FreeCAD Forum

Hi,

I have been attempting to design a seat for a motion sim. I plan to make it out of fiberglass, so the idea was to design the seat to put into my sim design, extract the inside of the seat to 3D print a mould/plug to shape the seat. After numerous unsuccessful attempts, using Part design WB (Not overly experienced at using CAD). I saw an excellent series made by Mango Jelly on the curves work bench. I went with using B-spline rails for one side of the seat then mirroring them, then adding the B-splines for the profiles. The Gordon Surface was then applied to create what looked like what I was after, unfortunately it has a couple of flaws in it, these were further exacerbated when a 3D offset was used on the Gordon surface. This is the finished B-spline frame before applying the Gordon surface From what I can see is that it has added a extra flap of surface which I have circled in the above picture. I have tried adding a couple of extra B-splines and smoothing the bends but it hasn't made any difference. The above picture is after a 3D offset was applied with infill added. It shows Further defects which are the two top red circles, These I can't find any obvious defects in the Gordon surface before the 3D Offset is applied and the lower two circles indicate the result from the extra flap from the Gordon surface.
Just hoping someone can point me in the right direction, I appreceiate your help in advance.

Regards

David




OS: Windows 7 Version 6.1 (Build 7601: SP 1)
Word size of FreeCAD: 64-bit
Version: 0.20.25065 (Git)
Build type: Release
Branch: master
Hash: 4de2ad46b2b9c78ac2721a0dbea7c19306261095
Python version: 3.8.6+
Qt version: 5.15.2
Coin version: 4.0.1
OCC version: 7.5.0
Locale: English/Australia (en_AU)

Looking your curves, I think you should better use sketches or interpolated curves instead freehand curves. Because it's better to have some continuity around corner and accurate curves. You should merge some points as well. As you seat is symmetric, you can work with only half curves (if its easier for you)

GlouGlou wrote: ↑Sun Sep 19, 2021 6:28 pm Looking your curves, I think you should better use sketches or interpolated curves instead freehand curves. Because it's better to have some continuity around corner and accurate curves. You should merge some points as well. As you seat is symmetric, you can work with only half curves (if its easier for you)

Thank you GlouGlou for your feedback, I will research your suggestions and see how I go, just thought I was so close as this has taken me weeks through so many different versions of the design.