Retrofitting a 1986 Maho MH400E

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16 Mar 2023 08:47 #266812 by D Jensen
For db1981 on page 127:
Here is a photo of my two 24VDC power supplies that go to the terminal strips X2-6/ X2-7 and X2-140/ X2-141.
As you can see in the photo they are a very basic 3 phase 6 diode rectifier bridges like you might find in the back plate of an old car alternator. They seem ancient in comparison to the DIN rail mounting ones these days.
I put my very crude Hantek 6022 USB oscilloscope on the X2-140/141 and you can see from the trace it has the high peaks of which you speak. I've also added a page out of the Heidenhain TNC 155 mounting instruction manual where you will see the exact same type of curve.They mention that the TNC has been designed for this type of power supply. From the oscilloscope you can see the time base is 3.33ms as you would expect from the 6 pulses per cycle at 50Hz. I'm not too confident of the voltage calibration, so I used my Fluke to test them. The X2-140/141 supply showed 25.7VDC RMS and the X2-6/7 showed 24.5VDC RMS. The machine was booted and homed so the 7K1 contactor is closed, or you wouldn't see voltages on those terminals. In that situation the X2-140/141 supply is loaded by the Heidehain and IZUMI PLC back planes so I think 24.5VDC RMS is okay. The X2-6/7 isn't much loaded in this situation so I'm going to leave it as is. It drives the gear change system.
The 6T1 transformer that supplies these 24VDC rectifiers incoming 415VAC is wired to the nominal primary winding which i would think is 380VAC, being German. But it also has +5% and -5% tappings if you want to fiddle with it. If you wire to the +5% tappings (3 off) the output voltage should drop accordingly.
Also, there is a 19T1 transformer that puts out 220VAC for the main supply to the Heidenhain controller, and in my case, also the Izumi PLC. I thought it wise to have both devices on the same supply connections. With LninuxCNC you might do the same. In this case the transformer primary tappings are labelled 400VAC, 420VAC and 440VAC.
Since the Heidenhain controller has it's own rotary switch that does a range of supply voltages one would wonder why the 19T1 transformer exists at all. I think it may be to isolate the machine from power surges from industrial settings or lightning strikes etc?

Good luck with it,
David

 
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17 Mar 2023 04:03 #266882 by D Jensen
A quick addition to my previous posts. This is my Heidenhain HR250 remote handwheel. Ugly looking thing, but works nicely. Downside is you have to go back to the console to swap axes and change gear ratio etc. Upside is it can bounce of the floor without damage and it has magnetic feet shown. Having it held steady is helpful for precision inching.

David
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17 Mar 2023 06:35 #266888 by D Jensen
For Glemigobles on p141:

It's better to work on the quill with the vertical head turned 90 degrees so the quill is horizontal. It's much more stable to work on than when the whole head assembly is on the bench. I've added comments on how to get the hand wheel off on my machine, in red on the drawing, which you need to do to disengage it from the quill rack. Although you see my hand wheel assembly disassembled in a previous photo, I only did that because I wanted to set less retraction force on the quill. The hand wheel assembly comes out in one piece if you are careful.
Then the whole quill assembly comes out as per the attached sequence, including all the tool clamping system. it's quick and easy. I've described in a previous post how to remove the clamp fingers which is also very easy if you first loosen that grub screw in it. It's easy to set to the correct depth after the whole system is refitted, then lock it fixed with the grub screw. It may be that the locking grub screw is a cap screw on some machines I've seen.
On mine, after I had cleaned the hydraulic system completely, and refilled it, I noticed that the pressure faded enough in a minute or so and the pump raised it again with a very short blip. i didn't see any leaks until I opened the pump door and saw a lot of oil in the drip tray on top of the pump. It turn out the bolts retaining the solenoid valves had loosened. I didn't touch them it might be the continual pressure pulsing works them loose over time.
If you have a rotary table, CNC or manual, it has hydraulic release and spring clamping just like the tool holders. So the hydraulic pump is necessary. With my CNC rotary table active the pump runs much longer on power up. Possibly some air in the rams. It's important that the rotary table remains unclamped during operation so I've fitted a pressure gauge on the table just to keep an eye on it. There is a pressure switch on those rams which I have currently wired to a warning lamp on the console. I'm thinking of wiring it into a circuit to inhibit the rotary table if the pressure goes low. It wouldn't be nice on the servo motor if it clamped unexpectedly.
So you have to set the pressure relief valve on the pump, then the pump pressure switch lower, then the pressure switch on the rotary table even lower so it doesn't switch when the pressure drops from tool holder changes, but still high enough for the rotary table rams to remain retracted. it's actually not as difficult as it sounds as long as you have a suitable pressure gauge. Some of the pressures are in the attached image.

