Zero Gravity Extruder - V1.0

[neotko 1,417]

ZGE Authors

- ZGE Idea and design & development by Charly - @Gudo

- Crazy Ideas and ZGE Logo by Sebas - @Neotko

 

General FAQ

Can I use other bearings?

NO. There's much math and simulations and beta testing on all the parts, if you fell like changing something just to save a buck, then this isn't the extruder for you, sorry!

Can I use a shorter square rod?

NO. I did bang Gudo with this many times, he is just so patient and explained me over and over how and why it can't. Basically that's the correct size for a umo/um2. Can you use 400 instead of 390mm, yea you can. But 390mm is the perfect length so it doesn't pick an eye while moving or hits you, and also is the length that allows the slider part to have always full contact with the square rod. So, like I said before, file the tip, because metal can hurt. (It never ever happened to me and I do look at the printer like a mad men when printing to debug stuff).

Could I move the holder to the other corner?

Yes, print it mirroed (that's something I did ask at the beginning, but after using it on the Left side I would not change it, it just make's sense... Hard to explain..

Can I use a cheaper drivegear?

NO (well you actually could if you redesign most of the stuff, but if you just want to extrude without quality you can do it by hand )

Can I just print it on ABS or PLA, or China cheap PLA?

NO. ABS for example size changes a lot, it can't get as much flex torsion without deforming as platec/greentec. Ofc if you thing you can, just do it, but don't come here asking why it fails Also the material used must be as precise as possible, that something that only good brands give. You wan't to have as many things under- control as possible when printing printing this with a bowden since the tolerances are quite hard. Short answer, we recommend Greentec / Platec for hightemp and strength.

- Could I avoid to print the Flexible material parts?

Oh yes, I forgot, there are parts that actually need to be printed on flexible materials like ninjaflex, recreus and a semiflex material. WHY? Just because (will explain all this on the video/tutorial). Most of them you can actually print them after installing the system, but also, well you can print them one by one very slow until you get the zge working

- Why the motor holder moves a bit when printing?

Because the system compensates the extrusion forces to avoid as much motion transmission to the printhead. Also, better the motor holder than the printhead, right?

- I have a dual printer, I wan't to use this!?

That's actually doable, Gudo even made a design that could work on a UM3. But... More or that someday. Basically we don't want to just make stuff that could work, but stuff that actually put something interesting on the table. There are many factors beyond making the extruder work on a um3 than just making it. Gudo actually I think did cover all of them, but then there's the part of the firmware. The UM3 firmware need's quite a lot knowhow to actually change parameters like Extrusion retraction while changing tools, prime amount, retraction amount, esteps, etc etc etc. So change this parameters on a um3 the user would need to know much knowhow to do stuff on linux without bricking the machine (editing stuff is really easy in the end but is a giant leap for most users). So for now we choose not to, but is there, if UM or maybe a modder makes a easy way to access the Machine Json files and edit them, then we might release it. Just because, it doesn't make sense to release stuff just for releasing stuff. Also, there's a big problemo for flexibles on um3, and that's the gap of air on top of the cores while they rest on the printhead.. So, could it work? Sure, but would it work everytime? That's the question... So, short answer, not yet.

 

More FAQ And important points about ZGE

Why we made it

Gudo and Neotko are moving forward this extruder because we are always pursuing quality, speed and precision. Bowden is a lightweight solution that creates quite a number of handicaps, like for example hysteresis (filament compression due pressure) making it impossible to actually control the extrusion. With ZGE Direct Drive this is now posible, for 1.75mm filaments and 2.85mm, without any compromise on Extrusion horse power.

Why don’t we sell it atm

Gudo and I (Neotko) have other interest than just selling upgrades. Is a nice idea, but we been crunching numbers and isn’t something we would love to be doing on the short time. I have a business and is starting to work and it demands my full time (except weekends where I try to keep improving every bit of the printer). Also isn’t that easy, to make a comercial version of the ZGE would requiere most probably a mold, and that’s freaking expensive, delivery, stock, gudo making sliders, me printing all the other parts, and that could be a nice dream but we don’t have a 100 printers farm to do it right, and sincerely is great to not need to defend something that you want to 'sell' it keeps the mind objective and fresh to new ideas.

So we have choose the YDIY (You Do It Yourself) path. I will make videos of how to print and assemble the key parts that requiere extreme love and care to do them right. Gudo I think can provide for some individuals the key parts, but don’t overwhelm him, if you don’t get one, you need to DIY.

