Hot End shooting sideways

I have two JHead MKV hotend and have the same problem on both (one is 0.4mm the other 0.35mm).Both fitted alternatively to the mendel 90 Kit.

The hotend keeps shooting filament sideways on both J-Head, I tried with PLA and ABS from Faberdashery and other vendors (FormFutura...). I cleaned carefully the chamber with a drillbit and a small wire, nothing seems to be blocked and I don't find any residue.

This is especially an issue for bridges where this small sideways extrusion lead to problems. The problem is more evident with ABS than with PLA since somehow it is more "soft" and extrusion sideways is more pronounced.

I have absolutely no clue about what is going on, I tried different temperatures but this didn't make any difference on this problem.

I found no forum thread on this very subject, only clue is on the wiki where it says that sideways extrusion is due to jamming.
I first thought that it was the hotend that was damaged or that I didn't clean well enough the hotend, so I bought a brand new J-Head but the problem is still there from the first firing.

Any suggestions will be appreciated, I am even looking at the E3D hotend but currently thinking that the problem will keep on going even with another type of hotend...

To get it to come out perfectly straight is a bit like balancing a pencil on its point. The hole has to perfectly round and free from burnt on plastic. Any imperfection that slows the plastic at one side will make it curl that way when extruded into free space. PLA is far more likely to curl the ABS but both tend to do it when extruding into space until there is enough weight to pull it straight.

It doesn't normally matter what direction the filament comes out in as it should be being stretched length ways and squashed against the layer below. Possibly you are trying to extrude layers that are too big for the size of nozzle you are using so it is not being stretched. Measure the filament diameter when extruded into mid air and make sure your filament width and height form a rectangle with a smaller cross sectional area.

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