Good Luck
David
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17 Mar 2023 06:38 #266890 by D Jensen
Sorry, I accidentally erased an image.
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17 Mar 2023 10:05 #266898 by D Jensen
For Mark:
I thought I had posted this on the hand wheel, but it looks like I haven't:

I like you effort on the hand wheel. On my MH-C 700 I have a Heidehhain HR 250 hand wheel. It only has the rotary dial, nothing else. I'm a bit envious.
It has two magnetic feet on it so it can be stuck onto the machine in various places, although none are really convenient and the feet scratch the paint of the machine. I might put something soft on them to stop that.
When I first got the machine I thought it was in a crinkle finish metal can. But it turns out it is a big lump of polyurethane foam. So you can bounce it off the concrete floor without damage. You guys might want to add foam like that to your designs. It is about the consistency of a modern car steering wheel and probably made the same way. You just make a mould and squirt foam in with an isocyanate foaming agent. As it expands it skins off on the the tool. They spray a parting agent on the tool first. Then spray polyurethane paint on it whatever colour you want.
Inside mine is a superb Heidehain chrome on glass encoder. Way overkill. It's happy to home down to 1 micron, depending on which gear ratio you program on the console. The encoder is in a metal can about 50mm diameter that is easy to open for inspection and service. The foam is about 150mm on each side. The hand wheel is made of the same foam with a brass boss inside for the encoder shaft mounting.

My Heidenhain console is on the old Philips mount arm so has the same ergonomic issues that had. Basically too far away.
A  particular issue of interest elsewhere here, is holding the release button during tool change. On my machine someone has mounted a two position rotary switch on the Y slide hear the coolant tap. It stays close to tool holder, always, since it moves with the slide, and I can rotate it with may right hand while holding the tool holder with my left hand. Or just switch it and leave the tool unclamped. Seems a handy solution to me. It's wired in parallel with the no latching button on the console.

Sorry this post is out of sync with the photo of it.

David

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18 Mar 2023 00:18 #266953 by D Jensen
This time a bit of indulgence:

I have some history of this machine.
It was quoted by Hahn & Kolb *Aust) PTY LTD in Melbourne Australia ex stock to Eric James Industries, Toolmakers, in Sydney, including tooling, training and delivery for $A80,000 net, in November 1982.
But it looks like it actually sold in July 83 for $A114,000 + 6% with the addition of the CNC rotary table and printer/reader. About 3.5 years salary for me as a Senior Engineer at that time.
In August 1987 it was upgraded to the Heidenhain TNC 155 by Electronic Services Company in Sydney for $19,260 +sales tax. That included 3 new Heidenhain linear encoders, replacing the original Philips ones.
After that it turns up in Ballerat, Victoria, where  bought it on mid 2012, for $8k.

Since I was a cub engineer I've wanted a nice workshop with some nice machines. This is the icing on the cake. Ill do the rest with photos just to show how much I wanted it.

On the interstate transporter where I bought it from
Arrival at my place from the transporter depot in Sydney. Rainy day
Ready for lift from my garage at road level after 8 years in the garage. Restoring a Fiat Topolino got in the way.

More to come
David
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18 Mar 2023 00:35 #266954 by D Jensen
First lift. "city crane". Really nice machine. Load cells on the legs so it knows if it will topple. Load cells on the lift, so he knows it's okay. Precision winch so it can inch at maybe 10mm/ s. Computer screen show lift versus boom length. WiFi safety helmets so I could communicate exactly what to do. We put each lift within 20mm of the spots I wanted. Fantastic. The lift height is a little daunting, but it allows the load to be gently pushed by hand to exactly the required spot while it maybe 50 mm off the ground. The house roof is solid Concrete but I think it wound punch through that if the slings broke.

Front lawn. Had to do the lift in two stages. Note the crane is now sitting on the neighbour's lawn. Good to have accommodating neighbours.

