Summary

This project is an elegant geared-drive, bowden feed extruder, based ontempo502's B'struder (http://www.thingiverse.com/thing:711401).

It combines the idler arm from there for PC4-M6 pneumatic/bowdenfittings, with ronanwarrior's high-resolution Greg's Wade Reloadedextruder gears (http://www.thingiverse.com/thing:97377).

The gear ratio is unchanged from ronanwarrior's original models, at 47:9(5.222:1). With the pictured motor, this extruder can push filament at 30mm/sec reliably (too much faster and my particular motor/controller/drivercombo stalls).

With a suitably-modified idler arm, it should be possible to use 2.85/3 mmfilament, if your stock thereof is all from the dark ages. ;-)

The B'struder "plate" has been heavily modified to remove all of theformer mounting holes, the thickness has been adjusted slightly, spacehas been added for a bearing where the motor axle hole used to be, oneedge has been extended out and thickened to hold the motor off to theside, large holes have been added to reduce its mass a bit, a small holewas added to the spring's end stop so that a screw can be driven in to

VanessaE

Greg'sB'Wadestruder -geared B'struder -bowden extruderfor MK7 / MK8 andsimilar gears - v2

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updated 11. 4. 2020 | published 11. 4. 2020

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tension the spring, and a few other holes and nut traps have been addedto the upright part to allow the top plate to attach to it.

On the large gear, the top and bottom surfaces have been re-faced andthe whole thing has been tidied up from the triangulated mess that STLrequires (just to make it easier to edit), and I modified it to accept an M5bolt (rather than the usual M8). I also thinned the center part down toaccommodate.

On the small gear, I increased the clearance around the nut trap andadded a flat to the side, to leave room for a larger range of set screwlengths.

The gears mesh together quite well, and have minimal backlash.

You can either print and use the idler arm included here, or grab one oftempo502's other variants.

The support objects for the base plate and top plate are provided here asseparate STLs, in case you want to give them weak/sparse print settings,or if you want to let your slicer use its automatic supports. Note that thesupport objects for the top plate are upside down in the STL.

Vitamins:

2, 625ZZ bearings.3, 623ZZ bearings.1, M4 x 4-6 mm screw, Allen, square, plain Torx, or something vaguely likethese. Cap-head preferred. 1, M5 x 35-40 mm hex bolt.1, M5 nylock nut, or two regular M5 nuts if you can get thin ones.1, MK7 or MK8 hobbed gear, or similar.1, PC4-M6 pneumatic/bowden fitting, or equivalent.

A "wood" or "sheet metal" screw of some kind, 3 to 3.5 mm in diameter,15 to 20 mm length. Something self-drilling would be best, but isn'tcritical. A suitable idler arm spring, 20 to 25 mm length. A few washers tofit the M5 bolt.Assorted M3 screws, nuts, and washers to put it all together. Lengthsrange from 8 to 45 mm. Two M4 or M5 x 16 screws for the 2020 mount, ifyou use it, plus two M3 x 20 screws if you're using the noise-reducingversion.

Assembly:

Print everything and remove the support bits :-)Press the 625zz bearings into the recesses in the base plate and topplate

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Press two M3 nuts into the two recesses on the inside faces of theupright part of the base plate. You may have to trim the holes andreach for your soldering iron.Trim the bottom of the small gear as needed (first-layer flare/elephant's foot) and insert an M3 nut into the trap.Thread an 8 to 9 mm M3 screw into the side hole and part-way intothat nut.Place the small gear onto the motor shaft, round end first, and threadthat screw injust enough to align the gear with the flat on the shaft.Insert four 10 to 12 mm M3 screws into the base plate and use themto mount the motor. Take care to orient the motor's connector/wirescorrectly for your setup. If you intend to use the 2020 mountingbracket, insert it between the motor and the base plate, and use15-17 mm screws instead.Assemble the idler arm:8a. Use your hobby knife and a 2 mm drill bit to clear out the filamentpath.8b. Trim the two holes at the end of the arm and press-in two 623ZZbearings.8c. Insert a third 623ZZ bearing into the recess in the middle.8d. Insert an M3 nut into the trap next to it.8e. From the nut-side of the arm (that is, the side that faces awayfrom the base plate), thread a 12 to 14 mm M3 screw into that nutand tighten it down. Don't over-tighten.8f. Carefully line up the threads and install the PC4-M6 fitting into theend. After installing it, rotate it a little so that one of the flats lines upparallel with the side of the arm (so that it doesn't scrape against thebase plate).File or grind a flat spot into the M5 bolt, ranging 15 to 25 mm fromthe underside of the head. It need not be particularly deep, maybe 1mm, but make the surface as flat as possible, or it can be slightlyconcave if that's easier. Exactly where you put this flat depends onthe specific hobbed gear you'll be using and how you orient it.Align the large gear with the small gear and the hole in the baseplate's bearing, flat side toward the bearing, and press the M5 bolt inand all the way through. Be sure you seat the head fully into therecess in the large gear.10a. Optional: before pressing the M5 bolt in, add a washer betweenthe large gear and the bearing.Insert an M3 nut into the trap on the underside of the base plate.Using a 20 to 22 mm M3 screw and a washer under the head, installthe idler arm into the base plate, with the curved side toward thehobbed gear (duh :-) ). You may find it necessary to insert one ormore washers between the arm and the base plate, to align the armprecisely with the hobbed gear when it goes in later.

