Comments sought on new build: A CNC Router for RC Gliders and Planes

I have been looking at your diagram for the limit switches trying to understand what you are trying to achieve. All the NPN/PNP proximity switches I have looked at require 0V and a positive DC supply as inputs to power the sensor, and give a switched output. I do not think the way you have shown them will work. Do you have a link to a datasheet for the sensors ?

Can I also make a suggestion to you - don't mark the AC inputs to power supplies with a "+" and "-" which implies DC. It would be very easy to connect all the "-" terminals together which would not be a good move.

Graeme

Graeme, the way I was trying to wire it up was that they were all linked and as they are NC that any sensing will drop out the power to the circuit (and at the same time light a lamp to indicate that a limit has been hit, may put in a buzzer too) I think I've got my head in manual switch mode and not proxy mode. Was all done in a rush, no excuse I know....

Again I was being lazy with the labeling and jyst copying and pasting....I'll put L & N on tomorrow.

Neil bit hard to read these schematics but looks to me on the power and Safety diagram you got something wrong.?
The Live is going thru the door contactor then into the 24Vdc contactor but you'll have no 24Vdc because 24vdc PSU is picking live up from other side of 24dc contactor which will never turn on.!

Need pick Live up for 24Vdc PSU before going into 24dc Contactor mate.

Next Limits. Other than what Graeme mentioned is the way you have wired Input from IP-M.? The inputs don't provide Voltage Ref you provide it one. So send 24vdc thru the Relay NO Contact to Input (+) and take Input (-) to 0Vdc.

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Originally Posted by JAZZCNC

Neil bit hard to read these schematics but looks to me on the power and Safety diagram you got something wrong.?
The Live is going thru the door contactor then into the 24Vdc contactor but you'll have no 24Vdc because 24vdc PSU is picking live up from other side of 24dc contactor which will never turn on.!

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It will certainly be safe then!!!!

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Need pick Live up for 24Vdc PSU before going into 24dc Contactor mate.

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Done...

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Next Limits. Other than what Graeme mentioned is the way you have wired Input from IP-M.? The inputs don't provide Voltage Ref you provide it one. So send 24vdc thru the Relay NO Contact to Input (+) and take Input (-) to 0Vdc.

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Cheers Dean I'm on this....wasn't quote sure how the IP-M worked with regards to the inputs, getting it clearer now.

OK, diagrams re-done...please check them as I can't see the wood for the trees!

Attachment 15033

On the drive enable I take it that just closing the circuit is enough, no voltage needs to be applied?

Attachment 15031

I'll start numbering the wires once it's good to go...

I can see a couple off issues with your limit switches (I think). Firstly without your Override switch being pressed, the state of the limit switches is not passed on to the CSMIO due to the relay contacts being open. Also as you are using NC sensors and have all six in parallel the only way for the CSMIO to see a change is if ALL sensors are activated.
I do not know what the enable does to the motor drivers, but as I see it pressing the override switch will either allow the motors to work or stop them. Nothing else can affect the enable. I think you need to look at how you are using the override switch.
I think it might become a little clearer if you view the sensors as switches like in this image
http://www.mycncuk.com/attachment.ph...id=15034&stc=1
I am not sure if you can achieve what you are trying with NC sensors.
Graeme

Graeme, sorry, I've deleted one too many lines, there should be a line to the A1 of the contactor giving it power from the common line of the sensor. The way I am seeing it is that the contactor is NO until 24V is put on to the coil then it closes the contacts hence making the circuit, the enable is then open which means it's unconnected and enabled and allowing the drive to send pulses to the stepper. Any sensor being activated will break the circuit and the limit switch overide will need to be pressed to put power back on the contactor so I can back the machine off the sensor. Pressing the overide switch will sound the warning buzzer.

Attachment 15035

give me a spanner any day.....I bloody hate electronics!!!

OK rant over.....just been down stairs and connected the 24V DC PSU up to the limit switches (2 only) I wired them so that the neutrals all went to a common din rail terminal, the signal from the first went to the +ve of the second and I measured from the neutral to the signal of the second with my multimeter. It lit both lights of the sensors and when any sensor was activated the 24V DC went to zero which was a result....far better playing with things than thinking about them on paper or screen!!!

New Wiring Diagram...
Attachment 15041

Attachment 15037

Attachment 15038

Attachment 15039

Attachment 15040

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Originally Posted by njhussey

give me a spanner any day.....I bloody hate electronics!!!

OK rant over.....just been down stairs and connected the 24V DC PSU up to the limit switches (2 only) I wired them so that the neutrals all went to a common din rail terminal, the signal from the first went to the +ve of the second and I measured from the neutral to the signal of the second with my multimeter. It lit both lights of the sensors and when any sensor was activated the 24V DC went to zero which was a result....far better playing with things than thinking about them on paper or screen!!!

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That looks better but be aware that you are wiring switches in series which contery to popular belief does work with Prox switches but just be aware that reaction time drops the more you have but it's not a problem with only 4 switches.

