48 volt steppers board selection
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@rexx Duet 3 is the only board that will handle 5A motors https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors
Note - The maximum input voltage for Duet 3 is 32V.
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@deckingman HC6 is not 48v boooo or is that just input... does it run 48volt outputs?
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@rexx said in 48 volt steppers board selection:
@deckingman HC6 is not 48v boooo or is that just input... does it run 48volt outputs?
On that basis that you can't get more out than you put in, then I'd say no.
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@deckingman there are up converters single phase to three phase and so on...voltage is not total power! but you are correct i cant get more out then was put in
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@rexx may have to look at the spider 48Volt maybe 32volts at 5 amps will not work at 48volts 5 amps only about 2.89Amps then..
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@rexx Personally, I think you are looking at this the wrong way. You did say that were looking at rebuilding a printer. So you are not looking to drive a heavy spindle as you would with a CNC machine cutting metal. In which case, why the fixation about using 48V? The link I sent you in my first post will tell you how to choose steppers - I suggest you take a look at that and have a rethink.
For info, my CoreXYUV has 6 extruders mounted on the UV gantry. The total moving moving mass of this gantry is about 3Kgs. I accelerate this mass at 1500mm/sec^2 up to 350mm/sec using Nema 23s rated at 2.8Amps but running at 2.3 Amps and using 24V. So unless your moving mass is going to be substantially greater than 6Kgs and/or you want to accelerate it substantially faster than 1500mm/sec^2, then you'll be fine using Duet 3 and 24V.
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@rexx
Don't want to spoil Duet3D's business, but my Fly Mellow super 8 has 2 high voltage driver sockets onboard and I managed to add three more with a bigtreetech EXT_MOT -
@o_lampe it actually has 3 HV on the 1.0
The 1.1 has been released and all 8 drivers can be used with 48v -
@jay_s_uk said in 48 volt steppers board selection:
it actually has 3 HV on the 1.0
Right, I see it now
There are only two red stepper connectors on mine but three HV sockets. (maybe I removed the third housing for a Molex cable?) -
High voltage 5160s are like hen's teeth at the moment though and unfortunately they don't make the 2160s in the same package size.
Might be best going for external drivers and feeding those with 48v. -
Also bear in mind that the TMC5160 drivers on Duet 3 can handle more current (6.3A peak) than plug-in drivers can. Plug-in drivers are limited by having little heatsinking area for the mosfets, small plug-in pin connectors, and on the main board smaller stepper motor connections and smaller capacitors for controlling voltage overshoot when the motors are turned off. So with a Duet you can use a higher current motor, which has lower inductance and therefore doesn't need as much voltage as a similarly-sized lower current motor.
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This is only partly true - the voltage input selection matters for torque at speed - so depending on how fast @rexx wants to drive the toolhead and at which accelerations that torque will be applied matters - the higher the speed, the more input voltage matters, and since 3d printer heads are lighter than spindles (and can print pretty fast!, its even more important.
Your example of heavy head printing slowly could probably work fine on 12v, you're only requiring (3*1.5) = 4.5N of force, assuming a 20T pulley (12.73mm pitch diameter) you're using a fraction of the torque (even assuming a modest 1.5 Nm of torque) that can be output (4.5N vs 234N on a 20t pulley) you have a few orders of magnitude of torque left in those large motors.
On a D3 Mini (2209's) I'm feeding two motors 1.65A RMS, print at 400mm/s and 15k mm/s/s accel for about a 1.5kg gantry, and this is the hard limit imposed by EMF from only using 27v. If i only print at 200mm/s, i can tip the entire frame of the printer by interrupting the crossbar with my hand, but above 300 its far easier to skip. This is the relationship that needs to be defined for @rexx - is the intended print speed (and accels) after the drivers can no longer overcome EMF at the rated 24V (32Vmax)?
This is what needs to be determined - just how fast his gantry can reasonably accelerate to print well in addition to what are the size of the current motors before requiring high voltage.
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duet3 can be modified to run at higher voltages , if you're willing to go that route.
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@luke-slaboratory It's true the a) motor torque will drop as speed increases and b) more torque is required for higher accelerations. But I'd have to disagree that beyond a certain point, increasing acceleration makes much difference to FDM printing.
You misquoted me by saying "Your example of heavy head printing slowly......" because I distinctly said "I accelerate this mass at 1500mm/sec^2 up to 350mm/sec " and I doubt many other people have machines that can actually achieve a melt volume flow rate to be able to print at 350mm/sec.
Admittedly my 1500 mm/sec^2 acceleration rate is modest but even at that, it takes a mere 0.2 seconds to go from zero speed to 350mm/sec and in reality, very few moves start from zero speed due to the jerk setting. So increasing that acceleration rate makes very little difference to the overall print time. And this all assumes that volume flow rate out of the nozzle is capable of matching the rate of change of velocity of the print head, which is seldom the case.
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Tl;DR
- Whoops on the tool speed.
- Acceleration is incredibly important to achieve faster prints and the primary path
- 35mm3/s is pretty achievable nowadays
- High voltage is an important feature to accommodate high speed tools and increasingly quick printers
- All of this is moot if the intended toolspeed is 200-300mm/s or less.
@deckingman said in 48 volt steppers board selection:
"I accelerate this mass at 1500mm/sec^2 up to 350mm/sec "
My bad - not sure why I saw 150. Maybe I conflated the 1500 with the 150 in my mind. not sure. I'll own it.
Regardless - 350mm/s tool speed (assuming that you're printing with a .4mm nozzle, .48lw, .2mm layer height) is only 30mm3/s, pretty medium-flow nowadays. Slice Magnum, Takoto, HF Dragon, Rapido, HIC, Nova, and the standard volcano is all in that range, with some in this list well above those capabilities. There are even higher-flow hotends in the market, starting with the Rapido, HIC, VolcanoMosq, Mag+, and a few others out there. I'd say a sizable portion own a hotend capable of 30mm3/s, especially if augmented with something like a CHT.
