by Spacexula, published

Brutstruder by Spacexula Sep 9, 2010

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Brutstruder by Spacexula is licensed under the GNU - GPL license.

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My design goal for this extruder was an extremely reliable, no compromise, extruder for the Makerbot, that builds on all the most successful ideas currently available in thermoplastic extrusion. At the same time I wanted an extruder that could easily be printed on a Makerbot build plate with a as large a raft as possible to allow those who do not have a heated build plate to print it easily.

Brutstruder is a hybrid of many successful current extruders. It get\'s its idler wheel from the Wades Extruder http://www.thingiverse.com/thing:1794, and the drive gear from the Mk5 Plastruder http://www.thingiverse.com/thing:3290">. It also get's a viewport from the Printruder II - Rear Breech Loading http://www.thingiverse.com/thing:3178, it's Electronics board holder from the Prinstruder II http://www.thingiverse.com/thing:1980, and it's legs are 2 of the DINO2 from Zaggo's Printable extruder holder http://www.thingiverse.com/thing:1912.

This design has been endurance tested in multiple ways.

I made the extruder lift 27 lb of water (this was before adding a 4th spring, and going to harder spring, no telling what it would lift now).
I fed it 3d Ink Plastic only throughout testing.
I have printed 36 hours straight with this extruder at this time with 0 failures.
I also fed it 1/8 inch ABS welding rods from the local welding shop.

Now you see why I call it Brut.


Detailed instructions for Brustruter will be over at the Reprap Wiki. http://reprap.org/wiki/Brutstruder

First print the Idler, and the Makerbot block, attach your motor with the Mk5 drive gear on it (the gear will be tight, and the grub screw will eat out a track for itself as it spins. Spin it 2-3 times to grind a track before assembly). Once the drive gear is attached use 2 25mm m3 screws to attach the Kysan gearmotor to the block. Place your 606 bearing firmly in the hole provided.

To attach the idler, you will use 4 50mm m4 screws (the same as a Wades Extruder), the order of assembly is bolt, 1 washer, idler RP, 1 washer, 1 15mm spring (the harder the better), and a 3rd washer. Thread the m4 bolt into the block and secure them to the m4 nut on the other side.

Just screw the hot end into the block and secure it to the 2 captive m3 nuts.

The mounting legs for this extruder are Zaggo\\\\'s http://www.thingiverse.com/thing:1912, but just print 2 sets of his Dino 2 legs.

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Could this be adapted to 1.75mm plastic?

Thanks a lot for this great design.

I swapped my MK4 for your brutsruder and I love it!!

tried to run more of the 3dink "plastic" through the brutstruder after printing with makerbot plastic and it failed within 15 seconds of putting down a raft (it hit a spot in the plastic and the mk5 gear started spinning, plastic stopped getting extruded). i was able to print a huge flawless keypad case with the brutstruder and makerbot plastic. easily a 2.5+hour print and 90x90+ size. I will try another roll of it (i got 3 total) i really wish i knew the trick to get this junk to work. i can literally print for 30 hours straight with makerbot plastic with no issues with the brutstruder or printruder2... i cant figure out what is wrong.

How hard are your springs, for 3d ink I have to have it really tight.

Also what diameter thermal barrier you using? Makergear stuff usually can take 3d ink stuff like a charm..

i am using the makergear solid peek with a .35 big head and heatcore element. the springs i have are 1/2" tall and so stiff that i can only compress them completely using both hands (if i try to compress a spring with my finger and thumb i cant get the coils to touch)

it works SO well with other plastics i am not sure what to do. i cranked the springs down really hard (almost all the way) and still got the same problem, extrusion fails immediately) is it possible to have it too tight you think? when i back the filament out its not flattened out too much the
teeth marks in from the mk5 gear are nice and crisp.

wow, you got some really nasty stuff them can't see an issue with what your are doing.

Congratuations, 3d ink finally killed 1 Brustruder. :)

That's just crazy, I have extruded 1/8 inch with mine before :)

finally got it to work. i switched to a new 5lb chunk and took out the springs then CRANKED the screws down



So far, liking it a LOT!

I'm printing in PLA (mostly successful, but with a few dropped patches) and I'm trying to sort out whether I have an under-performing power supply, some sort of freaky voodoo emf noise, or over-tightened springs. Are there any clear clues to indicate, "um, yeah, those springs are cranked waaay to
o tight..."

What springs are you using? I'm about to order some stuff of off McMaster so I might as well add the springs to my order and upgrade my extruder. I don't want to use springs that won't work well so if I could get some pressure range that would be good for the extruder.

