Tips on moving class E asteroids?

[Dfthu]

I have this craft and when I try to move it wiggles and I move all over the place. I heard of pulling and tried that but I couldn't move and I blew up the asteroid. Is this craft good or what do I need to change?

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Edited September 8, 2015 by Dfthu

[Sharpy]

When the engines are close to the asteroid, they will not pull but burn it instead. You must place them a considerable distance from the asteroid, like I did in my tug.

[Haruspex]

I have this craft and when I try to move it wiggles and I move all over the place. I heard of pulling and tried that but I couldn't move and I blew up the asteroid. Is this craft good or what do I need to change?

http://imgur.com/a/4pFzo

It's long with engines at the end and has wobbly joints (docking ports) and lots of potentially wobbly elements stacked one upon another (SAS rings, i never trust those - as well as large batteries and remote guidance units - to hold under pressure). Great as a spaceship, but will most likely snap when trying to push it against a heavy boulder. Make your asteroid pusher flat (if possible), compact and sturdy. Or at least strut the docked sections to each other. And put all those SAS modules and batteries somewhere where is no direct stress applied to them.

If did do something like that i'd put all that fragile stuff and the ore tank into a Mk3 cargo bay attached to the engine section, strut everything into oblivion and launch it all in one big piece.