Bowden Belt Extruder

Yet another "Extruder", yup ?*

*(we'd rather say feeder)

So true ! But this one is an anwser to a bunch of issues. My Bowden Belt Extruder, has required about 3 months of single work, then with the help of maker friends, 9 months was used for beta testing and overall adjustments. This is not a remake : it was engineered considering the expected specifications form start to end.

I started to 3d print several years ago and I've been used up to 100 lbs filament yet. I owned, designed and builded several printers, and encountered a lot of issues from one to another. My bowden belt extruder try to avoid most of commun issues and adds interesting features too. Maybe my extruder is not the best ever, but it probably stand close to most interesting ones. It's just one vision of what a good extruder must be.

If you plan to build your first printer, you'll probably in search of the best possible parts. Otherhand, if you own one, you 3d printer was already provided with a feeder. But, even if you never encountered any issue with it, you can think about an upgrade to improve print quality or get better features.

Design choices and why ?

1. Why the bowden technology ? For newbies, bowden means the feeder is distant from the printhead. The filament is carried thru a PTFE tube which makes a bow => bowden. By removing the feeding motor and parts from the printhead, you get a lightweight printhead. As printhead moves can be very quick on a 3d printer with a lot of direction changes, extra weight brings more vibrations and have a real influence on print quality. This is particulary pregnant if the other components are not totaly stiff or playless. Most critics about bowden comes about you could not print flexible materials with a bowden setup. Well, actualy, this is not totaly true. I print pretty decent flexible parts with my bowden setup. I see no difference compared to direct drive extruders. I can say why. Most of bowden kits are provided with one meter (3 ft) of bowden tube. And people use all the available lenght. It's a mistake. You want to keep the bowden distance as short as possible. As the maximum run of a printhead is usualy about 200mm, you should not need over 300mm to keep it moving freely. Otherhand, flexible filaments should not be printed too fast. It's important for a good bond between layers and a good overall print quality. If a bowden feeder is properly designed and if it uses a shorten bow tube, then a bowden setups have some advantages and no cons.
2. Why a greared extruder ? Easy awnser ! This gives extra power to the feeder and it brings more resolution to the extrusion. My bowden belt extruder brings 4 times more torque and precision compares to a direct drive feeder.
3. Why a belt extruder ? Most motor reductions use gears, mostly printed of course, and gears are noisy. Seccond, the belt can be tensioned with precision so it have no play, and there's mostly no wear so it's durable.

What makes it interesting ?

• Perfect path : the filament is driven constantly since out of the gear, no possible filament jam
• Torque x4
• Precision x4
• Strong engineering with structural straighteners : no bend.
• Quick insert : no need to open the extruder to feed a new filament
• A crank for fast feeding : my favourite, this is truely very handy !
• Very quiet unit : imperceptible in operation with silent drivers.
• Quick release of the idler : instant access to the hobbed gear.
• Two mounting options (rail or stile) : can fit any printer, aluminium extrusion ready.
• Compact size : 50% smaller than Greg's Wade Extruder.
• Radial insert of the motor shaft for strong and easy belt tensioning.
• Uses the MK7 hobbed gear, the best on the market actualy (better than MK8).
• Low cost.
• Easy building.

If you want to build your own Bowden Belt Extrudeur, you will need a set of printed parts available on thingiverse (Thing#1579394). If you don't own a printer yet, you can order prints directly on Thingiverse, otherwise there's different ways to get printed parts : request to a friend/maker with a 3d printer, ask at the nearest fablab, or order directly on 3Dhubs or Thingiverse. Note serious provider will send debured parts.

Two version of the printed parts are available. One with the regular marking, and one with unshown marking. Use whatever you like. You can visit my website for further details and the article in french : www.j-max.fr

Hardware :

You can order the hardware at any provider. All the hardware in use are commun standard parts. Usualy best price can be found on Aliexpress.com or Ebay. Just take your time and compare to be sure to get exactly the right part at the right price.

• 1x Nema17 motor (any kind at last 34mm long)1x GT2 2mm 80 tooth closed loop belt
• 1x GT2 2mm 16 tooth regular pulley
• 4x DIN912 M3x8mm screws (for motor mount)
• 1x DIN912 M3x20mm Screw (for idler's bearing mount)
• 1x DIN912 M3x25mm Screw (for idler mount)
• 1x DIN912 M3x30mm Screw (for crank mount)
• 2x DIN912 M3x40mm Screws (for the lock system)
• 1x DIN912 M5x40mm Screw (for the hobbed gear/secondary pulley axis) /!\ File a flat side for the MK7 screw*
• 5x DIN985 M3 Nylstop nuts (for M3 screws except obviously 8mm ones)
• 1x DIN985 M5 Nylstop nut (for the secondary pulley fixing)
• 1x M3 washer (any kind will fit, even if we use Nylon ones - used for the crank)
• 2x DIN127 M5 grover washer (for the hobbed gear/secondary pulley axis)
• 1x M5 washer (any kind will fit - used for the secondary pulley alignment)
• 1x 623 bearing (for idler bearing)
• 2x MF105 bearing (for the hobbed gear/secondary pulley axis)
• 2x 4x20mm springs (actualy we use recycled pencil ones - used for the lock system)
• 1x 3/8" 4mm push in fitting (for bowden 4mm teflon tube)
• 1x MK7 Hobbed gear (better than the MK8 IMHO)

Pastic printed parts :

• 1x Feeder body
• 1x GT2 64 tooth secondary pulley
• 1x Crank for secondary pulley
• 1x Idler
• 1x Lock

Necessary tools :

Before to start, be sure you own the appropriate tools for easy assembly.

• 1.4mm Allen Hex key (for hobbed gear and GT2 16T pulley)
• 2.5mm Allen Hex key (for M3 screws)
• 4mm Allen Hex key (for M5 screw)
• 5.5mm wrench for M3 nuts
• 8mm wrench for M5 nuts
• 9.5mm wrench for pneufit
• thin plyers (for deburing)utility knife (for deburing)
• 3mm bit (for deburing)
• 5mm bit (for deburing)
• a gas lighter (for deburing stringing)

*Thanks to ThomasK19 ;)

Assembly :

See video for deburing and mounting details. There's nothing fancy in the assembly process. The overall mounting time for the average builder will be about 30 minutes.

Settings :

Please folow the instructions of the smart Thomas Sanladerer, I can't do better ;)

Tom's 3D Printing Guides : Calibrating your extruder

Enjoy !

Feel free to contact me for any question or just to say you like it ;)