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Airtripper Bowden Extruder BSP Edition

by Airtripper, published

Airtripper Bowden Extruder BSP Edition by Airtripper Aug 2, 2013

Description

Full documentation for the extruder is here:
airtripper.com/1764/airtrippers-direct-drive-bowden-extruder-v3-bsp-edition/

#####Extruder Filament Drive Gear Review & Benchmark
airtripper.com/1676/3d-printer-extruder-filament-drive-gear-review-benchmark/

![Drive Gear Review & Benchmark](http://airtripper.com/wp-content/uploads/2013/11/mk8-filament-drive-gear-pulley.jpg "Drive Gear Review & Benchmark")

Airtripper Direct Drive Bowden Extruder BSP Edition
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Designed for 1.75mm Filament and Nema 17 Stepper Motor

This is the latest edition of the airtripper extruder series with many improvement tweaks and now is sporting a BSP fitting filament out feed socket.

The extruder has worked well with the MK7 drive gear and was able to push more than 3kg of force with stepper motor type SY42STH47-1684A.

I've not posted any information about the latest extruder design, however, the previous extruder design still provides a good reference.

airtripper.com/1071/airtrippers-bowden-extruder-v3-updated-design/

Mark

Recent Comments

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I put one of these (via an adapter plate) on a 5:1 geared NEMA17 stepper (was having trouble feeding fast enough with the stock ezstruder on my rostock max). I found a guy on eBay selling 8mm bore Mk7 gears. The problem (and I'm hoping it's not just some weirdness on my printer) is that the filament needs to take enough of a bend going around the drive gear that I can't freely move the filament forward through my bowden tube with the idler off - so I have to feed filament in/out of the bowden using manual control of the stepper when I swap rolls.

I'm going to try a version that bumps the infeed and outfeed away from the idler by 0.5 or 1 mm and see if that helps. Thanks for providing the OpenSCAD for that!

Aside from the minor alignment issue, it's working great!
Ah, good to know. I didn't know if the bearing was there to provide extra support for the motor shaft, reducing wear on the motor's internal bearing(s). If it just simply helps provide extra force, then I can probably do just fine without it.
The bearing still fits and supported. The bearing is optional though since the MK7 and MK8 drive gears provide good grip without lots of force.

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Instructions

Full documentation for the extruder is here:
airtripper.com/1764/airtrippers-direct-drive-bowden-extruder-v3-bsp-edition/

*If you are looking to upgrade from the previous version you would only need to change the extruder main body.*

##Printing

Skeinforge and Slic3r have been used but Skeinforge seems to provide the best results.

* Infill Solidity (ratio) can be between 0.2 and 0.3
* Layer Height 0.25mm

##Non-printable Parts List

*The parts below may be available as a kit from ebay; search airtripper to find the listing.*

More about the assembly can be found here: airtripper.com/1764/airtrippers-direct-drive-bowden-extruder-v3-bsp-edition/

* 2 x M3 Washers
* 4 x M3 Full Nuts
* 1 x M3 25mm Socket Cap Screw
* 2 x M3 30mm Socket Cap Screw
* 1 x M3 6mm Socket Button Head Screw
* 1 x M3 10mm Socket Button Head Screw
* 2 x M3 45mm Socket Cap Screw
* 1 x 608ZZ Ball Bearing
* 1 x 6mm ID Rubber Hose
* 1 x 1/8" 4mm BSP Push Fitting
I put one of these (via an adapter plate) on a 5:1 geared NEMA17 stepper (was having trouble feeding fast enough with the stock ezstruder on my rostock max). I found a guy on eBay selling 8mm bore Mk7 gears. The problem (and I'm hoping it's not just some weirdness on my printer) is that the filament needs to take enough of a bend going around the drive gear that I can't freely move the filament forward through my bowden tube with the idler off - so I have to feed filament in/out of the bowden using manual control of the stepper when I swap rolls.

