Straighten the Bowden Tube

[mrjohnk 0]

I'm just curious, does it make sense to suspend the feed unit above the printer, perhaps hanging upside down on the wall on a bracket to center it up above the machine, and let the bowden tube be relatively straight verses the high arch. I'm thinking this would reduce the feed friction, help to avoid breaking the feed material, and also reduce forces pushing on the extruder to help it move more freely. Full disclosure: I recently ordered my UM and I'm still awaiting its delivery. I thought this might make sense to do during the assembly process.

Thanks.

John

[fluxline 0]

i've thought of doing the same, one of those things on the list that seem to be minor improvements with lots of work. As a short term thing I did because of a now shortened bowden tube is move it to the center of the machine with a part I printed in soft PLA, not a big difference but helpful. It also has the added benefit of removing the humming noise that reverberates throughout the frame from the motor. I think the 'sitting above' approach might help as you said, just that the envelope of the whole machine is much larger. Not sure of any other issues it might bring.

[owen 18]

Not sure of any other issues it might bring.

An issue I've heard in the one of the forums here is that when the head approaches the center, it is a shorter distance to the extruder drive so the bowden will have to bend in one direction or another. This bending and straightening could cause a push of the filament. I haven't heard of anyone trying it yet though to find out for sure.

[mrjohnk 0]

Ah, good point. Thanks. Perhaps a modified approach, assuming this doesn't work, would be to at least reduce the total angle to a 90 degree bend instead of the full 180. This assumes still putting the extruder drive above the machine.

[greengecko 8]

I thought about that too. And my reasoning why it could be a good idea is that retraction could be a bit better as the retraction takes only in effect with a short delay (because the inner tube diameter is a bit bigger than the filament). I see the point that it need to be bended a bit, but the shorter and more straight the bowder tube is the more responsive should be retraction.

If anyone tries this, please let me know.

[fluxline 0]

good point about the angle, i usually print smallish parts at the moment and usually stick it toward the front to keep away from the bowden bends. i just wish printrun had a way to set the position on the bed at print time rather than going back and generating gcode again, but computer would need to be strong for that.

[phut 0]

Use G92 in the startup code to change the virtual position of the head.

This will cause the print to be offset by the same amount the virtual zero is offset from the real zero.

[snowygrouch 1]

You mean one of these ?

Sorry pics are rubbish, but couldnt upload WMV vid, so had to screenshot the vid...

I reduced the Bowden length by 55%, and its now almost straight, by having a super high tech (rubber bands)

extruder mounting system its can move around alot. Having the extruded fixed in the XY doesnt work well

(my 1st try had the extruder mounted on a vertically sliding rod in linerar bearings, and was rubbish :oops: )

So far it works very well indeed, and when combined with Bertho extruder and fan cooled hot end has

resulted in a 100% mechanically reliable machine. No plugs, no jams, no grinding, no overheating.

Happy to discuss further.

However I did this about 3 weeks after getting the ultimaker, so I do not have any data to back up my

design as being in any way worthwhile....other than that it appeals to me. Of course the standard

position for reel and extruder is FAR neater, and nicer to look at.

Regards

Calum Douglas