Hi folks. I have been considering building a prusa mk2 for a while now. My idea was to buy a single original to support the project then use that to build another (and then maybe more). When i looked into the ‘vitamin’ aspect of the machine i was struck by the cost of the motherboard. I currently am using a cheap as chips acrylic prusa i3 clone and have been rather amazed by what i can get it to do.
The ramps 1.4 motherboard with arduino mega(clones) it uses cost about £15 from aliexpress Compared to the £100 for the rambo mini the mk2 uses.
Could anyone explain what the advantages are of using one of these high cost motherboards? I’d imagine like with anything its the build quality for one but seeing as i have been using the hell out of my printer for about a year and a half and had no problems(apart from the memory card reader becoming rather temperamental)Are they really worthy of the massive cost increase?
Many thanks.

I wouldn't call the Rambo Mini a luxury motherboard, but it offers these advantages over Arduino/RAMPS:

• An adequate on-board 5V regulator that won't overheat when you add a graphical LCD, unlike the one on your Arduino.
• Software-controlled stepper motor current - no more pots to twiddle.
• 24V compatibility. Useful if you want to drive a bed heater larger than 200mm square without resorting to dual power supplies.
• I think the Rambo has higher bed heater current capacity than the 10A capacity of RAMPS.
• It will withstand some types of wiring errors that will kill Arduino/RAMPS instantly.

But the RAMBO still uses an 8-bit processor and its only connectivity is USB. Whereas if you choose a state-of-the-art board such as the Duet WiFi that I co-designed, you get all of the above plus the following:

• Super-quiet TMC2660 drivers, with up to 256x microstepping and higher current capacity for driving larger stepper motors.
• A web interface that you can use from your PC, tablet or smartphone - or all 3 simultaneously. Until you've used one, you won't realise how much nicer this makes using the printer. You don't need a USB connection, neither do you need to keep swapping the SD card between your PC and your 3D printer, because you simply upload files for printing through the web interface. There are some pictures of the web interface at [reprap.org].
• All configuration is done using a text file on the SD card, which you can edit in the web interface. So you never need to compile the firmware yourself (even though it is of course open-source). When you want to upgrade to a new version of firmware, you just download the new binary and upload it to your printer through the web interface.
• Support for an optional colour touch screen, although if you have a smartphone or tablet you may feel that you don't need one.
• Some users claim high print quality. This may be because the processor generates the step pulses at accurate ties, whereas 8-bit firmwares use the Bresenham approximation which generates steps at uneven intervals for most types of move.
• Delta printer users also benefit from segmentation-free delta motion and least-squares auto calibration built into the firmware.

There are some first-generation 32-bit boards arounds that offer some of the above advantages, but no other second-generation 32-bit boards that offer all of them.

Edited 2 time(s). Last edit at 02/25/2017 11:35AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Rambo Mini also has....

better stepper driver heat dissipation due to being on the board.
connectors have clips, so plugs don't fall out. (if you have appropriate plugs)
The build quality is also much superior

Its also the only board that genuine prusa i3 mk2 firmware binaries runs on....

Edited 2 time(s). Last edit at 02/25/2017 09:37PM by Dust.

There is not much there that warrants an 8 fold increase in price in my book.

Voltage regulator on the arduino is not a problem if you are connected to either a powered hub or a computer as +5v also comes down the USB cable. (if there even is a problem - -AMS1117 is rated at 800mA)
Pot twiddling is just as much fun as software tweaking.
you can use 24v on an Arduino/RAMPS board
10amps through the input connector is enough..if you need more make different arrangements (SSR or Relay directly fed from the PSU without connectors)
Killed an arduino?.....£6 buys you a new one
Web interface....no thanks..un-necessary complication
Text file editing instead of re-compiling....nothing in it.. Once you have the calibration defaults set in firmware they are less likely to get modified accidentally and they can be tweaked to EEPROM
Colour screen?...hardly use the existing mono screen - no benefit having a colour one
higher print quality (aledged) well maybe... but I don't plan on posting pictures of my prints and what I get is good enough for my needs
Delta bed calibration works fine as it is
Better heat dissipation?...fit a fan and keep the motherboard cooler as well - and be able to swap out a blown stepper driver and not have to replace the whole board
connectors that don't fall out? never had one fall out that wasn't pulled..
I don't run genuine Prusa Mk2 binaries...
superior build quality....Ahhh....got me there :-)

All the above is just my opinion please don't take offence. The Auruino/RAMPS is certainly getting old and newer boards will be needed to drive developments so if you feel you want to be part of that scene you will have to put your hand in your pocket.....