The good

It freaking works, it extrudes beautifully, it keeps working and working and delivering repetition and amazing precision even with flexibles. Bondtech dualdrive has a lot on that, it could be done with a lesser quality extruder gear, but it would give troubles, bondtech does work and work and work. It grinds a bit, NO, it pushes the filament over and over (and we get Zero commission from bondtech on this!). The system moves a 390mm square shaft of 4mm square. This was the first challenge. I have been testing a 3x3 thinner rod and it works beautifully, but it will only be of use for 1.75mm guys.

1.75mm requieres less heat to extrude, less pressure, but also it has a drawback, it need’s more rotation on the drive gear, this means more stuff moving. That’s why a 3x3mm is better, because it delivers less noise to the weak um head (more on that latter)

2.85mm requieres more heat to extrude, more pressure but also has the advantage of less rotation on the drivegear, this means less noise translated to the printhead, but more force. So for this the best is a 4x4 square shaft.

The Bad

The punny UM2 hotend. We are using a hotend designed specifically for bowden, and bowden has one advantage, remove pressure and movement on the printhead, that’s why any single force done on the printhead (even a wooble bowden shacking) can add noise to the prints. And for the ZGE this means that every rotation on the drivegear can, since the head has very easy to bend and flexible shafts, translate tinny bits on Z noise. Does this Z noise is perceptible? Well, is hard to see, but is there, most users that don’t have a perfect Z might not notice this, but since I’m a crazy guy I did noticed it. The first version was much more dependent of a perfect square shaft. Gudo made an amazing improvement to this problem developing a printable UJoint system that allows to remove the imperfections of a inexpensive rod (more on this later). And just yesterday, I got an idea (star medal for me on this since I’m really proud) we changed a part to be printed on flexible material removing almost 50% of the noise and making the prints look even better.

So... Does it print better than a Bowden? It freaking does. Does it has a bit more of noise on Z? Yes it does, sorry, that’s how things are. UM2 head, even the 8mm shafts can ‘bend’ and they keep wobbling making them very susceptible to Pressure from the drive-gears to the head. Every retract/extrude is a sudden move, that translates this sudden moves to the printhead. But with this last update the problem is hard to see, and most of normal users won’t ever see it.

The Ugly

To print a ZGE you need aprox 5h for the most delicate parts (slider+driveshaft) and they will need some post-processing. Add one hour of assembly for this part, that must be done with love and not by brute force. Also you do need a hightemperature material, like greentec, platec. Just because this part get’s heat from the bed, so if you print at 60, the air will get there to 35C, and that + extrusion forces = bends.

The Extruder head also should be greentec, platec. Is a very amazing material (we also get zero commission on this), but need’s hairspray on the bed and brims, and cleaning. I made a good article about how to add custom brims to the support, read it, read it again, and use it. You need all the parts to be printed perfect. More than 50mm/s can ruin the print and will add time to manual cleaning, that is less reliable than a 3dprinter.

You will need to calibrate your printer to the 0.02-0.03 closeness to the measures we will show as base. Just like Gudo and I did, we used one of the parts, print it and with a digital caliper of at least 2 decimal points, I did print the object 3 times, with different Horizontal Expansion values of -0.02 -0.03 -0.05. For me the winner was the 0.02. So as you can guess, the difference from printing it right or wrong is very very small. You need to keep that in mind for the main part of the ZGE, since is the most delicate part. First time I print one I did it horrible, and after printing 20-23 I thing I have enough practice to make a perfect ZGE slider+shaft.

The rest of the parts, need screws, nothing hard to find. There are two types of heads, one is more compact but need’s some special small 4mm mini shafts. The other, is more complex to assemble and is based on my Neotko-FatIRobertI extruder. Gudo also added a tension selector (very cool) to have 3 basic positions easy interchangeable. But is much complex to print. Also is taller... That... Well, shorter means less vibrations, taller more vibrations... Yea there are many many factors that we have take into account before posting this.

We still need to talk Gudo and I of what basic version we release. Most probably the slider, they key part, won’t have a step file release, but the others might, or not. The important is that all the parts will be easy to print, except the slider (the slider, as I said over and over here must be printed with love and finished more or less by hand).

The Main key parts you will need to get to DIY.

First of all, the square rod of 390mm, there are shops on ebay that cut on demand, but try to be ware that the tip you need to soft it (file it) for safety! You don’t want to loose an eye because you didn’t hear us out right?

For precision square shafts (they call them Key Steel or Parallel Key) the max length we where able to find is 350mm (on misumi) so that means that it would not work. It need’s to be a minimum of 390mm. Gudo might be able to provide this to some users, but again, ask once, if he doesn’t answer he is busy doing something more interesting, don’t hammer it. And you will need to pay for it, you know, square shafts don’t grow on trees.

