Build your own 3D Printer: Everything about extruders!

Build your own 3D Printer: Everything about extruders!

Hey everyone, Tom here, and when you’re
building a 3D printer, you’re going to be faced with a lot of options when it comes
to the core of the machine: Its extruder and hotend. So first off, the extruder and hotend are
two distinct parts and their names often get mixed up: The part up here that pushes the
plastic filament is what’s called the extruder, technically, it’s just a feeder, but “extruder”
is the name that stuck. The hotend – again, what a creative name – is the part that melts
the plastic and provides the fine nozzle for it to come out of. In this video, we’re
going start with the extruder and all the choices you have there. Well, actually, before
we get into that, there’s one crucial decision to be made overall: 3mm or 1.75mm. Filament
comes in two different sizes, with 3mm being the more traditional size and 1.75mm as the
newer option, well, as long as you don’t count in tech years, and that size can perform
just as well with cheaper components, and we’ll touch on that in a second. There is
not much of a difference of the print quality you’ll get when it comes to the two different
sizes, but it’s looking like 1.75mm filament is becoming the more popular and the new “standard”
size. The smaller 1.75mm filament relies more on the filament being pushed quickly and with
less force, while 3mm filament moves much slower and with a greater force from the extruder.
Both of these parameters are different by about a factor of 3. The larger 3mm filament
is better for super-soft flexible filament, but the newer 1.75mm extruders can print it
just as well as they support the filament path much more tightly now. Also, of course,
don’t get shafted buying filament by the meter – 3mm filament will get you roughly
3 times more plastic per length as 1.75mm filament, but it should also be 3 times more
expensive per meter. Should. Sometimes you’ll get charged just as much for 1.75mm per length,
which is part of the reason why buying filament by length isn’t really the best option anyways.
I personally run all my printers on 1.75 just because i tend to have filament in that size
and it just kind of stuck. So, that’s the first option you’ll have
to pick – while you can convert a 3mm extruder to 1.75mm, which i show you how to do, here,
you should get the right size right off the bat, also you can not convert a hotend from
one size to the other. The next big choice is going to bowden or
non-bowden. “Normally”, you’ve got your hotend strapped right to the extruder, often
even mounted right in there, but, if you’re going for a bowden setup, you’ll have the
hotend decoupled from the extruder with a teflon tube. This means there’s going to
be less weight to lug around as the hotend moves, but it also means that distance between
the extruder and hotend is going to introduce some backlash to the filament drive. If done
and set up correctly, it’s not going to be a huge difference for your print results,
but a bowden will always tend to print a bit sloppier if you give it the same starting
parameters. Of course, the lighter carriage with only the hotend on it will somewhat make
up for it as it allows faster acceleration with weaker linear guides and belts, which,
in turn, allows you to get crisper results with the same parts.
So next up for the extruder, it’s geared vs. non-geared aka direct-drive. And actually,
that decision is rather simple: You # need a geared extruder for 3mm filament, while
1.75mm works with a direct-drive extruder for 99% of all use cases. Geared 1.75mm extruders
that use the common NEMA 17 motors are rare, with the E3D Titan, which i’m testing right
now being a notable exception, but the gearing doesn’t hurt, either. You should keep the
diameter of the filament drive gear in mind for direct-drive types, as they act like a
rack and pinion with the filament, so the larger 12mm gears will output less torque
before the motor stalls when compared to the smaller 9 or 8mm types. You can’t just make
the filament drive gear infinitely small, though, as that will reduce the area the filament
is in contact with it and just make it grind through the plastic instead of gripping it.
Again, the 8mm types are a good middle ground there for both 3mm and 1.75mm filament. The
tooth profile also contributes a tremendous amount to the grip a drive gear will produce
– each gear should be sharp, not too deep and have reasonable spacing to the next one.
If the teeth are too sharp and deep, they will simply shave off plastic bits from the
filament instead of gripping it, if they are too dull, like regular spur gears that are
improperly sometimes used, they will just slip on the plastic. And if they are too fine,
like ones that are made with an M3 thread all around, they will have a huge tendency
to clog up with the tiny plastic particles you’ll inevitably create when driving filament.
Coarser profiles tend to have a bit of a self-cleaning effect. I prefer a profile that’s close
to something like an M5 screw, but slightly finer or coarser ones will also work just
fine. What also helps with filament grip are the
trendy dual-drive extruders, inspired by the Bondtech, that grip the filament from both
sides with a driven gear instead of having a flat idler bearing pressing on it from one
side and the drive gear only on the other. This tech is entirely optional for regular
use, but if you do get an extruder like that, you can be sure that you’ll never have grip
issues that don’t stem from a clogged hotend. So the rest of the extruder’s features are
more or less comfort features that make life easier. One of the big ones is an idler that
easily unlocks or swivels away and allows you to remove and insert filament without
unscrewing anything or having to drive the extruder motor to pull in the filament for
you. What can also be helpful is easy access to the drive gear from a cleaning perspective.
While i haven’t had stripped filament for many years now, when you’re getting started
and maybe haven’t tuned in your printer all that well yet, you might end up grinding
through the filament a few times as the extruder fails to push it through the hotend for whatever
reason. In that case, you really don’t want to have to disassemble the entire extruder,
so a spot where you can get to the drive gear just by opening up the idler or having the
drive gear entirely exposed somewhere might save you good bit of headache. And the last
bit should be size and mounting options. While size typically doesn’t matter as long as
it fits, you know, it’s more about technique anyways, the mounting options of a particular
extruder might be a big selling point. While RepRap-style printers use a de-facto standard
mounting pattern, newer designs often can’t easily fit to that. While these mount on top,
some printers like the Prusa i3 family, have mounts from the side, and unless your extruder
of choice fits directly to those hardpoints, you’re going to have find or design and
print an adapter, which can be tricky without a functioning 3D printer. Of course, bowden
extruders typically mount to the printer frame somewhere, so that’s a non-issue there.
Now, the good news is that there really aren’t all too many extruders out there that are
downright bad. I’d even go so far and say if you’re going for a 1.75mm, PLA-only printer,
your extruder choice can be based entirely on comfort features. Or looks. Depending on
what you’re going for. OctoPrint is a powerful, free open-source
print server that runs even on something as small as a Raspberry Pi. Check out Gina’s
Patreon campaign to help keep the project funded now that her previous sponsor has dropped
all support. Head over to to learn more.
In the next video of this series we’re going to take a look at what options you have when
it comes to hotends and what you should know for picking the one that’s right for you.
Thanks for watching, please leave a thumbs down or thumbs up on this video, use the Amazon
and ebay affiliate links from the video description for your 3D printing shopping trips and don’t
forget to subscribe! I’ll see you in the next one.

About the Author: Michael Flood


  1. Huh, is 3mm really the most common? I've thought it was always 1.75mm, I've mostly been using bowden printers though.

  2. so BQ completely abandoned Octoprint development? What future do we expect for it? I'm going to support via Patreon…

  3. Do make a video on Delta printers. Calibration, firmware and most importantly about determining their height and length ratios and build volume.

  4. Thanks for another superb video Tom.
    I'm seriously considering the E3D Titan, now I know you have one to review, I will wait till I see your video on it … can't wait.
    I would also like to buy a Big Box, but I am looking for something with a bigger print volume, something like the GMax 1.5 XT+. Ideally I wish E3D would do something that size.

  5. Great video Tom. I got my E3D Titan on release too. I plan to fit it, along with an E3D v6, to my BQ Prusa i3.

  6. I usually always agree with you Tom, but choosing between a 3mm and 1.75mm Filament extruder makes a big difference. 1.75mm Filament works great with standard Polymers, however specialized FIlament usually always works better with a 3mm. PVA as a tricky polymer and works betterr in 3mm than in 1.75mm. Also as soon to be published research shows, 1.75mm Filament tends to emits a higher amount of particles than a 3mm Filament.

  7. Some finer finer points on the 3mm vs 1.75 mm exist ofc, but this video is spot on for first custom build ones :3

    Oh, you kept reading to find the finer points? They are something like …

    – 3mm is more rigid than a 1.75mm counterpart. So if you have a brittle filament lying around ( mediocre PLA or a novelty filament) a 3mm part tolerates only rather careful handling before snapping. Don't try to change spools on 3mm filament , you may have a very snappy time D: (I speak from personal experience)

    – 3mm may require a more delicate extruder control, and a heavier duty hotend because of the larger mass being heated.

    – 1.75mm buckles easier . So a 1.75mm flexible filament is hard to extrude … it buckles and clogs in any slight gap that it's not perfectly directed. There are good 1.75 extruders for flexible filament though. And with 1.75 becoming more popular more filaments are available in both diameters, so there is more flexible 1.75 filament spools to choose from.

    – If you are gonna print BIG BUILDS you need 3mm for 1.5 reasons:
    1) speed of printing. A 1.75mm extruder needs to go faster for the same material per second being fused.
    1.5) You don't need the detail of a 0.3mm nozzle, so you may go with a .8 or even 1mm nozzle. Which will give you smoothier printing … and faster printing. But faster printing means faster extruding. A NEMA motor can only go so fast! …

    – For small prints the finer control on a 1.75 mm direct drive and small nozzles it may be worth it. Its kind of the opposite of the previous point i made.

    ¿ New to 3D printing ?
    3 or 1.75 mm filament ?
    Whatever your local distributors have. Whcih most likely will be 1.75. And its getting way more common and available.

  8. Built my own and nothing but issues due to the non flat bed. Over 2 years I have tried to get anything flat to arrive and UPS/USPS always bends them. I give up and I am about to buy a knock off of the Flashforge Creator Pro and that way if it comes bent it is on the manufacturer since the bed will be inside a fully enclosed metal case. The only way I could ever get anything for the bed to arrive flat, besides buying an entire printer, is if the item was shipped in a wooden frame.

  9. LOL, OMG you delivered that joke totally deadpan and didn't laugh. I signed up to support Gina the other day. What about Patreon for you? There are 3D printing channels that provide much less than you do, that have Patreon.

  10. Great stuff Thomas! I am embarking on a DIY large printer build and gathering info from all sorts of resources. This is a perfect merger and delivery of the info out there! Thanks and looking forward to more from the series.

  11. This is sad to hear. I will become a patreon for Gina Häußge. I am working on a project right now tom that I am using a pi zero as the basis of octoprint. (Octopi). I will mention this on my next Octopi-zero video. Thank you for spreading some awareness concerning this project. Most people think that open source is 100% free, with that said the devs and the people who contribute their time have to live as well. Since they all live in the real world, financial backing is a must.

  12. Excellent review as always please keep them coming. Looking forward to the review on the E3D Titan Extruder hopefully you will include super soft filament such as Nin*****x

  13. On your point about being tricky getting an adapter for your extruder… Check out for people who will print things for you for a small fee. That's how I'm getting my parts made.

  14. 1.75 * 3 is not 3mm 😛 its more like 1.75*1.75
    So its 75% more plastic per meter, not 300% as you said(3 times).

  15. Thomas, You should consider an DIY episode of building a 3D printer from scratch (buying and selecting components) for say less than $600 (or what ever). Component selection, assembly and testing.

  16. Hey Tom, do you have a link to the white bowden extruder used in this video (The one on the metal extrusions)?

    Thanks, James.

  17. I am really enjoying this series. I have my OctoPi, and RAMBo ready. I'm printing a delta frame on the printer here at the University of Alabama. I hope to be up and running by the end of May! Great vids Tom!

  18. Thanks for the excellent video. I would like to ask something about bed adhesion. After your suggestion I was using UHU stick for bed adhesion. It was very good for both PLA and ABS. In my last purchase of UHU stick, I have seen that it has a new formula badge on it and It performed very poorly with ABS. Did you notice anything similar?


  19. Firing up the new titan on a rigidbot tomorrow!!!!!!! I also am trying out Dyze design extruder and hotend combo on another printer

  20. Hey Tom, is there any way I could contact you via email, so I can do an interview for a college paper?

  21. Hey Thomas, regular viewer of your content. Quick question, has anyone ever tried using an RJ45 connection as a quick connect for 1. Heater block, 2. Thermistor, 3. Fan? Trying to find a way to quickly connect and disconnect these parts and the local hardware store (HomeDepot in Canada) suggested RJ45 network connectors. I'm sure it will work for the thermistor and fan as its not drawing a lot of current, but worried about the heater block.


  22. Are you ever going to do a video on that all metal delta that's always lurking in the background? If you have can someone shoot me the link?

  23. You said that 3mm filament needs a geared extruder. Ultimakers have been using direct drive on 3mm filament for years with no problems.

  24. Hello Thomas, I'm in the process of buying a 3d printer for the first time, I have a big roll of filament 200meters, it is flat about 5mm x 1 mm, I would like to know if the extruder will be able to feed that type of filament or it will need to be modified. Thanks in advance

  25. i have a kossel xl with modified 12mm magnets on the diagonal rods. smoothieboard, 1.75
    I struggle to get the speed up as its one of the "original" direct china extruders… do You have a prefered printable (or to be bought) geared extruderYoiu can recommend?
    Thanks for Your videos 🙂 appreciated..

  26. So I bought an i3 kit years ago and am pretty happy about it, but I would like to get into flexible filament. The current i3 has a direct drive for 1.75 mm. After looking into things a bit, I'm thinking about getting another i3 kit for 3mm flexible filament. I also am going to maybe move to a bowden extruder on the old printer as its just for PLA prints and I hear that can really make a difference. I'll convert the direct drive on the new i3 for 3mm use then. Are there not really 3mm direct drive extruder on the market anymore? I see lots of listed 1.75 units, but nothing listed as 3mm. Or maybe I just need a gear hob replacement for 3mm use and get a hotend nozzle for 3mm? If Anyone has any tips or can point me in the right direction, that'd be awesome.

  27. why don't they use a type of rubber to grip the plastic in the extruder instead of metal teeth? or would it just slip? but in that case, just apply more pressure.

  28. "You cannot convert a hotend from one size to the other" — that depends on the hot end — SeeMeCNC made a hotend with a teflon liner that goes all the way into the melt zone — converting between the sizes is as simple as swapping out the liner for one with a different inner diameter. (They provided liners for both 1.75 and 3mm.)

  29. What is a good hotend that has a mini motor in it but that is also light enough to fit on a mini delta printer like a 101 hero? My hotend is terrible but in general it would seem that the rest of the 101 hero components are ok. I don't want to throw it out… just upgrade the hotend without having the boudin thing where the motor is on the side. Any ideas? I remember you reviewed the tiny deltaprinter mini hotend but if I am not mistaken that one does not have a motor on it.

  30. You mentioned stuff about the drive gear profiles but didn't point to any specific drive gears as recommendations for building your own printer. Looking around online, I saw things but ultimately didn't know enough for what's good so I decided to come back here and ask you: any specific drive gear recommendations?

  31. Is there any advantage in having the effectively more steps per mm extruded that gearing gives if you use 1,75mm filament?

  32. hey tom, what are your thoughts of using a direct mount extruder and still mounting the stepper on the frame utilizing something like a cable drive or mabe a pto like shaft to get the effects of a bowden without the hassels of the tube?

  33. Tom. So when using the 3mm; do you use or can you use a larger nozzle and speed up your prints?
    Or should my question be can you go faster with 3mm without sacrificing quality?
    Thanks for your "to the point" vids.

  34. Hey Tom, have you ever encounter an extruder that refuses to calibrate? Doesn't matter the e-steps it always extrudes about 50mm

  35. I converted my anycubic i3 mega to direct drive and all I gained was trouble. flexibles printed fine and still print the same (at 35-30mm/s) maybe 5mm/s faster. same stringing which was close to nothing before. just more ghosting more issues (so many issues related to direct drive) and more heating on the extruder since now it's a tiny stepper. not to mention repairing and messing with my printer needs me to take the carriage off and unscrew the titan and take out my e3d v6 from there.

Leave a Reply

Your email address will not be published. Required fields are marked *