I'm going to try a version that bumps the infeed and outfeed away from the idler by 0.5 or 1 mm and see if that helps. Thanks for providing the OpenSCAD for that!

Aside from the minor alignment issue, it's working great!
Is the MR105ZZ bearing still compatible with this design?
The bearing still fits and supported. The bearing is optional though since the MK7 and MK8 drive gears provide good grip without lots of force.
Ah, good to know. I didn't know if the bearing was there to provide extra support for the motor shaft, reducing wear on the motor's internal bearing(s). If it just simply helps provide extra force, then I can probably do just fine without it.
I've posted a version of this, customised for the Makibox at youmagine.com/designs/airtripper-bsp-for-makibox
May I ask what is strout part for?
Hi Airtripper, I wanted to let you know I've discovered a flaw in the design for the Idler part. It is very important!

The idler bearing gets hit by the little screw on the MK8 filament drive gear, it only hits the edge, but it's enough to push the idler bearing away just a little bit, I've tried everything possible to push the idler further away from the carriage etc, but I think if it is possible to make a slight change in the idler, this can be fixed.

This makes the extruder prone to slipping, and the screw on the MK8 drive gear will show signs of wear since the bearing is much harder.

The fix would be to move the bearing towards the front of the extruder maybe just a mm or maybe even half a mm. I have checked it out and measured it, and it seems that the bearing is much wider than the area it needs to push the filament. Maybe it can be solved by simply adding a few washers behind the idler's part on the bolt that holds the bottom hook of the idler and goes through into the extruder motor. And maybe this problem is caused by the fact that I don't have a 4th bolt in place because no hardware store in my area has a suitable bolt (the short one that is positioned behind the idler).
Hi Ohmarinus,

I had a look at my extruder and have good clearance between the idler bearing and the MK8 drive gear set screw.

On my MK8 drive gear, the little set screw hardly sticks out at all, it's almost flush with the drive gear boss.

However, I have a flat side on my stepper shaft, which means the drive gear set screw will screw in more then a set screw on a completely rounded stepper shaft.

If you are using the same type of stepper shaft as I, the MK8 must be being shipped with a longer set screw than what I got.

The wide idler bearing is needed for those who want to use the plain insert gear, or any gear that don't have groove to keep the filament running in line.

I'll make a note of what you found for when I work on the next extruder design.
Okay, I have ground down the top of the screw, because the hex-tool could enter quite deeply, however it's still sticking out. So... I also ground a beveled edge on the bearing on the side where the screw was. It appears to work. I have a very detailed image uploaded for you so you can see where the screw has signs of wear:
http://i.imgur.com/6V4SnsG.jpg

Its still hitting the bearing, but it only causes a very mild push now, so I hope it stays okay. Trying the first print as we speak.
I always expected a bevel on stepper motor axles, so the set screw will be an issue on axles without a bevel.

Grounding a bevel yourself should give you the clearance you need if you can get it deep enough. I'm sorry you had to go to so much trouble, but once you get MK8 gear working, the trouble will soon be forgotten.

I just got another delivery of PLA filament from reprapworld and so far it has been perfect for bowden extruders and heated window glass beds. It needs to be extruded at 220 C for best layer bonding and there is no string clean up after printing. It might be worth you trying this filament out if you are looking for better PLA than what you use.
Hmm, reprapworld, I'm currently using Repraper filament bought through filamentenmeer.nl however, and I'm very happy with it. Extrusion temp 200º. The extruder is working quite well now, however it flexes when retracting and extruding. So I'm still thinking of designing my own extruder in the long run ;)

Currently printing with Natural PLA from repraper and it's doing very wel. How consistent is the thickness of the reprapworld filament and did you get the special 'Dutch' variant, or the usual one? Oh, and which color?
I tried adding a few washers, didn't solve it yet, however, I might just dremel off a piece of the screw, since I got a dremel, this shouldn't be too bad ;)

That would be the easiest solution. Another set screw should be easily found it I f* up.
Haha, somebody is making money off of your design:
http://www.reprap.cc//index.php?main_page=product_info&cPath=6&products_id=104

And they don't even use tubes but springs! Lazy bastards ;)
Is this allowed?
They are allowed to do this, with the type of license I applied.

