Retrofitting a 1986 Maho MH400E

On my machine, the coolant flow control has become sentient. I think Maho just went to the hardware store and bought the smallest household tap they could find. Mine changes flow settings at random. Probably tied in with the fact that I haven't cleaned out the coolant tank in the foot casting, and it was full for at least a few years before I got the machine. Draining and cleaning it are on the to do list, under the sub heading "shit jobs"
Mark

Oh, okay then. Mine came with a separate, steel box for coolant and a rather nice, if cosmetically beat up pump (tbh the entire machine is beat up). The box was empty of course. It's still worth it to clean the coolant reservoir IMO though I see how given your situation you might prefer installing something else altogether and forgetting the original system is even there. Especially since you can cut a lot of steels and cast iron completely dry with a bunch of carbide, cermet and CBN tools.

I had a lot of fun machining cast iron on my MH600 with a 16mm 6 flute carbide endmill. It didn't feel much different than cutting aluminum had which I thought allowed the machine to show its strengths well.

I should be easy enough to move the coolant to a separate container. The Maho pump is mounted on a loose sheet metal cover over the foot casting.

Hello Mark and Friends
I have a Maho 700 C. imported from Switzerland . I live in Auckland, New Zealand.
The machine has had little use as evidenced by the condition of the slide ways.. When the machine arrived the electrics worked but the Y axis would not work. This was due to broken Aluminium coupling. That fixed the machine worked well for a while then failed. A good friend in Germany helped. We sent a circuit board back to Germany and had the Eproms replaced. The machine ran again for a while. Now the machine is out of action again. My contact in Germany wants me to send the whole Heidenhain TNC 135 unit back to Germany for service and also renew the screen. This will be expensive and I wonder what next will fail. This machine is in a private work shop. I am trying to finish building a steam Launch engine. The TNC or CNC feature would be nice but I really just require a regular accurate milling machine with power feed.
The Maho has Indramat DC Servo motors driving 49mm ball screws on the XZ and Y axis. The amplifier is also made by Indramat. This 35 year old electronic equipment can only be serviced by the factory at huge expense.
Can anyone on this forum tell me how I can by pass the Heidenhain TNC and get my machine running again. I don't trust the original 35 year old electronics. The machine came through the tropics in a container. My guess is the heat from the sun has helped break down the plastic electrical components. My friend in Germany has a similar machine and it has given him no trouble.
Can you please advise me in what I should do. My age is 75. I don't want to scrap this superb machine. Thank you

Welcome Chris. I am also a Kiwi. I have assembled what I have learned so far in my Maho MH 400E conversion into one draft document. If you give me you email address I'll sent it through. Unfortunately you cant do private mail on this website, but I use the same user name on CNCzone, Practical Machinist, Madmodder etc, so just drop me a line with your address.

You said it stopped working again. What is the symptom this time? Is your 700C equipped with a fourth axis? Please post some pictures of the machine and its control cabinet innards.

The MAHO's are very modular in their electrical/electronic architecture. I found it quite easy to keep the bits which work (power switching/ relais control / motors and Indramat / Axis encoders) and only lobotimise the old 1980's brains. I had little knowledge when I started.

If you have existing faults, but don't trouble shoot them, it can make the conversion more differcult. I had to go that way, as I couldn't get a video signal on my old Phillips. In the process of the conversion I discovered an intermittant fault on the relays board edge connector, and two faulty Heindenhain EXE's.

It should take the same minimum equipment to convert your 700C:
- A PC running LinuxCNC
- Mesa motion cards .I used 5i25/7i77/7i84. If doing it over I'd add a 7i74 and 7173 as well, to reduce the discrete wiring a little.

I am assuming your MAHO also has Heidenhain LS-403 encoders for the axis position feedback, and probably has some flavour of Heindenhain EXE to do the analog / digital signal processing. However, if this A/D conversion was done internally in the TNC 135, you might have to buy three 602 EXE's off Ebay to interface the encoders with the MESA cards.

Does your 700C also have an 18 speed gearbox, and single speed spindle motor, or is it the two speed gearbox with the electronically controlled motor?
Mark

chris wrote:

Hello Mark and Friends

The Maho has Indramat DC Servo motors driving 49mm ball screws on the XZ and Y axis. The amplifier is also made by Indramat. This 35 year old electronic equipment can only be serviced by the factory at huge expense.

It is not sensible to maintain a 35 year old CNC control. Not only are modern controls better in operation, but theay are more relaible and much less expensive to fix.

One option is to use the Pico Systems PPMC to control your existing Indramat servo amplifiers. The PPMC is a set of boards for interfacing to analog servo drives and the machine's encoders. Of course, you have to take a look at the condition of the Indramat servo amplifiers and decide whether you want to keep those.

You could replace them with AMC, Copley or Servo Dynamics servo amps, or possibly, depending on the motor ratings use the Pico Systems PWM servo amplifiers and PWM controller. One issue is that for best results with the PWM system, you want to have higher resolution encoders that was typical with machines of this vintage.

