Planning on upgrading control board on Cetus...Einsy Rambo good choice?

So I can't help but want to give a Cetus a go. I currently have a 4 month old Prusa MK3 that I'll be swapping a guy for a Cetus extended here in the next few days. Whilst I intend on using the Cetus in its stock form for a bit I've decided that I want to upgrade the control board and maybe a few other things to make it quieter, allow me to modify the bed to a heated on (not a fan of the OEM heated bed option) as well as work nicely with octoprint.

The board I'm strongly considering is the Einsy Rambo (the same as in the MK3). I like the tmc2130 drivers and it has a respectable feature set, i.e. powerpanic, sensorless homing, SPI, etc.

My main concern is how difficult it will be to tailor for the Cetus. I've built two different printer kits so far but this would be my first foray into customizing something in this manner. Would definitely like input from those in the know.

So you want to downgrade from one of the best machines to a cheap printer???

I suggest you get psychiatric help ASAP

The controller on the cetus uses several non reprap standard pugs (platform heater and extruder are the worst, pin outs are completely unknown)



I also suspect that the hot end uses a thermocouple, not a thermistor, so it needs the required amplifier circuit

Edited 1 time(s). Last edit at 11/07/2018 08:10PM by Dust.

I don't consider moving from mediocre rods and bearings (which have already failed on the x axis after just 4 months) to high quality iko linear rails a downgrade, a lateral move at the worst. I do see the control board as the Cetus' weakest point, hence my desire to swap it. The heated bed will not be a problem adapting and hooking it up. I'm looking into the stock hotend to see what it will involve, but if it doesn't pan out I may swap it to a titan aero or something. Even in stock form I consistently see prints on par or better than a MK3. My MK3 has already had four part failures and the customer support was 50/50 on being helpful. My most recent issue, the failed rods, was brushed aside and I was told it was normal wear. I've gotten some top notch prints from my MK3, but I've learned it's not all that it's hyped up to be.

My main concern is the firmware and how much trouble it is to tailor to the Cetus.

Edited 1 time(s). Last edit at 11/08/2018 12:34AM by guycobb2.

The RAMBo series are almost certainly the best 8-bit boards available, and if you are sure that you want to use an 8-bit board and TMC2130 drivers then the Einsy is a good choice. TMC2130 drivers can't handle much current, so check that the stepper motors in the Cetus are compatible. The power panic feature needs an extra input from a power monitoring board.

But have you considered using a 32-bit Duet WiFi or Duet Ethernet board instead? You will get beefier TMC2660 stepper drivers with the same stall detect technology, power monitoring built in, and a built in web interface so no need for Octoprint. All the firmware configuration is done at boot time using a text file on the SD card, so you don't have to recompile and upload firmware to make configuration changes.

Whatever the controller, power panic needs a 24V supply. So if the Cetus is 12V then you will need to replace the bed heater and extruder heater, and either replace the fans or add a 12V step down converter.

Edited 1 time(s). Last edit at 11/08/2018 02:44AM 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].

Thanks DC42, my first printer was a Ultibots D300vs plus kit that utilizes your duet board and I like it just fine and it's a great product. I thought the Rambo a good choice since it's a little less cost than a duet as well as met the list of "wants" I had in mind. I have a power panic board I can utilize, a meanwell 350watt 24v PSU to power it all with and I've found I prefer octoprint due to it's plugins over the duet's GUI. I know I could run octoprint with a duet, but I think that would be too redundant and make my brain itch.

Edited 4 time(s). Last edit at 11/08/2018 04:44AM by guycobb2.

Thanks DC42, my first printer was a Ultibots D300vs plus kit that utilizes your duet board and I like it just fine and it's a great product. I thought the Rambo a good choice since it's a little less cost than a duet as well as met the list of "wants" I had in mind. I have a power panic board I can utilize, a meanwell 350watt 24v PSU to power it all with and I've found I prefer octoprint due to it's plugins over the duet's GUI. I know I could run octoprint with a duet, but I think that would be too redundant and make my brain itch.

Edited 1 time(s). Last edit at 11/08/2018 12:27PM by guycobb2.

I do indeed need to check the compatibility of the Cetus steppers with the 2130s. However, since I do prefer quality and still have my 0.9 steppers from my Ultibots printer, would there be any advantage to a duet with the 0.9 steppers, vs the Rambo and some 1.8 steppers. I won't pretend to full grasp microstepping or which would produce the best real world results, so I'll have to take your response at face value.

