What dual extruder setup are you using?

Assuming you're doing using one of course. I'm looking at options for my i3.

Thanks
Ian

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RepRap Prusa i3 RAMPS + Marlin
Bulldog lite extruder + Hexagon hotend + 1.75 PLA
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Dual bowden E3D V5 hot ends (bowden to keep the weight down) and dual D3D all-metal extruders on a (much hacked) Prusa i2. I'd prefer a hybrid (one bowden and one direct) to make it easier to print PVA support material, but that will have to wait until I can work out a triple extruder setup.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Interesting. I was looking at options last night and all the non-bowden assemblies look very very heavy, so I think bowden is the way to go. I thought I might start with one bowden just to see what effect it has on printing, I understand you get hysterisis (?) as the hot end is remote and the filament can flex/absorb some of the push between extruder and hot end.

Theoretically you can print faster with a bowden setup due to the reduced mass but it is still possible to get quality prints with a non-bowden setup (and it does eliminate the hysterisis issue). You can minimise the effects of hysterisis by making sure your bowden tube only has a single curve. The easiest way to do this is to mount the extruders upside-down, so that the bowden tube exits upward, instead of down.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

I'm being dim and don't understand what turning it upside down does. My filament for example is above the printer, so I would of thought feeding the filament directly into the top would reduce the flex the most. That's what I would of done in my naivity

When your X carriage moves toward the top, how many curves does the bowden tube have? Every curve introduces friction and lateral movement. If the bowden attachment on the extruder is pointing down, as the X carriage moves up you'll see a pronounced S-curve in the path the bowden tube takes.

If the bowden attachement on the extruder points up, you should get only a single bend in the bowden tube, regardless of how high your X carriage is off the bed.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Gotcha, ok that makes perfect sense