sliding joint question

[maker9876]

I have two 14mm plastic cylindrical bearings (in yellow in the left photo below) mounted horizontally, 10cm above each other.

In the horizontal plane they are separated, perpendicular to their axes, by 5mm so that a vertical 5mm plate (one face of the L-shaped angle iron in the below photo) can just slide up and down between them.

The plate is then connected to a platform which extends off to one side such that the upper bearing acts as a fulcrum and the lower bearing contains the plate.

My question is how to assemble this joint?

I can select the vertical plate as a joint surface. 

But how can I select a the outside of a cylinder so that the vertical plate will form a joint with it and move in the desired way? (And then do the same thing for the second cylinder?)

I'd like to assemble the whole thing and then, amongst other things, perform a stress analysis with the mechanism in a couple of different positions!

[maker9876]

Just created a little sketch to make it clearer (original file is probably a bit cluttered to include).

The question is, how to set up joints for an arrangement like this?

[Beyondforce]

I'm lost! Could you please make a screencast with explanation?

[maker9876]

Screencast is beyond me.

In the above photo there's a platform with two L shaped bars extending down from it.

Those bars are trapped by those wheels/cylinders such that the platform remains horizontal under load.

Perhaps what's confusing is I haven't shown the cylinders as being attached to anything? Of course, they are! 😉

 

[Beyondforce]

Okay, I think I understand now. If you want, you can attach the file and I'll show you what you need to do.
I would use the Planar Joint, since it's the Bars that are sliding on those wheels.

[maker9876]

That would be amazing.

Here's the file.

In the last step in the timeline moved to the platform to the right of the wheels so that you can "assemble" it into position. 😉

[Beyondforce]

Hi @maker9876,

I hope that's what you are looking for, if not, please let me know:

Cheers / Ben
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[maker9876]

Thanks @Beyondforce that's exactly it. You got it!

I recreated what you did.

Then did the same thing using Assembly (instead of Built As Joint). 

And implemented Contact Sets. Great!

At the moment am stuck on a higher level of detail. Have made the "wheels" in such a way that they can be "adjusted". The axles for the wheels go through these special "nuts" (see photo).

By turning the nut you change the position of the axle (by a few mm) and so change the position of the wheel.

The way we built the sliding joint doesn't quite work, since we only use one wheel (say the top one) as a contact point and the joint doesn't "know" about the bottom wheel. So if one of the wheels move...

Really what should happen is that, when you adjust the position of a wheel then the platform tips.

Can this still be done with a regular sliding joint?

[Beyondforce]

Anything can be done 😉

I wish you could make a screencast with explanation your challenge. With that said, I need the whole assembly in order to help you.

[maker9876]

I need to learn how to make screencasts.

Here's the file. F360 wouldn't let me export it as an archive this time.... Is it OK to look at?

The "wheels" are where all the joints are on the bigger metal frame. The idea is to insert the platform there. The difficulty is that individual wheels can be adjusted (by rotating the joint).

The purpose of having adjustable wheels is that I plan to weld the frames: nothing will be perfectly positioned.

[Beyondforce]

In this video I'm showing how to use the Screencast. I think it's in the end!
https://www.youtube.com/watch?v=CHUJX0ZJgd4

[maker9876]

It works!

Here's a screencast - hope it's a bit clearer.

IGES file attached to earlier post under the photo of the special "nut" if anyone wants to take a closer look.

[Beyondforce]

Could you please attach the file as *.f3d?
Click on File and then Export, choose from the drop down list *.f3d.

Great design.

[maker9876]

I tried to export as an .f3d before and got this message:

which is why sent an .iges file.

Just now created a duplicate of the file and started to break the reference links.

That worked for the first link.

But the second one (the first of the nuts) gave the following error message:

Anything else to try?

[Beyondforce]

Usually you just break the links and that's it. I'll try to with what I have got.

[Beyondforce]

I'm actually having challenges with it. I can't move the parts.
You should try to go to each sub component and break all the links! If you won't break all the links, you will keep getting errors.

[maker9876]

The sub components bolts are made of:

- bolt
- special nut
- plastic bearing

all fitted together with joints within the sub-component.

That assembly is imported into the file that you're looking at and fitted into the metal frame using one last joint. Which is the joint you should be able to rotate.

I'm not keen on breaking all the links because this is at an early stage and all of the sub-components are likely to evolve.

But in any case, F360 won't allow me to break the links for the nuts. Perhaps because they contain joints?

[Beyondforce]

1. Try to avoid linked components if you can.
2. Import the components to the MAIN assembly file and then create the Joints!
3. I won't be able to help you, if I can't play with the component.
You can create a test file, and in test file, you can just break all the links.

[maker9876]

That was tough. Had to rebuild quite a bit.

Here we are, an .f3d file with no links !

[Beyondforce]

I can see that the "inner_rack v6" is not reaching all the way to the Yellow "asymmetric_nut v10". is that on purpose?