Designing six-bar linkages

[phbalance]

There are all kinds of graphical methods to construct 4 bar linkages. Is there a graphical means to construct a 6 bar linkage? Is it more or less trial and error / experience? How do you know where to place the joints to achieve the movement desired?

 

[EngineerTex]

This is interesting.

I'm not sure how a 6-bar linkage works. I'm not even sure if I've ever seen one. I'm familiar with 3-bar (slider-crank) mechanisms and 4-bar linkages, but I would have thought that a 6-bar linkage would be some combination of one or the other or both.

Do you have an example of one in operation?

Engineering is not the science behind building. It is the science behind not building.

 

[GregLocock]

http://iel.ucdavis.edu/chhtml/toolkit/mechanism/sixbar/wattI.html

etc

Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

 

[williedawg]

do some searching on the net... lots of info out there on 6-bar linkages.

here's an interesting applet that the user can change for different patterns....might give some ideas.

http://www.saltire.com/applets/SixBar/SixBarLinkage.html

here's a website showing different examples of 6-bar linkages

http://synthetica.eng.uci.edu/~mccarthy/animations.html

as re the geometry and/or where to place anchors, it depends on what motion(s) you're trying to obtain and may very well be trial and error.
I did some of this kind of linkage design in SolidWorks and it took some (...ok, a lot of) time to get what I wanted.

 

[phbalance]

Good info. Some I've seen before, but don't really get down to the nitty gritty of actually designing one from start to finish. With 4 bars, there are certain graphical techniques that will determine where all the fixed and moving joints will be. Wasn't sure if there was a way to do 6 bars graphically. See the attachment for what I mean by "graphically."

That Synthetica program looks interesting though. I'll try to download and play with it.

Most interested in designing hinges for doors and covers where conventional single axis hinges won't do (like some kitchen cabinet hinges).

Thanks.

 

[FeX32]

6 bar synthesis is not so simple. More application specific.
For example. See the attached.


Fe

 

[phbalance]

Thanks FeX32. That's the most detailed info thus far.

 

[FeX32]

No problem. Optimization method synthesis is also a known method. You could for example set up an objective function that minimizes the error from a straight line. That paper has some good references as well.


Fe