[Ultimaker 2 Dual extrusion]

i try to understand the issue for my personnal culture (i'm totaly newb in 3d printing) :

two heads carry to much heat so it will hard to contain a good temperature for pla, is that ?

 

The 2 hot ends are temperature regulated so they will always maintain the desired temperature, therefore having 2 next to each other shouldn't be any problem, the hot ends will probably just reduce the power output to maintain the set temperature as some of the heat lost by the hot ends would heat up the other hot end. The problem I believe is that the other parts above it shouldn't be hot, are heating up because there is inadequate insulation between the 2 areas and not enough cooling from the 3rd fan behind the heat sink to remove all the excess heat from the white connector and other components in that area. Without fixing these issues, the white connector, Bowden tubing and filament expand and deform causing filament jams.

 

[Ultimaker 2 Dual extrusion]

This part is clear and well described in your posts. Forgive me for insisting, but there's something I don't fully understand... There are a few design flaws in the original UM2 print head which certainly contribute to the problem:

 

1. There is no heat insulation at all between the nozzle block and the lowest aluminium block. The heat is radiated pretty efficiently over the couple of millimeters gap.

    

2. The rear fan - not the strongest one - blows forward. Its airflow gets heated by the heat sink before it hits the PTFE isolator.

    

3. Surfaces which are supposed to radiate heat are not black anodized - and they are smooth.

 

Fixing points #2 and #3 help to convey the heat away from the parts that should be kept cool - but fixing point #1 would actually reduce the need for heating. There are insulator materials which could be placed between the nozzle block(s) and the lowest aluminium block - which would reduce heat transmission from the nozzle unit to the print head significantly. There is also physical connection through the stainless steel isolator, yes, but the radiation component is not insignificant.

What am I trying to say is - if the temperature goes "slightly" above the glass transition temperature using 2 hot ends, I find it strange that particular problem couldn't be fixed without making major changes.

I personally would be ready to accept "known issues" for the first release of dual extrusion.

 

If the next big announcement isn't the dual extrusion upgrade, then I will try out the Pryogel-XT blanket for myself, because if it does perform as well as advertised, and possibly added in conjunction with installing a small fan infront of the print head to reverse the airflow, than it would be a very cost effective solution. The blanket costs $30 for a 30cm x 30cm x 5mm square and can handle extreme temperatures

 

[Ultimaker 2 Dual extrusion]

Wasn't the conclusion about aerogel that the maximum operating temperature was something like 100C? I know this was talked about a few pages back. And most heat is conducted trough the metals, air is a horrible heat-conductor anyhow.

Latest news is that the R&D team just moved to a new building, so we are no longer sitting with 4 people in an office fit for 2. And, that we're working on the dual-extrusion, as well as looking into what is the best soluble support material.

I'm actually being pulled off Cura development to assist on dual-extrusion.

 

Nope, the Pyrogel-XT blanket is rated for industrial use up to 650°C/1200°F and I was thinking about the 5mm thick version.

 

[Ultimaker 2 Dual extrusion]

If heat conduction is a problem, would using an aerogel insulation blanket directly above the heater block fix the problem, or would a solid plate of about ~5mm thickness be better?

I found a cheap potential solution, Pyrogel-xt blanket , is it worth a shot to try it and DIY dual extrusion?

http://www.buyaerogel.com/product/thermal-wrap-tw350/