Shameless plug: Zesty Nimble extruder now on sale
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@(In)Sanity:
In a perfect world the filament would be the worm gear that threads down the extruder. This would remove bowden backlash and any extra weight from drive systems on the hot end. Spiral filament, hmm.
We just need nano-bots that play tug of war with the filament.. but at a controlled rate..
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@(In)Sanity:
In a perfect world the filament would be the worm gear that threads down the extruder. This would remove bowden backlash and any extra weight from drive systems on the hot end. Spiral filament, hmm.
We just need nano-bots that play tug of war with the filament.. but at a controlled rate..
Haaa, now your talking. I tend to think a bit out of the box, but I think you've got me beat.
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Tractor beam out of the print bed! We could use 2. One to hold the print down and the other to pull the filament through. No more adhesion problems.
LeadingLights is experimenting with a vacuum plate, but that is to hold the print bed surface down. Not the part.Warner Berry tried a screw that forced the filament down. It worked, but was not practical. I forget what the reason was why he stopped experimenting with it, sorry. The worm gear combination is the most reliable and is used in so many ways that it is completely understood.
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Tractor beam out of the print bed! We could use 2. One to hold the print down and the other to pull the filament through. No more adhesion problems.
LeadingLights is experimenting with a vacuum plate, but that is to hold the print bed surface down. Not the part.Warner Berry tried a screw that forced the filament down. It worked, but was not practical. I forget what the reason was why he stopped experimenting with it, sorry. The worm gear combination is the most reliable and is used in so many ways that it is completely understood.
Tractor bean would pull the carriage / effector down as well.. good for layer adhesion I guess
Maybe a tractor beam where attraction rate was inverse to material density..
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I am looking forward to getting my nimble to see how it compares with the other drive-cable extruder which I currently have in terms of retraction. It is not possible to retract as fast with a highly geared extruder, we all know that, it is not in dispute, but here's where I point out that whilst fast retractions are considered desirable, they are not necessary to achieve good filament control.
My current cable operated extruder can retract at 2mm at 14mm/s and get no blobs or stringing with PLA (you don't need 8mm as you are now using a direct extruder not a bowden). Yes there is a tiny pause for a retract/un-retract to take place so in the retraction torture object above you might expect print time to be slightly longer, but this is more than compensated for by having a direct drive, lightweight extruder on the effector or carriage which is almost always going to control filament better than a Bowden extruder. It seems using a smaller motor (you don't need a big motor due to the high gear ratio) and using less motor current enables the motor to reverse direction faster and can speed this up even more.
Brian/Lykle - what is the gear ratio on the Nimble from motor to drive gear?
Did you ever compare the nimble to the flex3drive? How did it work out for you? I read on thingiverse that a stepper amplifier could be used to get past the speed limitations of the high gearing, basically reverse gearing for your stepper using a belt and pulley system
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Hi so far I have not yet got around to installing my nimble, but to be honest it looks like it will work fine at extruding, its quite a simple concept really, long term success and reliability is something only time will tell. My flex3drive has been working for 18 months now, I replaced one minor part, and had a new drive cable but I was asking the cable to deflect a little more than was reasonable and that contributed to its failure, so not the fault of the cable itself.
There is no doubt in my mind as a long term flex3drive user that this concept offers some big advantages, lightweight effector/carriage, small unit, direct drive without the weight etc… but some drawbacks which are things that can be compensated for, such as needing to drive stepper motors at quite high RPM and reverse them again at quite high RPM, so you need fairly low inertia motors (don't try it with big long motors I'm using 34mm nema 17, but 20mm pancake should also be capable), the right motor current which is not always the highest current you can get away with, and the right approach to jerk, accel and max feedrate for the E-motor. (I will leave the two manufacturers of these units to provide the detail on how they each recommend achieving this).
Where perhaps I am finding a limitation on my kossel XL is to go up to really high print speeds forces the motor to try to retract beyond its current capabilities and I get stalling, I could print this fast with titan/pancake/short bowden (flying extruder), but the print quality, and the effect on inertia and tilt was greater than it is now. So I have improved print quality and calibration but am limited to around 100mm/s (which is enough for me). Its possible with a bit more tuning and help from the maker I might overcome this but nothing's perfect.
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Hi so far I have not yet got around to installing my nimble, but to be honest it looks like it will work fine at extruding, its quite a simple concept really, long term success and reliability is something only time will tell. My flex3drive has been working for 18 months now, I replaced one minor part, and had a new drive cable but I was asking the cable to deflect a little more than was reasonable and that contributed to its failure, so not the fault of the cable itself.
There is no doubt in my mind as a long term flex3drive user that this concept offers some big advantages, lightweight effector/carriage, small unit, direct drive without the weight etc… but some drawbacks which are things that can be compensated for, such as needing to drive stepper motors at quite high RPM and reverse them again at quite high RPM, so you need fairly low inertia motors (don't try it with big long motors I'm using 34mm nema 17, but 20mm pancake should also be capable), the right motor current which is not always the highest current you can get away with, and the right approach to jerk, accel and max feedrate for the E-motor. (I will leave the two manufacturers of these units to provide the detail on how they each recommend achieving this).
Where perhaps I am finding a limitation on my kossel XL is to go up to really high print speeds forces the motor to try to retract beyond its current capabilities and I get stalling, I could print this fast with titan/pancake/short bowden (flying extruder), but the print quality, and the effect on inertia and tilt was greater than it is now. So I have improved print quality and calibration but am limited to around 100mm/s (which is enough for me). Its possible with a bit more tuning and help from the maker I might overcome this but nothing's perfect.
In the nimble mods i seen basically a reverse pulley stepper amplifier. Wouldnt this solve the need allowing use of small steppers which will be able to start and stop faster than larger steppers allowing either the nimble or flex3drive to print at higher speeds?
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I don't know but its a reasonable suggestion, although if this was such a problem why is flex3drive 40:1 and nimble 30:1, is it possible to make a worm gear drive at 20:1? if so why haven't they?
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To my understanding the 30 to 40 range reduces the noticed effect of cable delay…. there is sort of a tiff between the two companies on that subject. Flex3drive believes 40 gives better precision while zesty nimble believes the extra is not needed and better speed comes from the 30.... anything less i believe shows too much of the delay effects in the print.
My theory (i am not even qualified but it seems to me) Is that the high gearing at one end minimizes the delay affect but to achieve speed you can reverse the gearing at the other end to minimize the downsides of the necessary high gearing at the other end using a small stepper and low power
basically youre not changing what the high gearing does, you are only lowering the steppers esteps and increasing the ability to spin that high gearing even faster
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Hopefully someone more qualified in this type of thing can say if this is correct or not
