Sweep Cut a solid

[Anonymous]

Hello all, I hope you can help.

I would like to create a feed scroll.  I know this can be done in solidworks (see link). But can this be done in inventor.

 

The Image is similar to what I'm after,  but my thoughts are that this is not possible in Inventor... yet.  Am I Right?

The Solid in the image wascreated as a rectangular pattern (1200-off) of a cylinder along a helix path that is then cut from the work piece. In essence this is exactly what im after but as you can see there are far too many surfaces and the resultant cut is jagged especially when viewed with the shaded with edges style not to mention its size the file size 11+ Mb and hence i cant attach it to this post.

Is my method the only method available out there at the moment or am I missing a trick?

Solid Works Sweep Cut

[JDMather]

All you need for the CNC is the path - not the geometry.  (in fact, the geometry confuses the issue as far as creating CNC path)
Considering manufacturing tolerance and clerance between conveyed part - why need perfect (can't manufacture perfect parts anyhow).

[whunter]

Do you model all your bolt threads? No. Is a sheet metal part a perfect representation of the real thing? No. It's called a digital prototype for a reason. What does it matter how you've accomplished the digital prototype, as long as it is an accurate representation of the real part. Plus, you know how you're going to machine the part anyhow, so weather your digital prototype is 100% correct or 99.917%, what difference does it make?

[JDMather]

Apparently the solid sweep cut in SolidWorks is severly limited

http://www.eng-tips.com/viewthread.cfm?qid=312336

[SBix26]

I beg to disagree, at least for the case of a fixed-pitch helix.  Sweeping a 3D solid will leave a helical cut with a perfectly consistent 2D profile.  The challenge for Inventor users is to work out what that 2D profile looks like.  But I agree, too, that perfection in the model is not necessary in the case of feed screws.  Nobody would dream of trying to produce one by NC directly from the model!

---

@kakaboo wrote:

I'm afraid sweeping of 2D profile - no matter how shaped and positioned in relation to 3D path curvature - will not produce results identical to sweeping 3D solid.

[cwhetten]

This is definitely not a simple problem.  Here is one cross-section, cut on a plane parallel to the helical axis.

This shape was created with the patterned cylindrical cut feature mentioned above.  The shape appears to be approximated by a series of elliptical arcs, each with a slightly longer major axis (vertical in this image) and a constant minor axis (equal to the diameter of the small cylinder--the dashed circle in the image).  The center mark of each elliptical section is shown, and they appear to be laid out in a parabolic shape, or maybe elliptical, or even sinusoidal.

Not an easy shape to sketch in Inventor, anyway.

[whunter]

Very nice!

I think you're on to something here: the locus (of the points) is probably sinusoidal (projection of the helix's path?). If you draw a circle at each locus, and construct a spline that's tangent to those circles' outer boundary, I think you'll have a very good approximation.

I'll try it and see what transpires.

In the mean time, here's an improved version of the IPT I posted originally. Now fully parametric (you can change the cutting depth, diameter, pitch, etc). See the parameters in the file.

[cwhetten]

The latest part you posted is quite interesting.  How did you come up with that approach?  The logical progression isn't quite clear to me, although the approximation is impressively good.

[whunter · Accepted solution]

Thanks.

I figured you have to take the 3D path into account somehow, and the easiest is just a silhouette of that 3D path/volume.

There's a 3rd, more terse approach, see attached.

Sadly, I'm working on a 4th method...

[whunter]

3rd method is the best I can do, the 4th method I had in mind doesn't give good results. Whom can I invoice for this ?

[kakaboo]

Dear whunter, let's talk about invoice later . For now please make sure the attachment contains readable data - I can't see a thing!

cheers.

[whunter]

Others in this thread could open it...

Did you roll down the feature tree? Also, it's in 2012 format.

[coreyparks]

I will try and reply to the correct thread this time, darn it.  If the 2D cutter profile is perpendicular to the helical cutter path will this give you the geometry you are looking for?  See attached.

[SBix26]

Nope.  For transporting bottles, the bottle needs to stand upright, perpendicular to the screw axis.  Your screw forces the bottle to lean over at the helix angle.  The screw can be fabricated by translating a vertical end mill along the axis of the screw as the screw is turned at a constant rate (for a fixed-pitch screw).  The trick is to figure out how to generate the 2D profile that results, since we don't have the ability to sweep a 3D object (cylinder, in this case) along a path (coil, in this case).

[kakaboo]

That is correct. By now all our attempts here failed to produce the exact cut. Perhaps we must wait for Autodesk team to develope such modeling feature

[kakaboo]

Sorry whunter, the previous message should be sent to sbixler. BTW, your 3rd method doesn't produce required results, so no invoice, pls

[whunter]

If the model is used in a drawing, it will look like the real thing. If you know what you're doing, it will take 5 minutes to produce a drawing that'll tell the machine shop how to make the part, and obviously it will work. I've made this point before, but it seems you want to have the last say and like to nitpick, while missing my point about digital prototyping.

I won't bother to respond to you again, you can have the last say. I've made my point, twice in fact, hopefully it will sink in this time.

[kakaboo]

Dear whunter, I had absolutely no intention of hurting anybody's feelings here. This is the issue of academic disscussion about Inventor's ability to perform very specific task, not the issue of manufacturing particular part. In this case - of course - the problem will be solved long time ago after 5 minute conversation with average skilled machinist.

Best regards,

Matthew Dobrski

[nmunro · Accepted solution]

Another solution, this one develops the 2D shape to sweep along the helix. (IV 2012 format). As others have said it would be nice if solid sweeps were included. Solidworks tool is pretty limited and fairly confusing on its own, but at least they are trying.

The interference between the tool and shaft is about .00017 in^3, very evenly distributed, likely due to the surface approximation. If you have IV Pro, the simulation shown in the included video (mp4 format) is included.

Neil

[kakaboo]

Bravo! It seems you've made exactly what dnewman ordered !

It is unclear for me, however, how did you get this 3D Sketch3 curvature. There's a work point set on Sketch 3 projection (how?), which is used for establishing Work Plane3, than you get this 3D Sketch3, later mirrored ... would you kindly guide me to this point?

[whunter]

Neil, I think you've got it. I went through your feature tree and the logic makes sense, it's better than my method.