# How can i drop my mesh on floor with rigid body

I have a floor and mesh (pen). Im dropping the pen on the floor. Floor is set to passive and pen to active. Added collision-on to floor. When the pen is not dropping on the floor. Its flickering in air. I want to add some few 8-10 pens on the floor so that it get collision with floor and with each. other.Any suggestion how it works.

• did you try with primitive collision shapes? Aug 28, 2020 at 5:26
• Try changing the 'floor' plane to a box in the collision setting rather than a mesh.
– Chuk
Aug 28, 2020 at 5:29
• The floating is caused by collision margins set to 4 cm. The pen's shape is problematic, It's too low poly for mesh to work and too misshapen for convex hull. You could try scaling everything up by a factor of 100, too. Physics engine doesn't like small things. Aug 28, 2020 at 6:21
• @Ron Jensen, is there any need for collision ? Just a rigid body physics will do the job properly right ? Aug 28, 2020 at 6:23
• It works for me as Ron Jensen suggested. He pointed all aspects correctly. In this scale I was able to stop moving only with Box. Also it s always good to have Origin in center of Object. @RonJensen please could you write it as answer Aug 28, 2020 at 6:54

Ok, I tried a few options and got a fairly stable simulation. Here is the result:

Steps:

• Scale the ground and pen up by 100 (physics simulations work better with larger objects. Also, the floating came from the constant collision margin of 4 cm which means that objects will already collide when they are 2*4 centimeters apart. While this value can be changed, it is better to scale the objects up)
• Apply the scale on the pen with Ctrl+A > Scale
• Set the origin of the pen to Center of Mass (Volume) (a wrong origin can mess up simulations)
• Use convex hull as collision shape (should be precise enough in this case. Mesh shape causes glitches)
• Use box as collision shape for the ground (except if you want to use a different shape)
• Finally, you might want to increase the Rigidbody simulation steps (Go to Scene Properties > Rigid Body World and increase Steps per Second and Solver Iterations, e.g. to 600 and 100)
• Thanks for the answer. If i want the same scale back. How it will work.
– atek
Aug 28, 2020 at 12:34
• Bake sim and parent all pens to Empty. Scale down Empty Aug 28, 2020 at 20:19