Retrofitting a 1986 Maho MH400E

not all docs online, but our server doesn't forget things....

Hello from Romania , very interesting and inspiring post , i own two Maho , one is 500c model ,this one can be retrofited with LinuxCnc  , but the second is 500W cnc 132  , point to point straight cut control , heidenhein ,  but  the model uknown ,  with  single servo  and 3 cluctch for each axis, 
question is : can be retofited with LinuxCnc?

Best regards 

Yea ans No, cause you on can move on axis at the time and you have quite a backlash in the spindles.
So a simple retrofit is not possible. But If you change to ballscrews and a servo for each axis you can retrofit it.
ThisOldTony did a Mac3 retrofit on a 400p there you see what I am talking about

I agree that retrofitting one of the single axis drive motor Maho's is not a very attractive project.

Hi , i agree with you , but i am not looking for any complex milling , not doing radius  , just want to use the mill as it is now  , manual or automatic positioning   point to point  straight milling , just want to save the money for retrofiting the 500C.
I must mention, the current controller is defective , looking for a contoller capable to use actual linear scales , with analogic ouput for servodrive control and ,very important , capable with aux programming  as plc , for clucthes control.
These conclusions made me think of Linuxcnc
Thanks a lot .

If you just wand to copy the control of the MAHO it might be possible but not very convenient. You could control the clutches by unlock pins.
But I am not sure, and tuning would be a challenge.
And i am not sure how to control the analog out

I again agree. LinuxCNC can control pretty near anything. but this might require some pretty significant program alteration.
Some of my ideas...
- Is there any switch in LinuxCNC to  inform it that it is only allowed to move one axis at a time?
- If not you could set your post processor to only output single axis motion lines.
- You would need to set LinuxCNC to absolute stop mode (G61.1) to prevent it trying to blend two axis at corners.
- When a new line of motion is parsed, LinuxCNC will expect the motion to begin immediately. The fact that it has to implement clutch changing and receive feedback that this has completed before it can start outputing the motion may be pretty difficult to implement.
- I looked at Remap, and doubt you can use that to modify the G0 and G1 behaviour. You might be able to do something with unused Gcodes, where your PP sends a "G0" line as G88.1, and then in Remap parse that to first do the clutch magic, and then G0 commands once the correct clutches are engaed.
- The actual I/O of LinuxCNC clutch control and feedback will be the easy part. If going to guess that this is 24VDC system and could be interfaced with a MESA 7i84.
- I'm guess that the axis drive is a single axis Indramat, or similar analog servo drive. A  7i97 to interface the motor drive and the linear encoders would likely work.
-I wonder whether you can net all three axis motion pins to a single analog output of the 7i97?
Mark

There are a lot of guys who are much smarter and more experienced at LinuxCNC , and one of them may identify a simple solution.

I think LinuxCnc , it is the most closer way to go , all i need is to trigger an output for each axis before starts to move ,  like a brake release or clutch engage , with no feedback , feedback is pretty hard to obtain , only with a current relay  or confirmation via NO/NC contact of a relay , but they are fast cluctches  and i guess will be just fine without feedback from clutches.
I will set the PP to send a line for every axis separately and then next axis ,   like G1 X ....     then   G1 Y.......  
The analogic ouputs from Mesa card   i will link them to an arduino board   , also  i will read the digital outputs for the clutches  and make a simple program  to choose the analogic value for axis that needs to move  and pass it to drive .
The drive is Indramat 1Trm2 , his operation is also questionable ,it is not moving smoothly, (i have to check , maybe it is the analogic command from contrller defective)  even  the machie has a few hours of operation ,  excellent mechanic condition.I got several drives to replace if need it , also step/dir or analogic.
Thank you guys .
 

I would use a analog Mesa card.

For the clutch control you could use the unlock pins:

linuxcnc.org/docs/html/man/man9/motion.9...OINT%20UNLOCK%20PINS

It‘s for indexers but could solve some of your issues.

The machine has trapezoidal spindles I think, you you could get in trouble with backlash and the PID tune. But you only move one axis at a time (I would write a ladder script to trip estop if two axis are unlocked at the same time)
You could go for a low P to prevent from overshooting.

As Manfred mentioned one big problem could be that you can’t link the analog out for all axes to one pin.