Earthing?

[Robin Hewitt]

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.

[Clive S]

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..

It's obvious Neile in the bin of course

[Robin Hewitt]

It's obvious Neile in the bin of course

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.

[Edward]

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

[Robin Hewitt]

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

[Edward]

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

[Robin Hewitt]

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

[Edward]

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

[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

[njhussey]

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....

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