I'll consider using a non-commercial type license on some projects where production quality needs to be high.

I don't fancy having my name attached to a company's shabby effort to reproduce something I've designed and selling it.
Yeah, me neither, thats why I let you know. On the other hand, it's also great that someone uses your design. But it's poopey that they don't even provide the tube with it for the idler but use springs as you so importantly mentioned.
I have this extruder all set up and everything. But it is not working. I am trying to push 1.75mm of abs through a tube of non-ptfe hose into a J-head Mark 5 nozzle with a .4mm nozzle. I am using my Rostock 3D Printer.
I am using a Sanyo 103H5208-10U41 stepper motor and the correct drive gear. i've calibrated the stepper motor to extrude exactly 100mm when the command to extrude 100mm is given. It just has not enough strength to force it through the tube and through the nozzle.
I bypass the nozzle and the filament pushes through the hose without a problem.
What do you guys suppose i can do to fix this problem and get printing?
I use the J-head MK5 myself and when extruding PLA, I only need around 500g to 1000g of force at 24mm/flowrate; so a good spec stepper motor and drive gear should work no problem, I would suggest to push the filament into the nozzle with your fingers to see if you can push with enough force to cause the hot end to extrude.

Remove the bowden tube from the top of the hot end so that you can force feed the filament into the nozzle with your hand. If you are unable to extrude any plastic by hand feeding the nozzle, then there may be a blockage in the hot end.

If there is no blockage in the hot end, you might start next with checking whether the stepper motor has enough current to operate properly.
Hey airtripper, I got everything ready, just checking, do you know what the E-steps/mm should be? In my calculations it comes out as 145.51 steps/mm I will test this later this evening when I have the new hotend in place.

Really curious to see how it will perform!! Didn't have the rubber tube, nor does any shop have that in my area, not even the car-parts shop so now I am still using springs... Don't know yet how it will perform, since the ceramic heater and thermistor aren't in place yet, but it looks pretty solid.
At 145.51 steps/mm, I guess the stepper motor is set to 1/16. I think with the extruder, it's about getting steps/mm as close as you can. Sampling 100mm will give you better accuracy than sampling 50mm. However, given that a lot of filament is oval shaped instead of round, doing a test print is the only sure way check if the settings are close enough.

You might be able to find scrap rubber sheets, maybe table mats, cup mats, that you can cut up and stack to replace the idler springs on the extruder.

You could continue to use the springs, but design and print a small handle to pull the springs back and aver the idler.
Hi, I have found a piece of rubber gasoline-tube from my old motorcycle ;)

It's perfect! However, I feel the idler is hitting the extruder body quite fast, and the gear is slipping because there is something wrong with my hotend. The filament doesn't jam completely, but after 20 seconds of printing it becomes very hard to push the filament through, even with a cooling fan pointed to the PEEK part.

I don't know whats causing this and I am worried that the PLA might be expanding too much in the PEEK part already and wedge itself slightly.. Will re-design the J-head cooler, however it's already one of the best coolers I've seen around so far, so I really don't know what else I can do to improve on the J-head.

Gonna try now to insulate the brass block with a piece of ceramic insulation to see if that makes a difference, but it seems the heat is travelling upwards on the inside of the hotend. I haven't had this with the 3mm version of the same hotend by the same maker.
I'm extruding PLA at 220 degrees C with less than 1000g of force, and the extruding force does not increase over time. I'm using the J-head MK5 from hotends.com and my cooling solution is two strips of copper from water pipe clamped round the hot end PEEK body. The copper pipes heat away from the hot end body to the aluminium hot end bracket which then is cooled by a small fan from the top.

