Success! Mini Machining Center under Mach3 control - Video link

[simpson36]

I am getting multiple inquiries on programming for the 4th axis and as much as I would like to I cannot always respond individually. I do try to respond to notices from this forum, so posting questions here is the best route.  Here are the answers to the most FAQ:

Everything you see in the videos is using strictly the Mach mill program, never the turning program. There is only one setup and one profile. I wrote a simple macro to implement the MACH 'swapaxis' function to run the 4th axis as a spindle. (thanks goes to Hood for this tip). I recently learned to also turn on the mill spindle while the 4th axis was still in 'spindle' mode. You see that with the grinding video.

I also wrote macros to calculate and perform threading. I participated a bit in discussing theory on the threading topic but in practice I do not use the Mach threading, so unfortunately I can't help with that.

Primarily I design assemblies in AutoCAD and then isolate the parts, move them to 0,0 and dxfout the geometry of each part in this way. Then using LazyCAM to pick up the dxf and generate the basic Gcode. I then usually find it convenient to make resulting 'programs' into subroutines and set up variables and write a small 'control header' to call the subroutines in order, and that is pretty much the technique.

Turning profiles are sometimes generated for MachTurn and then run on the mill by swapping the axis around with a G-code command for that part of the program, again usually called as a sub. Sometimes it is easier to lift a turning profile directly off the design in AutoCAD and then simply generate code from that profile for the Z axis.

[Fastest1]

Thanks for the details! Cant wait to try some of that.

[Peter Homann]

Hi Mike,

After reading your excellent trade study on servo drives, I've just ordered a Dugong Servo drive that I plan to use to drive my Lathe spindle which is a 400W 90Vdc motor.I've just had a thought. Do you know if the Dugong drive capable of being continuously run in 1 direction? Some servo drives fault after running too far in one direction.

Cheers,

Peter.

[simpson36]

Hi Mike,

After reading your excellent trade study on servo drives, I've just ordered a Dugong Servo drive that I plan to use to drive my Lathe spindle which is a 400W 90Vdc motor.I've just had a thought. Do you know if the Dugong drive capable of being continuously run in 1 direction? Some servo drives fault after running too far in one direction.
Cheers,
Peter.

Peter, I suspect you are addressing that question to me, so I should tell you my first name is Steve.

There must be some upper limit of encoder counts that the drive can handle, but I have not found it yet. Good question . .  I'll get an answer to this and post it.

EDIT: The answer is no, the register is 32 bits wide and rolls over when full so the drive will never fault from running on one direction too long.

One reason I liked the Dugong for a spindle drive is the built in braking resistor. A heavy chuck and workpiece can generate a lot of back current and the Dugong dumps it overboard instead of burning out the the drive. Using a servo motor on the spindle eliminates all of the threading problems and also opens the door for some interesting possibilities with cutting tools and grinding wheels attached to the cross slide, yes?

Incidentally, I have one of your excellent PWM speed controllers, which finally solved my speed control problems. Unfortunately, I can't use it with my 4th axis because of the swap axis function . . .  .

[Peter Homann]

Hi Steve,

Not sure where the Mike came from. Sorry. I checked with CNCDrive, they confirmed that there should be no issue. There shouldn't  be as a step/dir interface is a reletive one, as opposed to an absolute one.

With step/ Dir, it is move this increment from where I am.

I have one of the small servo drives from ImService. They fault after a short while of continuous running in one direction. Poor designas I see it.

Cheers,

Peter.

[simpson36]

Hi Steve,

. . . . . a step/Dir interface is a reletive one, as opposed to an absolute one. With step/ Dir, it is move this increment from where I am.

Peter.

The drive maintains an absolute position internally. Some drives have a built in homing capability, which one might assume would complicate a 'roll over' of the position register, but I have no experience with those drives, so I don't know how they address that issue.

I find that there is no standard criteria in designing servo drives (speaking only of those that I tested). One manuf may consider an internal homing ability more important than continuous running, if in fact that is the trade off, while another may decide the opposite. Leadshine, as an example, thinks in terms of OEM only and concludes therefor that the ability to reset a faulted drive is not an important issue, because (in their view) once the specific 'single purpose' of a machine is set up properly, there should be no faulting. This unfortunate thinking leaves the Leadshine drives usesless for a 'general purpose' machine tool, in my opinion, even though they are otherwise very good drives.

These are the kinds of differences that make evaluating and selecting a drive much more complicated than is generally thought. Your 'continuous running' question is a very good and valid one that did not surface during my review unfortunately, so I did not investigate that ability in each drive. It is a caveat for sure.

[spunk]

Homing sensor moved to back and oriented down to keep out as much swarf as possible.



I have my new Rutex servo drive and so far it is doing everything it claims to do, so I should get full speed and power from the motor. When I get it all back on the mill, I will make one final video and post the link. Questions, comments , criticisms or suggestions welcome.

may i ask what typ of homing/index sensor that is?

Cheers

Spunk

[Dan13]

Hi Spunk,

Looks like an optical sensor. A photo LED is used on one side and a photo transistor on the other side.

Daniel

[spunk]

and perhaps also the answer to how do you wire it into mach3? you'll need to power the LED thats the easy part...

how to get the transistor into mach?

Spunk

[Hood]

The output of the opto just goes to a pin on your interface (Parallel Port, SmoothStepper or whatever) and then you set that pin up as the Index in Ports and [ins Inputs. Simpson also is using it as a homing switch so he will also have that pins set up as the A axis home switch, again in Ports and Pins.

Hood