Creating a groove

[venche]

Hi,

I'm looking for some help on creating a grove. I'd like to make a curved groove similar to the red one in the picture attached on a ring like object. The green lines is where I'd like the groove to go. What would be the best way to approach this?

Thank you in advance.

OS: Mac OS X
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6712 (Git)
Build type: Release
Branch: releases/FreeCAD-0-16
Hash: da2d364457257a7a8c6fb2137cea12c45becd71a
Python version: 2.7.11
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

[HarryGeier]

I can´t tell how to do exactly in 0.16 , as this is an outdated Version.

But you would have to create a subtractive SWEEP along the line. A groove is a subtractive revolution.
The tricky thing is to create a sketch for the groove that starts "normal" to the line so SWEEP can work.

There are tutorials about SWEEP in FC 0.16 floating around.

[bejant]

venche, can you post your FreeCAD .fcstd file?

[tommeyers]

Venche,

I don't see a groove in the red object; I am assuming that you translated to english and a little got lost.

So, in a nebulous way I see a depression in that (seat?, foot rest?) Starting high at the back side and low in the center front side and a form that is ribbon-like.

With that in mind I think you can form a model like that red shape:

in v17:Create a loop representing the back (sketch bspline polar/closed) then create a loop in an offset plans for the front loop. Then loft between the two loops.

Then the form will have been created. Then apply other tools for opening the inner space or adding thickness to the shape.

Forgive me if I have experienced an optical confusion. As others have asked please post what you have and upgrade to v17.

RedRibbon.FCStd

(13.08 KiB) Downloaded 51 times

Tom Meyers

[venche]

venche, can you post your FreeCAD .fcstd file?

Yes here is the file I've been playing around with. Thank you!!

[venche]

I can´t tell how to do exactly in 0.16 , as this is an outdated Version.

But you would have to create a subtractive SWEEP along the line. A groove is a subtractive revolution.
The tricky thing is to create a sketch for the groove that starts "normal" to the line so SWEEP can work.

There are tutorials about SWEEP in FC 0.16 floating around.

Thank you for the advise and I'll download the latest version.

[venche]

Venche,

I don't see a groove in the red object; I am assuming that you translated to english and a little got lost.

So, in a nebulous way I see a depression in that (seat?, foot rest?) Starting high at the back side and low in the center front side and a form that is ribbon-like.

With that in mind I think you can form a model like that red shape:

in v17:Create a loop representing the back (sketch bspline polar/closed) then create a loop in an offset plans for the front loop. Then loft between the two loops.

Then the form will have been created. Then apply other tools for opening the inner space or adding thickness to the shape.

Forgive me if I have experienced an optical confusion. As others have asked please post what you have and upgrade to v17.
RedRibbon.FCStd

Tom Meyers

Hi Tom,

Thanks for the help. It's not a translation issue as much as not knowing how to describe an object in engineering/technical terms.

The red object is a chair. I'm looking to just recreate the depression part in an already created ellipse shape (file is attached).

My question was if it's possible to create the depression in a shape I've already created, or if I'd have to start from scratch and recreate the ellipse shape with the depression.

I hope this makes sense and thank you for your help.


I'll upgrade to v17.

[HarryGeier]

is this what you look for ?

0,17 , subtractive groove starting with a rectangle sketched on a datum plane normal to line at start point

2018-05-15 07_37_41-FreeCAD.png (112.28 KiB) Viewed 1366 times

[tommeyers]

Here is a lead for you. Take a look at mesh wb and search documentation for nurbs.

I studied tjat a little last week and i think you may find value thete for changing a shape. A good skill for what is called organic models.

Tom Meyers

[bejant]

Yes here is the file I've been playing around with. Thank you!!

After looking at your file, I would try a different approach to create the chair.

1. First I'd make a Sketch of the front of the chair. Or better yet, only the right or left half of the front of the chair.
2. Next I'd make a Sketch of a vertical cross-section of the chair, about 3/4 of the way towards the back, where the groove you mention tapers to nothing and blends in with the smooth dip.
3. The last Sketch would be of the rear of the chair.
4. Then try a Loft or Sweep through the 3 Sketches, from front to back. Tick "Create Solid" to True, or change the Property > Solid later if you forget. The Sweep or Loft wiull work best if each of the Sketches has the same number of segments in roughly the same locations.
5. Finally, select the front and back faces of the solid and apply the Part WB > Thickness tool to hollow it out.

I'd probably only use Sketcher and Part WB's (not Part Design) for this.