SpeedyDad

Try running the file through Netfabb to see if there is an artifact in the file causing the printer to get confused during that layer.

Duh, you are correct except all I had to do was open the PDF drawing of the middle print head body. 18mm it is.

What is the vertical separation of the X and Y rods on the Ultimaker 2? I'm having difficulty measuring it and I'd rather not get "close enough". I'm designing a dual extrusion head using the E3Dv6 hotend for my aluminum extrusion UM2 clone. Thanks.

That worked. I now have much better filament flow through the machine and while printing. I can now also use the change filament option without it trying to push too much through.

I'm going to try setting the e-steps first. I built the Ultmaker because wanted the symmetry you get when the hardware and software are made by one company. I tried a MK7 because the larger diameter should have reduced the over-extrusion but didn't like the way it fed. Much more skipping than with the UM2 feeder sleeve. I'm currently printing parts to build another extrusion frame Ultimaker based printed but I'm moving the electronics from my Prusa i3 in to it. Should be interesting to compare results.

OK, looks like I should have given more info.. The machine is fully set up for 1.75mm filament. I am running the 1.75mm version of the E3Dv6. I have the 1.75mm version of the iRobertl feeder with the stock UM2 feeder sleeve on the motor. I know the UM2 normally runs 2.85mm filament. I have set the onscreen ABS setup to 1.75mm filament so it should be feeding properly. Tension is proper. I'm starting to wonder if Ultimaker uses a different motor for the feeder motor with different microsteps?

I built an aluminum extrusion UM2. This one: http://www.thingiverse.com/thing:811271 I am using UM2 main board and the UM2 feeder knurled sleeve, I've set the filament diameter to 1.75mm in the on-screen setup and in Cura. When printing, i am getting massive over extrusion. I have to set the flow rate to 55% to get normal flow. I did a 100mm test extrusion using Pronterface and it extruded 180mm which agrees with the 55% above. When I do an "Insert Material" it tries to push way too much material through and ends up chewing through the filament when it can't push that much. If I set the filament diameter to 2.85m, it gets closer to proper extrusion but still not correct. Is there a way to set the steps per minute somewhere in the software? I know how to do it with my Prusa i3 but adjusting firmware in the Ultimaker seems to be a mystery. Can I do an M92 command in Pronterface to adjust it? I have tried the latest firmware, an older version and the Tinker firmware with the same results. Thanks.