ELECTRONICS WIRING

[Sesh]

Hullo Everyone,

I’ve been lurking around, though keeping my mouth shut, primarily as I don't have extensive knowledge of cnc. It’s been wonderful to be a part of this community albeit from the sidelines.
A couple of years ago I built a Shapeoko2 from the kit (the 1mx1m). I purchased it primarily to be able to cut precision parts for some kinetic sculptures i wanted to build. Never managed to cut anything on it beyond mdf and softwoods. I wanted to cut aluminum and brass. The problems were rigidity, the belt drive, and grbl(I know nothing of coding, so troubleshooting was mostly following the instructions blindly).
It finally dawned on me that I needed a new machine, started my research, and am in the process of building one, with a lot of help from youtube, and posts from here.
The mechanical part of things, though new to me, is something i can wrap my head around, but on the electronics front, I DESPERATELY NEED HELP.
I purchased some electronics, (pictures attached).
Theoretically, as I understand, the basic pipeline is: Mach3(or Mach4) - parallel port - breakout board - motor controller - stepper motor. This can then be detailed out to include spindle speed, the emergency stop, the limit switches, lubricant spray, etc.
Practically, I have no idea how the above theory translates into actual wiring, and am terrified of trying something and it blowing up.
Would greatly appreciate any help.
http://www.cnczone.com/forums/attach...d=335254&stc=1

Regards,
Seshadri

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[RCaffin]

I think you need someone with knowledge, test gear and physical presence.
Cheers
Roger

[Sesh]

I think you need someone with knowledge, test gear and physical presence.
Cheers
Roger

Thanks RCaffin, that would be ideal I know.
Sadly there's no one around who can perform that function.
Hence my need to post here.
I think i can safely say that i am a fast learner, the electronics should be easy to sort out as long as someone will answer questions😊

Regards,
Seshadri

[zipperhead]

I am currently building an 8' x 4' cnc router from a kit. The kit is from cncconversionkit.com. I chose the kit as it was the best value available to me here in Canada. I knew going in that it would not come with much in the way of instruction but given the volume of information here and on other sites I felt confident that I would be able to complete a working machine. I have no electrical or electronics experience but fortunately there are literally hundreds of people that do and freely share their knowledge. I successfully powered up my machine yesterday. I still have work to do like cable management, end and homing switches, power for the spindle etc.
Read, watch lots of youtube videos,take one step at a time, ask for help when you need it and you will get there.

Have fun

Paul

[john-100]

Hi Seshadri

do you have links to download the manuals for the breakout board and stepper drivers ?

there is not enough detail in your picture but this may give you a start :-




John

[Sesh]

Thanks a ton Paul for the encouragement, and good luck with your build too.

Regards,
Seshadri

[Sesh]

Hi John,
Wow! that I didn't expect. Thanks a ton! Yes I did have manuals for both. They are a bit above my level tho. Attached them below. I had inched along, drawing the connections to the drivers, and was wondering how to power them. Your diagram lays everything out quite clearly. Again, I cannot thank you enough.

I have a couple of questions, though.
1.Does this mean any -ve connection can be connected to any pin that says ground?
2.The drivers need 12-40VDC. Does the same power supply power all three drivers? Or do I need separate power supplies for each?

Regards,
Seshadri

[Sesh]

Oops,
forgot to attach files. Here goes.

Regards,
Seshadri

[john-100]

Hi Seshadri

you can use either a single power supply - for example a 36V 350W should be easy to find


or use three 36V 100W or 36V 120W power supplies

it all depends on whats available at the best price


on the breakout board all the terminals labled ground are connected connected together and , assuming its a desktop PC ,
will also be connected to the mains suppy earth via the printerport pins 18 to 25


as the stepper motor driver has opto-isolated step, direction and enable inputs

the stepper motor drivers power supply is likely to isolated from ground
as very few power supplies except for AT and ATX computer PSU have the DC outputs connected to ground

while this will work
you may find you need to connect the negative output to ground -
at a "star point" on the chassis thats connected to the mains earth
if you have an electrical noise problem

John

[Sesh]

Thanks again, John

From what i understand,


1.GROUND
The ground needs to go all the way to actual ground.

for eg, motor -ve to driver -ve to breakout board. From here it can go two ways?

a) via the parallel cable - pc - smps - electrical socket - ground
b) via the bob power cable - dc adapter - electrical socket - ground
Is this correct?