A shorter smaller screw. You know the four screws that hold your hotend? Well, one must be shorter, like 4mm taller, you can ‘sew’ it yourself indeed. Again, not easy to find. Gudo is amazing and he made me a few with the first kits he made for me.

I have a shop, I want to sell it!

Contact Gudo for this, you two might get along and do some business. I personally would love to see this extruder on every printer out there. But mind one thing, no shortcuts, no china quality. If you thing you are decent, come talk with Gudo.

I want it for my printer!

Our dream is to have this on as many printers as possible, a Bowden-free world. If you are a 3d printer maker contact us and we will study making a version of our ZGE for your machine. But remember this is Open Source, so we will focus on Open Source machines like UM, BCN, and probably others.

If we don’t support your printer, give us time, we are just two guys that love 3d printing and making our printers as precise as possible. Contact your printer company, if they give us access to your files we might do it! And ofc if you have a Solid Robust No Woobly printer, we are interested But ofc, Maybe Gudo just make's a better printer out of this UM.... But that's a history for other day

List of things to do:

- An assembly manual. Atm users that found IRobertI Feeder hard to assemble, should stay away from this, since this is probably 10x times harder and requieres much finesse to assemble and to print it. (sorry is just how it is)

- Video of the ZGE SliderUjoint system. I need time to do it, but is on my todobedobedo list.

 

Important before Downloading it

- The zip has STEP and STL files

- The STL files have TEXT that indicates the level of quality to print it, DO READ IT.

 

Quality Levels are

MIDQ - Medium Quality 50mm/s tops and 0.2mm layer is ok

HIQ - High Quality 40-50mm/s is ok but no more than 0.1-0.15mm layer height

HIQSLOW - Keycomponent 30-40mm/s max and 0.1-0.12mm layer height

TEMP - Version printable in PLA or any material at hand that will need to be replaced with a FLEX later

FLEX - Flexible material part. Print it after having the ZGE working (since is much easier). Recommeded Flexible material like NinjaFlex or Filaflex. Basically Very flexible.

Did you read everything?, are you sure? Ok, you can download

Zero Gravity Extruder at Youmagine by Gudo & Neotko

Much still to write about how to print this, assemble and use it correctly.

 

For now Check this OLD VIDEOS (REMEMBER THEY ARE OLD and they show OLD version assembly, but should give some hits to the pro users)

 

Example of BAD SliderUjoint print

 

Old post with a few print test videos and etc etc

https://ultimaker.com/en/community/35608-zero-gravity-direct-drive-extruder

Edited April 30, 2017 by Guest

[neotko 1,417]

Added a fast Assembly manual for the ZGE Short version. Even if you plan to use the tall version, play attention to the Bondtech Screw force and the 5mm drill bit cleaning. The important steps are applicable to both.

https://www.youmagine.com/documents/57843/download

[neotko 1,417]

Added Beta files to Youmagine in Zip files apart of the big one

Ultimaker 2+ Feeder Adapter to ZGE.

So you guys don't need to buy a Bondtech if you don't want to.

Z Vibration Dampener

Reduce noise on the print from sudden moves that can affect the print quality.

[chrisw 70]

I'm definitely interested in this setup, mainly for eliminating the in-tube binding that occurs when my UM2s are printing near the back wall. The sharp bend of the Bowden tube seems to cause too much friction. I still get functional prints, but there's uneven extrusion on the back wall area.

Until recently this never mattered to me because all my parts were relatively small and I could keep them more toward the front. But then I bought a couple Matchless kits and realized I could print much bigger things in reasonable time when using a 1.5 nozzle. Now my prints occupy near the max build space sometimes.

The ZGE setup looks like it could provide a more even flow. The only reason I'm not jumping into printing the ZGE parts is the size of that conversion project. It's a lot of parts and I don't have time to track down & order the hardware right now. If you ever put together a parts kit, I'll buy a couple

[neotko 1,417]

If you ever put together a parts kit, I'll buy a couple

Thanks! Indeed the DD removes the filament curvature since the extrusion occurs on top of the head. Also you use an extra 50-60cm of filament.

Indeed is a lot of parts to print, the assembly isn't easy since (specially two parts) need to be printed with love and assembled with care (not too much but enough). We would love to sell kits but the problem is that, how much could be 'ok' for people to pay for the work it takes? It's easily a 8-12h print with a few hours of assembly, cleaning, etc etc. That's why we don't sell it atm. We would love to be able to sell it, maybe in the future X company might get interest on selling kits? I suppose is a matter of 'if the users like it'.

One thing for sure. If you print the parts, one a day, with high quality, is quite easy to assemble, but takes time...

