A retrofit of a Stanko SMO 32 CNC milling machine (Ukrainian clone of a Maho)

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28 Jan 2022 13:04 - 28 Jan 2022 13:08 #233370 by Aciera

I unscrewed the top of the device to uncover contacts and there is a connection between the contacts when the machine is off. But then as soon as the voltage comes in the connection is closed

Now I'm confused. There is a connection and then the connection is closed?

[edit]
I think you might want to open the hydraulic line to make sure there is indeed no pressure in the system.
Last edit: 28 Jan 2022 13:08 by Aciera.

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28 Jan 2022 18:49 - 24 Feb 2022 15:27 #233397 by drogus
Honestly I’m confused too. When I measure the connection when the machine is turned off the resistance is close to zero. When I turn it on it seem to be disconnected cause I can measure 110V across one of the contacts and ground and no voltage on the second contact.

Good idea with opening the line, I’ll try that. That said, I’m not sure why would it work like that - if there’s pressure in the system the contacts should be disconnected even without voltage I think
Last edit: 24 Feb 2022 15:27 by drogus.

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29 Jan 2022 03:17 #233416 by Aciera
Remove the cable from the pressure switch and check resistance across the connections with the machine off and with the machine on. If the contact changes then there must be something going on with the pressure in line. If it's open both times then there is either pressure in the line or the switch is broken.

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29 Jan 2022 11:10 - 24 Feb 2022 15:26 #233425 by drogus

Remove the cable from the pressure switch and check resistance across the connections with the machine off and with the machine on. If the contact changes then there must be something going on with the pressure in line. If it's open both times then there is either pressure in the line or the switch is broken.

Thanks for the suggestions! 

I think that the pump and the pressure switch might be fine after all.

As @Aciera suggested I unscrewed the switch to remove any pressure from the pump. At this point contacts were conducting with zero resistance. Then I figured I will do a dirty test, ie. I turned the machine on and pressed the "hydraulics on" button for a split second and I got a nice splash of oil on the enclosure opposite to where the pressure switch is :D

That would suggest that the pump works. I screwed the pressure switch back in and measured the contacts and again, it was conducting. I turned the machine on, I turned the hydraulics on. I didn't hear the pump, but when I measured the contacts there was no connection there, which made me think that either the pressure is built very quickly or that the switch is broken. I put the camera in my phone into recording mode and I pressed the hydraulics to capture the moment when it turns on. Lo and behold, I present to you the quick action pump:



I think that with the valves closed it just doesn't need much to pressurize the line.

In summary the hydraulic pump might be alright and what affects the system are still the outputs from the CNC controller that keep the rest of the system from turning on. I think that this might have been also the issue when I first got the machine - it was booting to a further place, but tool clamping didn't work, so I think that the solenoid valve 5Y1 wasn't able to turn on because of some issue with the system.

The conclusion is that I guess I'll get to the retrofit sooner than I initially thought, which honestly might be for the better. Otherwise, even if I made the machine work with Heidenhain, I would have to learn how to use Heidenhain only to replace it in the future. I'm going to order all of the components this weekend.

Last edit: 24 Feb 2022 15:26 by drogus.

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29 Jan 2022 11:53 - 24 Feb 2022 15:26 #233428 by drogus
I wanted to fully confirm that the pump is working, so I hardwired 24V to the contactor leading to the solenoid valve and it works without any problems! (well, maybe the operator problem as I'm not used to automatic tool clamping yet)

Last edit: 24 Feb 2022 15:26 by drogus.

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30 Jan 2022 13:42 - 24 Feb 2022 15:26 #233542 by drogus
As soon as I verified that the pump works I wanted to go ahead with the retrofit. There are a few things to consider at the moment:

1. The Heidenhain EXE modules, which are used to translate analog signal into digital, are mounted directly in the LE 360 CNC controller. I don't want to keep it, cause it takes a lot of space and I can probably sell it for good money, so I figured it will be better to buy standalone EXE modules. Thus I ordered 3 Heidenhain 602D modules. They offer 1x or 5x interpolation and I don't need a resolution lower than a micron, so it should be good enough.
2. I was wondering how many inputs and outputs do I need. I think that 32 inputs and 16 outputs will be enough given that the original controller uses less I/O. I'm not 100% sure about the gear change, but I decided to go with two boards for now: 6i25 and 7i77. If I want to have more I/O then I will add a 7i84D board, but hopefully that won't be needed.
3. I'm not sure how to do a gear change yet. I've seen that RotarySMP used HAL ladders for that, but I'm a computer programmer with like a dozen languages that I used throughout my career, so I feel like I'd prefer to handle that directly in code. Still not sure how it works for LinuxCNC, but I'm curious to play with it when the boards come
4. I don't really like the wiring situation in the cabinet. In the Maho it's definitely done in a neater way and I'm thinking that maybe I'll design and order a custom PCB to clean it up a bit. Like a thing sitting between Mesa boards and the breakout board for the 24V contactors. But first I want to connect it as is so that I can verify all the functions.

I think that the best plan will be to go with various inputs and outputs of the current CNC controller and swap them with the new controller, cause everything needed for the machine to work should be included in there.
Last edit: 24 Feb 2022 15:26 by drogus.

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24 Feb 2022 15:26 #235708 by drogus
I had a bit of a downtime when it comes to working on the machine - ordering all of the electronics and parts took way longer than I had hoped for. Now I have everything I need (hopefully!), so I'll start the work shortly, but that's not why I wanted to reply here.

I've changed the subject to mention "Ukrainian clone of a Maho". I originally wrote Russian, but that's because "Stanko" or "Stankoimport" are associated with Russian machines, but the fact is that this name was stamped on most of the stuff coming from the east. And a few days ago it struck me that the documentation I say actually mentions Ukraine, not Russia as an origin of the machine and also another name for those machines was Odessa SMO 32. I know that it doesn't change much, but I figured that especially in the light of current events I should get the origin of the machine right.
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24 Feb 2022 16:37 #235722 by chris@cnc
Brother in heart. We are with you.

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24 Feb 2022 16:57 #235726 by tommylight
I am pretty sure he is not in Ukraine.

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24 Feb 2022 17:56 #235732 by drogus
Sorry for confusion! I have relatives in Ukraine (in Lviv, though, not on the west) and my wife's family has roots and relatives there too, so I have some ties with Ukraine, but I'm from Poland and I live in Berlin, so I'm not directly affected.

It's just that since I realized this and after the start of invasion I just couldn't let it sit like this. Again, I know changes nothing, but it just didn't feel right, especially now.
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