2.POWER CONSUMPTION
a) A single driver consumes a maximum of 40VDC at 2.8Amps, i.e.. 112W(rounding off to 120W). So 3 drivers = 360 watts? I have a MEANWELL RSP 320-48 at hand which I had purchased for powering the 300W spindle, It outputs 48V at 6.7A though. Will it blow the drivers that need 12-40VDC?
b). The BOB says power input of 11- 14VDC. Can I power it with another Power supply I have lying around (this outputs 24 volts at 3.75A). If this will also blow up the BOB, then I need new Power supplies for everything.
c). The 800 watt air-cooled spindle. This needs a VFD? there are 4 pins on the top. Is there anything I need to look out for when I am purchasing one? I think I will eventually move to a 1.2KW air-cooled spindle later, if the build seems limited by the spindle.
d). I have connected the limit switches in what I think is a Normally closed connection (I understood this as meaning the stepper is running until this switch is pressed).

PHEW!
Drawing attached. I hope I haven't screwed up too badly.

Thanks and regards,
Seshadri

[CitizenOfDreams]

I have a MEANWELL RSP 320-48 at hand which I had purchased for powering the 300W spindle, It outputs 48V at 6.7A though. Will it blow the drivers that need 12-40VDC?
b). The BOB says power input of 11- 14VDC. Can I power it with another Power supply I have lying around (this outputs 24 volts at 3.75A). If this will also blow up the BOB, then I need new Power supplies for everything.
c). The 800 watt air-cooled spindle. This needs a VFD? there are 4 pins on the top. Is there anything I need to look out for when I am purchasing one? I think I will eventually move to a 1.2KW air-cooled spindle later, if the build seems limited by the spindle.
d). I have connected the limit switches in what I think is a Normally closed connection (I understood this as meaning the stepper is running until this switch is pressed).

a) Yes, very likely it will blow the drivers. If your car tire says "40psi max" and you pump it up to 48psi, what do you think might happen?
b) Yes, powering a board that says "11-14VDC" with a 24V power supply will DEFINITELY blow it.
c) Yes, this spindle needs a VFD. If you are planning to upgrade to a 1.2kW spindle later, you should buy a VFD rated at 1.2kW or higher. Just make sure it works with the line voltage you have available (110V, 220V, 208 3-phase, 380 3-phase or whatever).
d) Yes, the limit switches are wired correctly. Another way to wire them is to connect all 3 switches in series - that way they use only 1 input on the BOB instead of 3.

[john-100]

Hi Seshadri

If you amend the power supply voltages your diagram is OK


I have added a touch probe and E-switch


the motor ground must go directly to the mains supply earth and must not be connected to the
breakout boards ground
this will bypass the drivers opto-isolation that helps to prevent stray currents flowing into the printerport

when you add a VFD for the spindle drive you will need to look for a VFD that works
with the breakout boards opto-isolators emitter & collector output

if not , it may need an interface to provide an analogue 0 to 10V control voltage for the VFD


possible PWM to analogue DC circuit





John

[RCaffin]

The Ground connections should NOT rely on signal cables - ever. Those cables are far too light. Ground should go through the power supplies, which will have solid mains connections.

Cheers
Roger

[Sesh]

Thanks, CitizenOfDreams , John, and Roger,

Ok, fixed on the NES-350 36 from meanwell for the drivers.
I have found this GS06E-3P1J for the BOB. The booklet says output 12 at .5A. Is this choice correct?

At this point, I need to ask another basic question. I understand that too much power can blow the drivers that need Max. 40Vdc and 3A per phase.
John, the NES 350-36 outputs 36V at 9.7A. So If I understand right, the Power supply I have is the wrong choice because it was outputting 48VDC? The 6.7A is not a problem?

I am trying to understand where the line is. CitizenOfDreams, by the same logic, wouldn't the 1.2KW powersupply blow the 800W spindle? I'm sure it wont, since you are telling me, but why?


Thanks and regards,
Seshadri

[john-100]

Hi Seshadri

the maximum supply voltage of 40V for the DM860m stepper drivers depends on the breakdown voltage of the transistors use in the H bridges
used to switch the current on and off to the motor windings
plus any extra the designer has added to ensure they don't fail in normal use

for example 60V devices will be OK with an extra 20V added to the supply by inductive voltage spikes as the motor current is switched on and off
or when the stepper motor becomes a generator as its driven round by a moving mass that can't be stopped fast enough by the motor

if it does not fail as soon you first apply 48V , its not going to last very long

as long as the power supply can supply the current demanded by the stepper drivers
the maximum current available does not matter apart from the extra cost


I have not found any reference to the current taken by the breakout board
without the part number of the relays I assume they take no more than 100mA @ 5V

if the 6 outputs are all on ( 3 step + 3 direction) and are at maximum of 16mA each plus the 2 relays
the total maximum current must be about 300mA
so a 500mA supply will be OK


the same goes with permanent magnet or shunt wound DC motors

you can run a 600W motor from a 1200W power supply

the current taken depends on the mechanical load on the motor until any motor protection if fitted
cuts the supply due to an over current or over temperature condition

John

[CitizenOfDreams]

Ok, fixed on the NES-350 36 from meanwell for the drivers.
I have found this GS06E-3P1J for the BOB. The booklet says output 12 at .5A. Is this choice correct?