I got my springs. They seem really strong. Maybe a little too strong. I haven't installed the motor yet so I'll see how it looks, but all 4 might be too many.

Honestly you only need it to float less than .5mm, so really hard springs are better, people have got this type of desgin to work without any spring whatsoever. Try it, it will likely work.

i used 1/2" x 1/4" springs with .38 wire width they are really strong and were available at my local hardware store. came in a pack of 6 seem to work quite well.

My idler wheel cracked and I managed to patch it up just enough to print out the Brutstruder and mounts. It's working excellently. I don't have springs however, just tightened the M4 screws against a 2mm metal rod.

Wow, it works without the springs? I would not have thought that, bet it makes it easier to load filiment also...

Yup. Works without springs.

It slips occassionally during the first layer where the nozzle is only raised to 1/2 layer height, but after tightening the screws a touch, it seems to be working brilliantly.

Not sure what over tightening will do to this. Only time will tell.

Actually I can tell you that one, I used WAY too large of springs in the design phase, it spilled more plastic out the cleaning hole (and on the side of the bearing), and it nearly cut the plastic in half. But by god it didn't slip :)

Other neat thing I have found is if your filament spool get's stuck and it causes a failure, if you unjam the spool the extruder will pick up where it left off, literally running over the failure strip like a 4x4 truck.

God I love Wade's style extruders.

Has anyone tried PLA with this extruder yet? I'd be worried that it would pinch it in half!

Rick (Makergear) has done a lot of testing with PLA and found no issues.

Does this mount directly to the Mendel? Or do we need an adapter, if so, is there one on thingiverse?

http://www.thingiverse.com/thing:4064http://www.thingiverse.com/thi... Mount

http://www.thingiverse.com/thing:4042http://www.thingiverse.com/thi... Use this version, it's smaller and made for RepRap

Have fun, let me know if you have any issues!

Mendel Brustruder Mount
Brutstruder RepRap

Printed one and cleaned it up (took a bit of work) and then realized my X axis was inverted, and the part is backward. Printing a new one now. I wonder if I could use the stock makerbot idler wheel bolt....

Absolutley, that was by design.

You can reuse what you have. The only new thing you need 2_m3 35mm. The rest are parts took from your Plastruder Mk4.

The Brutstruder is awesome, mine printed without issues, and I hope to have it installed by the week's end. Yeah!

One clarification request: on the linked reprap wiki page, and in the above comment, you mention that you need 2x35mm M3 screws, while elsewhere on this page you specify 2x25mm screws.

At least for my makerbot configuration, it appears that 25mm is the correct length... but I went with 35mm and w
ound up with some too-long screws. I think I remember reading that too-long screws can damage a Kysan gearmotor, so could you verify this?

Thanks, and thanks for an excellent extruder design!

... responding to myself... it seems like the 35mm screws were perfect for going through the printed dinos, and 25mm were perfect for the motors. So, it was just my own confusion about which screw went where.

Congrats on finally posting this mate!

It really is compact... further miniaturisation may not be possible! It's time the community gets working on a shorter hot end lol!

Any ideas on reducing the vitamin count?

Ohh yes, something fun is on it's way http://www.makergear.com/blogs/frontpage/1906622-hey-there-mk5http://www.makergear.com/blogs... We are going to need new legs :)

Ohh I could take the chafer to this design and get rid of 1cc worth of plastic, but I think your right, we are approaching the limit of the material, which is a good thing.

Vitimin count?:

2 m3_25mm
2 m3_50mm
2 m3 washers
4 m4_45
4 m4 nuts
4 10-15 (depending on how hard, harder the better) spr
mk5 worm gear or the brass knockoff off ebay
Hot end of choice

I think this is the lowest vitimen count of any extruder also.

I'm not saying that's not a good vitamin count... it's just my goal is eventually 0 vitamins outside of electronic components...

and then, those are printed...

Very cool. It looks like it would work great for plastic that varies in diameter a little bit like the stuff from 3D ink. I think that I'll try it out while I'm saving up for the $120+ for the steppers from kysan and other parts for Wade's extruder for makerbot.

This was pretty much designed for people who want to run Makerbot firmware on RepRap, or people who are having troubles with their mk4.

Nice work, I like it. These DC gearmotors are still open loop though, right? Do you find you need to re-calibrate them over time, or is it still the case where if you run it at full power the speed is fairly constant?

Never had to recalibrate, and never heard of anyone doing that at all. Most people run it full out at 255, becasue at any lower speed it becomes problematic.