How to copy and reverse keys?
 

I'm animating a fan(switch on the fan,running,switch off)
for this I want to copy and reverse keys,which set at starting,because fan starting and ending animation is same.
Please help me guys.....
Thank you.

go to the keyed frame that you want to copy, then right click on it, copy then go to the desired frame, right click and paste it.. see! simple... :)

here copying a set of keys is not a big matter,how to reverse them?

Its a fan, it takes 2 keyframes. Why not just key it again?

Seems lazy to me

I want the animation of a fan not with a constant speed from 1st frame to last......,I want the animation like when we switch ons it(slow),running(speed),switch off(slow).

yeah, that would take 4 keyframes in total, for the whole animation.

yeah,but that is my assignment,my faculty said that try as realistic as possible......
and here I want to know the concept "how to copy and reverse keys?"

I know in the graph editor it is possible to select a bunch of keyframes and scale them using the scale tool and the MMB. I wonder if you could scale right to a negative value? That would give you the reverse part and you can figure out how to copy a series of keys I'm sure.

thanks,but didn't catch you.......
please mention briefly with simple example,if possible with screenies......

u mean this kind of??
then copy all the keys, paste them after the last keyframe, then go to graph editor, select the pasted keys, move them to a little farther distance and scale them till they line up in reverse direction. then place them in desired frame gap.
downside is the gap duration maintainence..

thank you guys,now I understood.......
but I'll try this in my institute......
later I'll ask you doubts......
Thanks again....

or try trax editor too... it's real easy!!

Use the Dope Sheet
 

Copy and Paste Keys in the Timeline. Go to the Dope sheet and select the keys you want to reverse. Hit R for scale, a box will appear over the selected keys. Grab the right handle of the box and stretch the keys backwards to make the last key over lap the first key to reverse the keyed sequence.

Came across this post in 2017, and for future readers, wanted to suggest a useful resource: Autodesk's Bonus Tools.
They're in a free, downloadable package from Autodesk, and one of the included scripts provides a GUI for reversing animation keyframes without using a Dope Sheet, re-animating, or coping individual keys.
Maybe I was under a rock for a while, but just started using these and have been satisfied with the results.
Link is:
https://apps.autodesk.com/en/Detail/...50172702393827
Cheers.

it is only available for a Mac?