Retrofitting a 1986 Maho MH400E

Cool. Another milestone. Mine also has some audible pulsing. I should take another go at fine tuning.

My current situation is that it's enough for me to get the drives working properly (with limit switches and encoders) and I can get back to work, since I've been using an external VFD to drive my bolt on high speed spindle back on the Philips. The gearbox and main spindle hold a promise of further problems, since compiling files is completely new to me (all of this is completely new to me, as you've seen from my idiotic musings and the dumb problems I generate, describe then solve).

Any ideas why the Z axis DRO doesn't change position now when the axis is moved, but it did when drives didn't energize and the brake was released? This tells me the encoder is wired to work somehow, but it ceases to function once it's inside the feedback loop for some reason.

A big Thank You to all that are contributing to this retrofit thread. This is really useful information for MAHO machines and also others.
It is also proving out Marks retrofit documentation and also some of the variables that come up

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which I think is extremely useful information.
Glemigobles was wondering what model/series of indramat servo drive your machine has?

Bob

J Green,

My machine has the same 3TRM2 servo drive as Mark's. The BOM in the schematics from DMG list it's full name as 3TRM2-G11-W0/ZE5, and while it's physically just one board (usually now they're separate modules for each motor), it does have two modules listed for the X-Z and Y axes. So I guess they're subcomponents.

The motors are Indramat MDC 10.20F/MMA-0/S06 (two of) and one MDC 10.40C/MMA-1/S06. Can't tell you all the info on the motors since the plates are located in very inaccessible positions. I know they're 2000 RPM max and the axes torque are listed in the machine instruction manual (2x3,7 Nm and 1x8 Nm for the Z axis).

I can't stress enough how helpful Mark's been all this time, as well as other posters like PCW. I literally have no technical education to speak of (I studied literature at university) and I managed to get this far with help from the forum (and all the manuals of course, especially Mark's wiring diagrams).

If anyone else ever wants to test the limit switches on their MAHO MHXXX, mine has travelling push-button types of switches which physically press when they reach the axis limits. So instead of actually moving untuned axes around, it's far easier and way less stressful to just take off the covers and push the button with your finger. In my case, all three estopped correctly. I'm attaching pictures.

The X axis switch is located to the right of the X motor, under the cover for the ballscrew. The button faces up.

The Y axis switch is below the gearbox, its button faces towards the machine. You need to remove the cover with the holes that show the gear positions.

The Z axis switch is behind the largest cover that houses the two hydraulics pumps. It's the easiest one to reach with your finger.

Just press the button to simulate it hitting the axis limits, as far as the machine is concerned there's no difference.

I switched the X and Y axes to their correct positions (switched drive terminal blocks) and checked that they moved in the right directions.

Next, I started troubleshooting my problem with the Z axis encoder signal. I found a few loose wires in their crimp terminals (the smallest I could buy were 0,25 mm2, and yet a lot of the wiring is still too small if some of the strands somehow got clipped; then I have to fold the wire in half and get it inside the connector again).

Anyway, now the machine won't stay latched on after the machine is on button is clicked I was hoping to be tuning the servos today but I have no idea what caused this change. I checked all the relevant wires but after I release 3SH1, the 7RC2 relay switches off. It's not hardware estopped either since it turns on for as long as I hold the 3SH1 button. Looks like I just took an unnecessary step back

The Z DRO also doesn't show any movement if I manually turn the ballscrew. The brake is released when the 3SH1 button is pressed and the table moves slowly but that also isn't shown on the DRO. This is a big change in comparison to the time when I couldn't get the drives to latch on, the linear scale showed the table moving down then. Any thoughts on what wiring I might check?

In this state you know that the x and y scales, exe board and mesa inputs are all good. The logical thing to do is swap caples until you find what is causing the problem.
John

For the not laching problem, try to disconect the contact that goes to mesa from the start bouton ,and pres the start bouton and the soft bouton in gmoccapy.
The two contacts in start bouton may not be synchronized.
John

Can you take a photo from the axes hard limits of the machine?
John