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Exactly Clives point I think.!!! . . . There isn't a blood option for braking resistor on AM882 and tell the last time you or anyone else seen Nema 23 3Nm stepper motor fitted to Minimill using braking resisitor.!! . . . . . STOP TALKING SHIT.Quote:
Originally Posted by Robin Hewitt
Hahaha, this is getting interesting:)
In the EM806 and AM882 don't you have an over-current cut off with the red LED blinking? I think you really have to push them really hard, for instance, with high deceleration to get to that stage. I don't intend to drive this machine too madly:)
Also, I guess the psu will be able to cope with a bit of back EMF if I feel too adventurous...
Edward
Robin Can you please send me some of that shit you are on as it just might help me to understand what the f@*k you a taking about.Quote:
Originally Posted by Robin Hewitt
I keep taking breaks from PCB design. I am trying to wire up a 168MHz processor without resort to 4 board layers and it is not easy getting sufficient decoupling and copper down to get the power everywhere it needs to be. I am having real problems while you lot are having imaginary problems and I guess I am getting a bit jealous.Quote:
Originally Posted by Clive S
To quote Jesus, purely because it is hard to argue with Jesus, "You're far too keen on where and how, but not so hot on why" :nonchalance:
Can you point me to the document where HE wrote that please.Quote:
To quote Jesus, purely because it is hard to argue with Jesus, "You're far too keen on where and how, but not so hot on why"
You don't believe me? Google is your friend :hysterical:
I wonder WHY all the time.? . . . Often wonder WTF your on about and WHY you say the Shite you do.!! . . . . . Go back to the Stone age because your just confusing new users with BUM info that isn't relative to todays modern components.!! . . . . . Sorry to be so harsh but your going to cost somebody lot of wasted time and possibly money with such Rubbish.Quote:
Originally Posted by Robin Hewitt
Now that's the last I'm saying so OP can get back on track.
Edward:
You won't get near taxing those drives with Mill this size so don't worry about Over current etc. Just fit and enjoy.!
Regards Earthing then just use Star ground and shielded cable and you won't have any troubles. Size wise then 1mm is fine for motors and limits etc so just buy one size as it's easier and often cheaper as Some suppliers have minimum qty. 4-Core will do both
Brilliant, thanks Dean and everybody, I'll just get on with it.
I think this thread is quite old, but the OP asked questions that I was also interested in.
Edward
Calling me names and telling me I am stupid rather than explaining why I am wrong does rather suggest that you do not have a clue what you are talking about. Your appeal to authority, "because it's well documented why shielded cable is required" is a fallacious argument. Where is this document?
I like to understand "why", because that helps me know what and how. Trouble with earthing and screening, though, is that you can still get odd problems because you can't actually see or measure what's happening, particularly with intermittent problems.
Been testing my new machine, checking machine limits. X axis kept tripping around 20mm or so before it reached the limit (proximity) switch, although it wasn't clear which switch had actually tripped. Cables are all screened CY but run in same cable chain - limits in one cable, with motor Y and Z cables, but separated as far as I could by spindle cooling tubes. No other tripping problems, just this one point near the upper end of X travel. However, at this point the unrolling cable chain was next to the cable to X proximity switch (the usual unscreened thin stuff); I re-routed the proximity switch cable and the problem went away. Similarly, my earlier problems with home switch triggering went away when I moved the control box from its test position on floor in front of machine to its installed position bolted to frame with earth connection to star point. Moral of story? Use good earthing practice, screening helps, but be alert for the unexpected just in case.
I'm using 1.0mm CY for my Nema 23/EM806 combination, but buggered if I can work out where to put my braking resistors...
My mill either works or doesn't work depending on the route taken by the cable connecting it to the computer.
Everything was fine and dandy until I started putting things in boxes.
It's obvious Neile in the bin of course:yahoo:Quote:
I'm using 1.0mm CY for my Nema 23/EM806 combination, but buggered if I can work out where to put my braking resistors..
