I have a problem with printing.

[mrblade]

When I print ABS that is such defects.
[img]http://cs624529.vk.me/v624529555/225a9/iz6H3CBix04.jpg[/img]

When I print PLA , without heating the heatbed no defects on the product.

[Durandal]

How much air flow is there in the room the printer is in? ABS is much more sensitive to airflow cooling it than PLA is, so those layers might be when a cold breeze cooled the plastic faster than previous layers.

[Jimustanguitar]

Are you printing a solid layer in your infill every so often? Those rings look pretty evenly spaced to me.

[mrblade]

Are you printing a solid layer in your infill every so often? Those rings look pretty evenly spaced to me.

Even if the product is hollow then the same problem. It does not depend on the filling. Yes those rings pretty evenly spaced.

[Polygonhell]

Are you printing a solid layer in your infill every so often? Those rings look pretty evenly spaced to me.

Even if the product is hollow then the same problem. It does not depend on the filling. Yes those rings pretty evenly spaced.

Given how regular it is, what is he spacing?
My best guess would be something is hanging up the belt somewhere, each belt tooth is 2mm so if the spacing is a multiple of that, I'd start by watching these motors and idlers to see if something is catching.

[Eaglezsoar]

I would turn up the temperature of the hotend no more than 5c and try the same print again.