Some updates, Marlin update, new boards?

I have been watching the marlin github, checking it every few days. It looks like an update is coming,

The rc8 update had screen issues for us and some other random things. These issues were quickly rectified in the RC8 bugfix branch but the devs were making crazy fast progress so I didn’t want to waste the time trying to constantly update.

When the update is released I will try it out, release it in the forums if there isn’t any issues I will try and make all the crazy updated different versions that are sorely needed, 8mm lead screws, no therm, different lcd’s, try and make it so most people even if they did not get the kit, should not need to mess with the firmware.

This falls right in line with tomorrow’s shipment, Legit official Mini-Rambo 1.3 boards at a crazy good price! While at MRRF Barry and I got to chat with Johnny R from Ultimachine for a bit and, boom, better boards. A few guys from SeeMeCNC proved the rambo’s were better and made the introduction. The import Ramps are causing me to waste too much time and money so I am trying to get all my sourcing inline for a possible switch to the rambo mini, followed by the archim… The rambo boards are more expensive but should take significantly less time for me to deal with on the kits and troubleshooting side. So I will offer both but hopefully the price difference will be as little as possible for you guys and the board improvements and component quality is seriously impressive. US made boards!!!

I also think I am going to switch back to the other LCD’s that don’t require the ug8lib as I think they take less resources to run and honestly they always seem to run better.

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hmm well i hope its a crazy good price would be interested in that board myself lol

Hahahaha, “Don’t try this at home kids!!!”

How expensive are we talking? Because i want one or two.

1.3 or 1.3a? They handle the LCD differently on the two versions IIRC. I think the Mini RAMBo also is limited to 1/16 stepping instead of 1/32 on the RAMPS, but that’s not too big of a factor if the price is right. Looks like the heat bed output is a little weak for this (200W aluminum bed), so no ABS without an external MOSFET.

Very cool, I myself love ‘cheap’ and the price of the ramps board is awesome! That said the form factor is a pain. I have yet to get mine mounted in anything that doesn’t tick me off lol (I should have just printed your ramps enclosure to begin with). I have had my ramps stack literally sitting on the spoil board for about a year now (on my most used mpcnc).

I would love to have an all in one solution that I can mount inside of say a micro pc case or rack mounted blade (you know cut an lcd window out of the face of it install the lcd and boom instant sexy).

I have been holding off on using my laser machine until all of the issues are resolved with the firmware (then again I have yet to see any issues while using the rc8 load I have on there now - not moving the z-axis so I am guessing that is why it works).

Glad to see new fw is on the horizon!

With the Mega2560 board we’re using now it’s possible to reprogram the USB chip to meet the spec for the Windows 3D printer driver (set compatibleID to “MSPRINT”), which allows printing directly from 3D Builder in Windows 10 (The USB connection shows up as 3D Printer instead of Mega 2560 and 3D Builder then generates the gcode). Do you know if there’s a similar option with the Mini RAMBo?

I am hoping to sell them for $85 if I buy a bunch on the next round I might be able to do $80, no wires just the 4 plugs.

Barry, exactly, that sold me! That and I just got another batch of 50 boards and 10 had bad mosfets, 2 where physically crushed in shipping. I’m over it.

Bill, 1.3a it has a 15A bed rail instead of an 11a (or less on the import) on the ramps, but going to 24V should fix your issue, no externals. I am not sure about the windows thing but I can not imagine the windows slicer is worth the time? I need to look into what code they are using…yikes.

Put me down for one at that price.

Really trying to ship out the day’s orders before I plug this puppy in. So small, the quality difference is immediately clear.

Very nice. Will you carrie the wire connectors?

Just these plugs and I think I will offer them in singles they are actually expensive.

The wiring harness fits (pretty tight but it works well), I will remove the resistor from the firmware, and all the standard stuff should fit.

Hmmm, compared to the ramps boards there is very little info out there on the mini’s.

I am not sure how far I can push the drivers. I ran them for a little less than 5 minutes with my test script at the stock settings and this corner of the board gets piping hot. I believe the stock settings are equal to the drv8825 at .7v so 1.4A out of the steppers max 2a, which usually leaves the steppers warm but not hot.

Not sure If I should slap on some heatsinks or not. Maybe I need to sacrifice a board in the name of science. Torture test, I am pretty sure the thermal shutdown will kick in before anything really fails.

The documents say don’t worry about it. So far so good. The board is hot as hell but I don’t have a fan on it. I will slap it on the mpcnc turn it up a bit higher and run a print for a few hours and report back.

My Rostock has a fan on the rambo, probably a good idea.

I wish I had taken a video of Andy making the printer light up by throwing the carriage around.

I definitely reccomend a fan but I am going to torture test without one…just to see.

Did you break one yet?


I ran it for a long time on a parallel wired mpcnc, today I will run it on the series. I am very confident with a tiny fan these boards are are gunna be awesome since they work fine without a fan.

The flashing is a bit more involved the first time (I have updated the firmware page), but the LCD’s plug right in and work with the RC8 bugfix without all the edits shown for the older firmware. Pretty pumped about them.

Well I mixed up the hot end and the bed turned on the heat and popped a fuse. That was a new experience. Run out to the truck grab a space replace it and good to go.

I have no idea what is going on with the "digi"pots, they are PWM

// Motor current PWM conversion, PWM value = MotorCurrentSetting * 255 / range
#define DEFAULT_PWM_MOTOR_CURRENT  {1400, 1400, 1400}

I assumed this meant 1400255/2000=178.5pwm
178.5/255=.7 Meaning 70% of max current, max current is 2A, so 2
.7=1.4A this is what we run the 8825’s on and they just barely get warm.

Well nope, that is not what that equation means.

At the 1400 setting I just started to get thermal shutdown of the driver of one axis and after 20 minutes or so the steppers were so hot I could not keep my hand on them at all.

So what I learned. The built in drivers with no fan can supply more than our steppers can handle, with the slightest breeze it can go much higher.

Trying again at 1100, I think I am on to guess and check at this point because my google-fu is getting me nowhere to an actual equation, for pwm-digipot-current conversion. So far 1100 has the steppers running much warmer than usual, but no missed steps. SeeMeCNC uses the same boards and steppers and they have theirs set at 1000. So I guess I should go a little lower. Good news I guess.

I accidentally shorted the board (piece of metal hit the bottom) it rebooted and runs fine…

Here’s a link to details about the built in Windows slicer, looks like they’ve got most of the bells and whistles, though who knows how well it’s been implemented.

And here is a link which describes how to install the generic gcode version, it requires Windows 10 Pro or Enterprise to manually install.