Messages

5611

Mach4 General Discussion / Re: controlling JP-3163B in 6040T USB CNC with Mach4

« on: December 27, 2017, 06:22:25 PM »

Hi All,
sorry should pay more attention, that's Rob's box of goodies not OPs.

Looks good Rob.

Craig

5612

Mach4 General Discussion / Re: controlling JP-3163B in 6040T USB CNC with Mach4

« on: December 27, 2017, 06:19:42 PM »

Hi,
for that budget you'll get a good external motion controller Mach4 ready but not much more.

Nice pic of the box but the boards in it are different from the pic in your earlier post?

Hard to make out whats what...

Craig

5613

Mach4 General Discussion / Re: controlling JP-3163B in 6040T USB CNC with Mach4

« on: December 27, 2017, 02:42:53 PM »

Hi,
that controller board has three stepper drivers on it. If you remove the controller you in effect remove the stepper drivers as well.

The six white ICs on the board look like optocouplers to the driver ICs so it might be possible to 'insert' signals from another controller and have the drivers respond to it and
leave the existing board in place but the controller section of it would be idle.

While you could do that unless you have fair electronic skills it likely to be  a battle. I note that you said the power supply is 24V. That is a low voltage for steppers
and they will be pretty slow. The golden rule is that with steppers the higher the DC input voltage the faster you can spin them without stalling or missing steps.
Given the comparatively low voltage which could be a reflection of the voltage limits of the driver ICs then the effort to modify what you have just to use three
underperforming stepper drives becomes even less attractive.

It is highly likely that you will replace the stepper drives at some point. Those driver IC's are pretty tender. If one blows you have to desolder it and replace it.
If you cant desolder without damage to the board or you can't find/buy a new IC then you throw the whole board away. Even if the ICs didn't fail you will be
disappointed at the axis speeds you can achieve with only 24V.

The real option is to replace the controller with a Mach4 ready board, fit a breakout board should your selected controller require it, and replace those stepper drivers
ideally with a matching high (50-70V) voltage supply.

Clearly if you are buying quality parts the you may expect to spend $500-$1000. Is this within your budget? The fact that you have bought Mach4 means that you are committed
to getting a Mach4 controller, the simplest and cheapest from known manufacturers are $120. Such simple devices have 'one ports worth' of IO. They are adequate for
a simple router but lack the IO for any real expansion. The PMDX-424 has two ports, the ESS has three ports, the UC300 has five ports and the 57CNC has the equivalent
of three and bit ports. Any of these devices will work, all have reputable backup.

As for stepper drivers Gecko has a well deserved reputation for quality and reliability. The G540 is a breakout board and 4 axis driver combined. It is 50V capable,
good but not earth shattering. Many people use it with satisfaction, they are $300. You could also buy individual  Gecko drives which are rated to 70-80V but
they will cost something like $150 each

A number of experienced CNCers on the forum recommend Leadshine AM882 drivers, capable to 80V and up to 8A. They can be had for about $80 each, good value.

Craig

5614

Mach4 General Discussion / Re: First cuts

« on: December 27, 2017, 02:47:59 AM »

Hi,
you don't really need to buy much, you can make a probe and Mach4 has some good probing scripts.

To touch off jog your tool down slowly until it pinches a piece of paper between the tip of the tool and the surface of the workpiece. If the paper is thin
just <zero> the Z axis and your ready to go. If instead of a piece of paper you used a 6mm shim, as before drive down until the tool drags on the shim
and <zero> the Z axis but with the gage block height set to 6mm, look on Machs Offsets tab.

You can set up a probe, it requires the tool, which is earthed to the frame of machine 'pull down' a isolated resistively supplied metallic target atop your material.
The target is hooked to a dedicated Probe input on your controller. Thereafter you use a G31 command and the machine will drive down until the tool contacts the target
and then Mach will stop and allow you to zero axes with or without gage block heights.

There are a number of scripts that automate this process, but it still worth experimenting with a simple probe and G31 MDI commands.

Craig

5615

Mach4 General Discussion / Re: First cuts

« on: December 27, 2017, 02:28:42 AM »

Hi Rob,
good to hear that you are getting some results.

The simplest way to put a delay into a Gcode program is a G04 statement just after the spindle turn on command. I don't use Fusion and don't know exactly what
is in the post processor that you have but it is common to be able to set the post to insert a G04 line.

Another possibility is to use Machs built in facility. This would require that Mach has some way of measuring the actual spindle speed ie an index pulse.

Craig

5616

General Mach Discussion / Re: Home Offset

« on: December 26, 2017, 10:16:22 PM »

Hi,
did you ever get this sorted?

I'm interested in how you got on.

My guess is that as the home switch activates Mach backs off until the switch returns to in-active, from your description you have index homing in action, the servo
drives until the index signal is active and sets the machine coordinate to 1) zero, if no home offset is active or 2) home offset for that axis when active.

If for whatever reason the position accumulator in your servo drive was at 34567 say at the instant that the machine coordinate was reset. If however Mach sets
the machine coordinate to your home offset, say 20mm, with steps per of 500 say, then the position accumulator would suddenly be presented with a position
change of 20 x 500 =1000, ie the accumulator would jump to 34567 + 1000 =35567. That would constitute an instaneous jump of 1000 counts. If your following
error is set less than that, almost certain, then it would attempt to accelerate to the new position but fault 'following error' almost immediately.

What intrigues me is that my understanding of home offset is that it sets the machine coordinates to the required offset but does not issue a command to go to
that location. Therefore I would not expect the position accumulator to experience the suuden jump in position. Whats going on?

One experiment I would like to suggest is to temporarily mount one home switch somewhere in the middle of travel of one axis. Disable the index homing for that axis
and try it again. If my understanding is correct index homing is enacted by the motion controller not Mach. I do not use index homing nor even home offsets but such
experimenting I have done with home offsets suggests that Mach is performing as I expected. This experiment would allow you to rule the motion controller
in or out.

I think also that if the Machine Diagnostics page were open when you homed that axis you might see the machine coordinate entry change which may in turn give you some
insight as to whats going on.

Craig

5617

Mach4 General Discussion / Re: Spindle Controls

« on: December 26, 2017, 07:02:28 PM »

http://www.machsupport.com/forum/index.php/topic,35748.0.html

Craig

5618

Mach4 General Discussion / Re: Spindle Controls

« on: December 26, 2017, 06:59:49 PM »

Hi,
once NFS made an internal function called SpeedRateOveride its logical to connect the slider to that function.

Of course we can write our own function if the stock one doesn't appeal.

Craig

5619

Mach4 General Discussion / Re: Spindle Controls

« on: December 26, 2017, 06:52:17 PM »

Hi,
so you want the side control to be a speed setting rather than a percentage of commanded?

You could do that but you would have to code it. If you have a look in the edit screen page of the SRO slider you will find it doesn't have a script exactly but an in-built Mach
function called SpeedRateOveride.

If you wish to use that slider you'll have to break that connection and write your own script. Is that what you had in mind?

Craig

5620

Mach4 General Discussion / Re: Mach4 Spindle At Speed, Spindle Zero Problem

« on: December 26, 2017, 06:40:21 PM »

Hi Hakan,
that can't be correct....if it had zero torque at zero speed when you turned it on it would never start to rotate.

Its certainly true that induction motors have poor and poorly controlled torque at start up and over the years vast sums have been spent
to improve that basic limitation.

Induction motors are great and with VFDs remarkably speed flexible. If you want position control they suck.

Craig