Troubleshooting CNC setup

[Rickv100]

What would cause 2 Hitachi routers to short out(smoke, burning smell, no longer running) on my new CNC machine? I was not running the router hard when it happened. (30 inches per minute, .041 depth of cut on a 2" surfacing bit on MDF) I migrated my electronics C10 breakout board, Power Supply, 2-Nema23 435 oz stepper motors and wiring from my JGRO router and added another power supply and 2 new Nema23. The machine is now aluminum extrusion based machine as opposed to the MDF of the JGRO. I am wondering if that makes a difference. The Hitachi grounds through the router body and thought maybe there was electricity flowing into the router from the machine.

Since the incident I have went though and grounded the machine and the shielded cables to the limit switches. When I ran the Hitachi at 6 on the speed controller it would trip Mach3 with a limit switch message.

Rick

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[joeavaerage]

Hi,
were you trying to run the bit slowly?

Routers produce reliable power at high speed, either rated maximum speed or close to it. At part speeds they struggle and get hot.
Additionally the fan blade is on the motor shaft, so when running at part speed the fan has a reduced cooling effect, proportional to the square of speed.
Thus if you run your router as half speed the cooling effect is 1/4.

The Limit switch error you are getting is a result of the electromagnetic noise produced by the router, again, the noise tends to be worse at part speeds.

Craig

[Rickv100]

Thank you for replying. No. I had the router set at 5 on the speed controller. The Hitachi has a ferrite on the power cord. The router power cord is in a power chain from the router to the x Axis. My Z limit switch is located in between the loop. Picture and inverted U with the switch in the middle of the legs of the U. Would that cause a trip? I removed the switch for testing.

I had no problems with the electronics with the MDF JGRO frame and I am wondering if there are grounding issues.

Rick

[joeavaerage]

Hi,
you should not be using the speed controller at all, routers are working at their best when running at full speed. I would not run them at part speed ever.
That the brushes should be arcing badly suggests one or more of the armature windings have shorted turns, and those are almost always caused by overheating.
Once they start arcing like that the writing is on the wall....failure imminent.

The Hitachi has a ferrite on the power cord.

Good, but not good enough. You should have at least a two stage EMI filter on the AC input side of the router. That will help contain the electrical noise from the router
in the router circuit rather than leaking into the AC supply to your other electronics.

https://nz.element14.com/corcom-te-c...ase/dp/9586474

You should probably have two, one on the input to the router and the other on the AC input to your PC and motion electronics. The one on the router is to try to contain the noise in the router and
the one for the PC/motion electronics is trying to keep out any residual noise that has leaked out from the router.

Its also worth adding a little capacitance 0.01uF say to each limit circuit, or 'noise cancelling' or 'switch de-bounce' if your controller supports it.

Craig

[Rickv100]

I am using Mach3 as my controller software. The debounce was set at 500 on the older machine. I increased the debounce setting to 2000 to test.

For the 2 EMI filter this is being placed inline. So I would mount the filter into my electronics enclosure and then run correction from cord plug to the filter then filter to on switch and the rest of the electronics?

I am running 2 power supplies in my setup. I added a new driver and the new drivers required more voltage then my existing power supply. I am using a 48vdc KL-600-48 connected to 2- Dm556 drivers and then to 2- Nema23 425oz steppers for the Y and A axis The 36v I used for the X and Z are through KL 4030 drivers to NEM23 425 oz steppers.

I wired + to the + wire on the 36v PSU and then a jumper from the + connector on the 36V PSU to the + on the 48V PSU.

Rick Lathrop

[joeavaerage]

Hi,

So I would mount the filter into my electronics enclosure and then run correction from cord plug to the filter then filter to on switch and the rest of the electronics?

Yes, the PC, the motion control power supplies, even the stepper power supplies would come from this EMI line filter, the only thing that would not come off it would be the router itself, it should
have its own one. You need to understand that the router is by far and away the noisiest (electrically) device that you have, especially if using a speed control. You must prevent the electrical
noise from getting out and away from the router and prevent any residual noise from getting into the sensitive stuff, like motion control.

I wired + to the + wire on the 36v PSU and then a jumper from the + connector on the 36V PSU to the + on the 48V PSU.

Not sure what you mean but it does not sound right. The 36V supply should wire to the 36V drivers and the 48V supply to the 48V drivers. Only the 0V, (or COM, or earth)
of the two power supplies should be commoned to together with the 0V of the motion controller. Do not put a link between the positive outputs of the supplies.

Craig

[Vlod]

Check the Voltage drop when you run your router together with your machines. If you don't have sufficient power in your shop that will shorten their life as well…

[Rickv100]

This is something I need to check on. My shop outlets are wired into 4 sections. I need to check the breaker size if they are 15 amp or 20 amp breakers. If I have my drivers set to 2.7 amps each and I have 4 drivers is the amperage then 10.8 amps or should I calculate the load requirements as the total of the two power supply units potential amperage requirements? The 48volt PSU has 12.8 max amps. I need to check the other PSU amperage.

