SVG animation rotate a path around a center point.

Question

I'm currently having trouble getting this SVG to rotate perfectly on its axis.. as its a path. I've tried calculating what I thought should be the center point. Can anyone point me in the right direction as to why this isn't spinning absolutely perfectly around a centroid? Or how best to calculate it in the future?

<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 17 17" >
<style type="text/css">
    .st0{fill:#000000;}
</style>
    <path id="arrow" class="st0" d="M9.3,16.4c3.2-0.4,5.8-2.9,6.2-6.1c0.5-4.2-2.8-7.7-6.9-7.8V0.6c0-0.1-0.1-0.2-0.2-0.1l-4,2.9
    c-0.1,0-0.1,0.1,0,0.2l3.9,2.8c0.1,0.1,0.2,0,0.2-0.1V4.5c2.9,0,5.2,2.5,5,5.4c-0.2,2.5-2.2,4.5-4.8,4.7c-2.7,0.2-5-1.7-5.4-4.2
    c-0.1-0.5-0.5-0.8-1-0.8c-0.6,0-1,0.5-1,1.1C2.1,14.2,5.4,16.9,9.3,16.4L9.3,16.4z"/>

    <animateTransform attributeType="xml" attributeName="transform" type="rotate" from="360 8.425116062164307 8.459185183048248" to="0 8.425116062164307 8.459185183048248" dur="0.5s" additive="sum" repeatCount="indefinite" />
</svg>

https://jsfiddle.net/vfz5t0vw/

Answer 1

I am going to make an educated guess and say it is because you used the centre of the shape rather than the centre of the circular part of the shape. If that is the case, then the arrowhead will be resulting in an offset centre.

By my reckoning, the centre is at approx (8.4, 9.5).

Also you'll get better results if you rotate just the path - rather than the whole SVG as you are doing now.

Any remaining wobble is due to the fact that the arrow path does not appear to be perfectly circular.

<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 17 17" >
  <style type="text/css">
  	.st0{fill:#000000;}
  </style>
 	<path id="arrow" class="st0" d="M9.3,16.4c3.2-0.4,5.8-2.9,6.2-6.1c0.5-4.2-2.8-7.7-6.9-7.8V0.6c0-0.1-0.1-0.2-0.2-0.1l-4,2.9
    	c-0.1,0-0.1,0.1,0,0.2l3.9,2.8c0.1,0.1,0.2,0,0.2-0.1V4.5c2.9,0,5.2,2.5,5,5.4c-0.2,2.5-2.2,4.5-4.8,4.7c-2.7,0.2-5-1.7-5.4-4.2
    	c-0.1-0.5-0.5-0.8-1-0.8c-0.6,0-1,0.5-1,1.1C2.1,14.2,5.4,16.9,9.3,16.4L9.3,16.4z">
    	
    <animateTransform attributeType="xml" attributeName="transform" type="rotate" from="360 8.4 9.5" to="0 8.4 9.5" dur="0.5s" additive="sum" repeatCount="indefinite" />
  </path>
</svg>