Tool geometry was incorrect on that toolpath, quite a mistake on my part. I had issues earlier that with steps as i have said before and that evening i thought ill try some circles it should be a good test and when they didnt join i just assumed .... and then posted it ... thats what i get for rushing it!
Thanks Philip

To me it just looks like the tool geometry is wrong, as Komatias said are you using a ballnose ?. If so and the software thinks it is an end mill, then you will be left with material like you have in the pictures on the end points of the circles. You can change to an endmill or you can simply tell the machine to overrun the toolpath by a few mm.

If those steps were caused by backlash you would see signs of it on the top and bottom of the circles on the direction change, but they look fine, so it looks to me like you just have the wrong settings in.

The reason the steps arent in a straight line is becasue i assume each vector is starting in opposite directions and that is just the bow wave effect pushing material infront of the bit, so you get that alternating step effect, if you ran the same program with all the startpoints and directions the same on the vectors you would still have the steps but they would all be in a straight line, either overrun the bit or use an endmill, and even then i would overrun a few mm.[/QUOTE]