[chrisw 70]

I wouldn't mind making the printable parts myself, but the hardware (screws, nuts, bolts, square rod, bearings, etc) are the types of things that I expect could be difficult to get just the right items. If those metal pieces all came in a bag I'd buy a couple of those bags. There are enough variations in metal parts that I'd rather get ones that you know fit your design well.

[geert_2 558]

I like this direct drive concept with the motor separated from the drive gear and print head. This removes a lot of weight and inertia from the system. This should be the direction to go for the factory UM2++ or UM2+++, I think.

Have you tried magnesium as the drive shaft? This would weight less, but I do not know if it is strong enough, and if it is safe enough (as magnesium can catch violent fire when hot)?

Another question: what is the purpose of the long slider with coupler, connected to the print head? Wouldn't it be possible to connect the square shaft directly to the extruder gear (with only a small conversion piece to convert it from square to the round hole of the drive gear)? But without this long block? This would save a lot of weight, and complexity, I think? I guess you will have a good reason for doing it the way it is now; it is just that I don't see it.

[fergazz 60]

I wouldn't mind making the printable parts myself, but the hardware (screws, nuts, bolts, square rod, bearings, etc) are the types of things that I expect could be difficult to get just the right items.  If those metal pieces all came in a bag I'd buy a couple of those bags.  There are enough variations in metal parts that I'd rather get ones that you know fit your design well.

I thought exactly as @chrisw and I'm still using just one printer by now, is too risky

I will keep my eyes on it, looks awesome the idea to have a "close to zero" weight on the printhead

[lars86 42]

Awesome work guys!

 

I am currently hanging my extruder drive (my own design), over the printer with bungee cord, in order to run a shorter (~12") straight-shot bowden. It helps, but definitely isn't ideal. I may just have a go at getting your system implemented.

 

Have you guys observed much torque induced deflection on the square shaft? It seems like that could add back a bit of hysteresis to the system. Igus has some cool squart linear motion gear that could be a slick addition: https://www.igus.com/wpck/15459/DryLin_Q_Overview?C=US&L=en

[neotko 1,417]

34 minutes ago, lars86 said:

Awesome work guys!

 

I am currently hanging my extruder drive (my own design), over the printer with bungee cord, in order to run a shorter (~12") straight-shot bowden. It helps, but definitely isn't ideal. I may just have a go at getting your system implemented.

 

Have you guys observed much torque induced deflection on the square shaft? It seems like that could add back a bit of hysteresis to the system. Igus has some cool squart linear motion gear that could be a slick addition: https://www.igus.com/wpck/15459/DryLin_Q_Overview?C=US&L=en

 

Indeed Z wooble due directdrive occurs, with the flexible beta addon is minimal. Gudo and I are moving our printers to Corexy with rails where Z move due directforce disappears completely without the need of the flexible addon. 

 

Check this thread I post on twitter for progress. So far been using it without any issue for production

 

 

 

 

[lars86 42]

20 minutes ago, neotko said:

 

Indeed Z wooble due directdrive occurs, with the flexible beta addon is minimal. Gudo and I are moving our printers to Corexy with rails where Z move due directforce disappears completely without the need of the flexible addon. 

 

 

Actually I meant the square shaft itself getting "wound up" in torsion. Not an eccentricity in that shaft changing the height of the nozzle.

[neotko 1,417]

4 minutes ago, lars86 said:

 

 

Actually I meant the square shaft itself getting "wound up" in torsion. Not an eccentricity in that shaft changing the height of the nozzle.

 

Oh not really afaik. Extrusion is quite precise. Also mind that I been using 3mm square rod that’s more flexible without an issue, 4mm should just be better (ofc for 2.85).

 

The main issue of all is that noone sells steel key/precision rectified rods for 4mm longer than 375mm (or at least was never able to find any shop online). 

[zerspaner_gerd 383]

50 minutes ago, neotko said:

Check this thread I post on twitter for progress. So far been using it without any issue for production

 

 

That's cool!

 

Finally these crooked waves gone! 

 

Have completely lost sight of this.

[andywalter 7]

I love your idea! But do you have to use 4mm square section? What about maybe 2x10mm section.

https://www.cromwell.co.uk/shop/materials-and-maintenance/ground-flat-stock/precision-ground-flat-stock-2mm-x-500mm-gauge-plate-01-tool-steel/f/63500

supply 2x10mm in 500mm length. Ok this is annealed, not yet hardened, but could be hardened after being machined to size. Hardening won't alter the torsional stiffness, all it will do is increase the max torque possible, and reduce wear from the wheels running up & down it. But I don't hink that extruder loads & torques will be very high at all, so personally I could live with annealed.

