New Retrofit of CNC Mill using mesa card and Chinese Servo drives

Hi Everyone

First post here so firstly a little about myself.

I am 22 years old and like playing with cnc machines, and love robotics/automation. I have spent the last 5 years machining and running cnc machines, while slowly building my home shop up to a point where I can start my own machine shop. And I also built my own cnc router a few years ago running on Grbl. Currently have about 15 tons of stuff in a 12 m by 13 m shed so any mechanical stuff regarding making cnc machines I have got sussed. Got the full range of stuff(Manual lathes,mills surface grinder,bandsaw etc)
Where I am weak on is the electrical stuff. I know some stuff but this is where I know I will struggle!

Anyway

Last year I bought a Chevalier VMC from a local company with the intention of fixing it or else just completely retrofiting the beast.
It was made in 2001 so relatively late model compared to most out there and was in really nice mechanical condition. Plus it comes with all the goodies like a 10 k rpm spindle, spindle cooler and 24 tool changer. The machine had a power strike which took out the combined servo and spindle drives unit. everything else works fine. I have given up fixing it and want to just retrofit with linux cnc and have a bit of fun learning while I do it. I also have 6 weeks off from the 6th of dec to concentrate on this, so will have a nice chunk of time.

here is the machine:



So currently I have a servo drive and 5000 ppr encoder coming in from china and I will be trying to reuse the heidenhain servo motors and just fix new encoders to them. I will try get one motor working before starting on the rest.

I was planning on using the normal 5i25 and 7i77 mesa combination and running using +-10 volts anolog to control it.
So I have some questions now before I buy anything!

1: I am in the planning stage and could use either step and direction or analog control for my servos. The drives accept both options. If I use the analog option what happens is the servo drive relays the encoder output to linux and the position loop is closed within linux cnc. What option do you guys think is best? It would be great if some of the old hands here could chime in and give me some feedback. (andypuge) (Big Jim) (tommy light)

Other than that where is the best place to learn to come to grips with the mesa cards and advanced linux cnc? I have currently got a little simple BOB board working with a stepper motor and will probably put that on my router first but I don't really know anything about advanced Linuxcnc Stuff and from all the reading on the forum I have done the first learning curve seems pretty steep so any advice would be awesome.

Ps I think the plan will be to get 3 servo drives working first, then spindle, and finally toolchanger plc logic.

Regards

Andrew

It would be relatively simple to cut your teeth on Linuxcnc by setting up the router. You would probably only need a parallel port breakout board for that.

There you could familiarize yourself with Linuxcnc and how to configure it.

Then tackle the VMC. I would strongly encourage trying to salvage the existing servos and drives for that machine. At the very least reuse the old motors (they are unlikely to be hurt.) What brand servos did it have? What was the old control? A machine like that is likely to require 3ph electric, do you have that available in your shop? Sometimes resurrecting an old machine like that is as simple as replacing the controls back up battery and reloading the machine parameters. (but that can be a big task if you don't have and can't get the backup files.)

Totally agree with Todd about starting on the router, then onto the mill. That is exactly what i am doing.

Im also a machinist, with limited electical/ electronics exposure.

I started simple with an ebay mach3 parport BOB and a simple stepconfig setup on my xcarve router. Then got a mesa 7i76e (not cheap but one became available from Rodw, so i bought it for the router), slowly learned and configured mesa setup with MPG, buttons, touchscreen etc.
Now i have a much better understanding of the electrical / linuxcnc side of the retrofit, while keeping the mechanical hardware simple and inexpensive. I have my milling machine console plugged into my little router cnc at the moment so i can test and play with it at home. Then set it up in the shop on my mill when im happy with it.
Good luck. This forum is invaluable, and the help people are willing to give is amazing. Have fun.

Hi Todd

Sorry for the slow reply.

I have been busy playing with linuxcnc though!

My Cnc router is now working and cutting air fine when I send it a fusion360 gcode file. I just need to set up the spindle and I am away cutting. And I am just about to make a start on my big cnc mill now.

Here are all the answers to your questions.

My cnc control is a Heidenhain 530 control I think. The machine was made in 2001 so it is still pretty new relatively speaking.

The servo drives are propriety heidenhain (all 4 servo drives in one box) /

The original heidenhain control still works and everything still goes fine apart from all the servos and the spindle is toast i think, but the servo drives got taken out by a powersurge/lighting strike. They are definitely toast. (smoke comes out when connected to power lol!)

So my current plan is reuse the actual servo motors and put in new servo drives which I have bought. check out my post below for the details.

I would like to use the existing Heidenhain encoders though if I can but I am not sure if they will work. anyway I will add all the info to my post below.

Hi everyone

Here is a status update for you all and some more questions:)

So I have the router working with correct homing and everything else and cutting air, just need to wire up my spindle and I can cut parts. I am pretty happy with the router really. Linuxcnc works very well. It was pretty hard to find info about how to set up my system but I finally nailed it.

So next up is the is retrofitting my big cnc mill. Starting with the servo motors and new servo drives.

I have bought one chinese 4 kw servo drive from china for the X axis, and I have just scored a whole bunch of Yakasawa Servo drives and a 11 kw vfd for the main spindle. I bought 12 servo drives plus the vfd plus all sorts of other goodies for 164 New Zealand Dollars which is pretty sweet. The great thing about the Yakasawa stuff is that they make rotating the spindle for the tool change easy. I think all I need to do is send the vfd a spindle orient command without any fancy linuxcnc stuff.

So this is the current plan for my servos. I will use the chinese servo drive and chinese encoder with my X axis motor and try get these going. The chinese encoders are basely a copy of yakasawa servos drives. so everything should be pretty similar. I think this is how they work/how i will set them up. The position loop is closed between the servo drive and the servo motor. and I will tune the drives. I will probably actually set them up with step and direction first and just use the tuning in the drive. The Servo drives take in the encoder signals and then piggy back in on to Linuxcnc. So I can change the PPR to what ever I want I think within the options on the servo drive. Then Linuxcnc does a PID loop and sends +- 10 volts back to the servo completing the system. Let me know if you have any advice for this please! I am all ears.

So I will have heaps of questions as this goes on and hoping that all the incredibly helpful people I have seen on this forum will chime in and answer all my questions. And I will try do research before posting stupid questions lol.

So here are the first two questions

I want to reuse my heidenhain encoders if I can. Now I have done some research and I think that I have standard incremental encoders with 2048 pulses per rev. My encoders are the same as this link.

Link to same model of encoder as I have.

Can someone please confirm that these are standard TTL incremental encoders. I don't want muck around for ages because I have a absolute encoder or a sin/cos encoder which I think I can't use?

Apart from that please chime in with any comments and advice. Hopefully I get this making parts in the reasonably near future.

Regards

Andrew

What does that really mean AndyPugh?

I am also concerned with the fact that they are sinusoidal and might be hard work to interface with..

But I have some more questions now. My plan has changed slightly.. I managed to buy a whole bunch of Yaskawa servo drives and a variable speed drive second hand. The servo drives are 200 volts and the variable speed drive is 400 volts. standard three phase power in New Zealand is 380-400 volts. So I will need a stepdown transformer I think. my chinese servo drive is a copy of the yaskawa stuff so should all be similar.. Does anyone have any experience with yaskawa servo drives? and the yaskawa variable speed drives?

Regards

Andrew