Also, your machine may have Heidenhain interpolators for the encoders, you want to keep those if you remove the rest of the
TNC 135. I **THINK** they are separate modules in that system.

Jon

Hello Chris,

As Mark said, it is possible to replace the CNC control with LinuxCNC while retaining the servo motors and amps, as well as the linear glass-scale encoders. The machine design was indeed modular, with various components (such as the hydraulics pumps, encoder signals) acting "on their own", such that they don't require extensive PLC programming.

Thanks to the help from this board and especially Mark in particular, I managed to convert my Maho to LinuxCNC with Mesa boards, with no technical background. I did also have the real-life support of a programmer friend who knows a lot about Linux and was able to help me out on the OS side an electronics. Overall, it took me about a month to remove the Philps 432 control and have the machine working with LinuxCNC.

In your case, I would also consider what John wrote above - servicing the Indramat servo drives and motors would be quite expensive today, but you're also so far away from the qualified people in Germany that it might be better to replace them. That way you can avoid a lot of shipping which will either be expensive or take a long time. But that might be a last resort and is also expensive. Maybe the Indramats are still fine. They are slow by today's standard, but they are very reliable. If found I could depend on them even after a crash.

At least on my MH600 E, what I don't like about the drives is the 4:1 reduction between motor and ballscrew. It makes the machine very slow in terms of acceleration which is very noticeable with a modern control like LinuxCNC and modern, CAM-generated tool paths. The latter feature a lot of small movements in which the machine never operates at the desired feedrate. But that's not an issue coming from the Indramat drives, it's more the machine design.

The old Philips CNC didn't have block look-ahead and executed commands one line after another, with very short pauses between them. There was no need to have the drives respond any quicker than that, and it also allowed the engineers to use less powerfull motors which translated to lower power use and operating cost reduction. This type of economic design is very nice to have in a home or hobby workshop today I think. So there are pros and cons, but my entire machine uses up less power than a modern, reasonably-powered spindle on a contemporary VMC.

Anyway, hopefully we'll be able to help you out with your project. I may not be but the other guys can for sure.

Hello Mark
Thank you for your quick response. I will find your address and contact you ASAP
I need to work out how to put photos on this site.
The subject Maho 700 C has the 18 speed gear box.
Check List for TNC Problems written by a qualified technician
1. Machine Brand? – MAHO

2. Machine Model? – MH-C700 (1980)

3. Machine Serial Number? – 75323

4. Control Model? – TNC135 ST

5. Control ID Number? – N/A

6. Control Serial Number? - 550540D

7. Control NC Software Number? – Prg 214 330 06

8. Descriptions of Error or Problem? – Controller appears to be stuck in start up test



9. How Error or Problem occur (Step by Step)?
Initially I had to enter the parameters into B.3.2 of the manual then I was able to move the X, Y, Z Axis but after 20-30 minutes some contactors would drop out and I could not get it to run, I turned the power off for 20 minutes and then was able to run again. The next time it failed I couldn’t get the main running light on or the main enable contactor to pull in. at this time all the Lamp came on and nothing could be done with the controller. Now when powering up the Lights come on and stay on, nothing can be on. My Electronics Techician has found the 5 Volt rail low and put an external power supply on to bring it back up, Capacitors have been replaced.

10. To give complete error message display on screen? – None

11. Is error or problem intermittent or permanent? - Permanent

12. Can error or problem be simulated again? – contact dropping out issue ca can be simulated again.

13. Any History of error or problem? No

14. How long machine is in use? Hasn’t got many running hours. I don't believe this machine has been used in industry. A University or similar work shop. Maybe it has been broken down most of its life.


15. Brand of drives or inverter and motors? Model& Id. Number? Indramat
PLC Siemens – S5-010 6ES5010-EC31-Z
Drive – Indramat 3 TRM 2
Motors – Indramat MDC10.30D/MS-1/ S07 (3 motors)

16. Machine purchase from whom? Second hand from Switzerland

17. When Machine was purchased? By Chris 3 years ago
Thanks for your help. I had nearly given up.
Cheers Chris

Thank you for your response. This site is amazing. I have followed it for a while and finally built up enough courage to write. I am a bit out of my depth on this subject but learning fast. I have had three replies all with good advice and so much valuable information. And from Vienna! could not be further from little New Zealand.
I will talk more as I progress. Thank you.
Cheers Chris

Hello Jon
Thanks for your reply. Very much appreciated. I have been following this site for a while. I can see the only future for the Maho 700 C is to retrofit it CNC.
From Memory the Maho cost me about Euro 7000. At the time I felt it was a better buy than a new quality milling machine from Taiwan.
The Maho has some great features. I liked using it. When it is going!
You mention the condition of the Indamat Servo Amplifiers. How can I check this?
I will get back on this site with more questions. Thanks for your help.
Cheers Chris