Just because you cannot see the braking resistors does not mean you do not have them. It is all very well you behaving like a sheep on the border collie's day off, but it is only through understanding why things do not work as well as expected that we can improve them. No kind way to say this, you are a Luddite.Quote:
Originally Posted by Clive S
One problem I experienced with one of my motion controlled cranes was that the drivers - 6 of them - were placed too close together in the box (which was open top) and didn't have enough space to "breathe" and there was no fan. To start with, it would all function well, but after some minutes some of the drivers would start to have a life of their own:)
I put it down to the heat, the drivers didn't have the cooling base either. With a 3 axis machine, it is easier to give them space for ventilation plus I will use a small fan as well. I also had some minor earthing problems with another machine, so the lesson learned is to anticipate all this and be on the safe size to avoid later problems.
The Kflop communicates via USB, and I haven't had any problems in that respect, been using it almost daily for three years in my work as a photographer and for motion control you can't afford to lose steps or have a bit of backlash, it's servo motors and harmonic drives for every axis. I use a good quality shielded cable, with ferrite chokes at both ends just as a precaution.
Edward
Hi Edward
Laid out, open plan on the desk your Sieg SX2.7 will be working fine and dandy, I believe they always do. All the data lines are clear, it is not interfering with the telly.
It is only when you start putting things in metal boxes, using screened cables and connecting everything to ground things start to go wrong.
I don't know if anyone sees an improvement. If not our idea of how to do it may be flawed.
Robin
Well yes, but these electronic elements need to be kept in some sort of box or small cabinet to protect them from swarf and keep it all tidy. I will do it and then let's see how it goes, I will report back to you guys with pictures. I think I am going to make my own box to size as I have plenty of 20 x 20 alu extrusion and with that and a few panels it can easily be made to measure.
However, I am tempted to run the cables all in one length, direct connection so to speak, with as few connectors as possible, just using glands for the entry points on the panel.
Edward
Edward
You do whatever seems best to you, you cannot actually go far wrong. Don't worry about me an Jazz, I like winding him up and he likes screaming obscenities at his computer, it's a match made in heaven, no lasting damage has been done.
"Tempted to run the cables all in one length". Does that mean bring all 8 motor wires back to the driver? I would say bad idea because you still have to join them, the wires do have resistance and there will be heating. If all together in a cable rather than loose in a conduit, there is not much scope for dumping excess heat. Running 4 wires halves the resistance. Also, beware cutting any wires close to the motor, leave yourself plenty of wriggle room.
Robin
Robin,
I take it these "battles" have been going on for a while:)
I meant running a 4 core cable from motor to driver in one go, without connectors (XLR or similar) on the panel - less work soldering pins. At the motor side, just cut the 8 cables and solder/insulate accordingly to the 4 core cable.
Not that I've ever experienced any problems with connectors, but I am just thinking that once all is in place, I won't be moving the box anywhere, so using XLR or GX16 connectors is not going to be necessary, though I suppose it looks a touch more professional, if one is bothered about that.
If for whatever reason I need to disconnect a motor or something in the future, it's not a big deal to do it from the drive own connector.
Edward
Changing the subject a little, I read somewhere else in this forum that Dean's sensors are floating - that way it minimises cable runs.I didn't quite know what he means by floating and I'd like to know, maybe from the man himself, if he's reading, please.
I just saw a video by him talking about the repeatability of the cheapo proximity sensors and I think the trigger was the metal of the ballnut flange, or in any case, something that moved past the sensor to trigger it- sideways, rather than front on. So there was no possibility of trigger and sensor crashing into each other. I quite like this and maybe it's common practice to do it this way, although I have seen videos where the machine would crash into the sensor if it overrran a little.
Mind you, if the machine overruns, a crashed sensor is probably the least of the problems:)
Edward
He means that he (and I) have one home (or/and) switch for each axis and it travels on the axis with two triggers each end for it to see. Less wiring....
Sent from my HUAWEI VNS-L31 using Tapatalk
Thank you, Neil, I'm with you. Though in my head I am initially thinking that it may not be so easy to implement on a vertical mill, say, the X axis, sensor somewhere in the middle, hitting targets at either extreme...
I can see the opposite working, i.e. sensor stationary in the middle and triggers at the extreme ends moving.
