Dual Extrusion shift

Hi I recently upgraded from a single J-Head to a dual E3D on my gMax 1.5+. I have set and adjusted my extruder heights and tinkered with my Z Offset. I followed all the instructions provided to me correctly and my first layers are absolutely fantastic looking now. Everything seems to be going well, but I am noticing in my prints that sometimes the extruder is shifting between layers or colors. One of my first prints (I don't have images unfortunately) shifted almost one inch, and then upon my second attempt shifted again but in a smaller amount. My third version went well, so I moved on to Benchy. As you can see from the images attached to this post, I am still experiencing a shift. It doesn't seem to be affected by the layer, and only appears to be affected by the switching between extruders.

As you can see, the blue hangs over the one side of the print, and is flush on the other side. It should be hanging over slightly on both sides, with no slop. You can see in the door arches that the blue material doesn't actually seem to adhere to the black material. Finally, you can see from the very top of the stack that the blue appears to be shifting to the back and one side just ever so slightly.

Is this something to do with the distance between extruders? Is there some invisible factor at work here? Maybe my second material temperature is set too low? Any ideas would be helpful. I am going to mostly be using PVA support material for my second extruder so this is not a HUGE deal, but I'd prefer to get everything dialed in now and save myself the headache down the road.

(PS. You may have noticed I have a multitude of topics presented in the forum at the moment, they're all related to setting up my dual extrusion and getting it right! So if you think you'll be able to help with some of my other issues I would love if you'd take the time to check those posts as well, thanks!)


Thanks! What program is that you're running?

I also posted on reddit and I got a couple great tips about using one's grid feature on their phone camera, and calibrating the X/Y offsets that way.