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Springless Extruder design

Posted by sarf2k4 
Springless Extruder design
May 11, 2015 02:13AM
Hi, I am wondering about a springless extruder design found on most 'some proprietary' 3d printers such as zortrax and up or other brand that didn't use spring to grip the filament.

Is there any working design for this idea in reprap?

Do correct me if this has been posted before and I'm sorry for double post if there is any
Re: Springless Extruder design
May 11, 2015 02:38AM
Using a spring basically means that your extruder can apply the same force to grip the filament regardless of small variations in filament diameter (which can vary by +/- 5% or more).
Re: Springless Extruder design
May 11, 2015 02:41AM
Some sort of spring/tolerance is good IMO the first 3D printer I bought has static direct drive for filament and even their $100 per .75kg spool filament would grind/fail to feed at times.
Re: Springless Extruder design
May 11, 2015 02:45AM
I made a design where instead of a metallic spring the extruder was made of Nylon and used it's flexibility for tension. It works, but it has no real advantage over a spring based design. Why do you want a springless extruder, what do you expect it to do better?


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: Springless Extruder design
May 11, 2015 05:08AM
Quote
sarf2k4
Hi, I am wondering about a springless extruder design found on most 'some proprietary' 3d printers such as zortrax and up or other brand that didn't use spring to grip the filament.

Is there any working design for this idea in reprap?

Do correct me if this has been posted before and I'm sorry for double post if there is any

yes there is a extruder available but there is some explanation which is usefull :

what you'll find with those printers and printer companies is that the extruders they have made are built to really only handle the filament the company produced , usually it's overpriced and not actually the size you think it is.

The up! is one of those classic examples where the spring less extruder and hotend is designed to handle the 1.73mm filament they sell, they way they try to lock you into their filament is through two mechanisms:

1 - the hotend bore is only 1.8mm in diameter ( most reprap hotends are 2mm ) so any filament that ventures into actually being 1.75mm and slightly bigger by even 0.02mm can physically have trouble going into the hotend
2 - the drive gear and idler bearing is a fixed distance set perfectly for the 1.73mm filament, if your filament gets even very slightly smaller eg 1.70 the teeth in the drive gear won't grip it properly and will strip the filament fairly quickly,

a lot of these companies that try to lock you into proprietary filament do pretty much the same thing.

however the devil is in the design and the filament drive you use and the kind of teeth it has, i have produced 2 spring-less designs for two different sizes of filament drive and have an adjustable idler:

jgr extruder for mk7 sizes

jgr extruder for smaller diameter 7mm hobbs


the main reason i get away with no springs is because of the filament drives i use which are made from brass and have really nicely cut deep teeth which allow for quite a bit of tolerance in filament diameter.
i highly recommend the filament drives from reprap discount over the crappy knurled mk7/mk8 stainless steel ones as the teeth on the mk7/mk8 tend to be rounded and not really teeth.




-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-



Re: Springless Extruder design
May 11, 2015 05:17AM
Quote
Srek
I made a design where instead of a metallic spring the extruder was made of Nylon and used it's flexibility for tension. It works, but it has no real advantage over a spring based design. Why do you want a springless extruder, what do you expect it to do better?
I wonder if it makes it better in terms of grip, few days ago when I tried to print something, during the process of the border, the plastic didn't get extruded, more like I often give the plastic a little helping push to make it extruded, I suspect my gear grinding the filament, I'm using mk8 extruder design from geeetech. I already calibrated it and set up 1.75 with 115% on cura setting (to have an even spread on the layer)

I also wanted to reduce some sort of sourcing those vitamins because my area here didn't sell any 3d printer parts, more over, they don't know the specific part's official name
Re: Springless Extruder design
May 11, 2015 05:18AM
Quote
thejollygrimreaper
Quote
sarf2k4
Hi, I am wondering about a springless extruder design found on most 'some proprietary' 3d printers such as zortrax and up or other brand that didn't use spring to grip the filament.