Edward
Neil answered for me but no difference if sensor moves or Target moves. Infact it's common on mills for the Switch to be stationery and the targets or Ramps if mechaincal type Switch to move with table or saddle. See pic.Quote:
Originally Posted by Edward
Attachment 20385
Robin you don't whind me up and believe it or not don't curse you to the PC, like you it wouldn't listen.! . . . You do Piss me off with the one line sarcastic unhelpful replys and excrament which comes from your fingers.Quote:
Originally Posted by Robin Hewitt
However much as I'd like to go at it with you decided In the interest of not hi-jacking (more) Edwards thread and fact can't be arsed after long day I'm not going to endulge your delusion of whinding me up by replying to your challenge regards Screening and Metal enclosures.
Anyone who want's to follow your Stupid approach is very welcome to go for it.!! . . . . They will soon see who was correct.
Thank you, Dean. The picture says it all. Not only do you save on wiring, but you save on sensors too! I think I will implement something like this.
Edward
A couple of questions regarding earthing in a control box
I'm going to run the screened 4 core wire from steppers to sockets on the metal case and run the screened wire from the inside of the the case (soldered pins on the stepper connector insulated with heat shrink) is it sensible to cover the inside of the socket with copper tape as a screen and to continue the screen continuity? Would I be right in thinking that as the case is earthed I won't need an extra wire from the connector to the bus bar ? I'm going to use a bus bar to connect the earth wires (star earthing) should I bolt the bus bar to the case or insulate it? The switching power supply has a metal case I assume as it will be bolted to the case it doesn't need an extra earth wire. I assume all metal cased items such as stepper drivers are earthed by the mounting bolts, or is it better to insulate them and run extra earths to the bus bar. One last thing is that the boxes holding the connections from the steppers are plastic. Is it worth screening the inside of the boxes but having no electrical contact to the machine frame so that the earthing is only connected at the busbar. I hope this makes sense.
Cheers
Andrew
It's not that critical really but won't hurt if you want to go to that much trouble.Quote:
Originally Posted by the great waldo
Bolt the Bus bar to Cabinet and run all screen wires back to this. Because case is Earth via bus bar then won't need wire from connector body if that's what you mean.Quote:
Originally Posted by the great waldo
Just bolt them down to the case.Quote:
Originally Posted by the great waldo
No they will be fine. Don't over complicate things because you can easily introduce problems in your attempts to avoid issues. All you need to do is run all Screens and Earth's back to Star point. If you introduce extra Earth wires etc you can easily create ground loops.Quote:
Originally Posted by the great waldo
Mains things are.
Shields & earths back to Star point.
Stepper sheilds Earthed at star point only not motor end.
Run all signals wires far away from Mains voltage wires as possible.
Thanks Jazz
As the screen for the steppers is connected at the socket via the chassis should I leave both ends of the screen unconnected or is it better to run the driver end of the screen to the bus bar?
Thanks again
Andrew
Others might have a different view but I have done it like you and grounded the screens at the sockets and the plugs. But then I connected a ground wire bolted to the panel close to the sockets and ran that to the star point.Quote:
Originally Posted by the great waldo
Then you don't ground the other ends of the cable ie at the driver or motors
Thanks Clive.
Just for other forumites make sure there is continuity on the chassis holes for the sockets. On my box only one socket made a connection, all the others were insulated by the case coating/finish. This needs to be corrected.
Cheers.
Andrew
I'm also using an epoxy finish steel cabinet, and don't trust any mounting bolts to earth to the cabinet. I've used ground wires from sockets back to the star point, which is a stud welded to the inside of the cabinet.Quote:
Originally Posted by the great waldo
Yes I should have said that as I have also done the same thing with the mains earth to the star point.Quote:
Originally Posted by Neale
The key thing with grounding, is to avoid ground loops, which you potentially create anytime a screen had more than one ground connection.
However, in power wiring, ground loops aren't likely to be a problem. The point of grounding in power wiring is to contain noise. A ground loop there is unlikely to cause any problems. A prime example is if you wire up a VFD as per most manufacturers recommendations, you ultimately create a ground loop in the wiring, as the motor is likely to be grounded through the machine.
It's in signal wiring, especially low voltage i.e. 5V, where ground loops are far more likely to cause problems.