[jevs]

I am looking for some advice on the best breakout board and motion controller for what I want to do. I am not sure the DMM BOB is up to the task. If it is, then that would be great, but I think it has some limitations on the 4th axis (charge pump has to be off or something), and it has no indicator LED's which come in handy. Its also a bit spendy when I look at what you can get for $20 on eBay.

Here are the plans for a CNC router I am going to build:

New Windows 7 or 8 PC
Ethernet Smoothstepper (or other, please recommend something if there is a better option? Old computers and parallel ports are not an option for me)
DMM 220 Watt AC servo on the Z
DMM 400 Watt AC servos on the X and Y
Eventually a 4th axis that will probably just be a stepper motor (one of those Chinese setups on eBay)
Maybe a 5th axis tilt plate thing (not sure if the 4th axis would be swapped out when this is in use, or it should be setup to run both without any wiring changes)
Dust collection
2.2K spindle motor
VFD for spindle motor
Water cooling system for the spindle
Pokeys or something for the "hard" controls and/or a pendant
Mach 3

I could switch to steppers for the X,Y,Z but I think I will be happier with the servos and I don't think that decision means a lot for the BOB and motion controller. Except, the DMM BOB will have the right connectors for their cables/drives.

So, I need any other recommendations for the motion control and suggestions for the breakout board to meet the above needs. I am not sure if I want to go to a USB motion controller. USB and the way computers are now is a bit out of control. I am always running into problems now that they want them to charge cell phones, increasing current capacity, don't shut down when the computer is off etc. I think I want to stick to Ethernet, although I am not closed to other good proven options.

[mactec54]

jevs

There breakout board is designed to be plug & play with there system, it has a power filter, that is needed for the servo drives & is opto isolated which you want to protect your computer

Some are using the PMDX breakout boards with the Dmm system, but it is not a plug & play setup, I would not worry about the lights, they are not needed

You won't find a suitable $20 breakout board on Ebay for anything other than for stepper use

[jevs]

The right connectors for the drives are nice.

Most decent BOB's are isolated with opto-couplers.

The power filter appears to just be a couple capacitors that the power runs through (from what I can tell in the picture). I am concerned with sending all the power for the all the drives through those traces, but I am not sure how much the current draw will be.

I actually prefer to have each drive separately fused and use rail mounted fuse holders.

I agree the LED's are not needed, but they do come in handy for troubleshooting quickly. I have referenced them on my mill for troubleshooting before (more complex and more things running off the BOB). Sure I can grab a meter or a scope, but seeing a 5 cent LED might save me time.

I believe they are just step and direction, so I am not sure what makes it special for the servo drives that the others will only work for steppers? You will have to explain that because I have just begun to research the different BOB options.

It just seems like a basic $20-40 BOB other than a couple caps for the power supplies (which I would almost rather filter off the BOB). That is why I mentioned the low price options out there. If you have some more technical specs that actually makes it better, I would like to know because that would certainly sway my decision. I actually think what I am going to need is going to end up more expensive than the DMM, but I don't know yet

If you can provide some more technical advantages to the DMM board that makes it better for their drives that would be great other than the obvious plug and play drive connections.

I would be much happier to single source it with DMM as a "plug and play" package, but my concern is that the BOB will actually do everything I need.

The manual says:
NOTE ****:
If the Charge pump is engaged, A axis step is not available, but
A axis Direction could be used as another output, max V < 5.5

So, is this actually a fully functional axis that I can use with a 4th motor running along with the others (likely a stepper)?

Also, I think I might actually need a 5 axis if you take a look at my original post I may want to add a tilt table also. I am not sure if swapping back and forth between the tilt table and the "lathe" 4th axis is better, or just have them both setup as 4th and 5th axis (even though both won't likely be used at once).

As you can see I have lots of concerns and questions.

I do have a touch probe as well that I might want to use on the router....who knows.