Is there any working design for this idea in reprap?

Do correct me if this has been posted before and I'm sorry for double post if there is any

yes there is a extruder available but there is some explanation which is usefull :

what you'll find with those printers and printer companies is that the extruders they have made are built to really only handle the filament the company produced , usually it's overpriced and not actually the size you think it is.

The up! is one of those classic examples where the spring less extruder and hotend is designed to handle the 1.73mm filament they sell, they way they try to lock you into their filament is through two mechanisms:

1 - the hotend bore is only 1.8mm in diameter ( most reprap hotends are 2mm ) so any filament that ventures into actually being 1.75mm and slightly bigger by even 0.02mm can physically have trouble going into the hotend
2 - the drive gear and idler bearing is a fixed distance set perfectly for the 1.73mm filament, if your filament gets even very slightly smaller eg 1.70 the teeth in the drive gear won't grip it properly and will strip the filament fairly quickly,

a lot of these companies that try to lock you into proprietary filament do pretty much the same thing.

however the devil is in the design and the filament drive you use and the kind of teeth it has, i have produced 2 spring-less designs for two different sizes of filament drive and have an adjustable idler:

jgr extruder for mk7 sizes

jgr extruder for smaller diameter 7mm hobbs


the main reason i get away with no springs is because of the filament drives i use which are made from brass and have really nicely cut deep teeth which allow for quite a bit of tolerance in filament diameter.
i highly recommend the filament drives from reprap discount over the crappy knurled mk7/mk8 stainless steel ones as the teeth on the mk7/mk8 tend to be rounded and not really teeth.

Ahh.... thank you for the explanation, but i still wonder if the design can be used for all kind of filaments e.g 1.75 types?
Re: Springless Extruder design
May 11, 2015 05:28AM
Quote
sarf2k4
Quote
thejollygrimreaper
Quote
sarf2k4
Hi, I am wondering about a springless extruder design found on most 'some proprietary' 3d printers such as zortrax and up or other brand that didn't use spring to grip the filament.

Is there any working design for this idea in reprap?

Do correct me if this has been posted before and I'm sorry for double post if there is any

yes there is a extruder available but there is some explanation which is usefull :

what you'll find with those printers and printer companies is that the extruders they have made are built to really only handle the filament the company produced , usually it's overpriced and not actually the size you think it is.

The up! is one of those classic examples where the spring less extruder and hotend is designed to handle the 1.73mm filament they sell, they way they try to lock you into their filament is through two mechanisms:

1 - the hotend bore is only 1.8mm in diameter ( most reprap hotends are 2mm ) so any filament that ventures into actually being 1.75mm and slightly bigger by even 0.02mm can physically have trouble going into the hotend
2 - the drive gear and idler bearing is a fixed distance set perfectly for the 1.73mm filament, if your filament gets even very slightly smaller eg 1.70 the teeth in the drive gear won't grip it properly and will strip the filament fairly quickly,

a lot of these companies that try to lock you into proprietary filament do pretty much the same thing.

however the devil is in the design and the filament drive you use and the kind of teeth it has, i have produced 2 spring-less designs for two different sizes of filament drive and have an adjustable idler:

jgr extruder for mk7 sizes

jgr extruder for smaller diameter 7mm hobbs


the main reason i get away with no springs is because of the filament drives i use which are made from brass and have really nicely cut deep teeth which allow for quite a bit of tolerance in filament diameter.
i highly recommend the filament drives from reprap discount over the crappy knurled mk7/mk8 stainless steel ones as the teeth on the mk7/mk8 tend to be rounded and not really teeth.

Ahh.... thank you for the explanation, but i still wonder if the design can be used for all kind of filaments e.g 1.75 types?

they are mainly for 1.75mm and can handle fairly wide tollerances, for 3mm you would need a geared stepper motor and there are other designs on thinigverse specifically for those as well




-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-



Re: Springless Extruder design
May 11, 2015 07:44AM
And now for something completely different- a work in progress- see: [www.thingiverse.com]

I haven't worked on it for a while- it works great driving filament forward, has problems when retracting (due to speed of retraction compared to forward feed, I think).

