Retrofitting a 1986 Maho MH400E

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

Hi,

I just landed a number of Maho machines (in the US) and was happy to find this topic. Seems this forum has drawn a lot of new Maho owners since there isn't a whole lot out there.

Here is a list of the Machines:

(2) 600p's
(2) 600e's
(2) 400p's that are complete
(2) 400p's that are parts machines

These machines are all from a one owner small shop. He purchased the 400's and a couple 600's new from the factory and it appears there are a number of different accessories for the machines. None are turn key machines, all need repair or to be retrofitted. I'm still in the process of moving the machines to my shop so I haven't really dug into them. I'm hoping somewhere in the stack of books is a detailed parts diagram, would like to see the full working of the P machine travels without having to fully strip them.

Plan A would be to have all machines CNC, plan B would be to mount motors to the P machine hand wheel point and have joystick control with a DRO. We will see what comes of it. I've rebuild a few CNC machines but haven't gone through the process of adding ballscrews and motors to places that don't already have them.

Once I go through all the paper work, I'll try to get any good machine diagrams (if they're there) uploaded.

Hi Chris,

In your troubleshooting post, you state "Capacitors have been replaced." I also replaced the capacitors in my Indramat before I got started. figured it is cheap insurance to get rid of 30 year old electrolytics.

Do you have the set of wiring diagrams? Maho's vary a lot, so you really need to contact DMG and get a set of wiring diagrams specific to your machine. You need this either to troubleshoot the original, or retrofit.

I am not sure how the Heidenhain start sequence works. On the Phillips, you pushed the main Hydraulic start button, and also the on lathcing button.
If you push the Hydraulic start button, and the main contactors don't close, it sounds like your E-Stop chain is open. Have you checked the end stop switches? Pendant E-Stop jumper? The lube oil level sensors are very conservatively set. Make sure that way oil tank is over half full.

If you have the wiring diagram, you could jumper the Control On E-stop chain signal to bypass the Heidenhain, and and provide a control signal to the indramat to check it. However I wouldn't bother. There is no reason to consider faults in the indramat, until you can get the main contactor active. Whether for the Heidenhain or a retrofit, this needs troubleshooting.
Mark

Hi eflor8234,

The x00P is a half way house between manual and CNC. With the complicated clutch system to drive up to two axis at a time off a single motor, they are only capable of straight lines. This is what Thisoldtony has also bought. Maybe he needs some parts. I'd dump those on ebay, and concentrate on the two 600E's, which are much easier to retrofit (if even necessary). I hope you got the wiring diagrams. They are the important document. Parts lists less so.

Those rotary tables are tasty. Shame you are a continent away.
Mark

chris mcm wrote: Hello Jon

You mention the condition of the Indamat Servo Amplifiers. How can I check this?

Well, examining them for general appearance can be of some value. If they look horrible, darkened areas on the circuit boards, etc. then they may have limitied remaining life. Some others mentioned rplacing electrolytic capacitors, that certainly should be done on 30+ year old amps.

Also, if these are SCR servo amps, they probably should be replaced. Those have limited bandwidth and may not tune easily with LinuxCNC which by default has a 500 Hz bandwidth. Also, the SCR amps are really sensitive to power quality.
In 1986, the SCR amps had mostly been superseded by transistor PWM amps, so likely it is NOT SCR, but just thought I should mention that.

Another thing is if the machine has glass linear scales, you want to figure out what the resolution is, and if they are analog scales (can be determined by the part number on the read head) then there should be interpolators. You want to see if the interpolators can be separated from the CNC control. If so, you can have very high resolution position feedback.
If you can't separate the interpolators (built integral to the encoder input boards) then you end up with really coarse scale resolution.

Jon