Another Electronic Ploblem
Can someone help me fix this issue. Its actualy kinda weird.
Everthing works fine when im cutting wood. Stick a peice of alum in there and try cutting it and my steppers go wacky. My limits go off at random times.
But if i put a peice of wood under the alum so that the alum is not sitting on my alum bed then it works fine.
Can someone please help me fix this issue?
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What limits are you refering to?
As it cuts ok when insulated from the bed, then it would not appear to be a loading problem etc.
What type of router head do you have?
It sounds like you are getting some kind of leakage from the router to ground, if so this may be producing spurious signal into your drives.
Is the router feed 2 wire or three wire (have a ground wire)?
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
I'm going to believe that you have a stepper winding that is shorted, until you tell me that you delrin nuts driving your leadscrews....
The spindle has 3 wires and no ground. But there is a ground going into the VFD. Its a elsktrom Charlson Spindle.
I am refering to the limits of the machine. The X and Z keep going off.
And Yes it does cut just fine when its insulated from the bed.
I am unsure what you mean ViperTX.
Ground loops are ugly things. It sounds like the noise from the router is getting into the table through the conduction of the metal to metal.
First order of business is to get your table frame grounded to a good earth ground.
The isolation of the table ground from the logic (PC) ground via opto isolated inputs helps break a ground loop. Make sure any shielded cable is grounded at one end only. A lot of routers don't have a safety ground (double insulated). Motor noise has no place to go if the neutral line is long.
Use plugs on separate circuits to run the router and electronics. If you have the negative side of the motor power grounded to a metal chassis and it's grounded to the table then you have another source of conducted noise.
Either use a star ground where every grounded object in the mix pulls back to the same grounding point or get galvanic isolation between the logic side and the table/power side.
To test for ground loops, disconnect the PC from the wallplug. WIth an ohmmeter test between the PC ground and the table and router body (if metal). If you get a reading you have a connection between the two that should not be there. The two units share a ground at the the breaker box and if there is another path you get a ground loop.
I just noticed that If you touch the spindle and anything metal on the router at the same time it shocks you alittle bit. If that helps any.
Thats what I was getting at by asking what kind of spindle you had, if you have a VFD which has a ground, then the router head is three phase and if only 3 wires go to it, it does not have a ground, it may be a double insulated type, but usually 3 ph are not, in which case, you may want to run a ground wire to the router head if it has a metal case.Originally Posted by Smackre
If you have a 3 phase router and it is not suitably grounded, the router bit and armature may be directly connected electrically, so if there is a leakage or charge on these, it will leak to the metal table and go to ground wherever it can, and could be through the stepper shield or?
I would make sure any metal parts on the router head are at a good ground back to a common ground plate, and also run a ground wire from your table (often overlooked).
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
I think that re-inforces my previous post.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Well the outside of the spindle is alum. Should i connect the ground to that? And should of be the ground that connects to the VFD?
You could run the ground from the Alum case to the VFD ground, make sure this goes to the incoming system ground and also your ground plate (which you should have already set up)
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
It could be about vibrations. Aluminium is very soft material and the charge power on motor could be more variable almost all the time. When you put the piece of wood under, the direction of cutting could be more stable, so the charge on motor could be less variable. It's only an idea.
Smackre....isolate your VFD from your router...in other words set it on a piece of wood....so only the wires go to the spindle motor...also check the spindle wires and make sure the insulation is sound.
Try the router....if the problem disappears then your VFD most likely is shorted or the power input is miswired.
But it appears from what he says, he does not have a ground wire to his router, only the 3ph. Which is a no-no.
And if it is above ground electrically, then the only path is through the router bit.
Actually, another problem occurs in this instance is that if the ground exits this way, I have seen arc mark on the bearings as they are in this ground path.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
I just wanted to come back and thank you guys for your great help. I took a ground wire from the VFD ground to the Spindle casing. And i took an other one from the machine ground to the side of the table. And i added a Earth Ground and it solved all the problems. Thanks for helping me out.
Thank you for comming back and telling us that it worked!
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