Router is 11amp Hitachi M12VC.

I am guessing that Power Supplies should be on one circuit breaker. Router on another circuit breaker and Computer, Monitor and Controller card (5v wall wart) on another circuit breaker to divide the load? If I run 16 gauge extension cords do I have to worry about voltage drop? The shop is 60x40.

Rick

[Vlod]

You have a nice size shop man.
Don’t you have a dust collection system?
Turn on all machines you use when operating cnc and check the voltage next to the router.
If it lower than 5% then take actions.
Sometimes we don’t realise that when one machine is running we get shop vacuum and start cleaning the shop…
I would definitely upgrade extension cords to at list #12 but it depends what are you running…

[Rickv100]

My dust collector is running on a 220volt circuit.

Shop has 200 amp service. When I run the CNC I just have the machine running, dust collector and the shop lights. With a 12' ceiling I don't think interference is coming from the light ballast.

Rick

[Vlod]

It’s nice to have 200 Amps service or it’s a sub panel?
Is it single phase?
Sorry I made a mistake- if you have more than 5% voltage drop then you need to do something about it.
Just check it to illuminate a possibly.
I do run my routers at low speed a lot but not with 2” bit… sometimes more than an hour when cutting plexiglas and never have problem with excessive overheating.
Yes it’s better to run them at max speed but small machines cannot do it.
Another thing is a simply doll and oversized bit would destroy your router…

Switching type power supply and any power hangry devices bring harmonics in to power grid and as Craig said try to put some filters on all of them.
If you have an oscilloscope you can actually see them in your grid.

[Rickv100]

Shop has its own 200 amp service and electrical meter, single phase.

I am looking to get filters to install.

I do not have an oscilloscope just a digital multimeter.

Rick

[Vlod]

In addition you could upsize your extension cord to at list to #12.

[Rickv100]

Thanks to all for assistance. I mapped out which breakers control which outlets in the shop. I then put the Power Supplies on one circuit and the controller board, computer and monitor on another circuit. I was able to run on air gcode to surface the table. The job ran for 1.5 hours with no issues. The dust collector was not running.

I want to run again with the dust collector running to see if that triggers anything.

My Y and A steppers do run hot to touch. X and Y are cool to touch. Limited reading has said this is normal.

Should I break the 2 PSU's to separate circuits? The 48volt PSU has max inrush of 25amps on 115v and it is on a 20amp breaker. The 36volt has 6.5 amp input.

For the power filters. I will need a 20amp filter since the circuit breaker 20amp?

Rick

[joeavaerage]

Hi,
the power supplies can in very brief periods draw a lot of current but 99.99% of the time they loaf along at just a few amps. It is not necessary to split the supplies.
It would be worthwhile to install D-curve breakers, they tolerate substantial current flows in brief periods without tripping, just the ticket for motor circuits, SMPS etc.

The idea is to try to contain the electrical noise of a device, say a router, to its own circuit. If you put a two stage filter on the input that will go a long way to preventing
electrical noise form the router getting out and onto the main AC supply and thereby polluting the supply to your PC and motion control.

As added protection you should have another filter on the input of your PC and motion control electronics, hoping to suppress or reject any AC power supply noise
from the rest of the shop from getting into your sensitive circuits. Good two stage power line filters get expensive, especially large current types, you'll run out of money before you run out
of places to put them.

I want to run again with the dust collector running to see if that triggers anything.

Depending on the power of the collector and the type (universal motor verses induction motor) it could generate as much or more noise than the router. You are wise to experiment with it
to establish whether it is causing your noise faults.

I use an 800W 24000rpm asynchronous spindle very extensively, and have done for nearly ten years, its been absolutely brilliant. I use it sometimes with small tools, 1/8th and smaller, to cut steel.
It is not well suited to this service because you have to run it at part speed. I absolutely refuse to run it at less than half speed (12000rpm), and don't like running it at less than 3/4 speed (18000rpm),
and when I do run at part speeds I back-off the cut depth/stepover to reduce the load, down to less than 200W. I use this spindle daily for work, and I'd go broke if I wreck it....therefore I don't treat
it like that if I can at all help it.

I have another spindle based on a 1.8kW, 6.1Nm (cont), 18Nm (overload), 3500rpm Allen Bradley servo running an ER25 toolholder running in angular contact bearings. This is what I use for steel
and stainless. Unfortunately I was very carless and allowed coolant to get into the back of the servo and wreck the encoder......and until I can save up the money to repair or replace, its out of action,
hence I'm using my regular (24000rpm) spindle to do jobs which otherwise I would not consider, or risk it.

Craig