I am curious how others using MoI might approach creating a twisted chain link.

It is too bad we can't take tools from one program to another. SolidWorks has a flex tool which lets one create a flat link and then twist it. However, I am still interested in how it can be done in MoI. The image I posted earlier I created in TurboCAD by snapping a 3D Spline to some 2D Arcs and 3D Polylines and then sweeping the circular profile. But it is not very accurate.

hi try this way sorry bad engish .
make rectangle (rounded corner) 30x60 select it PLANAR shrink surface rotate end off surface 90 deg
join edge rebuild 0.1
make circle 10 and sweep




try this one

Hi Don - basically it's a matter of getting a good curve set up for the path...

The method that lyes shows there of deforming a trimmed surface by the surface control points is probably the most convenient way right now to warp a curve using only a few reference points rather than manipulating every control point of the curve individually.

In MoI v3 I will be working on some other kinds of deformation tools to try and make that sort of thing easier as well.

- Michael

Thank you both for the input.

Iyes, that is an interesting approach that I don't think would have ever occurred to me.

And then use "arrayGem" to make a 3d chain out of the result:



I've put the file on an open skydrive link:

https://skydrive.live.com/?cid=641344b395278ed0&sc=documents&uc=1&id=641344B395278ED0%21169#

Lyes,

Your are a freaking smart guy Oo

Ahh... ArrayGem, nifty tool.

Michael, I can't wait to see some basic deformation tools introduced, such as bend and twist.

Good job Lyes! The way you described by building off an existing path no doubt makes the purest shape.

Can someone please explain how to rotate one end of the PLANER? And how to get 4 control points for the PLANER?
I can make the rounded rectangle, with 10 control points, but am only able to rotate the whole thing.
What does the "shrink" command mean?
Thank You.

Hi bemfarmer,

> Can someone please explain how to rotate one end of the
> PLANER? And how to get 4 control points for the PLANER?

If you select a surface object, you can turn on its control points by using the Edit > Show pts button on the side pane here:




Note that you can't usually show points on a solid that is made up of a whole bunch of surfaces joined together - only on individual surfaces that are not joined to others. You can use the Edit > Separate command to break apart a solid into individual surface objects.

> What does the "shrink" command mean?

That's referring to the ShrinkTrimmedSrf command:
http://moi3d.com/2.0/docs/moi_command_reference10.htm#shrinktrimmedsrf

- Michael

Hi bemfarmer, also see these previous posts for some other examples of this method:

http://moi3d.com/forum/index.php?webtag=MOI&msg=1588.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=909.5

- Michael

Good idea Iyes... :)

Here is another method I learned from a fellow TurboCAD user but it works in MoI as well.

Snap a closed spline by control points to a rectangle and a line. Show points.



Extrude the rectangle if desired, otherwise direct entry can work.



Snap the four corners of the spline to alternating corners of the box.



Remove the box and sweep a circle on the spline path.

A few MoI links with materials applied and rendered in TurboCAD.

Thank you Michael.
I have been unable to twist or warp a Planar rounded rectangle derived from a NON-Solid rounded rectangle, after several dozen tries.
Cannot seem to get rid of the extra control points.

BUT, Starting with a SOLID rectangle, was able to create the chain link, as follows.
1. Create SOLID rectangle 60 x 30 in front view. Show points.
2. Create 2 180 degree arcs with 15 mm radius, to round solid rectangle. Show points.
3. Trim the solid rectangle with the 2 arcs and select and delete the corners.
4. Select and delete the 2 arcs.
5. Select right 2 control points, rotate, select center of rotation at center right, and click on x axis in right view, and drag 90 degrees,
to form the curved plane "bowtie".
6. Hi-Lite the "bowtie", and select the six edge segments, and join them.
7. Hi-Lite "bowtie", not edges, and delete.
8. Draw 5 mm radius circle, for profile, and sweep edge rail.
9. Delete profile circle and rail.

Ended up with several circles on the chain link... because ?...

Hi bemfarmer,

> I have been unable to twist or warp a Planar rounded rectangle
> derived from a NON-Solid rounded rectangle, after several dozen tries.
> Cannot seem to get rid of the extra control points.

Could you please post the file with your rounded rectangle in it that you're having a problem with?

One particular thing to note with this method described previously is that the thing you actually warp is a surface that you construct from the curve. Either draw in a plane surface and trim it with the curve or use the Construct > Planar command to build a planar surface from it.

Once you have that surface you delete the curve and then select the surface and turn on its control points with Edit > Show pts and manipulate those 4 surface corner points.

See these previous links for some illustrations and additional explanation of this method:

http://moi3d.com/forum/index.php?webtag=MOI&msg=1588.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=909.5

If you're still having problems please post the 3DM file with your geometry in it so I can see where in particular you may be getting stuck.


> Ended up with several circles on the chain link... because ?...

You mean the edges inside of the chain link? That's most likely because your path curve is made up of several sub segments. If you select your path and use Edit > Separate it will break it apart into individual segments and you should see that each segment of your rail path corresponds to one piece of the generated sweep.

That's not really anything to be worried about - that's normal to have a result like that.

- Michael

Thank you very much Michael.

WHOOPS, the 4 control point handles for the Planar, made from the rounded rectangle, were outside of my viewing screen.
Running ShrinkTrimmedSrf command moved them to be tight to the rounded rectangle Planar.

So the method :Create rounded rectangle, Planar, Delete rounded rectangle, ShrinkTrimmedSrf, Show points, Rotate 2 of the 4 control points 90 degrees, Sweep a circle,
works just fine!

This has been an excellent learning experience.

There is more than one way to do it.

May try to make some rope, like a dogs chew toy, with these, and similar methods...

Hello Michael,

I have a problem, if you take a look at the attached file you will find a surface (which is part of a Cylinder's lateral surface) when I use the Show_Pts command it shows control points of the original Cylinder. how can I have control points only for the surface I trimmed?

Hi Psygorn, select the surface and then press the Tab key and type ShrinkTrimmedSrf and push Enter.

If you want to make a surface that will smoothly deform though you may want to prepare a custom surface rather than the default cylinder - draw a circle then run Rebuild on it and extrude the rebuilt curve.

- Michael

Hi Michael, thank you for letting me know of ShrinkTrimmedSrf command.

However, I still have struggles to achieve what "Andre Samardac" achieved years ago in this video:

https://www.youtube.com/watch?v=PCAmSO8qW00&list=PLdnZa7Wc7RKAXiXgjW9pm1sdvQmjSPIq4

If you take a look at the attached file you would see that "blend" doesn't work as smoothly as Andre shows and it doesn't work good for the other object. (Select the red edges and operate Blend command) then you would see at the bottom corners there are issues for the Cylindrical shape and for the other object it is more problematic.

Note: I made the Cylinder by creating a circle then rebuilding the circle and Extruding it.

Also I have below Questions:

1- when the smaller surface is selected and I press "Show Pts" and then "Add Pt" could I have control over how many control points would be added? I mean could I determine how many rows and columns of control points would be added?

2- Does rebuild work on control points of a generated surface? ( for example a surface generated by loft command? )

- Psygorn (Drillbit)