I don't know what your set up is like, but I'm thinking that having a fan blowing across one side of the hotend might not prevent heat creep on the opposite side.

I've added a new image to this extruder above that shows how I did the cooling for the J-head, also shows how I attached the bowden tube as well - using old DVD drive casing. It should be the second image in the row of thumbnails above.

The idler is close to the extruder body for MK8 and the Plain insert drive gears, however, the contact between the idler and the body is due to the idler bearing axle being a bit undersized. Rapping a layer of masking tape round the axle might do the trick if there is room.
Wow, thats an interesting setup you got there.

I have an article on the reprap forums where you can see pictures of the kind of cooling system I'm using.

However, there is 'room' for improvement, that is, I can make the room inside the cooling part smaller so it directs more air along the PEEK part of the hotend, to keep it cooler.

Since air moves around a round object in a nice flow (goes around it without much trouble) it should theoretically also cool the backside. But when I make the room around the PEEK part smaller, this will surely improve :)

I'll keep you updated. I have fixed the hotend a little bit this evening, sweating with my tools in my room until it was done and it works ok for now. Will try to print tomorrow and calibrate again (since I moved from 3mm to 1.75mm and I notice more sagging in my bridges now, and I think retract is more needed with 3mm filament, it seems to retract too much with the 1.75mm, I've let the retract the same, so tomorrow I'll lower it).

Maybe you have some tips on changing settings when you go from 3mm to 1.75mm, besides the logical setting of filament width :)

Printing with a 0.5mm nozzle.

Oh, and here is the forum post:
http://forums.reprap.org/read.php?177,230578,299806#msg-299806
I've made a comment on the forum post pointing to the fan as the weak link.
The heat creep in the PEEK insulator points to the fan not pushing air fast enough.

I also watched the video for the Airtripper extruder you posted on youtube and can point out that the drive gear has enough grip to push filament to more than 4KG of force without slipping.
I would suggest using a file to remove some obstruction so that you can get better contact between the idler bearing and drive gear. Wrapping some masking tape round the idler hinge screw (held by the strut) may work as an easy fix.
Really nice design, I've been looking at it for months and now, finally, this week, I have ordered EVERYTHING to make my machine eat 1.75mm filament from now on.

I love how the geared extruders work, together with 3mm filament this is wonderful together, but, it was time for me to start working on something new.

This will: A) make my new machine much more stable and B) my old printer will inherit all the 3mm goodness of my new printer ;)

Will let you know how it eventually works, I really hope my push-fittings for the PTFE fit well.
Oh, and that MK8 filament driver better perform!! ;)
Any advice on how to get the spring assembly in place for the tension bearing? Maybe my screw is just too short. I am having trouble.
Springs don't really work with this extruder design, you need to be using a piece of rubber tube as shown in the picture.
The rubber tube gives free space to allow easy idler removal and assemble when you need to change filament.
I have a SeeMeCNC Rostock Max. It turns out that the 1/8" 4mm BSP Push Fitting bowden tube connector listed with this extruder does not come with the hotend kits from SeeMeCNC. If however a person wants to use the 4mm PTC quick connect fittings that come with the SeeMeCNC kit, it seems that the other hole will hold one well enough if enlarged slightly on the outer few mm. I just figured I would share. I have not tried it yet. I figure either the design would need to be mirrored or the stepper direction would need to be changed in the firmware.
Ok. Black ABS sucks. The ends of the mounting area breaks off a bit easy for me. You may want to enlarge the bit of black plastic at the to try to strengthen it up or avoid black filament for the part and mark it up with a black marker.
Slic3r version 0.9.10 gives me this message about the idler.stl file. I don't know what message is about, but I will just try to print it and see what I get.

