Servos and Drives questions..

Hey guys,

I recently purchased a Chinese VMC and it is being Built currently. there was a miscommunication regrading the servos, spindle motor and drives and I am now having to supply them for the machine. The main problem with that is I wasn't prepared research wise to do so.

I have found a few manufacturers in China who make the correct size motors and drives but I'm less familiar with Linuxcnc and what it requires in a drive, motor and encoder. I normally would spend the time reading and researching but the manufacturer needs the motors and drives by next week this time and most of the companies need a few days to configure, pack, and ship the drives.

The good news is I know all the sizes of the motors I need. But are there any special drive features I need to ensure are available for Linux CNC? I am happy to purchase whatever other hardware I will need to use with the drives but for now I just need to be sure what I am about to purchase is going to be compatible with Linux CNC be it the drive or encoder type etc.

Thanks so much in advance, I put the cheat sheets for everything below.

The motor sizes are as follows, x and y 110mm. 6n.m, Z axis is 130mm 10n.m, spindle motor is 5.5kw.

Spindle servo drive:



Spindle servo:




Axis servo motors:





Axis drive options:

Linuxcnc can work with most anything that is suitable for cnc motion control, with the possible exception of some serial controlled devices. I think the best way to determine what to get, is to pick the control method you prefer to work with.

That is good news, when you say control method, I'm a little confused, bare in mind I'm coming from steppers and mach3 for the past 6 years and have no experience with servos.
So any guidance is greatly appreciated.

Linuxcnc can do most digital position types, (step/dir, cw/ccw, quadrature), most traditional analog control, (with the right interface hardware), and as of recently ethercat (but support is still a little sketchy).

What Linuxcnc doesn't do is work with usb motion controlers (like a Smoothstepper) and other non realtime interfaces.

So if you want to do software stepping, pick something that can do step scaling, and accept ttl inputs. If you want to use hardware stepping, look for high resolutions, with differential inputs (most hardware stepping stuff supports differential signaling). If you want to use analog +10/=10v, pick something that accepts an analog velocity signal.

Infact Linuxcnc can control a servomotor with just a simple H-bridge amp.

You certainly know much about this, which would you select? This machine will be used for business, I know I needed something a bit more robust than steppers and the machine is fairly large which really needs servos. With that information which type would you select on a small size VMC for reliability, consistency ease of use etc..

I think my personal preference is for an analog velocity input control servo, using a Mesa 5i25 + 7i77 for the interface to the PC. But you might prefer using a digital position drive, with 5i25+7i76. One option is not necessarily better than the other, it's more about what you're comfortable with.