On Mon, 13 May 2024 at 22:50, Chris Albertson <albertson.ch...@gmail.com> wrote:
> Adding anything inside is the worst place to add material. Yes, without a doubt, but it seems fair to assume that the ganry has slides and other components on the outside, but not on the inside. The base beam has an Iyy (bending in the plane of the smaller dimension ) of 22in^4 Doubling it internally gives: 34.2in^4, so about 50% stiffer Doubling externally gives: 57in^4 so getting on for 3x as stiff. I admit I was imagining a thinner wall thickness relative to the overall dimensions, where the difference would be smaller. There is less to be gained than you might think from making the section solid. You can do the experiments here: https://amesweb.info/section/second-moment-of-area-calculator.aspx If stiffness is the key, then add a stiff material. Aluminium is 68GPa (moving away from measuring in bananas) Steel is 200GPa (this is the same for all iron alloys, hardened or unhardened, including cast iron) Titanium is 114GPa, so good for light, not for stiff. Carbon fibre is 181Gpa for uindirectional fibres, but more typically around 50GPa. Tungsten carbide is 600GPa (which is why solid carbide boring bars exist) Beryllium is 287 but probably out of both budget and COSHH limits. -- atp "A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics." — George Fitch, Atlanta Constitution Newspaper, 1912 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
