Saturday Structure – push rods

Sat, 1 May 2010

Push rods are used to take a movement from one point to another in a mechanism. They generally need to be rigid and relatively strong.

Presented here are three different designs of pushrods that I use in model.

The simplest is the strip of card. This is flexible; actively bendy in fact. It is useful for pushing over very short distances and for only a small amount of force It works well for pulling, in fact if the force being transferred is a pull force this is all you need.

By adding a crease down the middle of the push rod the rigidity of the push rod is increased dramatically. A simple push rod like this is useful even over fairly long distances. It is rigid but doesn't work well if twisted.

The final iteration is to take the strip of card and fold it round into a triangular tube. This is harder to make and bulkier than the other designs but stronger both in the sense that it is the most rigid and that it resists twisting.

  To receive new blog posts by email

Comments (2)

  • JayHavvic May 2, 2010 at 12:44 am

    Rob,
    I have seen a 4th

    Rob,

    I have seen a 4th way.

    It is used by Giuseppe Civitarese (PAPERPINO) in his Wandering in the Sky, Clown and Trike ( which I am currently building )

    The "rod" is square with a 'Z' stiffener inside.

    This makes a VERY stiff push rod.

    I really appreciate step by view into your thought processes.

    Thanks again.

    J

    • member May 2, 2010 at 10:19 am

      J – Thanks for pointing that

      J – Thanks for pointing that out! I think this is the kind of thing you mean. I use these for parts such as cam shafts which need to be particularly strong. The diagonal surface splits the tube into two triangular tubes. It stops the tube from folding flat and makes it stronger in torsion(twisting)

Comments are closed.