I am going to build a CNC machine, What do I buy?

[northwest]

Well, couple of tips I have been given: Put the Power supply on a removeable back plane in case it needs changing, separate the High Voltage from the Signal and use twisted pair or shielded.
So far so good. Cannot believe how difficult it has been to get a couple metres of 25mm wide trunking with some depth to it at reasonable cost. Fifteen quid in the end for two metres 25x40mm delivered. I have been told to put a wiring diagram together but frankly I am not sure what I am doing yet so a wiring diagram would be a spider going across a page right now. I will be sure of myself once I have worked out the VFD wiring and some of the ON lights, switches and of course the alarm light. I have bought a combined Red LED and Alarm buzzer light. Sometimes I am not in the same room so a buzzer makes sense, I would hear it from next door. But how and where to wire it is the thing.
I have a friend who is a spark has promised to come over and help out once I get started but I know he is very busy so the help will probably come from here. Which going by the advice so far almost guarantees success.

 

[m_c]

Hmmm, thanks for that. What size mill is yours? I'm thinking of converting a bridgeport size machine - I guess the ballscrews will be big, as will the motors? Do I need a dc motor for the head? I guess no reason why?

Im specing what i want to achieve its a mine feild of choice.


Hats of to those that have built them, just the choice and then finally nailing your colours to the mast and going for it is hard enough

For basic machines, you can't really go wrong with many controller options now. I don't think you'll find many CNC controllers that won't handle 3-axis in an acceptable fashion now. Some may not give as good performance as others, and may lack some features, but most will manage to move 3 axes controllably.

Electrics wise, for larger machines, servos are now a no brainer. Smaller machines, steppers are still a good choice, especially with modern drives. There is also the halfway house of closed loop steppers, for if you don't want the complexity or need the performance of servos. As long as you pick something suitable for what you're trying to move, it'll work. Even if you pick something unsuitable, it'll likely still work, just probably not as well as it could.

The big thing I'd say, is look beyond the classic Mach 3 and Gecko options that still dominate certain forums.

 

[m_c]

Well, couple of tips I have been given: Put the Power supply on a removeable back plane in case it needs changing, separate the High Voltage from the Signal and use twisted pair or shielded.
So far so good. Cannot believe how difficult it has been to get a couple metres of 25mm wide trunking with some depth to it at reasonable cost. Fifteen quid in the end for two metres 25x40mm delivered. I have been told to put a wiring diagram together but frankly I am not sure what I am doing yet so a wiring diagram would be a spider going across a page right now. I will be sure of myself once I have worked out the VFD wiring and some of the ON lights, switches and of course the alarm light. I have bought a combined Red LED and Alarm buzzer light. Sometimes I am not in the same room so a buzzer makes sense, I would hear it from next door. But how and where to wire it is the thing.
I have a friend who is a spark has promised to come over and help out once I get started but I know he is very busy so the help will probably come from here. Which going by the advice so far almost guarantees success.

As you're using a CS-whatever, you won't really have to worry about separating wiring. The higher voltage signal wiring, and differential signals to the steppers will eliminate problems unless you have some kind of major interference problem.

I've personally only ever done a handful of partial wiring diagrams for any of my machines. Most things are self explanatory. I.e. Step/dir outputs go from controller to drives.
What I do have though is some method of identifying inputs/outputs. Either in the form of a chart (excel file works well), or configuration file (I mostly use Dynomotion KFlops, so for my user programs I have a single header file that not only defines inputs/outputs for easier programming, I also add notes for each input so I know what physical terminal it connects to). That way if I do have a problem, I know what terminals I need to look at.
The only things I have wiring diagrams for, are things like interlock systems, just so to remind me how certain more complex things are connected i.e. if they're not a direct A to B connection, but perhaps go through various switches.

For alarm/warning lights, in Mach 3 you'll want to check out the MacroPump/Brains, and add code so the light/alarm gets activated either when the machine e-stops and/or finishes running.

 

[northwest]

The big thing I'd say, is look beyond the classic Mach 3 and Gecko options that still dominate certain forums.