OK I see what you are trying to do. Probably not what the manufacturer intended, but as all you are really interested in is the sensors switching off it should work fine.
Still a little unclear in my mind as to why you are taking the output from the sensors through the relay to you CSMIO. When the same signal is used to turn the relay on/off. Why not take the sensor output directly to the CSMIO ? could you please explain.

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Originally Posted by JAZZCNC

That looks better but be aware that you are wiring switches in series which contery to popular belief does work with Prox switches but just be aware that reaction time drops the more you have but it's not a problem with only 4 switches.

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Dean, what would be the best way to do it then? I'm going to have 2 proxys on each axis (maybe not the Z but I've not worked out where/how to put them it yet) as I want them tucked away (the Y axis ones are going to be in the enclosed gantry and the X axis ones are going to be mounted on the machine sensing the ballnut housing)

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Originally Posted by Graeme

OK I see what you are trying to do. Probably not what the manufacturer intended, but as all you are really interested in is the sensors switching off it should work fine.
Still a little unclear in my mind as to why you are taking the output from the sensors through the relay to you CSMIO. When the same signal is used to turn the relay on/off. Why not take the sensor output directly to the CSMIO ? could you please explain.

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Graeme, I want to rely on hardware to control the driver enable and just inform the software that there's been a positional error and not rely soley on the software to get the signal and then inform the driver of the error.

Pic of proxy data sheet showing they can be wired in series...

http://tapatalk.imageshack.com/v2/15...52402510f1.jpg

Neil Would you mind putting a link up to the data sheet. Thanks Clive

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Originally Posted by Clive S

Neil Would you mind putting a link up to the data sheet. Thanks Clive

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http://uk.farnell.com/webapp/wcs/sto...&storeId=10151

The one I photographed was out of the box...

Started on some wiring of the power circuit....

http://tapatalk.imageshack.com/v2/15...1640ddf0a3.jpg

Those cable markers are a right bugger to get on, that's what's taking most time...

Looking good!

The CS Labs controller was such a pleasure to work with I have to say :) so well laid out. Definitely a good choice on that one.

The whole build is coming together nicely look forward to seeing it move soon!

Cheers Francis...I'm doing the connections between the drivers and the IP-M tomorrow and then I'll start on the safety side of things...cant wait for it to move either it's been about 5 years in the making!!

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Originally Posted by njhussey

Dean, what would be the best way to do it then?

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That way is fine Neil I was more pointing out the side affects of wiring in series before some one chimed in that you can't wire prox switches in series.

One thing I meant to ask is that your not planning on sharing Home and Limit switches are you.? Because if so then it won't work.!

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Started on some wiring of the power circuit....

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I see you have the right tool at the ready.:joker: .Clive

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Originally Posted by Clive S

I see you have the right tool at the ready.:joker: .Clive

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My mate locked away all my hammers after my last keyboard smashing hissy Fit.! . :devilish:

What size box are you using there. I am being dense today and can't find it in the thread earlier (I know it is most likely there but just being thick today) Nice set up by the way and may borrow some of your design set up with the rebuild I am in the process of (If you don't mind).

Michael

PS yes when the hammer looks like a solution that is bothering me; it is time to go for a walk or have a cuppa in the house and not touch anything that can break.

I might not have put the size here Michael so it's probably not you. It's 600 x 600 x 300, feel free to copy anything as most of my inspiration has come from seeing others builds, it's only what I think is a good layout for the control cabinet as I've tried to keep all power items to the left with noisy ones (power supply) to the bottom right as far away from the drives as possible as suggested by Dean.

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Originally Posted by njhussey

it's only what I think is a good layout for the control cabinet as I've tried to keep all power items to the left with noisy ones (power supply) to the bottom right as far away from the drives as possible as suggested by Dean.

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Wow don't blame me.!!. . . :joker:

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Originally Posted by JAZZCNC

Wow don't blame me.!!. . . :joker:

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No blame.........but will be sending a few :beer: your way for all the help and pointers you've given me (I'll be picking your brains again soon I'm sure...)

Today I was checking the wiring and powering up the relay to make sure that it bought the power on and that the door safety switch worked etc. and on measuring the voltage found that our single phase power supply is 242V which I think will mean that my PSU (25V+25V) will be putting out too high a voltage, or at least be too near the 80V limit of the AM882s for comfort....will dig out my calculations and have a look tomorrow :(

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Originally Posted by njhussey

Today I was checking the wiring and powering up the relay to make sure that it bought the power on and that the door safety switch worked etc. and on measuring the voltage found that our single phase power supply is 242V which I think will mean that my PSU (25V+25V) will be putting out too high a voltage, or at least be too near the 80V limit of the AM882s for comfort....will dig out my calculations and have a look tomorrow :(

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Neil chances are your mains power will most likely fluctuate up and down depending on time of day and demand around. My varies wildly upto 257v.!! . . . The drives will handle some over voltage without damage if just a slightly up but obviously not good running all the time above Max.!

It's down to 236V today, powered it up and geting a nice 71V at the drives. The drives drain it down to next to nothing in about 20 seconds (not timed but it's a short time) I'll still at a later date put a 240V relay in and put a resistor across it to drain it quicker in case someone goes in the panel within that time.

Now on to the various safety circuits....time for some head spinning!!

