IDEA: Quad Extruder possible? Yes, with a new Design...

[dipicorg 1]

The best Feature of an Ultimaker is the Speed and this is also its Problem. The Hot End does not feed the Extruder. This is made by a stationary Feeding Mechanism and a PTFE Tube, which slips often out of the Brass.

The Solution to this Problem and Opener of new Feature (Quad-Extruder) is using flexible Shafts to transfer the Power to the Hot End. Using 4 flexible Shafts an 4 Tubes to pull the Filament from the Weels will terminate the Problem of the Plugs that occurs when the Filament gets to much Force to be pushed into the Hot End.

The Idea is the same used by tranporting the Filament to the Hot End, not by a Tube, but by a flexible Shaft. The heating Elements, Temperature Sensors an Nozzles can be put very near together. The Top of the newly designe Extruder will just have some Parts that pushes the Filament directly into the heated Nozzles.

Tell me what you all think about this..

[snowygrouch 1]

Sorry but to be honest I have absolutely no idea what you mean. A flexible shaft pretty much IS a PTFE tube !

I think you need to upload a sketch, or rephrase your text.

C.

[IRobertI 516]

I think what he means is to put the actual extruder part on the head. To get away from adding massive weight in the form of steppers on the head he wants to transfer the power of the motors via a flexible shaft similar to the extension thingies you can get for Dremels and the like.

IIRC this has already been discussed in some thread but it was a long time ago and I don't remember what came out of it.

[Daid 303]

IIRC this has already been discussed in some thread but it was a long time ago and I don't remember what came out of it.

Flexible drive shafts are not designed to handle reversal, that was the main problem with an idea like this.

[snowygrouch 1]

Daid is quite right, with retraction it would have loads of backlash. Also these drives are high speed low torque,

to get any sort of rigidity you need a large cable...then its huge mass anyway.

If you want to do this I would use a sliding spline driveshaft from an Radio Control Car. You can get

really nice carbon filled plastic components for those things. Super light.

Something a bit like this, which is from a Tayma RC truck...1/14 scale.

http://i1233.photobucket.com/albums/ff3 ... MG1721.jpg

Could work, question is by the time you add all that stuff on...will it be light !

[dipicorg 1]

I Robert I is right. But I have seen some flexible Shafts that can be used for both directions. The Dremel ones are not designed for that, so Daid is also right.

The Motors are positioned on top of the Ultimaker and therefore the Movement is just for an Area of 22x22cm and the Shafts are not tensioned much. If you think they are positioned like the Filament Feeder, that's wrong. The Part snowygrouch has posted is not my Idea.

[snowygrouch 1]

Well I look forward to see if it works, please post some pictures!

[m-wakileh 0]

One issue that must be considered is the rotation of the shaft due to x/y movements of the printhead itself (try clamping the motor end of the flexible shaft and see what happens at the printhead end during x/y movements)... perhaps not an issue using a big gear ratio... with gears there's that weight issue to solve... Perhaps it would be possible using a rotating threaded rod to advance the filament... then extrusion and retraction speeds will be slow...

[Arie_Dub 0]

how about a stiffer 'non' flexible shaft!!! so, reversal/extraction is possible!

[Arie_Dub 0]

A better holding mechanism so it won't slip out of the 'brass'.

[Arie_Dub 0]

How about what I was thinking. ...not only extraction of filament, but extraction of the hot end itself so it won't bump into or get in the way of the newly printed item while printing it. So only the hot-end doing the printing at that moment is 1-2mm lower that the non-printing heads and could be controlled by a 'off-head' stepper motor & flexible shaft & 'on-head' rotating disc/spring mechanism for retraction of hot-end.

[Arie_Dub 0]

Flexible shaft like a Dremel tool, a a stiff cable inside a tube!