No gears, but very high downward force because the threads are effectively a gear.

Edited 1 time(s). Last edit at 05/11/2015 07:45AM by the_digital_dentist.
Re: Springless Extruder design
May 11, 2015 07:52AM
Quote
thejollygrimreaper
Quote
sarf2k4
Quote
thejollygrimreaper
Quote
sarf2k4
Hi, I am wondering about a springless extruder design found on most 'some proprietary' 3d printers such as zortrax and up or other brand that didn't use spring to grip the filament.

Is there any working design for this idea in reprap?

Do correct me if this has been posted before and I'm sorry for double post if there is any

yes there is a extruder available but there is some explanation which is usefull :

what you'll find with those printers and printer companies is that the extruders they have made are built to really only handle the filament the company produced , usually it's overpriced and not actually the size you think it is.

The up! is one of those classic examples where the spring less extruder and hotend is designed to handle the 1.73mm filament they sell, they way they try to lock you into their filament is through two mechanisms:

1 - the hotend bore is only 1.8mm in diameter ( most reprap hotends are 2mm ) so any filament that ventures into actually being 1.75mm and slightly bigger by even 0.02mm can physically have trouble going into the hotend
2 - the drive gear and idler bearing is a fixed distance set perfectly for the 1.73mm filament, if your filament gets even very slightly smaller eg 1.70 the teeth in the drive gear won't grip it properly and will strip the filament fairly quickly,

a lot of these companies that try to lock you into proprietary filament do pretty much the same thing.

however the devil is in the design and the filament drive you use and the kind of teeth it has, i have produced 2 spring-less designs for two different sizes of filament drive and have an adjustable idler:

jgr extruder for mk7 sizes

jgr extruder for smaller diameter 7mm hobbs


the main reason i get away with no springs is because of the filament drives i use which are made from brass and have really nicely cut deep teeth which allow for quite a bit of tolerance in filament diameter.
i highly recommend the filament drives from reprap discount over the crappy knurled mk7/mk8 stainless steel ones as the teeth on the mk7/mk8 tend to be rounded and not really teeth.

Ahh.... thank you for the explanation, but i still wonder if the design can be used for all kind of filaments e.g 1.75 types?

they are mainly for 1.75mm and can handle fairly wide tollerances, for 3mm you would need a geared stepper motor and there are other designs on thinigverse specifically for those as well

So this is your design right, can be used on any hot ends? because I am planning to use it on my e3d v6 that I ordered, any suggestions?
Re: Springless Extruder design
May 11, 2015 07:54AM
Quote
the_digital_dentist
And now for something completely different- a work in progress- see: [www.thingiverse.com]

I haven't worked on it for a while- it works great driving filament forward, has problems when retracting (due to speed of retraction compared to forward feed, I think).

No gears, but very high downward force because the threads are effectively a gear.
I read about this design probably 1-3 months ago, I heard this was an early design used by early reprap machines (correct me if I'm wrong here). But getting the hollow threaded rod would proven to be hard as if getting hobbed bolt or aluminum profiles
Re: Springless Extruder design
May 11, 2015 08:36AM
If it comes down to sourcing a single ridgid spring or not i would say go for the spring design, it is not realy that hard to get a spring.
I hear the argument about higher force with a springless design and i went at that a couple of years ago with a slightly modified wade. While it did work rather nicely it held no real advantage. To this day i use a simple version of that where only a few mm of elastic double sided tape, the rubber kind, not the foam ones, are used to push the idler on the filament. That is enough to make it easy to change the filament and to compensate for the few 1/10 mm of diameter variation.
However, what i found is that the idea of the huge pushing force usually comes up because of crappy hotends that need way to much force to begin with. Instead of following the hughe force route i designed a new hotend that needs a lot less force, just like basically every modern hotend these days.
A slightly higher force might be needed for long bowden setups, but even then springless designs are excessive.
I used my latest extruder in this video [www.youtube.com] it makes use of the MK7 drives from RRD mentioned before, which i also find the best currently available.
The extruder is based on a normal NEMA 14 Motor and does not require gearing, it still is powerfull enough for high speed extrusion.