Above the house. About here I'm about s**ting myself. I did the slings. It was a really exciting fun day. That's my neighbours in the photos. Other neighbours passing by stopped to complain how ugly our lollypop ladies were. Usually they are good looking backpacker girls. it's a nice neighbourhood.

More to come
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18 Mar 2023 00:53 #266955 by D Jensen
Rear ramp. I built a Formply ramp along the back pathway with a slight slope towards the door. The crane was out of site from there so the WiFi helmet was absolutely needed to guide the drops onto the ramp. Only just enough length to fit all the assemblies. There it quite a lot the lift could tangle with and the breeze was coming up. Several stops during the drop to let it steady and stop spinning. It wasn't wise to pick a 35 degree C plus day to do it, but that's Sydney for you. In the middle of a Covid lock down you grab what you can.

Shed door. Note it just fits with 5mm to spare. even then it needed some rotation to get it through. I modeled it in Solid Works to be sure. But it still needed the door and it's jambs removed. A few days there just removing it and replacing it after. I was given a rather nice roller chain comealong that was handy to slide the loads. The assemblies are mounted on Formply also and with a bit of grease they slid okay Formply to Formply. I used the Formply after for the storage shelving in the shed.

And lastly:

Finished!!!! Two years later and a lot of work in between

Hope this inspires others. Break it down into manageable pieces at a time

David
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18 Mar 2023 01:41 #266957 by D Jensen
The inside of my machine was filthy. The cooling fan system sucks through a filter panel on the far side of the cabinet from the fans. Since the cabinet has gaping holes all over the place and the filter clogs,  the suction simply bypasses the filter and all the dirt and dust from the surrounding workshop covers everything. So I've reversed my fans to pressurize the cabinet instead. I've added a simple wooden box on the outside over the fan intakes and fitted a washable cabin filter from a modern car air conditioner to ensure the incoming air is filtered. I've removed to old incoming filter and left the metal mesh from it in place to stop accidental fingers poking etc. So the old inlet is now the outlet, plus all the other gaps and holes. I had some RCD trip issues previous to doing that. Another saga I'll get to later.

David
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18 Mar 2023 05:59 #266972 by D Jensen
Sydney generally is humid. Most of the time it's somewhere in the 65% RH range. But around February/ March it can be much higher. Recently I've been measuring 88% RH outside.
About this time last year there was a lot of rain and severe flooding in the western part of Sydney and elsewhere throughout the rest of the State.
Fortunately my house is relatively high, about 50 meters above sea level. Nevertheless the rain was relentless. Here is a photo of my shed entry during a downpour.
About that time the Maho was just beginning to run correctly. But it started tripping the RCD protection on the main incoming 3 phase GPO for the mill. I noticed a cooked plastic smell so I opened the contactor cabinet and to my amazement there was an arc crackling it's way down between the 1K1 and 1K2 spindle motor contactors, presumably to the DIN rail.
Since I just spent several months tracing and removing maybe 100 meters of redundant wiring and put the rest back neatly it was a bit demoralizing.
The wiring on these is all black for the high current contacts and red for the auxiliary contacts, so easy to mix up. In the end I removed everything one by one, labeling every cable with their standard IEC contactor numbers with my labeler.
All the main contactors were covered in dirt and some sort of crystalline deposit.  All were stripped down and cleaned, the metal parts in alcohol and the plastic in the dishwasher. By accident I noticed that may hands were acidic whilst doing so. So I touched the crystalline stuff with the tip of may tongue. Acid as all get out! Hard to remove even after the dishwasher. A lot of work. So my guess is that the machine has spent some time where there are acid fumes, maybe a plating plant. you can see a bit on the photo before cleaning, but it was mainly down the sides.
There various contacts that were a bit burnt. Fortunately the are some contactors that only use the auxiliary contacts and others that only use the power contacts, so I was able to reassemble most of them by swapping contacts around and getting mainly good for the ones in use.
But I also managed to source some identical contactors being made by Siemens? in China. So I bought a bunch and eventually set up all good ones. The Chinese ones are parts compatible but the moulding parting lines are a bit different so they are made on different tools. And I have a few spare new ones.
The 11K1 and 11K2 contactors were the most burnt. They are the ones the do the nid-nod on the spindle motor for gear change.
So it's been relatively trouble free since then with no RCD trips. But you can see why I changed the cooling fan filtering and pressurization.

David
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