I think you are right, the late John Stevenson was starting to champion all in one controllers based on Fanuc or Siemens style controllers, very fast, little overhead and value for money, just prior to his untimely death. I think he would have had something quite far into the market by now if he hadn't passed.
But we are all still here so we are just going to have to get on with it ourselves. My pal has gone to Siemens but I am sticking where I am right now as I am just getting to grips with it and understanding what is going on.

Give me a year with this and who knows where it will end up.

 

[northwest]

For alarm/warning lights, in Mach 3 you'll want to check out the MacroPump/Brains, and add code so the light/alarm gets activated either when the machine e-stops and/or finishes running.

You see, it all falls over right there. I am sure you know what I mean :-)

 

[northwest]

.75 is about 6 amps and its easier to terminate than .5

I would likely go 1mm as again is easier to terminate

This was it really Matt, sometimes it is not what the spec says but ease of assembly. I have really struggled getting slotted trunking of the right size and at the right price. I eventually found some 25 x40mm slotted trunking online at reasonable cost (£15) delivered, some places wanted £20 just for the delivery.

 

[MCKDAVID]

I hate starting wiring stuff like this, but once you commit it goes well

definitely prefer wiring a panel to a house say. Once you have the wiring diagram clear it's fairly straightforward. Like MC says the connections are clear enough, and it's mostly rinse and repeat 4 times for the axis drivers and limits... no the hardware isn't the issue, it's getting mach 3 configured to your system. I easily spent way way longer on that than the Hardware, and without a lot of help, I'd still be battering my head against that big dent in the workshop wall.. fortunately for me we have real experts here....

 

[northwest]

fortunately for me we have real experts here....

Even more fortuitous, they actually know what they are doing. I hear what you say about configuring Mach3, I am so invested in the software now that to change would be too much. The real issue is I don't use it day in day out and as my knowledge retention isn't what it used to be, some days I make silly mistakes. Getting there though.

 

[mtt.tr]

definitely prefer wiring a panel to a house say. Once you have the wiring diagram clear it's fairly straightforward. Like MC says the connections are clear enough, and it's mostly rinse and repeat 4 times for the axis drivers and limits... no the hardware isn't the issue, it's getting mach 3 configured to your system. I easily spent way way longer on that than the Hardware, and without a lot of help, I'd still be battering my head against that big dent in the workshop wall.. fortunately for me we have real experts here....

I'll take anything thats starting from new over being stuck in a woodfilled in my experience box not being able to fully fit


Thats the same with most software now, fortunate to have guys that will help some groups are proper a*holes

 

[mtt.tr]

Even more fortuitous, they actually know what they are doing. I hear what you say about configuring Mach3, I am so invested in the software now that to change would be too much. The real issue is I don't use it day in day out and as my knowledge retention isn't what it used to be, some days I make silly mistakes. Getting there though.

Im going to go Linuxcnc i like the overall power of it and i like programming if i can remember what i learnt as a kid inregards Linux is different matter, picking up c++ again was harder than expected

 

[minimutly]

For basic machines, you can't really go wrong with many controller options now. I don't think you'll find many CNC controllers that won't handle 3-axis in an acceptable fashion now. Some may not give as good performance as others, and may lack some features, but most will manage to move 3 axes controllably.

Electrics wise, for larger machines, servos are now a no brainer. Smaller machines, steppers are still a good choice, especially with modern drives. There is also the halfway house of closed loop steppers, for if you don't want the complexity or need the performance of servos. As long as you pick something suitable for what you're trying to move, it'll work. Even if you pick something unsuitable, it'll likely still work, just probably not as well as it could.

The big thing I'd say, is look beyond the classic Mach 3 and Gecko options that still dominate certain forums.

Good info, but, is there a way of rating the motor output, and stting that against the required torque?

 

[mtt.tr]

Good info, but, is there a way of rating the motor output, and stting that against the required torque?

Ask @Hood

 

[Hood]

Ask @Hood

Probably not the best person to ask, I don't even understand what is being asked

 

[minimutly]

Im going to go Linuxcnc i like the overall power of it and i like programming if i can remember what i learnt as a kid inregards Linux is different matter, picking up c++ again was harder than expected

Nooooooooooooo.........l

 

[minimutly]

Probably not the best person to ask, I don't even understand what is being asked

Well, how do you know what size motor you need for x, y and z axis for a certain machine - some ways are stiffer than others for instance?

