Retrofitting a 1986 Maho MH400E

Hello Mark, John and others!

Thank you for this thread, I read it twice now. I've been working on a Maho MH600E machine for a little over a year now and I'd love to do a LinuxCnc retrofit as well. While the Philips control is really nice - easy to use, well-designed, very functional, has all the G-codes that you have to pay for in modern controllers - it's all of limited use due to a memory limit of 17kB with no drip feed and only 2 axes simultaneous motion. So, no contouring or surface finishing, and a PITA to transfer programs to the machine from an 8 year-old laptop equipped with an RS232 port (at a glacial Baud rate with occasional errors of course).

My plan is to change the controller and leave all the old parts. My machine is almost the same as Mark's - 18 stage gearbox with the same speeds, Indramat driver and DC motors for 3 axes, a relay board on the door and LS403 scales from Heidenhain. The difference seems to be the work envelope (600x400x400 XYZ).

The only thing that broke so far was the CRT monitor which I replaced with an LCD, using a fantastic Chinese invention for converting vintage industrial graphics card signals to VGA. That's some serious money saved vs getting an ersatz display on ebay.

The first bit of bad news that I got just today was the quote I got from DMG Mori for the electrical schematics (which did not come with the machine) - ca. 750€! Ouch. This exceeds all the money I need to spend to make the retrofit using Mesa cards and my old computer... But I think it's a necessary evil, especially since I use this machine for work and wanted to do the retrofit in around a month when I have some down time. I don't have the luxury of time if I go with this plan. I'm going to read all I can and buy all the parts, and then find a good timeframe to do the work.

Should I start a new thread in this forum? Also, Mark, did you end up creating any repositories or pdfs as you planned in the beginning?

All the best,
Marcin

Hi Marcin,

Given that your machine is basically the same as my 400E everything in this thread should be applicable. If you want to post your retrofit into this thread go for it.

We made a github repository for the gearbox control comp here.
github
Its wiki has all that we learnt about the gearbox in it.

Send me your email and I can send you my draft "how to retrofit the 400E" document I have been working on. It is mostly complete, but I still want to make a Pendant , and we are still working on improving the way the gearbox.comp plays with LinuxCNC's spindle stop + spindle speed = 0 behaviour. There are two other german guys who are also working on retrofits using this draft as a basis. Maybe we could move to a Wiki, and all contribute to making a really robust "How-To retrofit Mahos" for all.

You should be able to prepare most of your retrofit without touching the MAHO. Set up the PC and Mesa Cards on a backplate which will mount onto the same nutplates as the Phillips used (See attachment, this is the plate which fits where my Phillips was). Since MAHO never seemed to make the same machine twice, your control cabinet may be different.


Things I'd do differently...
You have seen my ITX PC installation. If you do it similarly, rotate that PC through 90°, so that the MoBo edge connectors are at the bottom. I didn't have much space to get the various connectors in there.

In addition to the MESA 5i25 & 7i77 plug and go kit, and a 7i84 to interface with the MAHO relay panel, I'd now recommend you add a 7i73 to interface with a user control module. Also get a 7i74 and DB25M-IDC26 cable from MESA,so you can connect the 7i73 and 7i84 with patch cables, and not have to muck around reterminating them. I also bought Mesa's din rail adaptors. Not strictly necessary, but made mounting easy.

If you use the Heidenhain EXE board, make short cables from the 7i77 encoder inputs to dSub connectors, so you will be able to plug and play the Heidenhain's exe output cables.

I hacked the MAHO ribbon cables to connect the relay panel to the 7i84. You could also make up new cables in advance, so that you don't have as much down time.

I used a 17" Elu touch screen. It really doesn't need to be that big. If I did it again, I'd use a 15", but get a better screen, as mine has a crappy viewing angle.

Mark

Thanks a lot for the reply! I sent you a connection request since I guess that's how we can exchange PMs on the forum.

It would be really nice to use the control panel and/or pendant from the Philips, though I don't have any idea if that's really a good idea on the LinuxCNC front. I like how it has all the necessary stuff as discrete buttons and you can do a lot with the pendant in hand (which you actually have to since it's a tool room machine). By comparison, the modern pendants I see on sale on ebay etc. seem rather limited.

One thing that's a definite "must-preserve" function is a physical tool release button that can't be pressed by accident.

I have only read the available UIs wiki briefly so there's a lot of digging I still need to do.

This is a manual tool change machine, with hydraulic kick out of the 40 Taper tooling. The MH400E has no interlocks on the splash guarding. As a tool room machine, it will often be necessary to remove guards to fit outsized work.