I just want to buy one BOB that is right for the job the first time. If the DMM will do the job, then I would certainly get that one to save on connector hassles and time and single source support.

[mactec54]

jevs

If you are using the power supplies they offer, the on board filter is fused already (20A), will run up to 20amps @ 1000W way more than what you will need with the small motors you are looking at, the power supplies they offer, also have a fuse, so no extra fuse's needed

The drives are fully protected also, ( apart from wiring them incorrectly )

You have 2 X axes plugs, if you are not using 2 motors for an X axes, you can use one of those as a extra axes, this give you a full 5axes board, it also has PWM spindle control built in, plus(2) other relays & other inputs/outputs

You can assign the charge pump to another pin that is not being used, this then gives you a normal 4th axes output

It just depends what you want to do, but you will most likely end up paying more, to get the same in the end, as I said in the first post some have used the PMDX boads, that is the only other board I would recommend

[jevs]

"You have 2 X axes plugs, if you are not using 2 motors for an X axes, you can use one of those as a extra axes, this give you a full 5axes board,......."

Are you sure about this? If the schematic is correct in the manual, I don't see how this is possible. Pins 1(1A) and 3(2A) of the U5 Schmitt trigger chip are shown as being shorted together, which means you would have to cut a trace, add a jumper wire to a parallel port pin to separate the inputs so that the outputs could be independent. The circuits for the direction are also shorted together (although in not such a direct manor). So, unless the circuit has jumpers or dip switches or other means not shown in the manual or in the schematic, this does not seem possible?

This would be great if it is true though. I would think they would need to add a second input parallel port to make it feasible really though.... I guess I need to ask DMM in case the manual is just out of date or something?

I could make mods to it and get it to work even as shown I suppose..... I could cut some traces and jump over from the second smoothstepper parallel port.....I would just rather not have to mod the board.

[mactec54]

jevs

I had always thought that the (JMP1) jumper on the board, was to choose how to use that axes, I may be wrong on that as I have never used that axes that way

[ger21]

The CSMIO motion controllers are highly recommended by those that have used them. They would be my choice.
Not cheap, though. CS-Lab - CSMIO - CNC Ethernet Controllers- inexpensive solutions - CS-Lab CNC controllers CNC Machining CNC software

[mactec54]

jevs

I just checked about the X axes, you are correct, it can not be switch with just the Jumper, the Jumper only reverses the slaved motor if it is needed

[jevs]

Does anyone know how they hook up two power supplies to the DMM breakout board? Are they just hooking the outputs together into the breakout board?

I was thinking that an option might be to use the DMM breakout board and then just add a second board.

The second board could hook to the other parallel port from the smoothstepper to control more axis? I could just leave room in the cabinet for a couple more drives and another breakout board. Then I could add them in later when more axis are desired.


I did also check out the CSMIO stuff, but the only one with Backlash compensation ability would be about $800. Too much for me to spend. I think I would choose a smoothstepper and a separate breakout board for my application (much cheaper).

[mactec54]

jevs

I do them like this photo, you can use other types of terminal blocks

[jevs]

So it appears you do parallel them all together.
I suppose you then funnel them all through the DMM breakout board?

I have been looking at a lot of breakout boards today and what they can/can't do etc.

I think my best option is going to be going with the DMM board and then adding another BOB when I want more axis. The C32 BOB might be able to do everything, but I am unclear on the ERR/RES lines if they can take the alarm signal from the DMM drivers....etc.

I will just have to leave room for more stuff later.

[matth]

I just purchased a 4 axis 400w kit from DMM without the BOB. I already have one installed and like you I didn't like the fact that A axis and charge pump seem to be mixed up.
I will be using a couple of 10,000uF 100v Caps on my PSU's and again I didn't like all that current running through the BOB. I believe that the caps are not really for smoothing but rather for soaking up back EMF from the drive which is why they are rated at 100v.
I will be posting some pics of the electrical build within the next couple of weeks.

