Hi All,

I'm trying to design a functional small screw cap container:



I started with a helix and then created a triangular profile which I intend to rail revolve using the helix as the rail. Problem is when I do that, the rail revolve just makes one circle and does not follow the helix:



Could someone let me know what I'm doing wrong?

Also, I'll need to create the screw cap which I assume will be by using the boolean difference command. What would be the approximate tolerance I should use for a functional screw cap?

Many thanks in advance!
Gunter

There is a NutsAndBolds script.

Select the profile, click Construct-Sweep and select the Helix Rail. Select both solids and click Construct-Boolean Union. Draw a horizontal line at the top of the jar and click Boolean Merge to trim.

Hi Gunter, you want the Sweep command for that, not Rail revolve.

Some examples:

http://vimeo.com/30765016
http://moi3d.com/forum/index.php?webtag=MOI&msg=4623.1
http://moi3d.com/forum/index.php?webtag=MOI&msg=767.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=490.36

- Michael

Thank you Michael!
Gunter

Thank you dansperk!
Gunter

Hey Michael,

When I sweep the thread profile along the helix, I notice the profile of the thread seems to change as it goes down the z axis:



No idea why it does this and how to resolve it?

Many thanks!
Gunter

Hi Gunter, you need to set the "Twist = Flat" option in the sweep options:



- Michael

Hi Gunter
If you copy your spiral rail downwards so there are 2 and do a 2 rail sweep of the thread profile.
This will stop it from deforming



cheers
shayne

Great, thank you Michael!
Gunter

Thank you Shayne!
Gunter