Hotend jams - not blocked

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stillcool40
Posts: 33
Joined: Sun Mar 30, 2014 1:59 pm

Re: Hotend jams - not blocked

Post by stillcool40 »

looking at it Im sure any molten pla getting round the tube will immediately cool and harden making its own seal

Dreide
Posts: 176
Joined: Sun Sep 29, 2013 12:32 am
Location: Lausanne, Switzerland

Post by Dreide »

I guess it is preferable to have the joints between aluminum and Teflon where the material is either hot and fluid or where it is cold and hard. Because any material state in between could create congestion at the joint, especially when considering that the critical transition between hot and cold is shifting up and down in the extruder depending on the current temperatures, flow rate, retraction, etc.
Therefore, it makes sense to move the upper end of the Teflon tube further away from the peek piece, that is, further up into the cold end. The downside of this approach is, however, that the Teflon tube also insulates the filament from the cold end aluminum and, thus, receives less cooling. I guess this is bad because it makes the transition from hot to cold longer, something we want to avoid because half-heated material which is already soft enough to be pressed against the tube wall creates probably more friction than completely hot and fluid or completely cold and hard material. The question is how much Teflon with its low friction coefficient makes up for the longer transition zone, and the answer to this question probably depends on filament material being used.
Felix 2.0->3.0dual * Repetier (host+firmware) * KISSlicer Pro, Simplify3D * Cubify Design

Mayhem
Posts: 169
Joined: Tue Jan 08, 2013 4:15 pm
Location: Finland

Post by Mayhem »

Weird that so many people have these jams, my last jam was maybe a year ago.
I have v4 hotend
Felix 2.0----> 3.0
V4 hot end
Simplyfy 3D
Kisslicer
Autodesk fusion 360

Hugues
Posts: 270
Joined: Thu Apr 04, 2013 5:36 pm

Post by Hugues »

stillcool40 wrote:..

if the tube tries to ride up I think it hit the stepper wheel and thats it.

Has now printed two 5 hour jobs faultlessly....
why not,
but you don't want the stepper wheel to grind at your teflon tube and have bits of teflon making their way into the extruder.

And with all due respect, two 5 hours jobs does not qualify yet for a successful claim, although it looks promising i must agree.

Please keep us posted in a month or so about the outcome. Zero jamming is the goal.

thanks
Hugues
Regards from Switzerland

stillcool40
Posts: 33
Joined: Sun Mar 30, 2014 1:59 pm

Post by stillcool40 »

I agree with that.

I suppose the fact that so many folk are having the same or similar problems with a machine which, let's face it, is supposed to be one of the best and certainly one of the more expensive units.

maybe felix should be looking at the solution as part of "Customer care after sales service"

Dreide
Posts: 176
Joined: Sun Sep 29, 2013 12:32 am
Location: Lausanne, Switzerland

Post by Dreide »

stillcool40 wrote:I agree with that.

I suppose the fact that so many folk are having the same or similar problems with a machine which, let's face it, is supposed to be one of the best and certainly one of the more expensive units.

maybe felix should be looking at the solution as part of "Customer care after sales service"
If it was that simple...
First of all, zero jamming is not the only goal in extruder design and it becomes easily just a matter of preference which extruder you consider best. Besides zero jamming, I also want to have the extruder minimize oozing and perform well over a whole range of materials, temperatures, etc. And extruder performance should not depend on production tolerance either.
If so many factors play a role, testing and rating the results becomes very difficult. And people who make a modification, possibly one that cannot be easily reversed, tend to judge the outcome of the modification rather positively: after having put in so much work, it just has to be better.
Felix 2.0->3.0dual * Repetier (host+firmware) * KISSlicer Pro, Simplify3D * Cubify Design

stillcool40
Posts: 33
Joined: Sun Mar 30, 2014 1:59 pm

Post by stillcool40 »

well i have to say, it really is that simple

either your expensive 3d printer will run a job lasting a couple of hours or...
it wont

its a common thing for a manufacturer to issue a product and rely on "client" modifications to sort out problems and design issues

for my part if id wanted that sort of product i would have gone another route rather than here

seaton
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Location: Bunbury, Western Australia
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Post by seaton »

Mayhem wrote:Weird that so many people have these jams, my last jam was maybe a year ago.
I have v4 hotend
Ditto, If anything I know that if I retract too far I'll get a jam, so my retraction is set to about 1-2 mm depending on the material.

I also did the mod to change cold end fan to 12V and have wiper on filament entering the hot end to get rid of any dust/dirt.

Also the place I did get the most Jams was when I changing filament, I know now to have a high speed Retraction rate and also physically pull on the filament at the same time so it exits nice and fast


Stephen..
Stephen...

Felix 2.0 -> Felix 3.0 dual
Simplify3D Slicer, Kisslicer
Have you added your Felix to the Map? http://goo.gl/maps/HajnZ

http://blog.strobotics.com.au

Dreide
Posts: 176
Joined: Sun Sep 29, 2013 12:32 am
Location: Lausanne, Switzerland

Post by Dreide »

Similar here. I don't experience jams with PLA, not during the prints anyway. To change the filament, I just pull it out by hand, fast and at a rather low hot end temperature (usually while the extruder is cooling off already). And I try to not forget using the filament wiper. With the Felix 2.0 I used a small shroud for the cold end fan but left it at 5V.
Regarding retraction, I don't use more than 1mm for PLA, considering that PLA is rather incompressible and that 1mm at the feeder translates, theoretically, to 25mm at the nozzle.
Felix 2.0->3.0dual * Repetier (host+firmware) * KISSlicer Pro, Simplify3D * Cubify Design

Zennix
Posts: 5
Joined: Wed Jan 08, 2014 11:12 am

Post by Zennix »

Hi,
I had a similar problem printing with two extruders. First thing i changed was the mod from saamec. My right extruder works fine. Getting no jams anymore. But with the same modification at the second extruder didn´t change anything. After some retrations it stucks.
Then I machined about 20 Teflon spacers with different combinations of hole diameters and thickness.
After hours I gave up. i saw that the 6mm drill in the PEEK is the problem. The hotend and the coldend has 6mm too. So i can screw them into the PEEK and squeeze the Teflon.
My solution:
I drilled the coldend completely through with 4mm. Drilled the PEEK with 5mm. So the cold- and hotend has a defined stop and a distance of 2,5mm. Machined a Teflon tube like saamec did, but with 4mm tube and 5mm spacer.
Now after hours of printing I´m sure to post this as my working solutions.
Thanks to saamec for the idea.

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