VERICUT Users' Forum

Johnny_V

Member

Registered: 2005-01-24

Posts: 5

best practice for machine building

Hi,

I'm wondering how I should define the exterior of my machine (the cage which surrounds the table).
The machine is a horizontal 5axes machining center and the workpiece can collide with that cage, so I really have to define it.
As I know this will slow down simulation speed, would it make a difference if I create a single STL file for the whole cage or use a different STL for each wall?
If multiple STL's are the way to go, what about the component tree, should all STL's be under the same component ? :?

Johnny

Chigishev

Beta User

From: Moscow, RUSSIA

Registered: 2008-10-21

Posts: 51

Website

Re: best practice for machine building

The best way - different STL for each part. And the best-best-best way - use a Vericut modeller (blocks, extrude-revolve, cylinders) vis STL-models. If you import geometry as one STL-file - and Collision Check will be ON - simulation will be slow-slow-slow down.

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http://www.postprocessor.ru

Johnny_V

Member

Registered: 2005-01-24

Posts: 5

Re: best practice for machine building

Thanks, it really makes a huge difference.
I didn't know the difference between STL & native Vericut geometry was that important.
I wonder, would it make a difference for parts of the machine which are not included in the collision list?
In fact, up until now, all my machines are completely made up from STL files, because it's much easier to modelize a machine in a CAD system.
Maybe I should review all of them and replace the STL's with native Vericut geometry?

SergeV

Senior Member

From: Irvine, CA

Registered: 2004-10-08

Posts: 507

Website

Re: best practice for machine building

If the STLs are not in the collision list, they have a marginal effect on the performance.

2 factors will affect the performance with collision:

1) the number of triangles on the STL model will have the biggest effect, when 2 bodies are in a potential collision state, all the triangles are compared with all the triangles of the other components. If you have a STL model with millions of triangle, the CPU will work overtime... When you export the STL, use a larger tolerance to reduce the number of triangles. A component with a lot of flat feature can be output with a very large tolerance as the triangle size will not affect its shape.

2) If you select the model in VERICUT, you will see a blue box around the XYZ limits of the component. If the bounding box of 2 components intersect, then VERICUT will go into a more precise collision analysis and will compare all the triangles and their trajectory. As much as possible reduce the bounding box. you can do this by splitting the STL into multiple pieces. You machine cage is a good example, if built in a simple model, its bounding box always overlap the machine table therefore limits performance, if you split it into pieces, the performance is better because of the smaller bounding boxes.