snap rotating part to home position

[schnautza]

I have an assembly that has a base with a rotating frame (a shaft at both ends in a bearing). The frame is allowed to rotate +/- 90 degrees from its home position. I can use the contact sets to constrain the +/- 90 degree limits, but I'd like to also be able to rotate the part (using a simple click and drag) and have it snap into a "home" (0 degree rotation) position. The home position would have planes that are parallel for the fixed and rotating part. Any advice on how to do this?

[mdavis22569]

You can set up a Position It's under representations. You set it up with the way you want it..then you'd just override the constraint in the Position representation that you create

[Curtis_Waguespack]

Hi schnautza,

You can create an Angle constraint with a Constraint Limit that will do what you're after. I'll use an example here, but your selections might make the angles used different than what I show in the example:

I set the Angle to 0 deg, then click the >> button to show the limits options, and then select the Use Angle as Resting Position option. This option makes the assembly "snap" back to 0 degrees if you rotate it manually by clicking an dragging.

Then I set the min and max constraint limits to control how much rotation is allowed. Again, your values might vary depending upon your model geometry and what you've selected to define the constraint. Meaning you might end up with 90 deg as the resting position and the limits at 0 and 180, or something similar.

More on Constraint Limits (inlcuding a quick how to video):

http://help.autodesk.com/view/INVNTOR/2014/ENU/?guid=GUID-EBD2C784-0E71-452A-B5F2-22738D22D45A

I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com

[schnautza]

Curtis, I can't seem to get the constraint limits to work for this application. I'd like to attach a picture of what I have, but once again, it seems that all of my formatting buttons are mysteriously gone from this forum and I cannot attach a picture or format text... so I will try to explain as best as I can. I have a base frame that sits on the floor. There is a large bearing at both ends that supports a large rotating frame with a shaft at both ends. I have this shaft driven by a hand wheel with a worm gear, sprockets, and roller chain. All of these geared components are flexible and appropriately move with each other as I rotate my frame. I've built stops into the frame to allow a +/- 90 degree rotation. These stops are part of a contact set, so my motion is automatically constrained by them. I would just like to be able to drag the frame to any position and leave it there, but most importantly be able to go precisely back to the zero position with ease. Right now, I've been temporarily adding an angle constraint and then deleting it when I have it aligned properly, but there has got to be an easier way. I may try out the representations, but I am unfamiliar with how they work.

[JDMather]

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@schnautza wrote:
Curtis, I can't seem to get the constraint limits to work for this application.... 

I've built stops into the frame to allow a +/- 90 degree rotation. These stops are part of a contact set

I've been temporarily adding an angle constraint and then deleting it ...

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I would keep working on learning how to use Constraint Limits.

I would not use Contact Sets (other than for initial testing).

If you place a temporary "home postion" constraint - suppress it, don't delete it.  That way you always have it (I use this technique freqently for Dynamic Simulation applications).  Give it a name like "Home Position - Suppress This" as a reminder.

[schnautza]

I experimented with the constraints limits in a more basic assembly and found that the part will always snap back to home position when you drag it...is there a way that you can leave it in the max/min positions without suppressing it? I then used the same constraint techniques in my first assembly and could not even get it to snap to the home position. I would apply the constraint and then the part was still free to move (and stay) in any position I moved it to, including outside of the min/max limits that I set (with 0 as resting, +90 and -90 as limits). I don't understand why it won't behave the same as a simple assembly. Maybe having the roller chain/sprockets and worm gear assemblies are messing with it?