Working with a .obj imported mesh -please help

max_thelion

Hi, I'm new to Onshape and am still finding my way. I'm trying to design a tray for a mandibular splint in order to be able to add air vents to it to aid nighttime breathing.
Here is the link: https://cad.onshape.com/documents/4b57568fa0fb47a3526b38d0/w/bfb76977732198a88ff275bd/e/afe9340632cd73801882a4d9
I want to be able to extrude/remove to trim some clutter off the model and then I want to offset it outward to give it thickness. The problem is I can't get the extrude/remove to work and I'd be very grateful if someone can help me get this feature to work.
Many thanks,
Max.

MichaelPascoe

Onshape is made to work with solids (step, sldprt, & parasolid) and has little mesh support. However, in order to work with meshes in Onshape you will need the custom feature Boolean Plus by @MBartlett21.

Boolean Plus: 
https://cad.onshape.com/documents/84d939daceef6a928b8abcba/w/9e0dafb21fbe2ec8b983bbdc/e/eebc2fcbf29fac07f8f92ed1

max_thelion

Sorry, I just found out how to add custom tools. Many thanks again for your help, I really appreciate it.

GWS50

It might be worth using Meshlab or Meshmixer to get rid of the small mesh triangles that are floating around the main mesh. You can also trim away the mesh you don't need and fill the holes. I would suggest Meshmixer to start as Meshlab can be a steep learning curve. If your mesh is below 9,500 faces you can also use FreeCAD to turn the mesh into a solid which can then be used as a solid in Onshape. There are plenty of FreeCAD videos online on how to do this.
Use Meshlab to reduce the face count  - they are all free softwares.....which is amazing.
If you're on a Windows machine you can use 3D Builder to reduce the file size and fill holes. This is also free!

This is the Meshlab face reducing path. Meshlab is amazing but can be a bit baffling.