Stuck on how to start a particular drawing?

[Lazlow]

Hey Guys

Been using FreeCAD for a little bit and I am slowly getting the hang of most thing. Half the time I do a 2d draft and wind up starting over because I cannot pad it the way I drew it (learning curve). Most stuff I can stumble along and figure out. But now I am trying to design an air flow nozzle and I am stuck.

Picture a cylinder 25mm in dia and 5mm tall. On top of and concentric to it, is a cylinder 20mm dia and 10mm tall. On top of that is a 20mm(at base)cone. So far so good. Now, I want to add a series of 1mm wide by 5mm tall "fins" separated by 2mm running vertically on the outer skin of the cone and the upper cylinder. Think a round heat sink except the fins running virtically rather than concentric to the cylinder.

I am suspecting that the start is to draw the profile and spin it, but then how do I add in the fins or the slots between them? Can you "shape" a pocket?

Thanks

In concept this will be a three part assembly. An outer hollow cylinder casing that the above part drops into. Followed by a cone shaped lid that drops into the casing but over the above part.

[drmacro]

Not sure I fully understand how you envision the fins...but something like this?

Nozzle.png (42.72 KiB) Viewed 702 times

Or:

Nozzle-1.png (47.41 KiB) Viewed 702 times

[chrisb]

I cannot exactly imagine what you describe, perhaps a handmade doodle can help or a link to something similar in the internet. From what I understand for the fins: you may consider a DatumPlane which you place where the fins end, and then you pad up to first face.

[Bance]

You could use a pad and polar array feature, like this:-

EDIT Too slow

[Lazlow]

drmarco has it pretty close to the mark. The only thing a see off is that I wanted to maintain the skin to fin height constant. Which may just be an excess constraint placed by the concept I have in my head.

Thanks you

Now I have to tear into your example and learn how you did it.

Edit: Bance too.

[drmacro]

drmarco has it pretty close to the mark. The only thing a see off is that I wanted to maintain the skin to fin height constant. Which may just be an excess constraint placed by the concept I have in my head.

Thanks you

Now I have to tear into your example and learn how you did it.

Edit: Bance too.

Yes, because I was guessing I didn't constrain completely or necessarily where you may want constraint.

[Lazlow]

Made some changes along the way, but this is getting closer. Did a rethink and I am planning only two parts now.

The small holes are not correct(as in not holes). Is there a way to tweak the start point of the Polar Pattern?(other than the way I did it on the small holes). This is the first drawings that I have made that makes my Pi4 squeal. For whatever reason it is only using one core.

I did not understand why you put the fins "inside" the cone stucture the first time I drew this. Now I know.

[Lazlow]

Still do not like the way I had to get the holes but at least they are actually there now.

[Bance]

You need to change the position of the sketch, using attachment offset.

[freedman]

Looks good! You can put both rotational features in one polar array, if you like.