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Insert a short M4 Allen head screw into the end of the idler tensionspring and snap them into place between the idler arm and the baseplate's end stop piece, with the screw toward the end stop. They maybe loose, depending on the spring length and screw head thickness.13a. Pick the spring and screw up off the desk and snap them inagain.13b. Get down on the floor, retrieve the spring, get another M4 screw,and snap it in again.13c. Contact your local astrophysics expert and inquire how thespring ended up in another dimension, get a new spring, and snapthem in again.13d. Drink a shot of your favorite liquor, start praying to your favoritedeity, get another spring and screw, and snap them in again.Press the idler arm against the spring, and hold it out of the way whileyou slip one or two washers over the M5 bolt.Add your hobbed gear. If your gear has a grooved hob (rather than asimple flat profile), put that end in first. The number of washers youadded in the previous step depend on how well you can align yourgear's hob groove, if it has one, with the filament path provided bythe idler arm. Thread the hobbed gear's grub screw injust enough tograb the flat on the M5 bolt, but not enough to prevent it moving upand down freely.Thread an M5 nylock nut down onto the bolt, and tighten it downkinda tight (but not so much that you risk damaging anything) todraw all the parts together one last time, and then loosen itjust barelyenough that the printed gears can turn easily. The tighter you leavethe nut against the hobbed gear, the slower your maximum retractionspeed will be, owing to the additional load it places on the motor dueto friction between the base plate, the hobbed gear, the washersbetween them, and whatever parts of the lower bearing that rub onthe base plate. On the other hand, a tighter nut also means moreperfect alignment between the bolt, printed gears, and bearings. Youcan also use two regular M5 nuts here, one jammed hard against theother, so long as there is room for them, and the printed gears arestill free to turn.Tighten down the grub screw on the hobbed gear.Place the top plate over the stack, taking care to align its bearingwith that bolt.Thread in two 9 mm M3 screws into the two holes in the top plate thathave countersink flats, and tighten them into the two nuts youpressed into the base plate's upright part.Push a 45 to 50 mm M3 screw and washer into the diagonally-oriented hole running through the bottom-most parts of the top plateand base plate. Secure the other end with a washer and nut.Drive in a 15 to 20 mm self-drilling sheet metal screw into the holeopposite the tension spring. Something 3 to 3.5 mm diameter, with

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sharp threads that can bite the plastic nicely. Make sure the end ofthe screw engages the Allen screw in the end of the spring.Rotate the printed gears so that the small gear's set screw is exposedto the access hole on the side of the base plate.Adjust the height of the small gear, aligning it precisely with the largegear (I used the centerline of the herringbone as my guide), andtighten down the small gear's screw. Don't over-tighten.Apply a tiny amount of oil or grease to the washer(s) you insertedbetween the hobbed gear and the base plate, and a bit more to theprinted gears' teeth. Don't get any oil/grease on the hobbed gear orit'll get onto your filament.

The whole assembly can then be mounted to your machine by taking twoof the screws out of the back of the motor and replacing them with longerones, or by using the 2020 mounting bracket and M4 or M5 screws andsuitable T-nuts.

The bracket should be useful for mounting onto other things besides 2020extrusion.

There are two versions of the 2020 mount: a one-piece design that's just,well, a bracket, and a two piece noise-reducing design. In that one, printthe "B" piece in TPU and fasten it to your frame, then print "A" piece inPETG or whatever, build it into the extruder, and fasten it to the "A" piece.

This extruder was inspired by ask0045's geared B'struder (http://www.thingiverse.com/thing:1694683) and follows a somewhat similardesign.

Changelog

2020-04-11: Added noise-reducing version of the 2020 mounting bracket.It rotates the extruder by 90° as well, putting the motor and drive axlesparallel to the 2020 it's mounted on (I originally designed it for myHypercube).

2020-01-11: Rotated the motor by 45° so that all four screws areaccessible without removing the large gear (one via the holes in the gear).Reworked the 2020 bracket accordingly, so that the extruder keeps thesame overall orientation.

