Why does my loft kiink?

Post here for help on using FreeCAD's graphical user interface (GUI).
crobar
Posts: 142
Joined: Fri Aug 29, 2014 1:26 pm

Re: Why does my loft kiink?

Postby crobar » Thu Apr 13, 2017 3:26 pm

jmaustpc wrote:
Note that the OCC version used in your FreeCAD version is now very old and is also OCE. Does your Salome use the same version?

Another related tip....also there are different transition types in the sweep properties, they only apply if the path had non tangent joints.


It probably uses quite an old version (it's a build from 2015)

I used to regularly build FreeCAD from source but I'm on Mint Linux 17.3 and becasue of dependancy issues I can't do it any more unless I upgrade to Mint 18 (which I don't have time for at the minute), otherwise I would build the dev version to test it out there.
jmaustpc
Posts: 8098
Joined: Tue Jul 26, 2011 6:28 am
Location: Australia

Re: Why does my loft kiink?

Postby jmaustpc » Thu Apr 13, 2017 3:32 pm

crobar wrote:
jmaustpc wrote:
Note that the OCC version used in your FreeCAD version is now very old and is also OCE. Does your Salome use the same version?

Another related tip....also there are different transition types in the sweep properties, they only apply if the path had non tangent joints.


It probably uses quite an old version (it's a build from 2015)

I used to regularly build FreeCAD from source but I'm on Mint Linux 17.3 and becasue of dependancy issues I can't do it any more unless I upgrade to Mint 18 (which I don't have time for at the minute), otherwise I would build the dev version to test it out there.


I used to run something like 6 different oce/OCC version that I compiled with various different options, sometimes OCC bugs were regressions, so newer occ did not always solve some bugs. I am on my mobile phone so I can't test just now.
User avatar
NormandC
Posts: 12266
Joined: Sat Feb 06, 2010 9:52 pm
Location: Québec, Canada

Re: Why does my loft kiink?

Postby NormandC » Thu Apr 13, 2017 4:56 pm

ArminF wrote:Ich versuch grad' in 0.17

English please!!! This is the "Help on using FreeCAD" forum, its language is English, and I and many others don't understand German.

What is it lately with people posting in whatever language they want, anywhere???????????

If the mods do not put a stop to this, I will start to write in French here!!! :roll:
crobar
Posts: 142
Joined: Fri Aug 29, 2014 1:26 pm

Re: Why does my loft kiink?

Postby crobar » Fri Apr 14, 2017 9:28 am

bejant wrote:@crobar, I think you've made it too complicated. The plan view is a circle so the Sweep Path would be that portion of the ellipse between the inclined tangents of the handrail:

You could make 3 line segments (one line segment from tangent to tangent on the ellipse plane, and another two segments from the endpoints of this segment to the midpoint of that portion of the ellipse between these points on what will be the (arc of) ellipse plane. Use Part WB to make a Face from these 3 edges (tick Planar to True), then use Part WB > Extrude (tick Make Solid to True) and Extrude the plane downwards to create a solid. Change to the Part Design WB, create a Sketch of the top face of this Extrude, and Sketcher an Arc of Ellipse on the Extrude. You can use Link To External Geometry and make the endpoints of the 3 edges lie on the Arc of Ellipse. This will be the curved portion of the Sweep Path.



This is really helpful, thanks, I was planning to start figuring this out once I knew sweep or whatever would actually work

bejant wrote:You would only need to use one cross-section of the handrail profile. It would probably be easiest to correctly locate it at the end of a straight length of the handrail, then create the Sweep (tick Make Solid and Frenet to True). This should make for a smooth Sweep.

This off the top of my head so I hope that makes sense.


Unfortunately sweep won't work because you cannot control the profile rotation in the sweep, that's why I'm looking at loft instead.
crobar
Posts: 142
Joined: Fri Aug 29, 2014 1:26 pm

Re: Why does my loft kiink?

Postby crobar » Fri Apr 14, 2017 9:30 am

microelly2 wrote:The better way thna Loft/Sweep is to interpolate a BSpline Surface over the ribs:

Code: Select all


apts=[]
for s in Gui.Selection.getSelection():

   print s.Label
   w=s.Shape.Wires[0]
   pts=w.discretize(50)
   apts.append(pts)


bs=Part.BSplineSurface()
bs.interpolate(apts)
Part.show(bs.toShape())


Thanks, I think this method is actually the equivalent of what I did in Salome, or closer to it.
crobar
Posts: 142
Joined: Fri Aug 29, 2014 1:26 pm

Re: Why does my loft kiink?

Postby crobar » Fri Apr 14, 2017 9:31 am

ArminF wrote:Ich versuch grad' in 0.17 eine Skizze in zwei Ebenen zu machen und scheitere da noch kläglich. :cry:
Weiß einer wie ich das angehe?

Armin


Sorry, I'm sure this is helpful, but I don't speak German.
User avatar
bejant
Posts: 4125
Joined: Thu Jul 11, 2013 3:06 pm

Re: Why does my loft kiink?

Postby bejant » Sat Apr 15, 2017 1:28 am

crobar wrote:Unfortunately sweep won't work because you cannot control the profile rotation in the sweep

Maybe haven't done what I've suggested? What happens if you try a Sweep of only one shape along the Path, when Arc Of Ellipse is selected as the Path and Frenet is ticked to True?
My Part Design tutorials on YouTube (aimed at beginners).
crobar
Posts: 142
Joined: Fri Aug 29, 2014 1:26 pm

Re: Why does my loft kiink?

Postby crobar » Mon Apr 17, 2017 4:16 pm

bejant wrote:
crobar wrote:Unfortunately sweep won't work because you cannot control the profile rotation in the sweep

Maybe haven't done what I've suggested? What happens if you try a Sweep of only one shape along the Path, when Arc Of Ellipse is selected as the Path and Frenet is ticked to True?


See attached, the seep results in a shape unsuitable for a stair handrail because of profile rotation
Attachments
handrail_if_I_sweep_one_shape_on_path.fcstd
(13.28 KiB) Downloaded 8 times
UR_
Posts: 44
Joined: Tue Jan 03, 2017 8:42 pm

Re: Why does my loft kiink?

Postby UR_ » Mon Apr 17, 2017 5:57 pm

I think it's not forbidden to use more than one sketch for sweeping. Especially if you need more control of twisting profiles.
I simply not understand your global coord. system. :( Which faces should stay vertical?
Is this what you expect?

handrail untwisted.FCStd
(37.56 KiB) Downloaded 4 times

handrail topview.png
handrail topview.png (8.7 KiB) Viewed 105 times


Another example:
handrail with ecosystem.png
handrail with ecosystem.png (19.29 KiB) Viewed 105 times

handrail with wall.FCStd
(126.66 KiB) Downloaded 4 times


But caution: Your bending machine has to understand what you are doing :D
Otherise the whole thing has to be 3D printed :shock:
crobar
Posts: 142
Joined: Fri Aug 29, 2014 1:26 pm

Re: Why does my loft kiink?

Postby crobar » Mon Apr 17, 2017 8:05 pm

UR_ wrote:I think it's not forbidden to use more than one sketch for sweeping. Especially if you need more control of twisting profiles.
I simply not understand your global coord. system. :( Which faces should stay vertical?
Is this what you expect?


Thanks, but no, so the goal is to produce something like this:
example.png
example.png (159.55 KiB) Viewed 94 times


Imagine walking up the stairs with your hand on the handrail surface and you will see what I mean.

UR_ wrote:But caution: Your bending machine has to understand what you are doing :D
Otherise the whole thing has to be 3D printed :shock:


This would be produced using 5 axis CNC wood routing!