@dart16, you are entitled to your opinions, but some of the above are factually wrong.

"Voltage regulator on the arduino is not a problem if you are connected to either a powered hub or a computer as +5v also comes down the USB cable. (if there even is a problem - -AMS1117 is rated at 800mA)"

on a ramps 5v is from the regulator only, if d1 is in place. When 12v is applied to the regulator a circuit on the mega isolates the 5v coming over the usb.

"you can use 24v on an Arduino/RAMPS board"
Not out of the box. requires modifications. Some require replacement of surface mount caps.

"10amps through the input connector is enough.."
I disagree with your opinion here. Most standard 12v heated beds are 11amp for a start.

"Web interface....no thanks..un-necessary complication"
Strongly agree with your opinion here. Every single thing does not need to be on the internet or need a web interface!

"Better heat dissipation?...fit a fan"
Doesn’t need a fan as it has whole board for heat dissipation, that is the point. Also fans are noisy and fail.

"I don't run genuine Prusa Mk2 binaries..."
you didn't ask the question. The original author mentioned the mk2.

Edited 1 time(s). Last edit at 02/26/2017 07:09AM by Dust.

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dart16
Voltage regulator on the arduino is not a problem if you are connected to either a powered hub or a computer as +5v also comes down the USB cable. (if there even is a problem - -AMS1117 is rated at 800mA)

I have seen many tens of posts on these forums by users with exactly this issue. The 800mA rating of the regulator is ok but it's the power dissipation that is the problem. I ran some tests and I found that the regulator temperature is OK even with 15V input if you don't have an LCD connected. Once you connect a graphical LCD, the regulator overheated even with 12V input. YMMV, it depends on how much current your LCD backlight draws.

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dart16
Pot twiddling is just as much fun as software tweaking.

Maybe for you it is, but many user struggle with it, either because they don't know what voltage to set (the relationship between VREF and motor current depends on which drivers you have) or because they blow the drivers in the process. I think that most users of plug-in drivers have no idea what current their motors are running at. Software-controlled motor currents also allow you to reduce the current when performing operations such as homing and bed probing.

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dart16
you can use 24v on an Arduino/RAMPS board

Only if you are lucky enough to get one with 35V capacitors. Most RAMPS boards have 16V capacitors, which are likely explode quite dramatically if you apply 24V to the main power input (the bed power input is separate and is normally 24V-safe). And you will definitely have to provide a separate 5V supply.

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dart16
10amps through the input connector is enough..if you need more make different arrangements (SSR or Relay directly fed from the PSU without connectors)

Tell that to all the users whose bed heaters don't get hot enough, but whose RAMPS boards get plenty hot. Yes 10A is enough for a typical 200x200mm PCB bed heater; but PCB bed heaters have very wide tolerances (probably due to variation in the copper thickness) and some need as much as 13A. Once you add an SSR you lose some of the cost advantage of RAMPS.

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dart16
...
Web interface....no thanks..un-necessary complication

Unless you have used a good web interface, IMO you're not qualified to say. DuetWebControl is a huge step up from Pronterface and the like. It's USB that is an unnecessary complication. USB ground loops - which are inevitable when you connect 12V-powered Arduino/RAMPS or similar to a PC - are a common cause of trouble, the most common being hangups and overheating USB cables. The only board I know of that doesn't suffer from USB ground loops is RAMBO, which uses an expensive digital isolator on the USB interface.

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dart16
Text file editing instead of re-compiling....nothing in it.. Once you have the calibration defaults set in firmware they are less likely to get modified accidentally and they can be tweaked to EEPROM

Why do you think there are so many posts along the lines of "I changed configuration.h/downloaded new source code, now I can't compile Marlin"? btw you need to recompile Marlin even to make tower position corrections when calibrating a delta printer.

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dart16
...

Delta bed calibration works fine as it is

If that is the case, why do so many users struggle to get their delta calibrated well enough to get a good first layer?

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dart16
Better heat dissipation?...fit a fan and keep the motherboard cooler as well - and be able to swap out a blown stepper driver and not have to replace the whole board

Better not to blow the stepper drivers by overheating them or getting the pot-twiddling wrong in the first place. If you need higher motor current, a fan only gets you so far with plug-in drivers. Drivers properly heatsinked on a large PCB and a fan cooling the PCB gets you a lot further.

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dart16
All the above is just my opinion please don't take offence. The Auruino/RAMPS is certainly getting old and newer boards will be needed to drive developments so if you feel you want to be part of that scene you will have to put your hand in your pocket.....

