I can draw a tapered helix, and I can sweep a circle along it (which looks like an extrusion from a soft serve ice cream machine), but how can I draw a proper corkscrew (like this: http://tinyurl.com/lzvq8ku )? Thanks.

Is that a helicoid?
Delete the )? from your link.

You can post a picture to the forum.

- Brian

Ooops. Fixed the link. I'm not sure it's a helicoid exactly, as there should be a central core (ideally) which I just realized isn't part of a plain helix, so I'll have to add that. If necessary, I guess I can omit it, but I need to preserve the taper.

I tried a Loft with centerline and tapered helix. Looks good.

The ISO's look good.

Make a regular helix and a tapered helix, and centerline.
Maybe bolean with a skinny cylinder at the center, and round tip?

- Brian

I think Brian's method is something like the attached file, 2 curves and then do a loft between them. Is that close to what you are looking for?

- Michael

Another possibility is to use the Transform > Deform > Flow command to introduce tapering. That's where you'll surround the object with a cylindrical looking revolve (with a few more control points in it than a regular cylinder), and then make a second copy of that revolve edited to be tapered. Then select the object to be deformed, run Transform > Deform > Flow, select the cylinder surrounding it as the base surface, and the tapered one as the target surface. That will generate a tapering effect as in the attached file, it will allow you to produce the tapering in a non-uniform way.

Some of these kinds of things that squash surfaces down to some collapsed shape can somewhat easily generate a self-intersecting surface which then won't work very well with boolean calculations after that, that's something to keep in mind if you are going to try to intersect the surface in some later on step.

- Michael

Thanks for the tips, guys. I'm on my iPad at the moment, so I'll check these out tomorrow and let you know.

Btw, Michael, I'm not getting e-mail notifications of these postings even thought that's what I've requested in my profile. FYI.

Karl

Hi Karl,

> Btw, Michael, I'm not getting e-mail notifications of these postings even thought
> that's what I've requested in my profile. FYI.

Do you have it enabled under Options > Email & Privacy > "Notify by email of posts to me" ?

Do you get any e-mails at all about replies?

Also double check that you've got your correct e-mail address set up.

But it's possible that part of the forum is just not working...

- Michael

Yes, yes, and yes. Do you know if it's working for anyone else?

Brian's approach is exactly what I was looking for (my version below). So simple when you know how, and are using MoI. Great product, Michael.

Hi Karl, re: forum e-mail notifications

> Do you know if it's working for anyone else?

I'm not really sure if it is working for anyone else or not... I'll turn it on for a while myself and see if it works for me.

- Michael

I also haven't received email notifications lately, despite several new messages in subscribed threads. I thought it was caused by changing my email address a while ago.

Played around a little with the corkscrew.
After saving and reloading, it became a solid.

Just a quick note: I'm receiving thread subscription email notifications again, thanks Michael!

@Metin,

re:
> Just a quick note: I'm receiving thread subscription email notifications again, thanks Michael!

Hmmm, I did not do anything to fix it so I'm not sure why it wasn't working before...

- Michael

The email notification behaviour seems unpredictable. Sometimes it works, other times I discover that there are already multiple replies to a subscribed topic on the forum.

Well, it's not very important to me. This pushes me to become a more active forum participant. ㋡