Langmuir MR-1 spindle servo - 8000 rpm

[JAZZCNC]

Hi jon,

Welcome to the forum,

Ok well the spindle in the Langmuir is more than likely a custom setup that is in 2 parts. It uses a standard Servo motor that will be attached to a custom spindle cartridge, similar to how the Milling machine work but with an ER collet shaft and much shorter cartridge. However, I'm not sure how they are getting 8000rpm with continuous torque so I'm slightly dubious about their claims.!

Most servo's and especially large servo's in the 2,5Kw size have a rated speed/torque of around 2000 to 3000rpm with a maximum speed of 5000-6000rpm for a number of seconds, so how do they get a continuous speed of 8000rpm without a gear ratio, that would lower torque.????

How the servo drive connects up to the controller in its simplest form isn't any different from how you would connect to a VFD, you basically feed 0-10V speed reference and Run-Stop signals.
I the simplest form because Servo drives often have several methods of being controlled.? They can accept Step and Direction signals or Analog +/-10v. They also have several modes they can be run in, usually Position, Torque, and velocity/speed modes.

When being used with Step-Dir you would run them in Position mode, this mode is what you would use if using them to drive an axis. Analog +/-10v can also be used for position mode but step/dir is easier to use and setup so this is what most people would use if they have step/Dir signals.

Position mode is what you would normally use for an axis and wouldn't really use on a spindle other than if you needed to rotate the spindle to a specific angle, which you would do if you had an ATC for instance.

Torque and Speed modes are usually used with +/-10v where 0v is at a standstill and a positive voltage is CW rotation and a negative voltage is CCW.

Torque mode is pretty much what it says you control the torque with voltage, so if you wanted a constant torque the drive would try to maintain that torque level base on the voltage being given. You would use Torque mode for driving things like conveyors where you need to hold tension on a belt etc.

Likewise, the Speed mode is the same but the drive tries to maintain the speed based on the voltage given rather than Torque. This is the one you would use for a spindle as the drive will try to maintain the speed as the load varies.

Now the Langmuir spindle uses an ER collet so you can't run it CCW as it will loosen the collet nut, so in this case, then they will just use the analog 0-10v + output which is commonly provided by most controllers meaning it will only run in CW direction.
If you wanted +/-10v analog output you would need a controller which provided this and they are not common.

Many servos have the option to switch between modes using inputs, so for instance using a servo for a spindle with ATC you will want to switch between position mode and Speed mode. You will turn on Position mode to orientate the spindle when changing the tool and then put it back into Speed mode for cutting.
This is done by setting inputs on the drive high or low.


Now, to be honest, I'm very skeptical about what they are offering.? You might not know but others do know that we build routers and small Mills like these so I know the costs and time involved to build them and I don't see how they can make any money at the price they are asking.? At the moment they are just taking orders so it will interesting to see how many people actually receive them and when.?

Hope this helps and if need any help get in touch.

Edit: Forget to say, forget using Mach3, it's long in the tooth and no longer supported, Mach4 is very buggy and difficult to use and I wouldn't use that either.

I now use UCCNC control software and controllers from a company called Cnc Drive, They make both the software and the hardware so are designed to work together which makes them very stable and are very well supported.