No offence taken! Your opinions are bound to be shaped by your experience, and I guess you've had a better experience with Arduino/RAMPS than some. My opinion is was shaped by being introduced to the Duet on my first 3D printer, then using Arduino/RAMPS initially on my second one and finding it a huge retrograde step. I've also helped a few users get their Arduino/RAMPS printers working, and seen how much they struggle to get the motor currents right and their delta printers calibrated. But I still consider Arduino/RAMPS a reasonable option for those who are technically competent but on a tight budget.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Deleted

Edited 1 time(s). Last edit at 02/26/2017 08:06AM by dart16.

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dc42

I have seen many tens of posts on these forums by users with exactly this issue. The 800mA rating of the regulator is ok but it's the power dissipation that is the problem. I ran some tests and I found that the regulator temperature is OK even with 15V input if you don't have an LCD connected. Once you connect a graphical LCD, the regulator overheated even with 12V input. YMMV, it depends on how much current your LCD backlight draws.

Indeed....typically 540mA, which is quite a large slice of the available current....best to keep a fan blowing on the board then :-)

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dc42

Maybe for you it is, but many user struggle with it, either because they don't know what voltage to set (the relationship between VREF and motor current depends on which drivers you have) or because they blow the drivers in the process. I think that most users of plug-in drivers have no idea what current their motors are running at. Software-controlled motor currents also allow you to reduce the current when performing operations such as homing and bed probing.

Knowing what voltage to set is fraught with problems, not least of which is the variances in the sensing resistors, however turning the pot down until the stepper stops working and then turning it up 1/8 a turn works for me.. how hard is that? Oh.. and have a fan blowing on the board

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dc42

Only if you are lucky enough to get one with 35V capacitors. Most RAMPS boards have 16V capacitors, which are likely explode quite dramatically if you apply 24V to the main power input (the bed power input is separate and is normally 24V-safe). And you will definitely have to provide a separate 5V supply.

Well yes..we have no control over the quality or the specs of the components that go into the boards from far off shores. however the two RAMPS boards I have both have 35v rated caps, and trust me they were cheap!!

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dc42

Tell that to all the users whose bed heaters don't get hot enough, but whose RAMPS boards get plenty hot. Yes 10A is enough for a typical 200x200mm PCB bed heater; but PCB bed heaters have very wide tolerances (probably due to variation in the copper thickness) and some need as much as 13A.

How hot are you trying to get these things and in what ambient temperature? to get to 90 degrees from 16 degrees takes my heaters about 3 minutes @5 Amps, sure if you want to get there in 20 seconds you are going to need some serious current..just make sure your infrastructure can handle it (which in many cases it clearly can't). I dread to think what the actual safe working current through these Chinese wire PCB connectors is when the specs for the pukka ones can be as low as 12 Amps

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dc42
Once you add an SSR you lose some of the cost advantage of RAMPS.

Really?
SSR on Ebay
...

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dc42

Unless you have used a good web interface, IMO you're not qualified to say. DuetWebControl is a huge step up from Pronterface and the like. It's USB that is an unnecessary complication. USB ground loops - which are inevitable when you connect 12V-powered Arduino/RAMPS or similar to a PC - are a common cause of trouble, the most common being hangups and overheating USB cables. The only board I know of that doesn't suffer from USB ground loops is RAMBO, which uses an expensive digital isolator on the USB interface.

Fair point...I have never tried a web interface on my printers..but I can tell you that the web interface offered by a Pi doesn't float my boat, or the web interface offered by webcams, Perhaps it's because I don't carry portable devices I just don't see the need. Once a print is running I just leave it to it, what do I need a web interface for? All the 'hangups I have encountered have been caused by spikes on the mains. Never had one while using the computer while printing. Overheating USB cables? Really? Once had a problem in my day job with a building mains earth floating at about 20v because of all the PC switch mode psu's hanging off the spur, it caused problems with ethernet comms...but never seen a USB cable overheat.

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dc42

Why do you think there are so many posts along the lines of "I changed configuration.h/downloaded new source code, now I can't compile Marlin"? btw you need to recompile Marlin even to make tower position corrections when calibrating a delta printer.