"Warning: The input file contains a hole near edge 16.000000,33.000000,6.000000-7.300000,33.000000,6.000000 (not manifold). You might want to repair it and retry, or to check the resulting G-code before printing anyway."
I use either Skeinforge or Cura to print the extruder and get the best results from Cura.

I've tried to use Slic3r but had issues with infill leaving empty gaps.
I've not seen this error before.
Sadly, my luck with Cura has been really bad for anything with bridging. I suppose I could turn on support material and try it in Cura.

When it comes to the warning, maybe it is nothing. It looks like everything printed fine. I am running Linux and it seems to me that the Linux users may actually get some different errors than the Windows folks. I imagine different slicers may react to the hole (if it really exists) differently.

By the way, thanks for the lovely design. This is the first extruder I have printed. Now I just have to get the other bits. Mine will be going on the ceiling of a Rostock Max I got from SeeMeCNC.
Is there any particular reason BSP fittings are used? NPT is much easier to find on this side of the pond.
Thanks for the awesome design!
lmao i was just thinking i wonder if airtripper has upped scad file yet... upped 4 hours ago :) thanks for the design
looking forward to the scad file so i can change to 3mm and also change mount holes to 5mm
Where's the SCAD? (: I can only find 1/4 BSP around here, not the smaller one
The SCAD file will be uploaded soon after I've checked it. I'm going to see if it will work with the customizer.
Would be highly appreciated. I would like to use a slightly modified (mounting only) version on Reprap Morgan
Still no SCAD?
SCAD file uploaded
Could you please develop a version for 3mm filament as well, this would widen the market for your extruders.
I've worked out how to get a 3mm filament version to work with this design and it should be out shortly.
There will be a standard type and also a type to fit a planetary stepper motor.
I'd like to see that too. I have a MK7 drive gear for 3mm filament.

However, I'm currently having more problems developing a nice J-head holder for my Prusa i3 carriage that I'm working on.. Theres not so much bowden J-head carriages around and the ones existing don't work for me :(
Hi Ohmarinus, I have a 'tray' that bolts onto the Prusa i3 X carriage that the J-head slots into and a more traditional extruder sits on top of that, this may work for you, it came from thingiverse somewhere.
If you search for this it may work for you otherwise I will have to ask the guy who printed it for me where he got the design from. The Bowden head will just then sit on top of the tray maybe offset vertically from the top to match the M4 mounting holes and then just feed into the J-head.
I Think I found it!!! Is it this part?

thingiverse.com/thing:58451
Wow, it would be great if you could tell me where I can find that. I'm willing to try everything, however, I can even get inspiration from that part and eventually develop my own solution.

Let me know if you find out where I can find that.
Hi it is this part:
http://www.thingiverse.com/thing:104649
You could easily mount a bowden adaptor to the top of this!
Or you could just use this:
http://www.thingiverse.com/thing:108273
Thanks, I am checking them out, however, the part that I found from thinkyhead allows me to add a lot of things to it and already has a really good grip on the J-head without any other 2nd part connected to it.

I'll try out various methods :)
Hi Ohmarinus, There is now a bowden adaptor that would fit on the flat tray for the i3, I don't know if you have seen it yet thingiverse.com/thing:128900 , it might need washers or an extra nut and washers to bring it up to the height of the J-head which pokes above the flat top such that it locks into the J-Head hole in a direct extruder.
Hi, thanks for your reply, meanwhile I have started working in Rhino and going completely intelligent on designing the perfect modular carriage ;) Including a good bowden mount (very good actually) that also has a double function as you can connect a 40mm-fan duct on it to cool PLA and it has a built-in 30mm hotend cooler custom fit for J-heads.

The mounting system is specially made for the 'single plate' i3 X-carriage version, and is still a work in progress, but it is looking VERY promising :)

So happy to finally have Rhino working here so I can go completely wild on designing!
Hi Ohmarinus, please post your bowden mount when it is ready, and maybe can it be set up for a dual extruder too? Fans are necessary for ABS as well.
Cheers
Ian
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