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gudo

Zero gravity direct drive extruder

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Hi to all

The 2016 year had inspired some of us in 3D field, we are always looking to improve our jobs and our equipement.

For a long time I wanted to print with ultra-flexible filament without meeting all the difficulties due to the bowden tube on the one hand and the disadvantages of weight and power of the direct drive with the stepper motor on the head of printing on the other hand

The flexible shaft is an interesting solution but also has some disadvantages and requires a significant addition of adjustments in a specific software to remove them.

I tried to find a compromise between these 3 systems, here are the results

Extrusion in direct with the usual stepper motor and using the components of the original extruder or those of the upgrade.

The system is quite simple by replacing the Bowden tube  by a straight and rigid square shaft between the stepper motor and the feeder, the latter 2 being installed on pivot points to be able to follow freely the X/Y displacements.

There is little added weight, +/- 10 grs more on the print head, it's why it is called by Neotko " Zero Gravity Direct Drive ", thanks to him for that and also for giving some good ideas ;)

There is absolutely no play in operation, extrusion and retraction have become very accurate by having the full torque power.

Printing with very flexible filament has become almost as easy and fast as with the PLA

My average retraction setting distance down to 1.5mm (1 to 2mm maxi)

Now my average print speed is 60mm / s

The other settings remain in accordance with the usual settings depending on the filament used.

I improved the ringing by lowering the acceleration values ??and the X / Y jerk, (2500/15 UM2 extended)

Depth of 150 hours of test performed with different filament types without encountering problems,

the videos shows  tests of a hobby car tire wich is printed with the  2.85mm Recreus Fila Flex A82 Shore at 50mm/s print speed and 2mm/30mm/s retractation settings.

the Bondtech feeder parts are used here for the 2 print heads, a system with the UM stock knurled wheel is in preparation;

 

 

 

 

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some other works

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future UM stock feeder parts uses in a customized" I Roberti" feeder system

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Hi to all !

Thanks for your likes and kindly comments

Here carbon filament print test

220mm Twisted airfoil propeller blade printed with the 2.85mm Carbon Color Fabb XT-CF20 at, 0.5mm steel nozzle, 0.2mm layers, 50mm/s print speed, 255° print temp, 65° bed temp,1.5mm retractation distance.

 

 

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Damn i missed this post! Very cool stuff gudo, big fan. Fun to see that the same idea popped twice on the forum lately but with different orientations

So i beleive that the square rod is connected to the knurled wheel (or to a gear), when the head is moving i guess that the knurled wheel has some movement too, could it increase the grinding of the filament or not?

Would be really interested in that mod for one of my printer!

Edited by Guest

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Damn i missed this post! Very cool stuff gudo, big fan. Fun to see that the same idea popped twice on the forum lately but with different orientations

So i beleive that the square rod is connected to the knurled wheel (or to a gear), when the head is moving i guess that the knurled wheel has some movement too, could it increase the grinding of the filament or not?

Would be really interested in that mod for one of my printer!

 

Hi Didier !

Thanks, yes the direct extruder pivots freely on the print head for following the X/Y motion,

it turns around 60° yaw angle from the extrem left front corner to the extrem right back corner, the axis of this yaw rotation is in the axis of the filament, there is absolutly no impact on the knurled wheel rotation feeding, since now closed to 200 hours print works I have no any grinding issue or something else with the Bondtech wheels used, also no any backlash or friction problems on the direct feeder system.

I start soon to do tests with stock UM feeder components, stepper motor and knurled wheel, I will see if I will get the same result !?

Yeah ! it will possible to add it to one of your printer, it's a real" add on" plug and play, this will not require any modifications (hardware/software) on your printer,

With an another stepper motor, eventually we can leave everything in place just remove the bowden tube and add the direct system on the top of the machine.

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Oh yes indeed for the rotation of the feeder :)

So you use bondtech knurled wheel, is it like in the bondtech extruder? (two knurled wheel with a gear somehow?)

 

I use the standard Bondtech 2 gears feeder, the feeder has a 1/4 turn spring unloader key to release the spring pressure of the driven gear for change the filament by doing if it need a direct atomic nozzle cleaning in the same process.

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an alternative version inspired by IRoberti /Fat IRoberti Neotko solution

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How do you 'connect' the output of the extruder to input of the hot end? A piece of Bowden tube?

Just thinking on how It could be modified for an UMO head...

 

Hi Amedee,

With a piece of a standard PTFE tube, not UM Bowden tube

Neotko will soon test the system with 1.75mm mod on his UMO, the above Fat IRoberti feeder photo shows his future direct feeder.

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How do you 'connect' the output of the extruder to input of the hot end? A piece of Bowden tube?

Just thinking on how It could be modified for an UMO head...

 

Hi Amedee,

With a piece of a standard PTFE tube, not UM Bowden tube

Neotko will soon test the system with 1.75mm mod on his UMO, the above Fat IRoberti feeder photo shows his future direct feeder.

 

Yay!!!

Also afaik making an adapter to a UMO head would be just a matter of changing the x4 points where it screws (I think).

Woohoo can't wait to print some filaflex on day1!

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How do you 'connect' the output of the extruder to input of the hot end? A piece of Bowden tube?

Just thinking on how It could be modified for an UMO head...

 

Hi Amedee,

With a piece of a standard PTFE tube, not UM Bowden tube

Neotko will soon test the system with 1.75mm mod on his UMO, the above Fat IRoberti feeder photo shows his future direct feeder.

 

Yay!!!

Also afaik making an adapter to a UMO head would be just a matter of changing the x4 points where it screws (I think).

Woohoo can't wait to print some filaflex on day1!

 

Hi Neotko ! you think right ! :)

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Yes indeed, just the "bottom" plate would differ.

I was also thinking this plate could be a bit higher -- e.g. On my E3D head I need some clearance for the thermocouple amp. Obviously the height of the motor would need to be adapted to keep the axis perfectly  level.

Time to order BondTech gears... :p

Edited by Guest

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First test I was gonna finish the estep calibration but choose to insert Flexible 86A shore from smartmaterials

So.. printing flexibles with PLA settings (mind the temp change ofc)

 

 

Amazing, right now I'm already around 1k retractions in 21minutes and no error, good looking infill... amazing @gudo

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Very interesting stuff.

a) There's a visible reduction on ringing. Anders theory about part of the ringing coming from bowden/feeder/pressure seems likely.

b) There's a huuge reduction on blobs and z mark at highspeeds, clearly the zero backlash from the filament being on a bowden tube helps to avoid suden changes on pressure.

c) I just did some Recreus filaflex, 3k retraction test printing one of my keychains changing only the retraction distance to 1.2mm and it does work. But it does drip much more than smartfil. It will need some coasting adjustments to make fine details but small txt prints almost ok (mind the dripping). I was able to lower the print for the half of the print to 230C without underextrusion or problems.

Soo... WOW!

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A few shoots to illustrate my points.

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Prints using the same spool colorfabb signal yellow, same gcode.

First thing that changes radically, is how the tension of the filament + bowden isn't an obstacle. Also ofc, prints where done using Olsson Ruby.

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