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Originally Posted by njhussey

I'll still at a later date put a 240V relay in and put a resistor across it to drain it quicker in case someone goes in the panel within that time.

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Yes I would do this anyway neil because if your not isolating the drives enable signal then the motors will remain powered until caps drained and this will cause them to run on slightly before fully drained.

The door isolator turns off all power so it's just for drainging the caps in case someone puts their hand on something.....although I've got hot glue over the soldered terminals on the caps so you shouldn't be able to shock yourself...

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Originally Posted by njhussey

The door isolator turns off all power so it's just for drainging the caps in case someone puts their hand on something.....although I've got hot glue over the soldered terminals on the caps so you shouldn't be able to shoch yourself...

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Ok understand that side but still same applies has when you E-stop the machine will run on.!

I'm having the Estops (and AM882 alarms) go through a relay (and Pilz??) which will kill the power, the limits I was going to wire through a relay and to the enable of the drives.....

Hi Neil,

Looking through your build log on post #555 showing the control box -

Looks like the positive red DC output cable from the capacitors is going into an MCB. Is this correct and is this how you are intending to add a fuse? I'm a bit confused as I'd expect the MCB to be on the mains AC input side, and instead to see blade fuses on the DC output. Can you elaborate as I'm about to start my linear PSU build.

Thanks

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Originally Posted by routercnc

Hi Neil,

Looking through your build log on post #555 showing the control box -

Looks like the positive red DC output cable from the capacitors is going into an MCB. Is this correct and is this how you are intending to add a fuse? I'm a bit confused as I'd expect the MCB to be on the mains AC input side, and instead to see blade fuses on the DC output. Can you elaborate as I'm about to start my linear PSU build.

Thanks

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I'm looking to get some of these but had forgotten about the MCB's. I was going to use them but I'm not sure they're the right thing at all! Lookig at something like these http://uk.rs-online.com/web/p/fused-...inals/8239552/ although I do quite like the idea of the 12V fuse holder EddyCurrent uses but not sure for a work environment?

Hi Neil,

Ok, thanks. Then I'll stay with my original plan which is 6A MCB type D on AC side of PSU, and automotive blade fuses on the 70V DC side. I plan to fit a trial 1A fuse on the DC then jog an axis to deliberately blow the fuse. Then I can make sure that it blows cleanly and there is no residual arcing from the 70V. I'll then fit the intended rating. I think Eddy and Irving both went this way.

But the DIN mounted fuse probably is the way to go for how your machine will be used industrially. Do you know if the 5x20mm fuses need to be specific for DC? This was where I got stuck with this option because reading around AC and DC currents seem to require a different type of fuse and so I went back to the automotive type which are definitely for DC. I wondered if that was why the fuse wire was such a curly shape on the DC blade fuse instead of the straight wires in the AC ones, to make sure there was a clean burn/break rather than continual heating, expansion, and arcing.

I'm not coming from a strong electronic knowledge-base so the above are just my views / thoughts.

As for the rest of your build looking very professional now, well done.

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Originally Posted by routercnc

Ok, thanks. Then I'll stay with my original plan which is 6A MCB type D on AC side of PSU, and automotive blade fuses on the 70V DC side. I plan to fit a trial 1A fuse on the DC then jog an axis to deliberately blow the fuse.

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Interrupting the supply to a stepper motor driver (or many drivers for that matter) whilst running can damage them, so I wouldn't recommend that test.

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Originally Posted by routercnc

Do you know if the 5x20mm fuses need to be specific for DC? This was where I got stuck with this option because reading around AC and DC currents seem to require a different type of fuse and so I went back to the automotive type which are definitely for DC.

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I read somewhere that if the DC rating isn't specified for an AC fuse, you can use it with DC but only at half the AC voltage rating. Don't quote me on that though...
I would trust the 5x20mm fuse more than the blade fuses - running a 240V AC fuse at 70V DC seems more reasonable than using a 12V DC fuse at 70V DC.

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Originally Posted by Jonathan

Interrupting the supply to a stepper motor driver (or many drivers for that matter) whilst running can damage them, so I wouldn't recommend that test..

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OK good point, but out of interest is that any different to an e-stop? My latest control box (when finished!) will cut power to the drivers via a relay which seemed to be a common approach.

Ok so back on this again after doing work for the last week or two....

Got my estop circuit working using this modified drawing...

http://images.tapatalk-cdn.com/15/04...6aecd970dc.jpg

I've got to put the AM882s alarm signals daisy chained in the estop circuit but I think I know how to do that using another relay with 2 x NC connections.

Next problem is I keep blowing the 6A C type MCB when switching on....I'm guessing that I need a soft start to stop the inrush into the caps....can someone help with this? I'm guessing a thermistor with a relay/timer?

We get this as well but it's not consistent sometimes it'll pop once or twice other times straight away and that's with the caps fully discharged. At the moment I'm living with it but if there is a solution I'm all ears? D type breaker?

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Originally Posted by fvfdrums

D type breaker?

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I thought about that but I think I'll go for a thermistor through a timed relay or whatever people recomend...

Don't mess about with thermistors and shit just put a D type MCB and you'll be sorted.