Pro mechanica Slider

: Hello. : : I'm trying to design a 4 link mechanism with a slider...I cannot get the slider to function correctly...what am I doing wrong? : : So, you finally got it up and running and now, you're trying to learn some stuff. Good for you! It might help, though, if we knew how far you got. Not much I can make out of a 'desperate cry for help', which, while plenty dramatic, lacks in content and basic information. For example, Steve, how far did you get? Did you make 'connections' between your links? Can you drag your mechanism? Why Mechanica and not Mechanism Design in basic Pro/e? If you haven't gotten this far, we need to back up and find out if you're taking a class, have a teacher, are using a geriatric tutorial that ought to be retired and living in Florida on Social Security?
I know, from other posts, that you're using Wildfire on an XP system, so that's a start. Now, fill us in, if you'd be so kind. A nice story, something entertaining, if it isn't too much trouble.
David Janes

So, you finally got it up and running and now, you're trying to learn some stuff. Good for you! It might help, though, if we knew how far you got. Not much I can make out of a 'desperate cry for help', which, while plenty dramatic, lacks in content and basic information. For example, Steve, how far did you get? Did you make 'connections' between your links? Can you drag your mechanism? Why Mechanica and not Mechanism Design in basic Pro/e? If you haven't gotten this far, we need to back up and find out if you're taking a class, have a teacher, are using a geriatric tutorial that ought to be retired and living in Florida on Social Security?
David,
Thanks for your response...yes, finally got the program up and running:-) It took some work but finally did it.
Sorry about being vague...I've built the mechanism. All ground points are made with the exception of the slider link itself. I am uncertain as to how to approach the slider. Should it be made from a ground point? All pin joints are made correctly, The mechanism runs as long as I don't have the slider attached to it...so I know i'm not correctly creating the slider. this is where my problem lies and am not certain how to approach it. I wish I had a tutorial that used a slider as it would be benificial. would it help if I uploaded a small KB image of it to show you what it looks like...(although a 4link mech with a slider isnt too hard to imagine..lol)
If a pro-mecanica tutorial with a slider is found somewhere on the net, a link to it woudl be great....the whole problem is creating somehting with a slider.. I can create the rest of it....lol
Thanks for your help and concern.
Steve

: I am uncertain as to how to approach the slider. Should it be made from a ground point? All pin joints are made correctly, The mechanism runs as long as I don't have the slider attached to it...so I know i'm not correctly creating the slider. this is where my problem lies and am not certain how to approach it.
You approach should be to analyze what degrees of freedom you need for the movement you want. Points, for example, allow three degrees of freedom, all rotational about three normal axes, but no planar movement. Your slider, as the name suggests, needs planar movement. Point connections to the ground body (base, first, fixed component of the assembly) are preventing the slider from sliding. Use an axis in the direction of the motion you want plus a plane to eliminate the rotational dof; or use two normal planes. Establish the sliding connection and test if it moves the way you want before connecting it to the rest of the mechanism with a pin type connection.
: If a pro-mecanica tutorial with a slider is found somewhere on the net, a link to it woudl be great....the whole problem is creating somehting with a slider.. I can create the rest of it....lol
is a site where I've found a lot of useful tutorials, tips and tricks
David Janes

Uh... not to be picky but there is a joint called a planar joint and one called a slider. The latter almost always gets placed in the wrong direction and then you need to reorient it. You might try a planar joint or even a 6DOF joint and put "0 valued" drivers sequentially on each axis and see when it fails. Also try changing some of your pin joints to either spherical or cylindrical. Does it say "No compatible set of hinges found?" If not what error do you get?
The joint placement depends on if you are trying to relate some part to ground or to another part. Possibly you are picking ground when you should be picking another part? or vice versa.
So I'll guess you are using Mechanica because Pro/Mechanism doesn't come up when you ask it to... (no license) Right?
I seem to remember a book written about Mechanica Motion on Amazon... this would give you the basics. Is there a new one about Pro/E Mechanisms? Hmmm maybe someone here should write one.
-meld
David Janes wrote:

: Uh... not to be picky but there is a joint called a planar joint and one : called a slider. The latter almost always gets placed in the wrong : direction and then you need to reorient it. You might try a planar joint : or even a 6DOF joint and put "0 valued" drivers sequentially on each : axis and see when it fails. Also try changing some of your pin joints to : either spherical or cylindrical. Does it say "No compatible set of : hinges found?" If not what error do you get? : : The joint placement depends on if you are trying to relate some part to : ground or to another part. Possibly you are picking ground when you : should be picking another part? or vice versa.
Right, you identified the two problems: 1) to get the slider moving in the right direction and in this instance, in only one direction; 2) to get the rest of the mechanism attached to the slider so the whole thing moves.
Good thing is that Steve already has the 4-bar part articulating correctly and he know in what direction the slider must move. Now, to get it connected properly. : : So I'll guess you are using Mechanica because Pro/Mechanism doesn't come : up when you ask it to... (no license) Right? : It should, it's part of the Foundation Advantage package. YOu just have to know how it works, where to find the connections and how to launch the application.
: I seem to remember a book written about Mechanica Motion on Amazon... : this would give you the basics. Is there a new one about Pro/E : Mechanisms? Hmmm maybe someone here should write one. : Well, a tutorial would be nice, anyway.
DJ

Oh - I can't keep up with PTC's packaging and terminology. Once upon a time, I was told that MDX will do kinematics and MDO would do real dynamics (forces) Don't know if these terms have meaning now. But I do believe you need to feed PTC extra money to get real dynamics capability.
So, if you go to Applications/Mechanisms with an assembly active and then hit the round dot icon and pick Dynamics (somewhere down in there) you'll either get more icons or a license warning.
I think you could also do a search on your license file for the word "Dynamics" If you have multiple seats it doesn't necessarily mean that this option will work on all the seats, depending on how you bought it.
-meld
snip

: Oh - I can't keep up with PTC's packaging and terminology. Once upon a : time, I was told that MDX will do kinematics and MDO would do real : dynamics (forces) Don't know if these terms have meaning now. But I do : believe you need to feed PTC extra money to get real dynamics capability. : At this point, nothing Steve has said or asked for indicates that he needs anything more than kinematics which he should have with just about any seat of Pro/e. Not sure about dynamics, that could be extra. Don't think I've ever seen a side by side comparison, this is what you get with kinematics and this is what more you get with dynamics. Which one has springs, dampers, force/torque, gravity?
David Janes

Usually people need to calculate force sooner or later... I'd say everything you mention would be available in dynamics only. -meld
David Janes wrote: