In this video let's look at the slightly unusual but very cool geeetech A20M. I want this to
be a non-boring look at the printer for people who are thinking of buying it so this will
be quicker than your standard unbox and build video but let me know in the comments what
you think about the style because I personally can't stand long build videos, but maybe just
me. Anyway.
If you've already seen my video here you will know I picked this up with my own money for
around half price in the black friday sales at banggood which is how I would recommend
buying it as it's very expensive at the normal price.
So - This is notably not a new printer, in fact it's been out since at least may 2019,
but seems to have flown under the radar to some extent, probably for various reasons
not related to its main feature - it can print in two colours.
many printers can print in two colours by means of two separate hotends, but this one
has a special hotend with two inputs and one output, and some clever stuff inside that
allows that to work.
There are two models in this line up, the A10 and A20 both of which come in one, two
and three colour versions. Going off the headline features of this printer
quickly, it's a bowden printer meaning the extruder isn't on the hotend, there's a heated
bed which is slightly larger than an ender 3 at 250mm build size in all three dimensions,
the max hotend temp is around 240 in my opinion - this being due to a non all metal hotend,
there's a 4 line LCD and the nozzle is a 0.4mm so everything is pretty standard aside from
the two colours.
Let's get into the box then.
You get a manual but I am going to be brutally honest here - I didn't like it. It felt like
mostly other than skimreading it at the start, it wasn't very helpful. You're better off
figuring out what goes where yourself, especially if you've previously built another printer
of this style like an ender 3 for example.
The printer does come mostly assembled too compared to an ender 3 or v2. This is the
frame already put together and for mine it didn't require any calibration, the belt was
OK out of the box too. Nice to see even the z screw already installed as that's something
a lot of people struggle with on enders.
The bed is a bit disappointing. I understand the printer initially came with a coated glass
bed, but it seems like they've cheaped out with this...sticker thing. It works OK, but
I don't like it. Annoyingly it's an odd size too so getting a glass bed is a challenge,
if at all possible. Please comment if you know anywhere that sells them.
This is essentially the rest of the printer. The base is pretty robust with a metal case.
It's well built and not cheaped out on, although notably the screen lights up when you move
the bed...not uncommon but still not sure why we haven't fixed this yet.
So All you need to do here is screw on the frame from the bottom through two holes.
Of course I couldn't just do that without losing the screws into the base box, but every
mistake is an opportunity, so while I did have to waste another 15 minutes removing
the bottom to get into this to get two of my screws back, we do get a look at the board
and screen.
Side note, if you're actually assembling one of these, it's easier to not lose the screws
inside by having something to balance the frame on, this creality glass bed box was
the perfect size.
The board is an 8 bit atmega chip with soldered on drivers that appear to be nothing special.
They aren't silent at all.
Here's the PSU specs if you're interested.
I had to remove the LCD too annoyingly to get my last screw back. I really suggest not
dropping the screws in, in case you didn't already get that idea.
Back together, you have to next put the bowden extruders onto the top of the frame. They
are a bit of an odd design to me, being used to the square-ish ones you tend to see elsewhere.
They're a bit like the BMG style ones I guess, they should work well in theory but a lot
of people seem to have a problem with them. Anyway they go on the frame with those normal
nut things that you always get for mounting.
After that the spool holders go on, you have to use the front two holes, ignoring the back
one. I actually don't really like this setup, it makes it quite tricky to thread the filament
in, it's possible I haven't got it quite right but the instructions are not much help. We'll
get onto the filament runout sensor in a moment.
This thing is a strain relief sort of setup for the hotend wires I think. Nicely all the
hotend wires are in one plug block so once you've added this part, you just plug the
lot in, then you're supposed to zip tie it all, which I guess stops the plug coming out
while the hotend is moving around. Seems ok.
The printer comes with some "levelling paper" which was useful as one leg was slightly shorter
on the printer base. Nice of them to think of that.
Finally just a case of plugging in the various wires and noticing that the z limit sensor
was really hard to plug in. Everything else was very much like building an ender 3 including
the x axis wiring which was almost identical.
Now the filament sensors. They're supposed to go on these screws here, and it's not too
hard to work out how. I think maybe you should put some tube here somehow but I haven't.
Either way, something like this.
Next up just checking x, y z work, which they do. And then testing the extruder, you can
hopefully see the gear moving there.
My model for reasons unknown didn't come with an SD card, so this made initial tests even
harder than usual as I had no test models. Bit annoying as it meant I couldn't test anything
until I'd setup cura.
Luckily cura has a profile for the a20m so it was pretty easy to get to that point. Add
an sd card with some gcode on and we can mix in the firmware using the on screen menus
to test both sides of the nozzle. All good, and again you may have seen the result in
the other video. If all you want to do is gradients or mixes
or manual colour changes using the menus then you never need to worry about extruder settings
on this printer, but of course you will want to so I'll cover it very briefly here.
The a20m profile comes set up with two extruders and the menus in cura will look slightly different
due to there being two tabs, and it's worth noting that some settings seem to be shared
across both tabs while others aren't, so it takes a bit of getting used to, which I haven't
really yet myself. There's a dual extrusion section which is the main thing to look at.
You almost certainly will realise on your first multicolour print that the dual extrusion
settings don't work that well for this printer. I've linked below to a profile I managed to
make based on some help from a user on our discord channel, this is how I managed to
get a decent print as you can see here. The long and short of it was that retraction and
purge lengths on this printer have to be really quite huge to get good results.
And that I guess brings me to my feelings on this printer.
I know other youtubers have previously reviewed and played with this printer and generally
the concensus is that it's not a beginner printer. I both agree and disagree. There's
intrinsically nothing hard about this printer in terms of building or using it, but at the
same time, I am glad that it's not my only printer and that's because of a few aspects.
It's noisy, it strings badly without high retraction, it's a pain to load compared to
other printers, the build plate is an odd size, I'm even going to complain that the
levelling wheels are too small. But on the flipside, it does work. I've not
tried it with anything but PLA yet, but I have had very little problems with it so far
on PLA. It hasn't blocked surprisingly, and the print quality is actually very good even
at higher print speeds. Single colour printing is fine too, and there is a potential solution
I've not yet looked into for the size of the purge tower which is a thing called a purge
bucket which I may cover in future. Of course purging is also a constant per layer, meaning
if you print ten of something it will purge the same amount as one, so this means that
one small two colour model is actually the most wasteful way to print on this particular
printer.
And do remember that you have the firmware based mixing too which gives some astounding
results as I already covered.
So I guess that's about as close to a balanced review as you're going to get. My advice?
Buy it as a second or third printer. Or buy it with a view to also get a cheap ender 3
or something. It's definitely a good printer but you will wish you had another, I'm sure
of that.
Anyway that's about all I wanted to say so thank you for watching, as usual please comment
below, also please consider subscribing, joining us on discord, links all below in the description.
Thank you for watching!