Hi Chris,

Thank you for responding and sorry for my delay on the reply. I was doing some "homework" before continuing this thread.

After sending my initial post, I found your "walker7 and studying your model and realizing mechanical linkages are possible on sketchyphysics, I decided to finish my scissors lift model. The model is attached. For convenience I'm attaching your Walker (which is Ted Jansen's legs, which I was also planning to build) model as well. Thank you for sharing it on the warehouse.

So my question now is why my model is not working? I know I could have used less joints, but even with the extra joints I tested (sketchy play) some of the bar "double linkages" and they worked as expected - some of them. It's just the whole system that is not working. I wonder if you could shed some light.

In regards to this model I have also a couple of simple questions:

a - Should I have done any specific grouping or non-grouping for this to work? Is there a specific type of grouping you'd recommend? I didnt make any of the hinges to be part of any group, just as a safety measure (also looking at your Walker model). Can we safely include joints inside deeper levels of grouping and still expect them to behave they way we want? Can nested joints access objects nested inside another hierarchy?

b - I notice the hinge joint representation on the model has a "direction". I tested an "x" linkage with two bars (a real pair of scissors), and was able to make both bars spin on both directions (clock wise and counter clock wise), so it doesn't seem that the hinge has a direction. But could you confirm that please?

I also have some basic questions about sketchyphysics that the docs dont cover. If it's ok with you I was hoping to start posting them here, on subsequent mini-threads, and then we can put the answers together in HOWTO or FAW formats. I could help with that if you'd like. Maybe it's time for a wiki, as I found it hard to dig and put together knowledge from the forums.

Thank you for your time and sharing your work and knowledge,

Andre Philippi

CPhillips Walker model based on Ted Jansen's leg mechanism.

My finished scissors lift mechanism that is not working. yet

Hi,

I'm trying to build a scissors mechanism, but I'm having some problems.

Everything seems to be working fine (rotation around the center hinges) when I have the 4 bars and the 2 center hinges. However, when I add one of the side hinges at the end of the bars, the mechanism doesn't move how it's supposed to...

I wonder if I should also add some sliders moving along the Y axis, or if there's a better way to make the whole thing work.

Thank you in advance,

Andre

Scissors.skp