Because they do not understand what they are doing. They need to investigate why it will no longer compile, ask questions (like I had to) and look for the answer. Re-compiling the firmware is no different than making configuration changes in a text file..it is just a different way of using variables. In fact, in some cases having to re-compile will force the correction of errors before you can screw up a print with an erroneous entry.
I don't see having to re-compile as a minus, if anything, it makes the variables more secure

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dc42

If that is the case, why do so many users struggle to get their delta calibrated well enough to get a good first layer?

for exactly the same reason, they haven't understood the mechanics well enough

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dc42

Better not to blow the stepper drivers by overheating them or getting the pot-twiddling wrong in the first place. If you need higher motor current, a fan only gets you so far with plug-in drivers. Drivers properly heatsinked on a large PCB and a fan cooling the PCB gets you a lot further.

No argument here...there is plenty of advice on setting the stepper current safely, if you can't be bothered to be careful and remove the power before going near the pot with a metal screwdriver the most it will cost you is about £2 for a new driver. By properly heatsinked i take it you mean that the underside of the chip is flow soldered to a large pad to dissipate the heat....but to where? the PCB? The PCB is not the best place to dissipate the heat to - the atmosphere is.

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dc42

No offence taken! Your opinions are bound to be shaped by your experience, and I guess you've had a better experience with Arduino/RAMPS than some. My opinion is was shaped by being introduced to the Duet on my first 3D printer, then using Arduino/RAMPS initially on my second one and finding it a huge retrograde step. I've also helped a few users get their Arduino/RAMPS printers working, and seen how much they struggle to get the motor currents right and their delta printers calibrated. But I still consider Arduino/RAMPS a reasonable option for those who are technically competent but on a tight budget.

This is not the hobby to get into if you have little or no technical aptitude, there are far far far too many things that require adjustments. It is, however, a great hobby for those who want to tinker. Buying something along the lines of a Prusa i3 mk2 as a first printer is a sure fire way of wasting 700$ if you are not prepared to learn how to fix stuff.

Are you saying that those people you have helped that have struggled with an Arduino/RAMPS setup wouldn't have struggled with a duet as a first printer? It might have worked straight out of the box but I seriously doubt it would do so for long.

If you have a use for the added features that the 32bit Duet affords then you put your hand in your pocket and buy one, I don't consider any of the reasons put forward on here so far worth the price tag.

Phew....back on topic!!

Just spotted this ...
Full disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi. ;-)

Edited 1 time(s). Last edit at 02/26/2017 09:33AM by dart16.

We're OT as you pointed out, so I'll try to keep this short.

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dart16
Really?
SSR on Ebay

That is a zero-crossing DC-AC SSR, great for controlling an AC mains voltage bed heater, no good for controlling a DC bed heater. The cheap DC-DC SSRs you get on eBay are also no good for controlling a DC bed heater because they have a large voltage drop and dissipate a lot of power. Lots of people burn them out trying to use them. Even with a massive heatsink and fan, the voltage drop causes a substantial reduction in the heated bed power.

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dart16
..but never seen a USB cable overheat.

Every few weeks, someone starts a thread because this is happening to them.

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dart16
Because they do not understand what they are doing.

IMO we shouldn't expect someone building a 3D printer to learn even a small amount of C++. Compilation is for firmware developers, not end-users (other than end users who are also firmware developers).

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dart16
Are you saying that those people you have helped that have struggled with an Arduino/RAMPS setup wouldn't have struggled with a duet as a first printer?

They would certainly have struggled with fewer things. Unless the towers are precisely positioned - which is rare - manual calibration of a delta printer is difficult (although it's a lot easier since I published the web-based version of my least-squares calibration algorithm).You need only visit the Delta section of this forum to see how much people struggle with delta calibration when it isn't built in to the firmware.

In the early days of RepRap, it was reasonable to expect builders to have reasonable electronics and software knowledge. Now that the market has expanded so much, I don't think it is reasonable to expect that any more. Good kits should be designed so that the mechanics will run smoothly and accurately when assembled correctly, and good electronics should require the user to have only basic wiring and software skills. There are those who enjoy hacking electronics and firmware, but most 3D printer owners would rather the electronics and firmware just worked. They will still have plenty of work to do by way of experimenting with temperatures, filaments, first layer heights, slicing parameters etc. to get that perfect benchy.

Edited 1 time(s). Last edit at 02/26/2017 10:33AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

The OP's question was about reasons for buying a more expensive board and, IMHO for all the obfuscation, there is still precious little anyone has put forward to justify the price tag. For £20 you can buy a miracle of modern(ish) electronics that can perform magical feats at the press of the print button, for £100 you can buy a controller with some bells and whistles - if bells and whistles are your thing.

disclaimer: In the interests of fair play I would like to establish I have NO financial interests in Arduino/RAMPS at all :-)