From a capability standpoint the drives are just like stepper drivers with Step, Direction and enable but also have an alarm/fault output for feedback. They don't give you an encoder output to close the loop back to your controller. In this fashion they seem to be just like the closed loop stepper systems. Because of this they don't require anything special from the BOB and any board that takes your fancy will do.

[mactec54]

matth

You just change the charge pump pin number, or don't use it, & you have the A Axes, to do what ever you want with it, lots are using the 4th axes with no problems

The Drives are nothing like a stepper drive, good luck with trying to run an AC servo on a stepper drive

The communication is by any of these methods, Pulse/Direction or CW/CCW, and Analog communication modes

The Dyna 3 Drives do have Encoder feed back to close the loop in the control, the Dyna 2 drives were made to keep the cost low

[mactec54]

jevs

This will give you some ideas as well, as how you can install the Drives, Breakout Board & wiring

[jevs]

I just purchased a 4 axis 400w kit from DMM without the BOB. I already have one installed and like you I didn't like the fact that A axis and charge pump seem to be mixed up.
I will be using a couple of 10,000uF 100v Caps on my PSU's and again I didn't like all that current running through the BOB. I believe that the caps are not really for smoothing but rather for soaking up back EMF from the drive which is why they are rated at 100v.
I will be posting some pics of the electrical build within the next couple of weeks.

From a capability standpoint the drives are just like stepper drivers with Step, Direction and enable but also have an alarm/fault output for feedback. They don't give you an encoder output to close the loop back to your controller. In this fashion they seem to be just like the closed loop stepper systems. Because of this they don't require anything special from the BOB and any board that takes your fancy will do.

How will you utilize the alarm lines? This is one thing I was not sure of with using a different BOB.

I would want to use the charge pump, so I assume that makes the 4th axis useless to me. I will have to add another BOB to do anything else.

[matth]

matth

You just change the charge pump pin number, or don't use it, & you have the A Axes, to do what ever you want with it, lots are using the 4th axes with no problems

The Drives are nothing like a stepper drive, good luck with trying to run an AC servo on a stepper drive

The communication is by any of these methods, Pulse/Direction or CW/CCW, and Analog communication modes

The Dyna 3 Drives do have Encoder feed back to close the loop in the control, the Dyna 2 drives were made to keep the cost low

A stepper drive takes Step, Direction pulses and generally has a enable input. In this way the DMM Dyn2 drives are exactly the same. I never said you could use a stepper drive instead and I am certainly not trying to do that. I am just using a different BOB which talks to the Dyn2 drives just like it would with stepper drives!

[matth]

How will you utilize the alarm lines? This is one thing I was not sure of with using a different BOB.

I would want to use the charge pump, so I assume that makes the 4th axis useless to me. I will have to add another BOB to do anything else.

If you want a 4th axis and a charge pump you can not do this with the DMM BOB which is why I am using my existing board. With the alarm outputs, I will just tie them together back to an input pin on my BOB and set them up in Mach3 as a limit/estop/whatever is suitable.

[ger21]

Here's a nice device for connecting multiple power supplies together.

Power Supplies | Protoplant

[jevs]

If you want a 4th axis and a charge pump you can not do this with the DMM BOB which is why I am using my existing board. With the alarm outputs, I will just tie them together back to an input pin on my BOB and set them up in Mach3 as a limit/estop/whatever is suitable.

I could see that working, but I think you will need to isolate the line's with a diode like they do on the DMM BOB? This way one alarm can't feedback into a different drive when it goes high?

It appears they are using the alarm lines to turn on a FET that basically pulls the e - stop to ground. If you did it like this, you wouldn't even need another input, however it might be easier (avoid using the FET).

[jevs]

Here's a nice device for connecting multiple power supplies together.

Power Supplies | Protoplant

Those appear to be for hooking supplies in series. DMM hooks theirs in parallel. Those would be a good way to get more voltage though.