Schaublin 125-CNC retrofit.

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10 Aug 2023 11:22 #277530 by RotarySMP
I didn't realise how simple and elegant it is to set up a state machine in a comp.

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10 Aug 2023 11:50 #277531 by rodw
Replied by rodw on topic Schaublin 125-CNC retrofit.

I didn't realise how simple and elegant it is to set up a state machine in a comp.

Yes its pretty cool! I was surprised how easy it was to code. Without the state machine there would be lots of nested if/else spaghetti code!
The hard bit is often to decide what algorithm to use. If you get it wrong, it can be  a lot harder than it needs to be.
its an ideal demonstrateion what a component should look like. Short (68 lines) with a single, clearly defined problem being solved.
Why I've never used classic ladder. :)

 
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11 Aug 2023 18:22 #277656 by smc.collins
that's a nifty little program, I'm curious to see how accurately it can control the variator.

I'd think the contactors would be kinda difficult to switch accurately for short durations.

Mark, put some flyback diodes in the contactor dc coil circuit, i was thinking this might be flyback voltage
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11 Aug 2023 20:01 - 11 Aug 2023 20:03 #277664 by rodw
Replied by rodw on topic Schaublin 125-CNC retrofit.

that's a nifty little program, I'm curious to see how accurately it can control the variator.


Thanks, me too.
I just realized it needs an enable pin becasue from the original video, it is not allowed to move without the spindle turning. Something like:

pin in bit enable = 0 "set true when spindle is running with spindle.0.on";
if (!enable) //insert before switch statement
    return;
Last edit: 11 Aug 2023 20:03 by rodw.

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12 Aug 2023 04:05 #277695 by spumco
Replied by spumco on topic Schaublin 125-CNC retrofit.

Mark, put some flyback diodes in the contactor dc coil circuit, i was thinking this might be flyback voltage
 

Would flyback voltage still spike and cause issues if the contactors are manually activated (i.e. screwdriver)?  I'm genuinely curious.

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12 Aug 2023 09:38 #277714 by tommylight

Mark, put some flyback diodes in the contactor dc coil circuit, i was thinking this might be flyback voltage

 
Would flyback voltage still spike and cause issues if the contactors are manually activated (i.e. screwdriver)?  I'm genuinely curious.


So am i.

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12 Aug 2023 12:41 #277727 by scotth
Replied by scotth on topic Schaublin 125-CNC retrofit.
Something like this should solve noise problems.

www.ebay.co.uk/itm/235117259923

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12 Aug 2023 12:56 #277728 by Aciera
Replied by Aciera on topic Schaublin 125-CNC retrofit.

Would flyback voltage still spike and cause issues if the contactors are manually activated (i.e. screwdriver)?  I'm genuinely curious.

Given that there is no energy stored in the inductor (ie no collapsing magnetic field) I don't see where that voltage would come from.
 
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12 Aug 2023 16:30 #277737 by spumco
Replied by spumco on topic Schaublin 125-CNC retrofit.

Given that there is no energy stored in the inductor (ie no collapsing magnetic field) I don't see where that voltage would come from.
 

Me either, but I don't know everything about magic smoke.  Like maybe there's some sort of induced field in the coil when the main contacts make/break - and I've never learned about this situation but it's obvious to everyone else.

Once the magic smoke discussion moves past my internal understanding of "electricity is like water through a hose, only not" I have to start asking questions.

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12 Aug 2023 22:33 - 12 Aug 2023 22:34 #277762 by smc.collins
a 20ohm fuel injector charged with 12v dc, can emit s much as 140v on shutoff depending on operating FZ and duty cycle.

a typical 24vdc contactor coil has a impedance of around 30-50 ohm. The flyback voltage could easily reach 140-200v on coil off especially if the contacts bounce as the field collapses. It's worth a look. ALOT of DC coils have built in diodes to prevent this, but maybe this unit does not. 
Last edit: 12 Aug 2023 22:34 by smc.collins.
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