Spindle thoughts for Primo

Hey guys I have been running the Dewalt 660 on my Primo but I think I would really like to have RPM control and a bit more power so I was looking at 65mm spindles.
Thoughts on water cooled vs air cooled spindle?
I do this as a hobby and water seams to add some complexity with the pump and water and my rig is in a unheated garage.
Is water that much better than air cooled or other things I should consider?

i run 1.5kw air cooled spindles on both my Primo and LR3. I didn’t want to deal with water lines and all that. So far i haven’t had any issues with heat on the mounts for either. My LR3 mount is printed from ASA though. Im about to print a new mount for the LR3 that will have a lot more coverage on the spindle but i don’t expect to have any heat issues still.

Thank you for the insights on your setup.
I had thought about doing the same, printing the mount out of ASA or ABS.
Yeah I have to agree the extra complexity of the water lines for my hobby machine I think is more than I want to deal with.
Any other advise when considering a VFD spindle that I may not have thought about?

I dont have a ton of run time on either one yet. The one i got for my Primo was purchased from VEVOR. They were out of stock when i was ready to get one for my LR3 so i went with one off of ebay. I have no idea which is better. Main thing im learning is while the VFD comes with a manual its very broken english. I have had to ask several questions and do tons of googling to find out what settings need to be changed in the VFD and what not. I have a post now trying to get RPM where i can see it.

Also on my LR3 build thread there are the links to each of the spindles i have…

Hopefully that info helps you some. And if you follow along you can learn as i do LOL


Thank you very much I will follow along for sure.

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Okay so after some back and forth I think I want to say with a 110v Spindle kit to keep wiring in my garage easier. I know it’s not a lot of work to add 220v but everything else I have is 110v so that makes the most sense to my setup. With that said I am looking at this kit:
RATTMMOTOR 0.8KW 110V Spindle Motor Kit, 800W Water Cooled 65mm CNC Router Spindle Motor 110V 400HZ+1.5KW VFD 110V Single to 3 Phase Inverter+65mm Mount Clamp+ER11 Collet+80W Water Pump for CNC Router https://a.co/d/9PHW0h1

I confirmed the controller has RS-485 interface.
Is there anything else I need to consider?

Also that kit has the plugs but needs wiring to connect the Spindle and VFD , any recommendations on wiring to use?

Then of course, how to hook that up for spindle direction and speed control in the CNC program. I’ve done manual and CNC machining, and having the G&M code tell the spindle to run at different speeds for hogging and finish passes, ramp up and down at sharp corners etc. is invaluable. Are you handling that? Thoughts from folks on best way, which controller etc?

That is my next bridge to cross for sure, if anyone has some good guide or links I would be happy to have them.
My MPCNC is controlled via a Duet 3 board so its a little different than Marlin.
I know there are the PWM to Analog signal converters so I am not sure if I need one of those or not just yet.

It looks like the Rattm 800w air and water cooled units all use PWM input.

Electrical is definitely an area I wish I was a little smarter.
Connection page from the manual:

Anyone know what or how I might connect this to a Duet 3 board based for On/Off and Speed control?

There are a number of topics on this forum discussing connecting a VFD to a control board. While the fragment of the manual you publish does not say explicitly, based on other topics, your VFD is expecting an input of 0V to 10V on the “Analog Voltage Input,” which will be mapped to the min and max RPM of your spindle.

To get PWM of a control board to set the RPM of the VFD there are two pieces of work:

  1. Setup the firmware to take RPM commands (either M3 or inline), and map those to specific PWM values on a PWM enabled pin on your control board.
  2. Conver the 3.3V or 5V PWM signal generated by the control board to a 10V signal expected by the VFD.

You don’t say what firmware you are using. I checked the Marlin source, and could not find a board definition for any of the Duet boards, nor a pins file for a Duet board. Assuming Marlin, you are going to need to have the following two defines in your firmware build:


The PB0 and PC9 are pins for the SKR pro board. You will need pins specific to your Duet board…and the PWM pin needs to support PWM.

Once the pin is defined, there are settings in configuration_adv.h for turning on spindle support and for mapping the RPM settings in the g-code to PWM values.

As for converting the signal to 10V, I’ve seen a couple of circuit diagrams mentioned in a couple of topics on connecting control boards to VFDs. And there are references to a conversion board. A quick search yields this board for converting from 5V to 10V (not sure if the Duet is 3.3V or a 5.0V board.