Inventor General Discussion

Reply
*Caldwell, Larry
Message 11 of 23 (97 Views)

Re:

12-05-2002 12:54 PM in reply to: HomeMadeSin
I think it can be done. I posted an airplane prop
awhile back as did Jeff. I'd probably do it another way now but I'll see if I
can make an example file tomorrow and post it.

~Larry


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Thanks
Tom.

Frankly, this is one of my fears (that Inventor isn't set-up - yet - to do
this type of feature). I just couldn't face learning P/E. Besides, at another
pump manufacturer, the P/E guys didn't tackle this issue either - they "faked"
it for visual purposes, not actual dimensions.

I would try MDT.....something else to learn.
Troy
Zellers

*Stocking, Matt
Message 12 of 23 (97 Views)

Re: Complex Lofting Question

12-05-2002 09:57 PM in reply to: HomeMadeSin
is there a reason you can start below the curved
surfaces?


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I
have a need to form what is known as a Francis vane impeller (double
curvature). Lucky me, huh? Anyway, I understand the loft method for generating
a shape from multiple planar sketches, but how on earth can you generate a 3D
sketch on a non-planar surface??? As far as I can tell, 3D sketch is only for
sweeps. A couple of good similar examples of what I'm trying to do would be
either a propeller for a airplane or a boat if you were trying to do the
lofting outward, STARTING (I repeat - STARTING) from the hub surface which for
both of these objects are curves....Thanks in advance.

Troy Zellers

Valued Contributor
HomeMadeSin
Posts: 50
Registered: ‎10-01-2003
Message 13 of 23 (97 Views)

Re:

12-05-2002 11:44 PM in reply to: HomeMadeSin
Matt:

I'm re-creating a part from a hand-drawn file dating back to 1967. I would have to imagine that many face the same issues with converting old 2D to 3D drawings.

At any rate, either old and redrawn or new design, it is necessary to define the lower edge of the vane and the upper edge and loft between if no intermediate sections are available (they aren't in my case). The problem is the lower surface that applies to the lower edge or profile of the vane is curved, so a planar sketch beneath the curved surface would allow me to generate a vane, but it would be completely different than the actual piece.

It seems the correct way to do it (if programmed) is to create a 3D sketch (actually 2) and loft between. Then the difference between the actual part and the 3D model would be how the loft was done (computer versus pattern maker). I could live with that. Unfortunately, the tools in IV don't seem to accomodate 3D sketches used for lofts or the creation of a 3D sketch via a 2D sketch projected on a surface (not a planar surface). Until then, I'll have to do what I am doing: sending the actual vane to a 3D scanner and input into 3D file (the vendor uses Solidworks) and drop the "dumb" file into the overall drawing. It is a work around that I hope is not permanent (rev. 7???)
*J, Dave
Message 14 of 23 (97 Views)

Re:

12-06-2002 02:12 AM in reply to: HomeMadeSin
I think this problem is the same one we were trying
to solve in "Barrel Groove..." We were trying to loft or sweep to get a cam slot
around a barrel. The best answer I saw involved a coil, but that probably won't
help here. Anyway, check out that thread in here and CF for help.


 

 


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Matt:

I'm re-creating a part from a hand-drawn file dating back to 1967. I would
have to imagine that many face the same issues with converting old 2D to 3D
drawings.

At any rate, either old and redrawn or new design, it is necessary to
define the lower edge of the vane and the upper edge and loft between if no
intermediate sections are available (they aren't in my case). The problem is
the lower surface that applies to the lower edge or profile of the vane is
curved, so a planar sketch beneath the curved surface would allow me to
generate a vane, but it would be completely different than the actual piece.

It seems the correct way to do it (if programmed) is to create a 3D sketch
(actually 2) and loft between. Then the difference between the actual part and
the 3D model would be how the loft was done (computer versus pattern maker). I
could live with that. Unfortunately, the tools in IV don't seem to accomodate
3D sketches used for lofts or the creation of a 3D sketch via a 2D sketch
projected on a surface (not a planar surface). Until then, I'll have to do
what I am doing: sending the actual vane to a 3D scanner and input into 3D
file (the vendor uses Solidworks) and drop the "dumb" file into the overall
drawing. It is a work around that I hope is not permanent (rev.
7???)

*Howard, Jeff
Message 15 of 23 (97 Views)

Re: Complex Lofting Question

12-06-2002 02:22 AM in reply to: HomeMadeSin
See CF "impeller (IV6)" for a quick attempt. Might be something useful in it
for you.

