Honest review: The RepRapElectro RAMBo

Can you tell me if Delmar Berry lives here?
Well, that’s something this board isn’t ever going to ask you. Find out if the RAMBo is at least a bit more subtle than Rambo.


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 ADC 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.

Get a RAMBo at http://reprapelectro.com

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