Retrofitting a 1986 Maho MH400E

Hi Mark,

what are your final PID-Values after tuning the axis?

I followed the tutorial gnipsel.com/linuxcnc/tuning/servo.html but don't get the following down without oscilation (P at a max. Value of 4,5). I can also change FF1 in every direction, i got no change of behavior. i can do what i want, i have always a following error of about 0,3mm with 500mm/min.

Bernd

Hello Bernd. Here is what I have at present. I am not completely happy with the Y axis. I had to limit its top speed a little as it starts oscillating at higher speeds and occasionally would trigger a following error. I played around a lot with various P, FF1 and FF2 settings, but do not yet have anything better than the following. I and D values are 0:

| X | Y | Z
P | 6.5 | 5.5 | 7.5
FF1 |0.22 | 0.228 | 0.218
FF2 |0.0021 |0.0015| 0.002
Max | 45 | 40 | 45
Acc | 50 | 50 | 50

Please let me know what values you settle on.

I didn't get anything done on the MAHO recently, except welding and panel beating a hole I put through the in the corner of a rear splash guard, by leaving a spanner laying there during testing. Was a good lesson in keeping body parts out of harms way. It didn't struggle at all to insert a 19mm open ender through 2mm sheet steel.

When I got the machine, it was complete except for the LH splash guard door. Rene of CNC-Baumgartner.de must have parted out a 400E, as he advertised a LH splash guard on Ebay Kleinanzeigen (Germany's craiglist). So buying that saves me a bit of fabrication work.

Mark

Hi Mark, thank you for the values. finally i resolved the problem.
I installed a not "stable" version of LinuxCNC on Jessie. (reading the docu would help sometimes ). I reinstalled Wheezy with 2.7 and it works. Now the FF1 does change the tuning.
I have almost identical values, Pgain are about 20% lower then yours.

Hi Bernd,
have been away for a while, sorry for not replying. If you still need the cards let me know. As far as I remember batteries are behind the control unit / underneath the monitor. You don't need a puncher as you can simply connect the machine to your PC via RS232. A terminal program like HTerm can be used to read and write data to and from the CNC.

Christian

Hi Christian,

thank you, in the meantime i already made the retrofit to LinuxCNC, the machine is running. I still have to do some cabling work on the user-panel, and the gear shifting is not implemented, but the rest is ok. as I'm not very good in electronic stuff , for me it was easier to change the scales to new ones with RS422 signals...

Lately I have been working on a number of different things with respect to the MAHO. None are quite finished.

When I go it, one X-axis Bellows was missing, and the other falling apart.





You can get them off Ebay sometimes for about €200 each, but know that they disintegrate over time. A friend who has rebuilt a number of machines, gets custom bellows made in China by this company, and has been very satisfied with the quality.
BF ACCESSORY LTD..
No.023 Yan shan industry district Hebei province China
P.O.Box 061300
E: bfaccessory01@outlook.com
T:+86 183 3178 0564



The sales guy, LeoZheng communicates really well. He promptly told me they couldn't do the wire hangers, but proposed an alternative with it guided on the PVC ribs.



Given a quote of under €100 for two bellows including shipping, I figured I'll give them a try. Hopefully they will arrive in a couple of weeks, so I can put the guarding back on.

Also got lucky in Ebay. CNCBaumgartner in Germany must have parted out a MH400E, and were selling the LH side wall splash guard. This is the only guard part I didn't receive with the machine, and getting it from Rene sure saved me a lot of work. The Post lost it, so he had to spend a few hours chasing them, but it showed up last week. His service and communication was also very good.