I’m Tom and this is my review of the RepRapElectro RAMBo.
So i have used a few different 3D printer mainboards so far, ranging from the dinosaur
of boards, the RAMPS, over the super-cheap Sanguinololu and the newer Melzi to the bread-and
butter Printrboard. Now, what i have here today is the RAMBo, which is kinda of the
nicer and newer version of the RAMPS. And just like the RAMPS, the RAMBo was designed
by Ultimachine. Since every manufacturer changes a couple of things when they make the boards,
and so did RepRapElectro who sent me this board, i want to start out with what the reference
design and hence the official RAMBo looks like and then move on to whether or not RepRapElectro
are doing a decent job of manufacturing it. This is Rambo. And this is RAMB-o.The design
centers around the fact that this board is basically an Arduino Mega 2-5-60, which is
the center part, along with five stepper drivers down here and the full set of corresponding
power transistors and thermistor inputs for a full dual extruder setup. In fact, there
are a total of five power outputs, two of which are limited in their output current
by either the board design or the transistor used, so those are labeled as fan outputs,
which makes sense. You can still hook up a _really_ beefy fan to the fan 0 output, though.
Staying with the power components, the RAMBo has three independent supply rails instead
of the two typically seen on the RAMPS or just one on some other boards. Which means
that you can use different power supplies and voltages for each / the heated bed, the
hotends and the motor drivers. Or you can tie them together and use one beefy 12V or
24V supply for all parts. The supply for the logic part of the board, like the ATMEGA and
the logic side of the motor drivers is provided by a step-down converter, which is a nice
step up from the regular linear voltage regulators. Less heat, more efficiency and generally a
_better_ design choice. Now, right next to the buck converter you might notice some parts
that you rarely see on 3D printer electronics: fuses. Now, they might sound like there’s
not much to get excited about here, but instead of using no fuses at all or using self-resetting
polyfuses which often cause more issues than they solve, the RAMBo uses _real_ fuses. One
for each voltage rail - the most loaded one for the bed gets an automotive blade fuse
and the other two rails are each secured by one of these nano fuses, which come in these
holders, so they’re easy to swap out in case something should have gone wrong. There
is also some reverse polarity protection built into the RAMBo’s design. Overall, that’s
a really nice power design so far. Moving on to the motor drivers, you might
notice two or three things here: One, the driver chips are soldered directly onto the
board.This is good and bad in a couple ways. It does allow for better cooling, if you wanted,
even through the bottom of the board, but it also means that you can’t really replace
a blown driver. Now, i haven’t killed a driver in a long while, and if you’re a
tiny bit careful, you should get along with this just fine. But i know it’s going to
bother some people, so for those, there is the option of hooking up an external driver
through these pins. Two, there are no microstepping jumpers, like on the RAMPS and pretty much
every other board. That’s because microstepping is controlled by the onboard ATMEGA microcontroller
via software. Which i think is pretty neat, but usually you just set that to 16 times
microstepping anyways and be done with it. Three, there are also not fiddly potentiometers
for adjusting the current to each motor. Now that is a huge step forward, because just
like microstepping, you can now set the current through software. There’s an DAC chip onboard
that does the job the potentiometers used to do. So no more adjusting them that tiny
bit clockwise to keep your motor from skipping and then realizing you have set it 1.1V instead
of the 0.8V that you read were recommended somewhere. With this, you simply set it and
forget it, and in case you ever need to adjust the current, you can do so in a reproducible
way. The drivers themselves are the classic Allegro
A4982 chips, which work well for normal printers, even if they are not quite as powerful as
the newer Texas Instruments DRV8825 chips. The motor output for Z is split into two connectors
which can supply two motors in parallel for printers that use two motors for their Z-axis.
Moving on to the logic part of the RAMBo, you’ve got the option of hooking up all
six possible endstops and four thermistors. As far as expansion options go, you get a
serial port, SPI, analog pins and a generic expansion header, so if you want to, you can
easily hook up an LCD screen or an SD card reader. Also on board are in circuit serial
programming headers for both the main processor as well as for the tiny one that is only responsible
for interfacing with your computer. So in case you manage to screw up the bootloader
and brick your board, you can always recover it if you have a programmer at hand.
