Example: Closed coil Compression Spring.
Creation uses a single helical pull operation showing the quickest method. Tips on the correct use of the Pull tool.
Transition between working and closed coils showing a perfect blend and not a crease - the easy way with tips on selection, trimming blending and combining.
Compression Spring details:
OD 6mm
Wire Dia 0.25mm
2 1/2 close but not exactly closed coils both ends. (0.01mm coil separation)
Overall height 10.6 mm
Other: *Smooth transition between closed and working open coils.
Open coils 1.5mm spacing - 6 full turns
* Optional > the fastest way is shown.
First sketch out the spring shape:
Information from spring catalogue or from calculations:
Create a point at the spring wire center:
The OD is 6mm, so I use 3-0.25/2 or enter 2.875
Calculation to create the closed and working coils in a single Pull (Iterative) command:
Note: The overall height of the coil center line, is the actual spring height less 1x wire diameter 10.6-0.25 =10.35
The full height of the coil consist of 3 sections:
1. Approximated closed Coils > calculate or enter formula
2. Working Coils 6x1.5mm
3. Approximated closed Coils > enter first result
Select the point > Pull
Select Revolve Axis Z
Select Options - Revove helix
In height column, type (10.6-0.25-(6*1.5))/2 > TAB to calculate the closely coiled height (note this value), now type the Pitch value which must be a larger than the wire diameter , say 0.26 ,otherwise the Cylinder thickening process will not be created.
Note the Full pull length indicator icon is now active:
Select to create the first coil center line wire length section
Note the Pull helix command is still active but the pull full height icon symbol is now inactive:
Type the working coil height or the formula 6*1.5 TAB > type the working coil pitch 1.5
Note the Pull full height icon symbol is active - select it to add the working coils.
Repeat the first closely coiled section results or repeat the full formula > Height: 0.675 Pitch: 0.26 > Enter
Note the Full pull icon is active :
Check the Z height between the end positions:
The full coil consists of 3 sections unjoined (not connected):
For a simple spring without a blend transition between the 3 coils:
Box select coils
Select the Cylinder tool
Enter the wire radius 0.25/2
Note the kink in the coil will be visible in any drawing view:
If preferring to not have any visible kinks on the model, then the wire helix end sections need to be blended.
First, ADD a point on the curve when it is to be split: Sketch > Enable 3D ( Constraint sketcher)
Usage Tip:
Do not attempt to select 'through' the coil - have the curve ends to be selected at the front of the model.
Tab>
Repeat for touching curve:
Now use the Split Curve command from the Sketch tools
selecting the curve at the point position to split it
Repeat for all curve ends:
If creating drawings, place a point at the original curve intersections for dimensioning purposes.
Split the curves and delete the curve end lengths and the points on them:
Select each curve end > key B ( blend)
Select the Add Tangent guides
or Alt ( Ctrl +Alt) selecting each curve individually
Comfirm the blend by selecting the green Tick
Join up all the 3 helix sections and the 2 curve blends:
Select the first insecting coincident curve end position > Fill (key F/f), repeat by pressing the key F/f to complete. The whole coil is now a single spline as shown.
If a drawing is required, it is important to rename the points:
Finally to add thickness to the center line curve, select it, then select the Cylinder tool from the Design Tab - Insert menu
Enter the wire radius
The transition sections are tangent:
A Detail drawing can be made:
Model points and a circle are required to create dimensions (requiring renaming). Helix spline surfaces can not be otherwise dimensioned.
With practice, the coil spring can take only 4 minutes to completely model with transition blends as shown or less without the blends.
Comments