I currently only have the tool release pinned to a front panel button, without any software interlock, so I could test stuff. You guys just reminded me that I was intending to look at the schematic to see if MAHO had implemented a hardware inhibit on the tool release if the hardware spindle_stopped is not active.

...Just checked, looks like there is no hardware inhibit, so I'll have to do a software inhibit in the HAL.

I haven't implemented the tool changing set up yet. I was going to do it like this...


Andy, how did you implement the tool release inhibit in your HAL? I have the physical input "Spindle_Stopped" coming in, which is currectly netted into the gearbox.comp as an inhibit for the gear change. As it is an input, I am allowed to reuse that already netted signal as an inhibit for the toolchange aren't I?


We already discussed using the original Phillips keyboard (can't find that thread). As I understand it, you can not net buttons from a single keyboard to both HAL functions and to user space keystrokes.
forum.linuxcnc.org/10-advanced-configura...ace-component#114374
Given Gmoccapy, I really dont think there is must benefit trying to keep the Phillips keyboard other than nostalgia.

The MAHO pendant doesn't have a jog wheel. I'd have though that is the single most attactive feature on a pendant. Mine will have E-Stop, Tool release, a 4 way rotary switch for jog axis selection, another 4 way rotary switch for jog increment, and a jog wheel. I think I'll also add an external connector to the pendant to plug in a touch probe or tool height setter. Since the MAHO is so small, all other functions are on the touch screen or the user panel buttons, and thus within easy reach.

Mark

Hi Mark,

ive done the tool change inhibit with a and2:

addf and2.0 servo-thread

net wzloesen <= hm2_5i25.0.7i77.0.0.input-19 and2.0.in1
net toolrelease and2.0.out => hm2_5i25.0.7i77.0.0.output-02

under the part # ---manual tool change signals---
i added the and2.0in0 to the following line:

hal_manualtoolchange.change and2.0.in0

this way, the tool release is only possible if the machine is waiting for tool change, so the spindle is not moving at this moment.

Thanks Bernd, how do change a tool if there is no program running, does the Gmoccapy tool change button activate this pin? For example if you are just setting up and want to mount a touch probe?
Mark

Thanks for all the input guys.

That's terrible to hear about your Renishaw probe Andy. I only have a Haimer 3d Taster and have so far managed not to break any tips.

Re: the Philips control panel and pendant, reading this thread I just thought that the panel was probably the most work-intensive element of the entire retrofit. The barebones alternative is a keyboard and a touchscreen, though I was hoping to use an Eizo LCD panel I replaced the old CRT with, and that's not a touch screen.

As for the pendant, my personal pick for most useful feature that's not on the Philips is setting zero points with a button for each axis. I saw that on a hobby Stepcraft machine, though that pendant was separately purchased by the user. When it comes to using the jog buttons you can set them to continuous, which handily moves the axis by simply pressing a direction button, or to incremental, which is very handy for finding workpiece edges (e.g. on a Haimer taster you can see each press of the button move the dial 0,01 or 0,1 mm so you can very easily get it to where you want it).

Maybe it's just that I've gotten used to doing things this way but I find spinning the jog wheel for longer distances kind of annoying, especially on slower speeds (which the Maho doesn't have a high speed, at a whopping 3m/min X rapids and 2,5m/min Y and Z rapids). On the other hand, precisely moving only a 0,01 or a 0,001 seems finnicky with a wheel since they're kind of designed for fluid, continuous operation. On the Maho I press the button once and there's no risk of me pressing it more than that.

In the end, I'll just go with a simple solution that works first and then move on to making improvements incrementally. We'll be able to share our findings and get things just right in the unspecified future

Anyway, on the MH600E I find that the table is large enough that, more often than not, I can't reach the control panel easily so some kind of pendant is a must.

EDIT: guys, this is a very dumb question, but now that we have a connection with Mark, how exactly do I send a personal message? I can't find any help feature in the forum controls

You are correct that there is no pressing need to make a user control module. You can control LinuxCNC with just a regular keyboard and mouse, or touch screen. I am using wireless logitech combined keyboard/scratchpad at present, with the intension of not needing a keyboard once everything is finished and configured.

I suggest you download the LinuxCNC liveCD to try out Gmoccapy. The way that Norbert has implemented the touching off soft keys and offset's is extremely intuitive and easy to use, but I don't think there are pins defined to hook into those functions, so you'd have to get into the code to put those functions out onto your pendant.
linuxcnc.org/docs/html/gui/gmoccapy.html#_jog_hal_pins

With LinuxCNC you can switch between continuous jogging, and your user defined increments.So if you set increment 1mm per click, your jog wheel can move you across the table very rapidly.

If this forum has no private message system, you can also PM in the CNCecke, with you email so I can send the draft manual. I have the same user name there.
Mark