Now, i think that covers what the RAMBo design can do. Hint: It does practically everything
you’d possibly need unless you’re thinking about using that insane E3D Kraken watercooled
quad-hotend. There are specialized boards that cater to those needs, but for everyone
else, the RAMBo is a pretty good choice. So how well did RepRapElectro do when it comes
to actually manufacturing the board? As it turns out, pretty well actually. The build
quality is absolutely perfect as far as i can tell. All the solder joints are done properly
and the only thing that _isn’t_ spot-on is this one transistor that is off by half
a millimeter, but of course, working just fine. RepRapElectro chose to use these green
detachable screw connectors, which seem to be a very popular option these days and generally
work well. Just keep in mind that these are running right on the edge of their current
capabilities for the connector for the heated bed, as they are only rated for 10A of current
- that is, when you go by UL standards. IEC would rate them for 15A, but either way, if
you have a really beefy heated bed and want to make sure that stuff isn’t going to start
smoking, your best bet is to solder the power wires directly to the bottom of the board
on both the power input and output connector. The connectors for everything else are nice
locking-type connectors, and the matching plugs come with the RepRapElectro RAMBo. Though
they _are_ crimp connectors, so you’ll get the best results with those connectors if
you have the proper crimping tool. They also include an adapter board for the SmartController,
which is the full package of a big LCD screen, an encoder input and an SD card reader. You’ll
_also_ get three mechanical endstops, along with pre-crimped connectors and wires for
those, as well as some wiring for two thermistors. And a USB cable.
The other spot where they deviate from the reference design are the power mosfets, those
are marginally less nice ones here. But they are still very, very decent transistors and
a much better choice than for example the ones that are used on the RAMPS. The RepRapElectro
RAMBo is also not the very newest revision 1.3, but the older 1.1b version. The only
_big_ difference between those is that the USB port is isolated from the rest of the
board on the newer versions. Is that a good addition? Yes, it is. But is it something
you really need? No, and the RAMBo 1.3 and 1.2 are some of the only or even _the_ only
boards that offer isolated USB, simply because it rarely ever becomes an issue that you’d
need to worry about. There are a couple of extra protective measures on the newer RAMBos
as well, and those basically protect the board against user error. So as with every other
board, you should take care when handling it.
Now, the special thing about RepRapElectro is that even though they are a business from
Canada, the actual boards are shipped directly from Hong / Kong. They are still made and
tested to the standards RepRapElectro sets, but you will have to wait for the HongKong
post to deliver your package, along with possibly dealing with and waiting on imports and customs.
HongKong post isn’t quite as slow and upredictable as the China post, but you can still expect
to wait on your board for three to six weeks. Now, because of this, the boards from RepRapElectro
aren’t quite as expensive as locally-grown RAMBos, which are $170 plus shipping and tax
or imports from Ultimachine, but also not quite as cheap as the you-don’t-know-what-kind-of-components-you’ll-get-board
from some of the Aliexpress sellers including Geeetech, which start at about $80 including
shipping but plus imports. RepRapElectro is selling the RAMBo for just
below $100 including shipping as an introductory offer, the regular price will get a bump to
$120. Both plus imports. Either way, i think it’s still a pretty good deal if you’re
in the market for a RAMBo board since you’re essentially getting a high-quality board for
not much more than the ones from Aliexpress. So, to sum things up: Is the RAMB-o a good
board? Yes, very much. It’s a well-designed board that i’d put in the upper middle class
of RepRap boards since it really is a rock-solid design with a couple of nice features that
will make using your printer a good bit more comfortable, like being able to adjust the
motor current in software. It’s not one of new fancy 32-bit boards and doesn’t have
an insane amount of extruder outputs, but it’s a very good choice for 99% of all users.
Will you want to order it from RepRapElectro? I would. Yes, it’s going to take a while
to get to you, but other than that, there really isn’t anything to complain about.
RepRapElectro really seem like good folks, they credit Ultimachine properly and are even
working on releasing a complete, GNU FDL-licensed user manual for the RAMBo. Plus, it’s kind
of good deal, as you basically get to choose between a simple Printrboard from PrintrBot
and a RAMBo from RepRapElectro at currently the same price.
So that’s it for today, as always, thanks for watching. If you stuck around to this
point, congratulations! Let me know what you thought about the length and in-depthness
of this review in the comments below.