft Body .
2. In the Draft Body dialog box, from the Type list, select Face.

In the Parting Object group, with Select Parting Object active, select the parting object.

For this example, a datum plane is selected. 3. Specify the draw direction. 4. Select the faces you want to draft.

For this example the front face was selected. 5. In the Draft Angle group, specify the draft angle.

For this example, specify a draft angle of 15 degrees. 6. In the Match Faces at Parting Object group, from the Match Type list, select None. 7. Select the Extreme Face Point Overrides Stationary check box to apply the draft from the parting object to a point on the face of the body that is furthest from the parting object. 8. Click OK.

The draft is applied from the top face of the wide pad on the left.

A. Original solid body.

B. Draft applied from a point on the face of the body furthest from the parting object.

C. Resulting drafted body. 9. Edit the height of the smaller pad, so it is tall enough to have the furthest face from the parting object.

A. The new modified height of the smaller pad.

B. The draft updates based on the new face height of the modified pad, which has now become the furthest face from the parting object.

Draft a body by resizing selected faces

This example shows how to draft the selected faces of the solid above and below the parting object. The interior faces of the slot are resized to accommodate the drafts.

1. Choose Home tab→Base group→Draft Body .
2. In the Draft Body dialog box, in the Type group, set the list to Face.

In the Parting Object group, with Select Parting Object active, select the parting object.

For this example the datum plane is selected. 3. Specify the draw direction. 4. Select the faces you want to draft.

For this example the four side faces of the solid body are selected. 5. Specify the draft angle.

For this example, a draft angle of 15 degrees is specified.

Though sufficient inputs are provided to create the draft, you cannot apply the draft at this point. You must resize the faces of the slot to accommodate the draft. 6. In the Faces to Move to Drafted Face group, click Select Face and in the graphics window select the faces of the slot. 7. In the Settings group, from the Draft Method list, select Isocline Draft. 8. Click OK to create the draft.

Draft a body to remove an undercut

This example shows how to create a single-sided draft and fill the undercut region with material.

Choose Home tab→Base group→Draft Body .

In the Draft Body dialog box, from the Type list, select Face.

In the Parting Object group, select the Use Drafted Body as Parting Object check box.

Specify the draw direction +ZC.

In the Draft Angle group, in the Angle text box, type 10.

In the Face group, click Select Face and select the faces.

Click OK.

Draft Body dialog box

Type list
Edge

Face

	Lets you select the faces to be tapered. Adds draft to a selected face from an inferred stationary edge.

Parting Object

Use Drafted Body as Parting Object

Uses the drafted body as the parting object.

Select Parting Object

Lets you specify a sheet body, datum plane, or planar face as the parting object.

You can select only one parting object. If you select a datum plane, NX creates a temporary sheet body on the datum plane and uses it as the parting sheet body. Parting sheets can be planar or non-planar.

Draw Direction

The default draw direction is +ZC, or the direction normal to the datum plane specified as the parting object.

If you are drafting a part or a pattern of a part, the draw direction is the direction that the mold or die must move to separate it from the part or pattern.

If you are drafting the mold or die, then the draw direction is the direction that the part or pattern must move to separate it from the mold or die.

Stationary Edges

Appears when Type is set to Edge.

Location list

Specifies the method used to select stationary edges.

Lets you select stationary edges both above and below the parting edge.

Lets you select stationary edges above the parting edge and in the same direction as the draw vector.

Lets you select stationary edges below the parting edge and in the opposite direction as the draw vector.

Face

Appears when Type is set to Face.

Select Face

Selects the faces that you want to draft.

Draft Angle

Angle

Specifies the angle of the taper that you want to draw.

Match Faces at Parting Object

Match Type

When Type is set to Edge:

None	If edges above and below the parting object are not symmetric, the drafted faces will not match. A step face bridges the gap.
From Edges	Matches the shorter face by bridging from its stationary edge to the edge of the longer face at the parting object.