In short, don't try to increase the power, reduce the resitance.


[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]
Re: Springless Extruder design
May 11, 2015 08:46AM
Quote
sarf2k4
Quote
thejollygrimreaper
Quote
sarf2k4
Quote
thejollygrimreaper
Quote
sarf2k4
Hi, I am wondering about a springless extruder design found on most 'some proprietary' 3d printers such as zortrax and up or other brand that didn't use spring to grip the filament.

Is there any working design for this idea in reprap?

Do correct me if this has been posted before and I'm sorry for double post if there is any

yes there is a extruder available but there is some explanation which is usefull :

what you'll find with those printers and printer companies is that the extruders they have made are built to really only handle the filament the company produced , usually it's overpriced and not actually the size you think it is.

The up! is one of those classic examples where the spring less extruder and hotend is designed to handle the 1.73mm filament they sell, they way they try to lock you into their filament is through two mechanisms:

1 - the hotend bore is only 1.8mm in diameter ( most reprap hotends are 2mm ) so any filament that ventures into actually being 1.75mm and slightly bigger by even 0.02mm can physically have trouble going into the hotend
2 - the drive gear and idler bearing is a fixed distance set perfectly for the 1.73mm filament, if your filament gets even very slightly smaller eg 1.70 the teeth in the drive gear won't grip it properly and will strip the filament fairly quickly,

a lot of these companies that try to lock you into proprietary filament do pretty much the same thing.

however the devil is in the design and the filament drive you use and the kind of teeth it has, i have produced 2 spring-less designs for two different sizes of filament drive and have an adjustable idler:

jgr extruder for mk7 sizes

jgr extruder for smaller diameter 7mm hobbs


the main reason i get away with no springs is because of the filament drives i use which are made from brass and have really nicely cut deep teeth which allow for quite a bit of tolerance in filament diameter.
i highly recommend the filament drives from reprap discount over the crappy knurled mk7/mk8 stainless steel ones as the teeth on the mk7/mk8 tend to be rounded and not really teeth.

Ahh.... thank you for the explanation, but i still wonder if the design can be used for all kind of filaments e.g 1.75 types?

they are mainly for 1.75mm and can handle fairly wide tollerances, for 3mm you would need a geared stepper motor and there are other designs on thinigverse specifically for those as well

So this is your design right, can be used on any hot ends? because I am planning to use it on my e3d v6 that I ordered, any suggestions?

yes my design, the groove is based around my hotend and the jhead which have identical grooves, the e3d groove should fit as well at least at the top, the sources for the extruder is up on thingiverse and it shouldn't be too hard to modify to fit the e3d as well




-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-



Re: Springless Extruder design
May 11, 2015 09:01AM
I'm using some 3mm ID high temp automotive silicone tubing instead of springs on my extruder and heatbed. Seems to work well.
Re: Springless Extruder design
May 11, 2015 10:12AM
Quote
sarf2k4
I read about this design probably 1-3 months ago, I heard this was an early design used by early reprap machines (correct me if I'm wrong here). But getting the hollow threaded rod would proven to be hard as if getting hobbed bolt or aluminum profiles

As far as I know, it is my original design. Hollow threaded rod is not needed, though it could be used. I just used two nuts, one left hand threaded and one right hand threaded. Hollow threaded rod isn't difficult- just drill a solid rod and run a tap through it.

I have some ideas to fix the retraction problem and may revisit the design soon.
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