BTT kraken support.
I would love to use RATOS but there is no config file for the BTT Kraken board yet. I have tried to go through the setup saying its a BTT Octopus board while loading the correct Kraken firmware from github onto the sd card. Consequently I have emptied the printer.cfg file and pasted the config.cfg from the BTT Kraken github.
Anybody got a clue on how to get the BTT Kraken working on RATOS?
15 Replies
I just recieved one the other day. What machine are you intending on running this on? You need at least 7.5A RMS rated steppers to make use of the first 4 drivers, anything less than that and litterally any of the other supported boards would've been a better choice (as long as you put in driverrs with a sensible sense resistor. 0.022 is too low for accurate microstepping on normal 3d printing steppers).
It's a custom V-Core 3.1 AWD machine. Running 48v, on LDO super powers. I mainly chose this board over the Octopus due to the better cooling of the stepper drivers without resorting to external drivers (which would in turn increase complexity).
There's absolutely no point in anything more than a decent fan to cool 5160 stepsticks with heatsinks when running the 2804's. Just how far past the stepper rating are you planning to push them, and who told you you need more driver cooling?
Granted, the 2804's have a torque problem, they're primarily useful on small machines to gain extra top end velocity. If it's acceleration you're after, the 2504AC's are a much better bet, and at 48V you'll have max torque up to around 800 mm/s where you'll struggle maintaining flow at any sane layer height anyway.
Ill be pushing them as fast as I can for prolonged prints, all steppers are actively cooled. Nobody told me to me to get more driver cooling, that's my own preference š
Interesting what you mention on the 2804's vs 2504AC's I do have a set of the 2504AC's laying around so I'll experiment with them. Flowrate will not be a problem for this printer though, I'm running a custom extruder/hotend combo that should be able to push around 150mm3/s, I'll show more on that in due time.
sounds interesting! I will add Kraken support at some point in 2.1.x, @MDFPereira is already working on it, just remember the caveats - you're gonna need nema36 or 42 to handle enough amps for accurate microstepping.
Iām interested in that custom hotend š
Taking care of it today.
Will send you a message š
Not yet š
Sorry for digging this thread out. But could you explain me this please a bit more in detail? According to the datasheet of the Kraken there is a max. current of 8A noted for M1-M4, but there is nothing stated that you need at least 7,5A steppers anywhere.
That is directly related to the sense resistor used in the board.
It has been made for nema23 and upwards. So, every smaller motor like nema 17 used in ratrig machines have issues with micro stepping when using the Kraken.
Thanks for your response, but what does this mean for me exactly? Will the accuracy of my prints be worse, will steps be quit, will it be louder?
Is it possible to use it with the provided LDO Speedy Power Motors of the V-Core 4 or will I just have troubles with it?
Bought it a while ago for a different project which I have stopped in favor of the V-Core 4.
Indeed, which i think reflects quite poorly on BTT (and Voron who have their name on it). It's not rocket science, it's directly stated in the TMC datasheet, if they bothered to look.
The lower the sense resistor, the less precise the current measurements and thus more current is required to maintain an acceptable level of microstepping accuracy
These drivers work by chopping the voltage so that the current measured through the coils is as close to the requested current as possible.
You can use the last 4 drivers with the more regular sized sense resistor of 0.075, that will work well for the 2504AC's but it's not great for light-weight extruders for example.
The first 4 are 0.022, which is obscene and basically useless for 3d printing.
A CS of less than 16 results in poor microstepping performance.
So basically divide those numbers by 2 and you've got yourself your minimum current
Thanks for the details, I have decide to better use the octopus so I can be sure that I won't have the issues.