Also, do you have any experience with the Cetus? Would you consider the MK3 to a Cetus a downgrade as Dust blatantly stated?

So many printers and you still want to buy?

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guycobb2
I do indeed need to check the compatibility of the Cetus steppers with the 2130s. However, since I do prefer quality and still have my 0.9 steppers from my Ultibots printer, would there be any advantage to a duet with the 0.9 steppers, vs the Rambo and some 1.8 steppers.

0.9deg motors can give better print quality on delta printers, because of the improved Z resolution they give in particular. But it's generally considered that 0.9deg motors don't provide any significant increase in print quality on Cartesian/CoreXY printers, provided that the Z leadscrew pitch is chosen to give sufficiently high Z resolution.

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guycobb2
Also, do you have any experience with the Cetus? Would you consider the MK3 to a Cetus a downgrade as Dust blatantly stated?

I have no experience with the Cetus.

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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].

So the Cetus being belt driven linear rails on all axis, 0.9 steppers should help some, an I understanding correctly?

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guycobb2
So the Cetus being belt driven linear rails on all axis, 0.9 steppers should help some, an I understanding correctly?

Does it have any gearing on the Z axis? What is the Z steps per mm?

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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].

If you mean any geared reduction then no, not that I'm aware. No clue on the z steps/mm.

[youtu.be] Jump to 5:52 to see a little closer look of Z axis.

Looks like it's an un-geared Z axis with either a 16- or 20-tooth pulley. If the Z motor is 0.8deg, that will give you 100 or 80 steps/mm @ x16 microstepping, which is a full step distance of 0.16mm or 0.2mm. You might get some benefit from using a 0.9deg stepper motor for the Z axis, especially if you want to print at layer heights of less than 0.2mm.

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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].

Very good. Thanks sir. I believe on their site they advertise 0.05 layer height capability. I'll know more about it after I get my hand on it. I appreciate your responses.

How does the duet maestro 2 compare to a duet wifi? Best I can tell, the main thing is lower stepper current capability and no wifi of course. I'm sure it's without other features as well that I'm missing. The 0.9 steppers I have, have a rated Voltage: 2.8V and rated current Per Phase: 1.68A. How does that translate to real world usage so I can know what to look for in a control board? My ignorance would tell me that I would take 1.68 and times it by two since there are two phases. However that can't be right since that's more than even the duet wifi is rated for and I know the steppers work fine as they were the ones I used with my old duet wifi.

... you can drive steppers with much lower current, than specified.

But you too can use "external" drivers by simply wiring the STEP and DIR pins to the driver inputs - have some stepper-drivers with up to 70 Volts and up to 6 Amps current ... and others with "only" 2 Amps, but DC voltage of 325 Volts(!!) pretty good running with Arduino based controllers

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guycobb2
How does the duet maestro 2 compare to a duet wifi? Best I can tell, the main thing is lower stepper current capability and no wifi of course. I'm sure it's without other features as well that I'm missing. The 0.9 steppers I have, have a rated Voltage: 2.8V and rated current Per Phase: 1.68A. How does that translate to real world usage so I can know what to look for in a control board? My ignorance would tell me that I would take 1.68 and times it by two since there are two phases. However that can't be right since that's more than even the duet wifi is rated for and I know the steppers work fine as they were the ones I used with my old duet wifi.

There is a comparison chart at [duet3d.dozuki.com]. The main differences are:

* Maestro has TMS2224 stepper drivers. These support stealthChop2 and interpolation to x256 microstepping from any microstep setting; but no stall detection.
* Maestro is less expandable, it supports just 2 more stepper drivers and 4 GPIO expansion pins
* Maestro is available in Ethernet only at present
* The microcontroller on the Maestro is slightly less powerful, it's still a 120MHz ARM Cortex M4 with 128Kb of RAM, but without a cache or hardware floating point

The quoted currents are peak per phase. In 3D printers, stepper motors are typically run at between 60% and 85% of the rated current per phase. The 1.68A rating of your motors is higher than we recommend for the Maestro; OTOH my delta uses 1.68A motors too and I only run them at 1A, and even 1.3A is easily handled by the Maestro if you fan-cool it.

btw TMC2130 drivers are a little less capable of handling high currents than the TM2224 on the Maestro, according to Trinamic. Prusa uses the 2130 drivers with low-current high-inductance motors and 24V power in his i3.

HTH David

Edited 1 time(s). Last edit at 11/12/2018 08:14AM 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].