Retrofitting a 1986 Maho MH400E

21 Nov 2017 17:02 #102146 by RotarySMP
That is really frustrating for wait for those balls to arrive, only for them to be junk. Maybe you should post a request for help finding either a reliable ball suppier or a Ball screw refurbisher on Practical Machininist

or if you like I can ask on the German language machining forum...
for a recommendation?
21 Nov 2017 18:07 #102148 by drimaropoylos
Hi, yes plz ask in that site.
21 Nov 2017 23:36 #102162 by tommylight
Do you have any bicycle repair shop near you? Try there ! I neded some 6.320mm ones some 6 years ago and having no way of getting them, went to such a shop. Got 200 of them for 10 euro, set them up and they are still happily working! I am aware that i lucked out on that, but worth a try, they had only 4 sizes of them.
22 Nov 2017 14:52 - 22 Nov 2017 15:00 #102189 by RotarySMP
From the Zersannungsbude...

This place has bearing balls:
It was recommended that you contact them which the exact size you need, which may be something they havent listed in the web shop.

There was a short discusion about replacing every second ball, and recommendation that the balls are normally toleranced G5.

The recommendation came for this overhaul facility:
Last edit: 22 Nov 2017 15:00 by RotarySMP.
22 Nov 2017 16:37 - 22 Nov 2017 16:41 #102194 by drimaropoylos
Thank you Mark, I will contact them to order the right size I need. The replacement of every second ball with one smaller (spacer) helps the balls not to rub with its other. But with halve the balls make contact with ballscrew and nut, the forces on every contact point during accelerations and decelerations is now doubled. I don’t have enough knowledge on the subject to decide such a change in the ballscrew. I am open to suggestions and opinions on the subject.
Tommy thank you for the suggestion. The problem is not to find the balls, the problem is to find ball with the right tolerances (or better) and size with the originals. I have find balls from local stores, but they sound and feel terrible in the ballscrew.
Last edit: 22 Nov 2017 16:41 by drimaropoylos.
26 Nov 2017 20:20 - 04 Sep 2018 20:16 #102369 by RotarySMP
Didn't get anything done on the MAHO last week, but yesterday I reinstalled the ribbon cables.

I took another shot a troubleshooting the "machine on" relay not latching on. I'd already isolated the problem to the MAHO relay panel. I'd been overthinking it, wondering if there was some logic wired into the panel.

I did basic continuity checks according to the wiring diagram. Pulled the 19K1 relay and the manual brake release switch. The problem is in the row of plug in screw connections along the bottom of the MAHO relay board. Resocketing the middle terminal plug closed the circuit.

Turned everything on and sure enough, the control latches on. Woohoo, as I can now move on to getting some motion.

I'd noticed an intermittent contact problem alone that row of plug in screw connections before. The 7i84, and 7i77 pick up 24V and 0v from there, and I have a couple of times where LinuxCNC errored out doing start as they were not getting power. If the the pins in the plugs are worn out, It will be easy enough to buy replacement connectors, and just use the plugs.

Out of batteries on the laptop, but I'll add photos tomorrow in case someone else has the same problem.
Last edit: 04 Sep 2018 20:16 by RotarySMP.
28 Nov 2017 16:38 #102444 by RotarySMP
I am a little confused by MESA's instruction for grounding the analog drive control wires shielding...

7I77 14
The 7I77 provides six channels of +-10V analog servo interface on connector TB5.
Minimum load resistance is 2K Ohms. Normally analog servo drives use differential inputs
to avoid ground loops. Suggested wiring is shielded twisted pair with 7I77 AOUTN to drive
AIN+, 7I77 GNDN (adjacent to AOUTN) to drive AIN- as the twisted pair and 7I77 GNDN
connected to the shield at the 7I77 end only.
The drives common or GND signal should be
connected to the 7I77 power GND with a separate wire.

That the +10 / -10V wires for the first axis connect to TB5-3 (GND) and TB5-4 (AOUT0) is clear, if somewhat confusingly named. But do I also connect the shield to TB5-3 (GND) or do I connect that to the 7i77 power ground along with that separate wire coming in from the Indramat ground?

I am going to use CAT 5E, as it good quality shielding, and I have some. I plan to run three separate cables, one for each axis, or would it be better to use only one cable with a twisted pair for each axis and common shielding?
28 Nov 2017 16:47 #102445 by PCW
Replied by PCW on topic Retrofitting a 1986 Maho MH400E
Do the drives have differential inputs?
if so the wiring is

GNDN --> CABLE SHIELD (7I77 end only)

Drive GND --> frame GND
28 Nov 2017 17:33 - 28 Nov 2017 17:36 #102447 by RotarySMP
So that means I connect both the AIN- and the shield together into TB5-3? Seems weird to me.

I found this in google.
so I guess the do get wired together.
Last edit: 28 Nov 2017 17:36 by RotarySMP.
29 Nov 2017 09:15 - 29 Nov 2017 14:03 #102472 by RotarySMP
I made the three +10/-10V cables. Now I have a question about the Indramat gound. The Indramat terminals have three ground connections, one for the shield of each axis cable (MAHO terminated the shielding in three places - The Indramat, the Phillips connector and in the middle of the cable to the Phillips housing).

The three axis grounds have continuity between them. Should I run three wires to the 7i77 field ground or just one?
Last edit: 29 Nov 2017 14:03 by RotarySMP.
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