Jeff
====================
"HomeMadeSin" wrote in message
news:f129fe2.-1@WebX.maYIadrTaRb...
I have a need to form what is known as a Francis vane impeller (double
curvature). Lucky me, huh? Anyway, I understand the loft method for generating
a shape from multiple planar sketches, but how on earth can you generate a 3D
sketch on a non-planar surface??? As far as I can tell, 3D sketch is only for
sweeps. A couple of good similar examples of what I'm trying to do would be
either a propeller for a airplane or a boat if you were trying to do the
lofting outward, STARTING (I repeat - STARTING) from the hub surface which for
both of these objects are curves....Thanks in advance.
Troy Zellers
Valued Contributor
HomeMadeSin
Posts: 50
Registered: ‎10-01-2003
Message 16 of 23 (97 Views)

Re:

12-06-2002 06:05 AM in reply to: HomeMadeSin
Wow. I mean wow! That's a sweet looking part. I guess Inventor can handle it, but it will take me a good while to figure out how you actually made the vane and if I can do it with what little info (2D drawing) I have. Thanks!

Troy Zellers
Contributor
SeanS
Posts: 12
Registered: ‎04-28-2003
Message 17 of 23 (97 Views)

Re:

12-06-2002 08:40 AM in reply to: HomeMadeSin
If I understand you correctly, you are trying to loft a profile consisting of two complex curves (i.e. the high and low pressure sides of the blade) in a radial direction from the hub out to the outer circumference. Correct?

Why is it necessary to start and end with curved profile sketches as opposed to planar ones (which could be inside the hub diameter, and outside the actual blade diameter, respectively) which are then cut to size?

Can someone tell me how to access that sample impeller blade file (I am using WWW interface)?

I have created boat propellor blades using Inventor, by creating a coil (thin rectangular helix) to define the high pressure side of the blade, cutting the blade shape axially, and then tweaking the edges.

If you can use any 3D path (and my understanding of Inventor might be a bit off here, so bear with me) as a rail for a loft, could you not use a helical path as a loft rail? I don't know if that would help in your case...

If you know what the starting loft profile would be in 3D at your hub, could you not create a work plane parallel to the hub axis, intersecting the leading and trailing points on your 3D profile, then project that profile to the work plane, and use the new sketch to define your loft?

Just brainstorming out loud...

-Sean
*Keller, Kent
Message 18 of 23 (97 Views)

Re:

12-06-2002 10:13 AM in reply to: HomeMadeSin
From the FAQ Sean posts weekly

WEBBASED CF:
http://discussion.autodesk.com/WebX?14@67.Wd6TaaEbdXF^1@.ee940b5

NTTP CF:
news://discussion.autodesk.com/autodesk.autocad.customer-files


--
Kent Keller
Member of the Autodesk Discussion Forum Moderator Program

http://www.MyMcad.com/KWiK/Mcad.htm

"SeanS" wrote in message
> Can someone tell me how to access that sample impeller blade file (I am
using WWW interface)?
>
*Howard, Jeff
Message 19 of 23 (97 Views)

Re:

12-06-2002 02:44 PM in reply to: HomeMadeSin
I posted a more coherent version of the vane in CF that might be a little
easier to follow.

Good luck with it,
Jeff
====================

"HomeMadeSin" wrote in message
news:f129fe2.14@WebX.maYIadrTaRb...
Wow. I mean wow! That's a sweet looking part. I guess Inventor can handle it,
but it will take me a good while to figure out how you actually made the vane
and if I can do it with what little info (2D drawing) I have. Thanks!
Troy Zellers
*Caldwell, Larry
Message 20 of 23 (97 Views)

Re:

12-07-2002 06:14 AM in reply to: HomeMadeSin
Well, got hung up yesterday, but I see Jeff
jumped in there. ... Nice job Jeff! ... I went ahead and did a Silver
Tongue as an example of another way to do curvy curves. It's under
Jeff's.

~Larry


style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
Thanks
Tom.

Frankly, this is one of my fears (that Inventor isn't set-up - yet - to do
this type of feature). I just couldn't face learning P/E. Besides, at another
pump manufacturer, the P/E guys didn't tackle this issue either - they "faked"
it for visual purposes, not actual dimensions.

I would try MDT.....something else to learn.
Troy
Zellers

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