Upgrade questions fro beaver mill VBRP Mk2 with Anilam Crusader II controls

[JAZZCNC]

My advice is to dump the servo's for AC brushless with Step/Dir drives and go with Centroid Acorn Controller.

The Centroid control Software is built proof tried tested over many years and comes with built-in conversational Cam.
The Controller is 4 Axis with Spindle encoder input and 0-10V analog Output for speed control. With more than enough I/O for Mill.
http://www.centroidcnc.com/centroid_...ontroller.html

You can buy AC Servo's cheap enough from China which will work fine. This combo will give you great machine with strong control that won't cost a fortune.

[Clive S]

Bloody hell Dean.: Welcome back from the dead

[mekanik]

Bloody hell Dean.: Welcome back from the dead
+1

[Breg90]

Thought I would stick up a few pictures:















Thanks to those that commented. I'll knock up an I/O list and post next.

Adrian

[Breg90]

Hi,

Few things in life got in the way of this. However eventfully I have knocked up a I/O/functionality list. See attached file.

I find my self ending up looking at centroid solutions. What am I missing by not looking at others? Note this is a hobby, but I'd rather build something that is reliable and hopefully more saleable if I ever look to part with the mill in the future. I feel that the centroid solutions are more 'industrial' than the various MACH 3 (or 4) solutions.

Any comments welcome.

Adrian

[battwell]

id do as dean says- motors are small enough to replace with ac servos- ran in position mode.
closed loop isnt required- as the loop is then closed in the drives (full closed loop systems are pretty expensive to set up)
then choose a control capable of what you want/need. (governed by i/o number and working functions)
personally id go with either uccnc - due to ease of setup and working features, or kflop as i know these both can be expanded to do exactly what you want reliably. (i dont know how much i/o upgrade etc can be done with acorn re modbus capability and so on- but this sort of thing is a must if you want perfect control over spindle/ mpg etc etc.

[m_c]

First off, some comments about your IO list, starting at the top.

I'd personally consider motorising the knee, but you need to consider if the quill alone will provide enough travel, by the time you factor in variations in tool height, and the size of work you're likely to do. DaveK has just done it to his, and uses it to compensate for tool length. I wouldn't be using the knee to provide extra travel for machining, because as you say, they're not designed to running up and down constantly, and certainly not at high speed.

Scales are good for getting the best accuracy possible, but to use reliably, you really need to use a double closed loop. If you rely on just the scales, tuning servos reliably can be a major problem, as any backlash affects the loop, so can cause some very erratic results.

Scales do not eliminate homing. Most scales are incremental output i.e they only output what direction they're moving, and how much they're moving.

I'd personally stick with the VFD, as it gives more automated control. With a CNC, you want to be able to set it running, then walk away and ignore it, not have to go back to adjust things.

So of the top of my head, to achieve that is going to cost a lot of money for a suitable controller.
The only reasonably priced controller that I know that can do dual closed loop is a KFlop, but I think even that may struggle for the required number of channels.
Say you run the motion using step/dir (the servo drives handle the inner closed loop), that is potentially 5 outputs.
Then with the existing scales, that's 3 encoder inputs, plus the spindle, so 4 inputs needed.
Now IIRC that potentially leaves one more step/dir output, and two encoder inputs (one of which you'd most likely want to use for a MPG). The problem is the step/dir channels share the same pins with the encoder inputs, but some of the step/dir outputs can be multiplexed across, so I think you can get a total combination of 12 step/dir and encoder channels.

The reason I've not mentioned analogue, is the KFlop only has 8 encoder inputs, so if you use it to close the loop, 6 of those inputs would be needed for the 3 main axes alone. That potentially only leaves a combination of two step/dir outputs and encoder inputs . Although I think when used with a Kanalog, you can use the full 8 analogue outputs and 8 encoder inputs, and still get another 4 step/dir outputs.



It might be worth considering the Centroid All-in-something DC controller. It's not cheap, but I'm pretty sure it's designed exactly for retrofitting this era of machine with DC servos, but I'm not sure if they can make use of the dual encoder loop. It would however save you the cost of new motors/drives, but then you're reliant on being able to get replacement motors/encoders should one fail.

Failing that, you're into the realm of step/dir and/or closed loop without the scales, in which case, pick whatever software/controller you think will suit your needs best.


And just realised, add a probe to your input list. They make setup far easier!