Screw thread

[J4NY4R]

Hi!
I have problem to design this kind of tapered thread (its start, middle and end are different). Please may you guide me how to do it? I will be thankful if you attach a .catpart file to examine it.

 

[MrCATIA]

Use the Profile option to vary the radius of the Helix

 

[MrCATIA]

There are 2 ways to model a screw: either add the thread to the root diameter, or remove the thread profile from the major diameter. In my model shown below, I removed the profile.

My screw is based on three profile sketches: the major diameter (red), the root diameter (green) and the thread profile (hidden). I used the first profile to add a Shaft representing the main body of the screw. Then I added a Helix using the second sketch as the Profile. Then I added a third sketch of the thread profile to sweep along the Helix as a Slot feature.