 

[mtt.tr]

Nooooooooooooo.........l

Well i enjoy sticking needles in my eye

 

[Hood]

Im going to go Linuxcnc i like the overall power of it and i like programming if i can remember what i learnt as a kid inregards Linux is different matter, picking up c++ again was harder than expected

Mach3 is very powerful and has the advantage of being relatively simple to get the power out of it, Sam (forget his second name, sorry!, goes by the name Skunkworks) who is into Linux CNC in a big way once said to me he would never have thought it possible to do the things I have done with Mach3. He always thought that anything more than a basic machine was out of the question and things like complex toolchangers were just a non starter, they are not and they can be done without too much trouble and learning.


Linux CNC is undoubtedly extremely powerful but you need to get right into the guts of it and be a programmer to get the best out of it and back in the day help was not available and you were treated like a leper when you asked questions, things may have changed in that respect over the years but I don't really know as it put me off.

Mach4, to my mind, is similar to Linux in that respect and it was something I wasn't willing to do as I have enough to do without having to learn more than the basics of programming.

The higher end Chinese standalone controllers such as the SZGH I now have on the lathe are excellent and are fairly configurable but they are definitely not as configurable as a PC based controller but on the lathe it is superb, for a mill I think I would miss too many features I can get from Mach.

The latest Masso controllers look good but again I think they may have limitations in a similar way to the Chinese controllers.

Lots of other options on the market such as UCNC and SimCNC but for me Mach3 and the SZGH are the two I am happy with.

 

[Hood]

Well, how do you know what size motor you need for x, y and z axis for a certain machine - some ways are stiffer than others for instance?

Two ways, well 3 I suppose.
First is to use one of the online calculators/programmes that the likes of Kollmorgen have. The downside is you need to know a lot of different numbers and facts about the axis to even be able to input the data required for it to then calculate.

Second is look at what others have used on similar machines, problem with that is people are happy with different levels of performance so you have to decide what you think you would be happy with.

Third is the way I did on the Churchill lathe, mounted a flat bar of known length (fixed in the centre so it balances) to the end of the ballscrews then added weights until it moved, I was then able to find the Nm required to start it moving and thus I knew if I was around that value for continuous torque output then I would have no issues at all and in reality was probably oversizing.

 

[mtt.tr]

Mach3 is very powerful and has the advantage of being relatively simple to get the power out of it, Sam (forget his second name, sorry!, goes by the name Skunkworks) who is into Linux CNC in a big way once said to me he would never have thought it possible to do the things I have done with Mach3. He always thought that anything more than a basic machine was out of the question and things like complex toolchangers were just a non starter, they are not and they can be done without too much trouble and learning.


Linux CNC is undoubtedly extremely powerful but you need to get right into the guts of it and be a programmer to get the best out of it and back in the day help was not available and you were treated like a leper when you asked questions, things may have changed in that respect over the years but I don't really know as it put me off.

Mach4, to my mind, is similar to Linux in that respect and it was something I wasn't willing to do as I have enough to do without having to learn more than the basics of programming.

The higher end Chinese standalone controllers such as the SZGH I now have on the lathe are excellent and are fairly configurable but they are definitely not as configurable as a PC based controller but on the lathe it is superb, for a mill I think I would miss too many features I can get from Mach.

The latest Masso controllers look good but again I think they may have limitations in a similar way to the Chinese controllers.

Lots of other options on the market such as UCNC and SimCNC but for me Mach3 and the SZGH are the two I am happy with.

Time investment, it would be wrong to say anything is overall better i cant get behind preachers, which is why your post hold a high regard

 

[Hood]

Just to add to the above, you also have to take into account power as well as torque, you can have all the torque in the world but if you don't have enough power you are going to be disappointed. Thankfully with servos I would say, in the main, that if you have enough torque you will likely have enough power but always go with the continuous ratings over the peak when you are spec'ing things.