For modeling a spur gear in creo you need to have some basic data like base circle dia, Adendum, Dedendum, pitch circle dia, no. Of teeth etc.

- Do you know what is new in CREO 3.0 ? CLICK HERE

- In the last article on gear we discussed about nomenclature of gear. BASIC GEAR TERMINOLOGY

**Using Relations we are going to model a gear:**

**1) Drawing a curve using Curve from equation.**

Select the curve using equation and paste the following equations in to the notepad:

r = 2.819

ang = t * 90

s = (PI * r * t ) / 2

xc = r * cos(ang)

yc = r * sin(ang)

x = xc + ( s * sin(ang))

y = yc – ( s * cos(ang))

z = 0

Click on save and ok. Following curve would be developed in creo:

**2) Now extrude a circular blank of dia 6.5mm and thickness of 1.75.**

**3) Collect all the basic data required to model the gear.**

Sketch the base circle pitch circle, Addendum and dedendum

Here in this tutorial we would take the following values:

- Root Diameter : 5.376
- Base Diameter : 5.638
- Pitch Diameter : 6.000

Sketch the above diameter circles in creo

Now the critical point comes. How to draw the involute profile of teeth.

**4) Create two datum points as below:**

**Point 1:**Make a datum point which is intersection of involute curve Dia 6.00mm and the curve which we made:

**Point 2:**Make second point as the intersection of three planes Front, Top and Right.

**5) Draw a Curve connecting the above two datum points:**

**6) Insert Evaluate feature in Creo by INSERT — MODEL DATUM —– EVALUATE.**

Type “Measure” as a name of the feature.

Now click on create then enter “angle” as a measurement parameter

Now you need to pick the Top datum and Curve that you created last.

Click on Done.

Save the part.

**7) Copy the Involute curve by -30 degree angle. You will get the new copied curve as below.**

Double click the 30° angle and carefully enter

:

**angle:FID_MEASURE + ( 7.5 / 2 )**Click YES to enter the relation

Note : If you can’t use the above feature then. You have to enable the config option allow_anatomic_features

**8) Mirror the Copied Curve taking the top datum surface as reference to it.**

**9) Move the copied involute curve**

Click edit then Copy.

Click on Edit then Paste Special

Click on check box of “**Apply Move/Rotate transformations to copies” ** then click OK

Now click on Rotate in the popup menu taking axis of the cylinder and -15° as the rotation angle. U’ll get the following result:

your involute curve for gear tooth is generated

**10) Extrude cut the teeth as the section below.**

**11) Pattern the extrude cut feature by taking axis of the gear.**

Enter 24 as number of pattern and 15° increment angle.

**12) Finally Extrude cut a hole of Dia Ø2 from center.**

Hola your gear is designed.

For reference you can download the above model : CLICK HERE