Need help with dual extruder

[longshot]

Another dual extruder question.

So I've been working with Bubbasnow's design regarding the dual extruder design.

http://www.thingiverse.com/thing:278076" onclick="window.open(this.href);return false;

I've put dial indicator inplace of the extruders to see if I can actually level this thing. I can get it in within a half a thou on all towers. So i know full well it can be leveled.

The problem is when i introduce the dual extruder design. After some work with shims I'm able to approximately level the nozzles.

The problem I'm running into is this.

Legend:
Red, Green Yellow, Blue are the positions of the nozzles
Orange refers to nozzle 1
Light Blue refers to nozzle 2
Assume Nozzle 1 and Nozzle 2 are offset by 1000 in the Y direction


So after much calibration I've run into an issue.

In red position, Nozzle 1 (orange) is pinning the paper, while Nozzle 2 (light blue) is high and just grabbing the paper.

In blue position, Nozzle 1 (orange) is just grabbing the paper, while Nozzle 2 (light blue) is pinning the paper.

In green position, Nozzle 1 (orange) and (light blue) are both about even.

In Yellow position both nozzles are even.

I have zero clue how to fix this.

If I shim to make up the difference at red position, its just going to tilt and make thins worse at blue position and offset what I have at green position.

If i adjust printer radius, it might help red, but because position blue and green are not perpendicular to the towers, l'll probably just make a huge mess of things.

It just doesn't make any sense. I'm using Tricklaser's Carbon Fiber arms and E3D V5 nozzles. I shouldn't have any arm issues. They should be all the same. My effector plate should be flat. otherwise i'd see a consistant nozzle 2 hitting the plate. Its like there's a bump between position red and blue.

Please help.

[Nylocke]

Check out the Z=0 thread in the troubleshooting forum. Several of us have a similar problem, where the firmware's view of your machine isn't the same as the actual build of your machine, which results in some dips and spots where it "flies" off the platform. Generally has to do with the tower rotations in the firmware.

[bubbasnow]

are you nozzles offset in firmware or software?

[Polygonhell]

Look at how your wiring/bowden tubes are getting to the printer, at the edge of the build area, the arms don't provide a lot of rigidity and it can result in the platform twisting a small amount. It's none issue with one print head with 2 or more it results in an inability to get the two heads level across the bed.
On my V1 machine the issue was the wiring which I was running to side of the bed, as the platform moved away from it, it was twisted slightly by the force, I could correct the twist by moving the wires around by hand, I relocated all my wiring to the top of the printer.

The leveling the heads issue is what makes dual extruders such a pain in the ass to actually use.

As was mentioned Nylocke it can also be caused by slight errors in the geometry, notably tower positioning and orientation, that can be corrected in software, but it's something of a trial and error exercise.