Dual hobbed extruder December 08, 2018 06:58AM |
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Re: Dual drive extruder December 08, 2018 07:26AM |
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Re: Dual drive extruder December 08, 2018 11:46AM |
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Re: Dual drive extruder December 08, 2018 12:51PM |
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Re: Dual drive extruder December 08, 2018 09:01PM |
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Re: Dual drive extruder December 09, 2018 02:31AM |
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Re: Dual hobbed extruder December 09, 2018 03:10AM |
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Re: Dual hobbed extruder December 09, 2018 03:17AM |
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Re: Dual drive extruder December 09, 2018 03:44AM |
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Quote
Srek
For me a reason to not do it is that it is unnecessary. I have thought about filament transportation with multiple points of contact, but in the end they did not offer any advantage. A well designed classic direct drive will develop enough force for well over 100mm/s. Another issue is size, such a setup will be larger than a single point of contact drive.
Re: Dual drive extruder December 09, 2018 06:36AM |
Registered: 7 years ago Posts: 1,007 |
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Diggrr
..it was the only way I could get TMC drivers to pull a 4 Kilo roll of PLA..now I just like it, even with new drivers.
Dual hobbed MK7's made for 1.75mm filament only.
Re: Dual hobbed extruder December 09, 2018 08:35AM |
Registered: 6 years ago Posts: 26 |
Re: Dual drive extruder December 09, 2018 01:58PM |
Registered: 7 years ago Posts: 93 |
Quote
MKSA
What kind of hotend/filament (1.75mm) requires that much force ?
Anyway, the key factor is the hobbed gear/idler. With a good one, it is possible to pull 40N using a geared Nema17 42mm. To push is an other story. You better have a well guided and short path between extruder and hotend.
The MK7 hobbed gears quality can be shitty. So to put two bad extruders in series is a complex, heavy, costly solution.
The Bondtech is based on a good design used for more than a century in the steel industry notably. You get the extra force and in addition it lessens the damage to the filament, comes handy when there is a lot of retraction.
Re: Dual drive extruder December 09, 2018 02:39PM |
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Re: Dual hobbed extruder December 09, 2018 02:48PM |
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Re: Dual drive extruder December 09, 2018 03:00PM |
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Re: Dual hobbed extruder December 09, 2018 03:20PM |
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Re: Dual hobbed extruder December 09, 2018 03:30PM |
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Re: Dual hobbed extruder December 09, 2018 03:34PM |
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Re: Dual hobbed extruder December 09, 2018 03:52PM |
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Re: Dual hobbed extruder December 09, 2018 07:01PM |
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Re: Dual hobbed extruder December 09, 2018 08:56PM |
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Re: Dual hobbed extruder December 09, 2018 09:36PM |
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Re: Dual drive extruder December 10, 2018 04:48AM |
Registered: 8 years ago Posts: 622 |
Quote
dc42
Quote
Srek
For me a reason to not do it is that it is unnecessary. I have thought about filament transportation with multiple points of contact, but in the end they did not offer any advantage. A well designed classic direct drive will develop enough force for well over 100mm/s. Another issue is size, such a setup will be larger than a single point of contact drive.
You might find [somei3deas.wordpress.com] interesting. Summary: in the particular case of using a mixing hot end, where the same piece of filament may get moved back and forth many times, the Bondtech (dual drive) extruder performed much better than the Titan (single drive) extruder. This doesn't prove that the dual vs. single aspect is solely responsible for the difference (the shape of the teeth on the hobbed shaft may have been different too), but it seems likely that it was the major factor.
Re: Dual hobbed extruder December 10, 2018 05:24AM |
Registered: 7 years ago Posts: 93 |
Re: Dual hobbed extruder December 10, 2018 10:31AM |
Registered: 6 years ago Posts: 26 |
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MKSA
Quote
herve robert
triple hobbed:
[attachment 108576 frame00015.png]
Just wondering why the "idlers" are set that way, on the same articulated arm ?
Re: Dual hobbed extruder December 10, 2018 11:24AM |
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Re: Dual hobbed extruder December 10, 2018 12:56PM |
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Re: Dual hobbed extruder December 10, 2018 02:50PM |
Registered: 6 years ago Posts: 26 |
Re: Dual drive extruder December 10, 2018 11:10PM |
Registered: 9 years ago Posts: 5,232 |
Quote
Deckingman
On my machine, I needed 5mm of retraction on the Titans but only need 3.5mm on the BMGs. I suspect this is due to the spring tensioner causing some wear of the filament during the retract so it needs higher un-retract due to the reduced filament diameter. I didn't get around to playing with different retract / un-retract distances but that may have been a cure.
Re: Dual drive extruder December 11, 2018 06:02AM |
Registered: 7 years ago Posts: 1,007 |
Quote
o_lampe
Quote
Deckingman
On my machine, I needed 5mm of retraction on the Titans but only need 3.5mm on the BMGs. I suspect this is due to the spring tensioner causing some wear of the filament during the retract so it needs higher un-retract due to the reduced filament diameter. I didn't get around to playing with different retract / un-retract distances but that may have been a cure.
I believe the Titan deforms filament more and therefor needs to push harder to overcome Bowden tube friction. That also has an effect on retraction length IMHO.
There's simply more zigzag-filament in the same Bowden length.