It is not a good choice for two reasons. First, 0.5A may not be enough. And second, it's a phone charger type power supply. This kind of power supplies is made with two things in mind: size and cost. A quick look inside one of them may give an engineer nightmares for a week.
Get a real power supply, probably 2A or more.

At this point, I need to ask another basic question. I understand that too much power can blow the drivers that need Max. 40Vdc and 3A per phase.
John, the NES 350-36 outputs 36V at 9.7A. So If I understand right, the Power supply I have is the wrong choice because it was outputting 48VDC? The 6.7A is not a problem?

9.7A would not be a problem. 9.7A is the maximum current the power supply can provide. As long as it's more than the maximum current the load consumes, it's fine.
Same thing with the spindle. 1.2kW is the maximum power this VFD can output. It can run a 1.2kW motor, a 800W motor, or even a 1W motor if you can find one. Right now one of my customers is running a 2.2kW spindle with a 7.5kW VFD - just because that was all we could find in an emergency.

[RCaffin]

Too much voltage causes breakdown. Never use a power supply with a voltage output greater than the spec for the device. Doing so causes damage - spitzen und sparkzen.

Current rating is different: that is the peak current the supply could provide IF the device called for it. Having excess current capacity does no harm at all. You should always try to use a supply which has some reserve capacity.

Cheers
Roger

[A_Camera]

It is not a good choice for two reasons. First, 0.5A may not be enough. And second, it's a phone charger type power supply. This kind of power supplies is made with two things in mind: size and cost. A quick look inside one of them may give an engineer nightmares for a week.
Get a real power supply, probably 2A or more.

That is not a phone charger. All the phone chargers I have seen lately are 5V and the Samsung I use and have used before are pretty good, but it is no more than 5V, so it is not suitable if he needs 12V. I agree, he should get a better quality 12V supply with minimum 2A. The one he found seems a cheap poor quality switching supply.

9.7A would not be a problem. 9.7A is the maximum current the power supply can provide. As long as it's more than the maximum current the load consumes, it's fine.

This is not really right. In theory yes, but in reality no. Especially switched supplies are crap for this purpose, so if you use them you should rate them much higher than your theoretical current needs. Also, remember that when motors, especially stepper motors, start up they suck a lot more currents than the rated motor current. The power supply must be able to cope with that extra need. In general, if you use a switched sully you should at least have 1/3 times extra current margin from the supply, so if you need 3x3A then the minimum is 12A, not 9A. Considering that these cheap Chinese supplies are not really reliable regarding their data, if the name plate of a supply says 9.7A you can be happy if you get 8.7A out of that without voltage drop.

[CitizenOfDreams]

That is not a phone charger. All the phone chargers I have seen lately are 5V

It is a "phone charger type" power supply - built to the same standards (or lack thereof) as cheap no-name phone chargers. It is possible to find well-built power supplies in this category, but it's a roll of dice. Since physical size is not much of a concern in a CNC router, it makes more sense to buy a full size frame type power supply.

This is not really right. In theory yes, but in reality no. Especially switched supplies are crap for this purpose, so if you use them you should rate them much higher than your theoretical current needs. Also, remember that when motors, especially stepper motors, start up they suck a lot more currents than the rated motor current. The power supply must be able to cope with that extra need. In general, if you use a switched sully you should at least have 1/3 times extra current margin from the supply, so if you need 3x3A then the minimum is 12A, not 9A. Considering that these cheap Chinese supplies are not really reliable regarding their data, if the name plate of a supply says 9.7A you can be happy if you get 8.7A out of that without voltage drop.

The accuracy of Chinese power ratings is a different can of worms altogether. But yes, I agree, you should allow for some margin when choosing a power supply. And use common sense - if you see a power supply that is obviously too small and/or too cheap to produce the claimed output current, pass it up.

[RCaffin]

I will add another thought here. Switched Mode power supplies are very fine for many things, but you should NOT use them for motor drivers. The RFI from the power supply can interfere with the switching in the driver. Instead you should use a very basic power supply: transformer, diode bridge, and capacitor. No, not even a regulator chip. By and large, motor drivers are built for this sort of voltage input. And if it sags a bit at the rare peak load - too bad, don't worry about it.

Cheers
Roger