 

I've done some torsional stiffness calcs, 4x4mm square rod J' = 36, 2x10mm rod J'=23.3 so it's 2/3 the stiffness of 4x4.

The weight is also greater, as 2x10  20 is > 16, but not hugely heavier, especially if you can counterbalance the whole thing.

 

My own homebuilt UMO extruder uses 2 smooth aluminium wheels 30mm dia with grooves in to stop filament sliding out sideways, these wheels are sprung together as well as both being geared to give drive. Advantage is I don't grind the filament if anything slips. But the bowden tube is not ideal and I have to retract about 4mm to avoid oozing, and I'd like to reduce that & get better flow. I'm now wondering if I can get 4 small outside-diameter roller bearings 10mm long, 2 per wheel, and these would clamp each side of the 2x10 rod & be located in the middle of the wheel.

 

FWIW stiffness of 3x3 rod has J' = 11.4 . Formula for square rod is 2.25 x r**4 courtesy of roymech.co.uk

Edited January 7, 2018 by andywalter
fix error

[amedee 349]

The rod needs to go through the BondTech gear, so anything bigger than 4x4mm won't fit unless you completely re-design the extruder.
(The clearance is already minimal with 4mm...)

[andywalter 7]

Ok, so I think you have the 4x4 shaft going through the bondtech extruder, and that bit has some gearing which drives 2 clamp wheels, or something like that. I think I'd want to roll my own, using 2 separate parallel drive shafts, so avoiding having any gearing in the printhead.  My 2x10 rods would just go straight hrough tthe middle of my pinch wheels, and if they have to grow a bit in diameter to make everything fit, they can.

[darkdvd 988]

[neotko 1,417]

17 minutes ago, andywalter said:

Ok, so I think you have the 4x4 shaft going through the bondtech extruder, and that bit has some gearing which drives 2 clamp wheels, or something like that. I think I'd want to roll my own, using 2 separate parallel drive shafts, so avoiding having any gearing in the printhead.  My 2x10 rods would just go straight hrough tthe middle of my pinch wheels, and if they have to grow a bit in diameter to make everything fit, they can.

 

 

If you want to see how it works the thingiverse has a full stl with the assembly so you can just see how it works

[amedee 349]

26 minutes ago, andywalter said:

Ok, so I think you have the 4x4 shaft going through the bondtech extruder, and that bit has some gearing which drives 2 clamp wheels, or something like that.

 No, it directly goes through the BondTech gears -- see the exploded view:

 

(We are just using the BondTech gears, not their complete extruder)

 

Edit: to be clear, I am referring to the 'Drivegears', not reduction gears...

Edited January 7, 2018 by amedee

[LordHokage 7]

This is kinda old. But I still have a UMO+ with everything stock. Would this still work??

Additionally, are there any mods for the terrible UMO extruder?

[amedee 349]

It is still running strong on mine and I believe on @neotko and @nilrog printers...

 

Note that the torque needed for 2.85mm filament is definitely bigger than for 1.75; for the 2.85mm version you might want to use a stronger filament...

Alternatively if you just want to change the extruder, BondTech is a safe choice and a drop-in replacement.

[rowiac 53]

17 hours ago, LordHokage said:

This is kinda old. But I still have a UMO+ with everything stock. Would this still work??

Additionally, are there any mods for the terrible UMO extruder?

 

I use my UMO+ daily and last year I installed a clone UM2+ printhead assembly, but I replaced the nozzle and coupler with OEM ones after several months of use.  I also recently installed a clone UM2+ feeder/extruder assembly using the existing extruder motor and this has been working well.  It is much quieter, especially during retractions.  The BondTech, as @amedee mentioned, is a good choice, but for my purposes, a $12USD clone feeder was a no-brainer.

 

You can also change to the GT2 belts and pulleys for a little more dimensional precision (less backlash).  I did this quite a while ago.

[LordHokage 7]

@rowiac,  @amedee,

I do intend to change the GT2 belts, just didn't know where to start. But my question on the extruder still stands because it has been giving me lots of headaches since forever ;(. But would the ZGE still work without the UM2 printhead and directly on the UMO+ printhead

Edited March 5, 2022 by LordHokage

[medicalmodeller 5]

Can I resurrect this thread?   I own an UM3 and an UM2Go - that has the same print head as an UM2+ 

I am having real problems printing flexible material on my UM3.    I wonder what the cure might be

I understand that a direct drive feeder is not really possible on the UM3.  However would upgrading the feeder to Bondtech VV2 extruder helps on the UM3??

The other option is to make a Zero Gravity Feeder for the UM2Go.  Am I right that it should work albeit with a short drive shaft of course??

THanks