Re: acceleration - the below plate is assuming 400mm/s print speed, 15k acceleration, 8mm/s instant velocity change, except for the first layer. 4 perim, 40% infill. Its predictions are pretty bang-on compared to as-printed, within ~2% of predicted with this profile and this plate.
This is the same plate, except I've dropped the acceleration to 1500mm/s/s
Now - what happens when increasing the acceleration to 4500?
You save an estimated 5hours of print time, and use 13.5N of force instead of 4.5. That adds up after a while.
Lets go to the ultimate "theoretical" limits - does it fall off? you have 3kg gantry, and a conservative estimate of 234N of force, so you can accelerate at a theoretical 78k mm/s/s.
Obviously mechanics won't allow this to happen, but at least lets see what happens to the print times. I've verified that the slicer decreases time alloted beyond 78k accel, so this model should be accurate.
All the way at 78k, you've only saved another 2hrs beyond the 15k estimate. This is where these diminishing returns are really found, assuming your hotend is limited to ~35mm3/s.
But, increasing acceleration is the best real way to increase speeds - increase your jerk too much, you get ovals instead of circles, lose corners, and all sorts of other bad behavior. Acceleration is something that can be increased near infinitely, assuming that you have the power and rigidity to do so, among other plastic-melting limiters.
But, the point stands - at 15k, I can double my productivity over 1500. At 4.5k, I save an appreciable amount of time that adds up. its not inconsequential, and assuming that your machine is built correctly, quite repeatable.
All of this was done without fiddling with the Z-axis speeds - if I switch to a belted or a faster Z, this gets significantly better as alot of this time may be calculated from z-hop.
But, many Common hotends out there can easily go past 35mm3/s - This is where the high speeds and high voltage come into play, and something that is important to address. One can't effectively use high-flow hotends if their tool never gets to the high speed, necessitating high acceleration, demanding high torque.
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@luke-slaboratory
to be fair, your example prints faster because of the many travel moves. I'm not sure if "I" ever had a print plate with so many individual parts, nor if it's the average usecase....but it's impressive to see what's possible in theory
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@luke-slaboratory TLDR but ref volume melt rate, I recently demonstrated printing a vase in under two hours with an average volume flow rate in excess of 70 mm^3 / sec. Or to put that into perspective, that was a 1.5mm nozzle, 1.8mm layer width and 1.2mm layer height at 80mm/sec print speed.
At those melt rates, the challenge is not print head speed, but cooling the part sufficiently before the next layer.
I have since tried a 1.8mm nozzle and estimate the volume flow rate as being around 100mm^3/sec but I haven't been able to cool that 2mm layer width/1.5mm layer height @80 mm/ sec head speed sufficiently to actually produce anything other than a collapsed blob
Edit. The 350mm/sec print was done years ago but it was with a 0.5 mm nozzle and 0.3mm layer height, not a 0.4mm nozzle and 0.2 mm layer height.
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Shouldn't matter - single large part, many small, and to be clear - my print and travel accel is the same - 15k. No difference there. If its a big part with many infill sections, its still 15k. perimeter? 15k.
I'm not doing this to speedboat either - these are for parts that go out the door.
One of my common profiles is to print at 70mm3/s with a .8mm nozzle, in PLA. To do this, I admittedly drop to 5k accel for now since the plastic lays down neater (it tends to drag, but this is probably from the magnum+ hotend getting too cold on the lower portion of the block, causing the material to be less molten and not wanting to bind)
I'm hoping to get there on my smaller 400x400 machine that currently is limited to 400mm/s by swapping out for lower inductance motors.
Or, I could swap up to 48v, which would get me the tool speed I need to keep my hotend fully flowing. That again, would match the 70mm3/s on just a .4mm nozzle.I use CPAP blower - WS7040. Its sufficient to cause a jam in the hotend itself - I can turn on and off flow in the hotend by ramping up and down - this is something that's been captured in other setups than mine, and is just a weird thing I have to account for with the mangum+ hotend.
I understand the cautionary tale of not going for omega upgrades when you're not going to be able to use them, but honestly the market for 48v boards is being driven by many more people than just me - its a real need as melt zones continue to grow and mechanics(and software!) are more able to support the higher flows.
I could use the current-providing capabilities of the 6hc's 2/5160's, but it doesn't match what I need it to do otherwise, and for the premium and market position of the 6hc, I feel that its a valid concern that it doesn't support this option.
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@luke-slaboratory I understand what you are trying to say but I don't think you've made a convincing case for using 48V. My point is that I use 1500mm/sec^2 with 3Kg + of moving mass but that's still well within the torque capability of those 2.8Amp motors (running at 2.3A) even at 24V. If I had a "sensible" hot end which weighed say 300 gms instead of 3Kgs, then I could use 15,000 mm/sec or more for the same torque. That's still less than half the 6 + Amps that the Duet board is capable of. I guess we'll just have to agree to differ.
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@deckingman sorry for the super late reply life been a round latley but i am back in and read the posts and if you are correct i should be ok with only a duet 2 not Duet 3 hc6 but (duet 2) as you said only 2.3 A actual @ 24VDC i have the 178 oz 1.8 deg i forget the MH resistances but i would love to use the duet 2 instead of 3 i think ???..
the duet 2 is rated to 2.8A-firmware set to 2.4A do you think i could use this under your limits above?
i am only driving 3 nema 23x57mm and 2 pankcake nema 17's at 24VDC the duet 2 does goto 32 VDC
feature wise the duet 2 is fine less the close peek amps.
