Recommended 4 pin plug/socket type etc

[glynster]

Thanks Neale, I will look into XLR, didn't think of that - I suppose they must be well rated since phantom power is usually 48v. When you say that you used them on your router, do you mean for the power???

[Neale]

When you say that you used them on your router, do you mean for the power???

I use them to connect stepper drivers to the steppers. I'm also using NEMA23, 3Nm, running at about 4A (from memory), from an analogue driver running at a nominal 68V. Taking a quick random sample from one supplier, their XLR 4-way connectors are rated at 7.5A per contact. There is a voltage rating as well, but typically those are only relevant for making/breaking connections under power. Do that with a stepper driver, and the rating of the connector will be the least of your worries. Stepper drivers - they don't like it up 'em... It's why I prefer to use latching connectors.

I'm currently building my second router. The first one is MDF. That's why the second one is welded steel! You can learn a lot from even a simple, under-powered, wobbly machine like mine. Good luck with yours.

[cropwell]

A lot of people use these ;_ http://www.audiospares.com/home.php?cat=1025
They are relatively cheap and rated up to 60v (I think). If you use the 4 pin for steppers and something else for homes, limits, probe and Estop then you can't plug the wrong thing in to the wrong socket.

Rob

[glynster]

That's a good tip about not breaking connections while live Neale - hopefully I might have had the common sense not to but I often amaze myself with my own foolishness. I suppose it's the risk of an accidental break in connection I need to be really worried about.

I will be using these digital drivers http://www.cnc4you.co.uk/Digital-DSP...?search=CWD556

I had assumed that voltage would be regulated by drivers and that they would put out the same voltage to the motor regardless of input providing it was within the input range. The specs say they can handle an input voltage of 24v to 50v. The power supply I have is only 36v - what difference did you find from running yours at 68v and does the spec say that they can take that kind of voltage?

[Neale]

I don't want to go into the technical detail (it's been done before on the forum!) but in hand-waving terms, stepper motors need current because it's current, not voltage, that generates a magnetic field. However, to push lots of current into the coils in the motor, you need plenty of volts to get it flowing. One of the jobs of the stepper driver is to take whatever voltage it is supplied with, and use that to push current into the motor windings. It will regulate the voltage applied to the motor to get the right current and stop it going over the set value (that is, the value that you have told the stepper driver to use). However, if there isn't a high enough supply voltage, it takes longer for the current through the windings to build up to the right value, so smaller magnetic fields, so lower torque available. My power supply is about 68V because that is about the highest that it is safe to use with my M752 drivers. I haven't tried a lower voltage so don't know from personal experience how much difference it would make. In any case, my MDF machine is not capable of particularly high speeds, so it wouldn't be a good test. I over-specified the motors and electronics for my first machine as I had a feeling that I would be upgrading eventually and could then re-use them. This description is also why the voltage you use with the drivers is way, way, over the nominal "max volts" specification that you will find on a stepper motor spec sheet. Don't worry about it - the driver will sort it out as long as you don't go over the motor's current rating.

You also have to watch for overloading the drivers. Under certain circumstances, the motors will generate a reverse voltage that gets added to the supply voltage that the driver sees. Your power supply is 36V and the max supply for the drivers is 50V, which should be fine.

[Clive S]

Ok Neale is correct regarding the steppers and current etc. But if you want to future proof your electronic to use on another machine then the drivers you have chosen are not good enough.
You would be better buying the steppers from cnc4you and using AM882 or EM806 (the newer version) but the AM882 are fine and cheaper as they both can take up to 80 V so then you would need a 70V power supply for them.
The difference between 36V and 70V is night and day. It is one of the biggest mistakes that people do with using underpowered drives. ..Clive

[Neale]

Can't disagree with Clive - new machine is being upgraded to EM806 for X and Y. As I said, I doubt if the lower voltage would have been an issue for my current router but that's because it's a pretty ropey machine. New machine deserves better and will get the higher voltage.