When Type is set to Face:

None	If edges above and below the parting object are not symmetric, the drafted faces do not match. A step face bridges the gap.
To Isocline	Matches the shorter face by bridging from its isocline edge to the edge of the longer face at the parting object. The draft begins at the tangent face.
Tangent to Face	Matches the shorter face by bridging tangent from the input face to the edge of the longer face at the parting object. The draft begins at the tangent face.

Match Scope

Appears when Match Type is set to any option except None.

All	All but Selected

Repair Parting Edges

Appears when Match Type is set to any option except None.

Automatically repairs sharp mitered edges on the drafted surface.

None	A sharp edge between parting edges will remain sharp. An edge between drafted faces will be sharp.
With Fillet	A sharp corner between parting edges will be repaired with a fillet, causing the parting edges to be tangent continuous to avoid a sharp, concave corner between drafted faces.
With Lines and Fillet	A sharp corner between parting edges will be repaired with fade-in lines tangent to the parting edges and a fillet between fade-in lines, causing the parting edges to be tangent continuous to avoid a sharp, concave corner between drafted faces. Fade-in lines are useful for an overly acute sharp corner where a fillet alone would need to be overly large.

Fillet Radius

Appears when Repair Parting Edges is set to any option except None.

Specifies the radius of the blend used to repair the concave corner.

Extreme Face Point Overrides Stationary

Appears when Match Type is set to None.

	Applys a draft from the parting object to a point on the face of the body that is furthest from the parting object.
	If you edit the body such that the furthest point on the face is at a different location, the draft is applied from the new point. The face furthest from the parting object in the original body. Draft is applied from a point on this face. The face furthest from the parting object in the edited body. Draft is applied from a point on this face. Parting object

Faces to Move to Drafted Face

Appears when Type is set to Faces.

Select Face

	Selects the faces that are allowed to move during the draft operation. Selected faces are extended to the drafted face.

Edges to Move to Drafted Face

Appears when Type is set to Edge.

Select Edge

	Specifies the edges that are allowed to move during the draft operation. Selected edges are extended to the drafted face.

Settings

Draft Method

Isocline Draft	Constructs a ruled surface where the surface tangent at any point has the same slope, and where slope is measured as an angle relative to the draw direction.
True Draft	Constructs a ruled surface for a case where, given the draw direction and a parting curve, anywhere along the curve the angle of the curve tangent is smaller than the draft angle. When this condition exists isocline draft is not possible.

Tolerance

Specifies a distance tolerance between the input geometry and the resulting body.

The default value comes from the Modeling Preferences dialog box. For more information, see Modeling Preferences — General.

Preview

Preview

When selected, the body will update automatically as soon as you have specified enough parameters. If not selected, the body will update on Apply or OK.

Show Result

Displays the part as it will appear and disables selection in the dialog box. Apply or OK may be selected. Click Undo Result to restore the original graphics display and enables selection in the dialog box.

Isocline and True Draft methods

Isocline method

The entire face you are drafting will have the same angle at any section you cut through. This is the default method for creating a drafted surface.

An isocline surface is a ruled surface where the surface tangent at any point has the same slope, and where slope is measured as an angle relative to the draw direction.

		Draw direction, parallel to the centerline of the trimming cones. Stationary edge. The half-angle of the cones equals the specified draft angle. The apex of the cones follows either the stationary edge, or the section curves that are created from the stationary plane and the original faces to be drafted.

True Draft method

The True Draft method is useful when the faces to be drafted have edges that are nearly parallel to the draw direction, or when the Isocline method cannot create the required draft.

A True Draft surface is defined by a set of lines that have the following characteristics:

		Plane through point on stationary edge, normal to the face to be drafted and parallel to the draw direction. Stationary edge Line through point on stationary edge and parallel to the draw direction. Line through point on stationary edge on the plane at an angle equal to the draft angle, plus 90 degrees to the line that is parallel to the draw direction. Draft angle plus 90 degrees.