2020-01-10.2: Re-linked standard library to account for recent changes.

2020-01-10: Added bridging over the 2020 bracket's two mounting holes,and made them bigger, to actually fit M5 screws. Sorry for the errors, folks.It's only just recently I've found myself needing to actually USE thisextruder again, to say nothing of needing the 2020 bracket. :-)

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2020-01-09: Added bridging over some of the baseplate's holes, andtapered the studs on the top plate's diagonal screw, eliminating the needfor supports.

2020-01-06: Exchanged the motor mount screw holes for slots, so that youcan move the motor as needed to set the gear lash and compensate forwear. I also added insets around the 2020 bracket's two M5 mount holes,so that you can use 16 mm screws to fasten it to the 2020.

2019-12-08: No functional changes this time around... I just replaced the2020 in the .blend with my own model (created from Misumi's Series-5technical drawing), swapped the motor model for an updated, more-detailed version I created from it, which I use in other projects, andreplaced all the screws, nuts, etc. with better ones, for the sake ofappearance in the .blend (and the render).

2018-03-13: Many parts were not properly rotated and aligned for printing(although most slicers can easily correct this). Fixed. Also corrected thelength of the M5 bolt in the .blend (and all-parts .stl). If you've alreadyprinted this since 2016-10-22, you don't need to do anything.

2016-10-22: Somehow the motor's screw holes got lost from the revised2020 bracket. Fixed.

2016-10-21.6: Replaced the bracket with a much shorter version thatshould keep everything out of way of anything attached to the 2020extrusion.

2016-10-21.5: Fixed the bracket. I forgot to add a hole for the small gear topass through. Derp. :-)

2016-10-21.4: Replaced the mounting bracket with an "L" version thatshould be more useful.

2016-10-21.3: Added a mounting bracket to fit 2020 extrusion. Holes aresized for M4 screws.

2016-10-21.2: Noticed and fixed an error in the base plate (a vertex gotmoved for some reason, screwing up the top of the baseplate where themotor goes).

2016-10-21.1: New .blend with all the screws, bearings, and otherhardware included, a few existing bits simplified (well, sorta), andredundant stuff removed. The actual printable parts are unchanged. Addedan exploded view diagram, should help with assembly.

2016-10-20: Replaced all files with version 2. The first version had aproblem with the M5 nylock nut working loose enough to allow the bolt

Model Files (.stl, .3mf, .obj, .amf) DOWNLOAD ALL FILES

and large gear to lean sideways, making the extruder noisy and somewhatinaccurate during retracts. Now the end of the bolt is held steady by anupper plate screwed onto the base plate, into which one of the two 625ZZbearings has been moved. The base plate has been modified to add thenecessary holes and nut traps for those screws. This new version is MUCHquieter since the gears now stay well-aligned, and it can reliably turnabout 10 percent faster, as well. The printed gears themselves areunchanged from v1.

3D Printers > 3D Printers - Upgrades

Notes

Print everything at a somewhat high infill density - 40-50% ought to do.

How I Designed This

I started by loading the B'struder plate, and removing all of the holes, savefor the central one and the small one that holds the idler arm. I then un-triangulated the whole thing to make it easier to work on, created pocketsfor the two bearings, and so on.

I then added an extension for the motor, with the two aligned to place a0.15mm gap between the two sets of gear teeth.

Finally, I created the top plate starting from an ordinary cube, with lots ofedge subdivision and beveling to create the "L" shape and roundedcorners.

All work done in Blender.

The Blender work file depends on my standard parts/materials library,which can be found here: https://www.prusaprinters.org/prints/16640-my-blender-3d-printing-partsmaterials-library ... If you get errors regardingmissing objects/materials, download that file and do whatever you need toto get Blender to pick it up.

The two bearings depicted in the .blend are from my 71⁄2-shot-pellet-based 625ZZ model (https://www.prusaprinters.org/prints/7455-625-625zz-bearing-using-7-12-shot).

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Find source .stl files on Thingiverse.com

geared-bstruder-wades-small-gear.stl

geared-bstruder-wades_v2_top_plate.stl

b-struder_arm_m6.stl

geared-bstruder-wades-big-gear.stl

geared-bstruder-wades_v2_-_all_parts.stl

geared-bstruder-wades_v2_2020_bracket.stl

geared-bstruder-wades_v2_base_plate.stl

geared-bstruder-wades_v2.blend

geared-bstruder-wades_v2_2020_noise_reducing_moun.stl

geared-bstruder-wades_v2_2020_noise_reducing_moun.stl

The Author has not uploaded any print files.Try to search in User print files section or generate and upload yourown.

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