E3D Cyclops problems. Suggestions wanted please

I have recently installed an E3D Cyclops and am having huge problems with leakage into the cold areas and then blockages. I'm looking for advice, please.

I am printing PLA and insert both filaments when the heatblock is cold. I then allow it to heat up and feed material through from both extruders as far as possible. After heating, printing is OK when one feed is used but when it changes over to the other filament it refuses to print. Upon inspection I generally find that the unused side has formed a plug in the heatblock and is stuck solid.

Why is this happening? Thinking it may be leakage past the PTFE tube I have changed this on both sides, I have ensured that the PTFE ends are straight and at right angles. I have tried higher and lower temperatures but all of these have had little to no effect.

Any ideas, please?

Thanks.

Richard

I had the same experience with a cloned Cyclops. I believe the heatbarrier doesn't work well, although I've put copper grease between heatsink and those heatbarriers. IMHO the flat surface doesn't provide enough surface area compared to the threaded M6 heatbarriers.

Also the thin PTFE tube has a loose fit and filament from the other side can creep upwards. I've read there is 1.8mm ID PTFE available. Maybe a better choice for these short inner tubes.
My suggestion ( to e3d too ) would be to use bigger diameter heat barrier and better clamping method to improve contact area and heat transfer into the heatsink.

Edited 1 time(s). Last edit at 12/09/2016 04:39AM by o_lampe.

One of our Duet users had a similar problem with a Diamond hot end. The fix was to configure the slicer to use firmware retraction, so that it sends G10 to retract and G11 to un-retract instead of G1 E commands. In RepRapFirmware, when using a mixing hot end, firmware retraction retracts all the filaments feeding that hot end even if only one of them is being used. This avoids the unused filaments jamming in their heat breaks. See section "Extruder retraction" at [blog.think3dprint3d.com].

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].