Add a contact set to an assembly and then set limits on the motion. Use a contact set to stop movement when bodies collide, as they would in the physical world. To avoid slow calculation time, limit the number of components in a contact set to only the components necessary.

Open the file Cylinder Body Sub_Assy.iam, located in \Tutorial Files\Cylinder Clamp.
Use the left mouse button to click and drag the blue shaft on the assembly. The shaft can move in a linear and rotational direction. You can also pull the piston and shaft completely out of the body. The linear and rotational freedom is intentional so that the piston can move in a higher-level assembly.
Before proceeding, use Undo to restore the piston to the position it was in when you opened the file.
On the ribbon, click Inspect tab Interference panel Activate Contact Solver. The command activates, but no components belong to the contact set yet.
In the browser, right-click each of the following components, or in the graphics area right-click the components. Select Contact Set in the context menu. A check appears next to the entry to tell you the component is part of a Contact Set.
- Cylinder Head Cover_Front
- Cylinder Head Cover_Back
- Piston
Push and pull on the piston shaft. The piston body movement is limited by the physical contact with the front and back cylinder heads.

NoteRapid mouse movement or continued drag movement allows the piston to pass through the cylinder cover bodies. This intentional behavior enables you to move contact set members in or out of a closed body.
Pull the piston until it comes in contact with the Cylinder Head Cover_Front component. In the Interference panel, click Activate Contact Solver again to deactivate it.
Right-click the Cylinder Body and clear Enabled to make it easier to select internal parts.
When you turn off Enabled, a component displays transparently for reference, and you cannot select it. A component that is not enabled appears green in the browser. To re-enable a component, right-click the component in the browser, and click Enabled.
On the Assemble tab in the Position panel, start the Constraint command. In the dialog box, do not change any settings.
Click the end face of the Cylinder Head Cover- Back, as shown in the following image.

Rotate the assembly or use Select Other to select the back face of the Piston, as shown in the previous image.
Click More , and specify the following:
Maximum: 35mm

Minimum: 0
Click OK to create the constraint and close the dialog box.
Drag the piston rod. The piston stops at either end.
In the browser, right-click the cylinder body and select Enabled.

Experiment with Limits settings to change the range of motion. In the browser, edit the constraint. Expand the Piston, right-click the last Mate constraint, and select Edit. If you click Use Offset As The Resting Position, you can enter a default value for the piston position. If you drag the piston and let go, it snaps back to the resting position.

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Comments

Comments13

b.eralWed Aug 24, 2011 3:10 pmSomething isn't working.
I right clicked on head cover. head back and piston - in each case enabled was checked,
but the piston still slides past its limits
gferrerMon Sep 12, 2011 10:47 amI was totally lost from 6. Wish a clearer/better instruction is available.
pchen016Sun Sep 18, 2011 5:32 pmb.eral dont click enabled but click "contact set" which is right under it
gezildireThu Oct 13, 2011 11:01 amIn Step 10 when saying "Select Other" it's the "Second Selection" box?
bill.boganTue Oct 18, 2011 7:41 pmHi b.eral,
The step is actually wanting you to Select Contact Set in the context menu. Since the word Enable is also there, it is confusing. Thank you for drawing our attention to that issue. It has been corrected.

Cheers,
Bill Bogan | MFG Learning Experience Team
bill.boganTue Oct 18, 2011 7:42 pmHi gferrer,
Thank you for pointing out that the step was vague. It has been revised to be more specific.
Cheers,
Bill Bogan | MFG Learnign Experience Team
bill.boganTue Oct 18, 2011 7:49 pmhi gezildire,
When you have components that lie atop or obscure one another, you can pause the cursor over the components until a small mini-toolbar (Select Other) shows up. That mini-toolbar is what is being referred to in this step.
Nile_Wed Oct 19, 2011 9:56 amWhen I click 'use as the resting position'* the piston basically locks at the resting position I choose. Is it a bug? Rest all is working fine with me.

Good to see prompt replies from the developing team, thanks!

*The last tip after point 13.
gezildireThu Oct 20, 2011 4:21 amIn the previous topic we used the "assemble" command,now the "constraint". It seems that in general they do the same things, but somehow(that I miss) they differentiate?
bill.boganThu Oct 20, 2011 7:54 amThe difference between the two lies in the additional things you can do with the constraint command. You can create transitional constraints, motion constraints, and apply limits. The Assemble command applies constraints, but only those relative to putting components together.
More discussion on the additional constraint capability is here: http://wikihelp.autodesk.com/enu?adskContextId=REDIRECT_IDD_UC_GEOM_SELECTION_DLG&language=ENU&release=2012&product=Inventor

Cheers,
Bill Bogan | MFG Learning Experience Team
spfurlongThu Oct 20, 2011 9:16 amNile_ and I are having the same issue, when I click use as the resting position it locks the piston.
Right click Last Mate in Browser under Piston
Edit
Select Use offset as resting position
Maximum selected and set to 10 mm
Minimum selected and set to 0 mm
Ok
And the piston is locked on the end face of the Cylinder Head Cover- Back
Redo steps to get to Edit Constraint dialogue,
Uncheck Use offset as resting position
Keep Maximum at 10 mm and Min at 0 mm
OK
Piston is limited to 10 mm offset from end face of the Cylinder Head Cover- Back
But no snap back....

What am I missing?
Thanks, and sorry for the length
bill.boganThu Oct 20, 2011 9:31 amThe resting position looks to be anchored after the first attempt to move it. I unchecked the resting position option and moved the piston. I then turned it back on and could move the piston, and the moment I let the cursor go (mouse button up) the piston snapped into the resting position. After that I could not move it again.
Not sure if this is "as designed" or "an issue" needing resolution. I will investigate further.

Bill Bogan | MFG Learning Experience Team
bill.boganThu Oct 20, 2011 11:29 amUpdate: The Resting Position "drag" issue is known and is being addressed.

Bill Bogan | MFG Learning Experience Team

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