Recommended 4 pin plug/socket type etc

Hi, I am planning my electronics enclosure for my first CNC router. I want to interface to the electronics enclosure with some kind of plug and socket so that I can easily move the router and electronics box independently or replace machine cables should they get snagged etc.

I will have 3 axis and so 3 motor control cables each with 4 pins (would that be that 5 with the screening connected to earth?). I would ideally like the sockets to be panel mounted on the front of my enclosure. Do you think 4 pin DIN would suffice? Can they handle the current OK? I dont know of any other 4 or 5 pin panel mounted jacks and sockets.

Also, what kind of interface should I have for the limit switch cables? Would you include the BOB in the enclosure and have a parallel port socket on the enclosure too? Like I say, first build, not sure what the done thing is.

Muchos Gracias

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Originally Posted by glynster

Hi, I am planning my electronics enclosure for my first CNC router. I want to interface to the electronics enclosure with some kind of plug and socket so that I can easily move the router and electronics box independently or replace machine cables should they get snagged etc.

I will have 3 axis and so 3 motor control cables each with 4 pins (would that be that 5 with the screening connected to earth?). I would ideally like the sockets to be panel mounted on the front of my enclosure. Do you think 4 pin DIN would suffice? Can they handle the current OK? I dont know of any other 4 or 5 pin panel mounted jacks and sockets.

Also, what kind of interface should I have for the limit switch cables? Would you include the BOB in the enclosure and have a parallel port socket on the enclosure too? Like I say, first build, not sure what the done thing is.

Muchos Gracias

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How can anybody give you a sensible answer re current handling for plugs and socket if you do not say what motors you are using and power supply etc.

It might be better if you start a build log so that all your posts are kept in one place I have read all your posts and I think you just might be jumping the gun a bit and going down the route of wasting a lot of money.
Download Sketchup or another drawing package and try and put some sort of sketch together as what you are trying to achieve. Please don't buy any electronics until you have an idea of exactly what you want.
I am sorry if this is a bit harsh but it will save you loads in the end. Good luck with the build and remember we all started out as newbies. ..Clive

I wouldn't be happy with DIN connectors. They are not particularly robust and they are going to be pushing the limit in current capacity. I use XLR personally. Easily available (although more costly), robust (used a lot for stage equipment which is always being plugged/unplugged and generally abused), connectors latch together so vibration doesn't make them fall apart, and fairly chunky pins which seem to handle the current. Also take CY cable without too much effort. I'm sure there are other more industrial connectors around but I used the ones that I know. I bought from Rapid Online in bags of ten or so, and fitted sockets on both router and control box with a set of leads to match. I'm planning to use them again on my new router, for steppers and for limit/e-stop connections, although as the control box will be attached shall probably have plugs and sockets at the control box end.

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???

Hi Clive, I appreciate your concern and I've taken your cautions on board. I have already built my machine and I am at the stage of determining electronics. The plans I am using call for Nema 23 motors 3.1nm and thats what I am using. I dont have the budget to buy top of the line drivers right now unfortunately. So I did go down the kit route purely because its my first build and I am learning how everything goes together - pretty much as soon as this is finished I will be making another one - it's not my "forever cnc" so to speak.

I didnt think to mention power ratings when I asked - I figured the DC current of home CNCs to be nominal and well in-line with standard audio visual power ratings. But you are right I should have thought about that. I havent bothered with a build log because I only built a Solsylva machine, they have been made and documented dozens of times online and I didnt think anybody would be at all interested.

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Originally Posted by glynster

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

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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.

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

Wow! I take my hat off to you an you only started looking 3 weeks ago and two weeks ago you were asking questions re screws and now the cnc is finished apart from the electronics. Re the power ratings I don't think you can compare them with audio visual ratings the cnc motors could draw anything from say 3A to 5A ..Clive

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?

I've been lucky enough to get to work full time on my machine. The Solsylva parts were easy to come by and the plans are fully step by step from Solsylva so they are a doddle to be honest - the only hard part was converting all fixings and materials etc to metric and scaling up from 18x24 to 600x1200mm. Solsylva plans dont cover electronics at all and some of the parts use US terminology or are not easily available in the UK or in equivalent metric sizes so I agree I might appear to have asked a serious of otherwise baffling questions.

I admit my plans have been at times confused, erratic and jumping all over the place. I am overcoming quite a serious illness and a multitude of life changes which doesn't help. The CNC build is largely a distraction/rehab project for me. My initial plans were to build something "spectacular" until other people's good sense and advice brought me down to earth with first building something much more modest like a solsylva machine. A couple of months ago I didn't even know the first thing about how a CNC router worked - I just knew that as a woodworker I could really use one. So I followed the Solsylva plans as a discipline of learning.

I admit, it's so complex that at times I have felt like tossing the whole idea in the skip but I just try to take one day and 136 problems at a time :-)

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.

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

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.