Messages

1911

General Mach Discussion / Re: New guy frustration LOL

« on: November 26, 2019, 06:41:42 PM »

Hi,

I do not drill into the vacuum plate, that would be real dumb and after a few holes you would lose the vacuum anyway.

Yes, that is the point. Thus in order to do a PCB you have to remove it from the vacuum chuck after being isolation routed then
set it up on a spoil board with EXACT registration before you can drill the through holes. Considerable messing around.

I use 1/2 polycarbonate because I was given a whole bunch, as a spoil board. I anticipate that when I drill through holes the
underlying spoil board will get drilled a wee bit as well. Also when I run around the periphery of the board will an endmill to
cut/machine to final size likewise a groove will be machined into the spoil board. Because the blank is double sided taped to the
spoil board it does not shift and so I do not have to do ANY mid-process alignment/registration.

If I have to flip the board (two sided) I use registration pins, actually short lengths of 1.6mm welding wire, into holes drilled
while the board in in the upright position. Too easy!!!

Craig

1912

General Mach Discussion / Re: New guy frustration LOL

« on: November 26, 2019, 05:34:52 PM »

Hi,
my mill is flat to within 4um over its XY surface but the problem is the PCB blank material is not perfectly flat,
even with good name brand board you can expect up to 10um over 100mm deviation from flat.

A good vacuum chuck should 'pull' a PCB blank flat to within the flatness of the chuck.

I find that Autoleveller allows Z axis placement within 6um over the entire PCB blank despite the blank
having as much as 0.1mm warp/bow. Thus when I isolation route boards I command a Z axis depth of 0.05mm (50um)
( using 1oz or 35um copper PCB) and that results in perfect isolation WITHOUT undue cutting of the underlying fibreglass.

I have used vacuum but disliked the fact that if drilling through holes in your PCB then you lose vacuum. You can of course
drill holes last and retain the PCB with tape, after all the hole drilling is not especially sensitive to placement in Z but of course
is critical in XY. Additionally I found that having to make a different vacuum chuck for different sized boards tedious.

I use double sided tape to hold the board down onto a sacrificial polycarbonate carrier that fits into my mill vice. The polycarbonate
gets replaced every 50 boards or so. The double sided tape does a good job of holding the blank, it does not 'pull' it flat with anything
like the surety of vacuum, but still not bad. Then its probed using AutolevellerAE. For an 80x100mm the probing takes about four minutes.
Thereafter the isolation routing takes place in an identical fashion be it vacuum chuck or doublesided tape/Autoleveller.

All-in-all I find the doublsided tape/Autoleveller combination to be effective and fast, especially as almost ALL my boards are one offs,
without the overhead of the vacuum plant and vacuum tooling.

Craig

1913

General Mach Discussion / Re: How to correct losing steps?

« on: November 24, 2019, 06:37:11 PM »

Hi,
a Google search on that part number suggests the stepper has 5mH inductance, by no means the worst out there, but
by no means the best either. In a  23/24 size motor you should be looking for 1mH or less if you can but certainly less than 2mH.

Craig

1914

General Mach Discussion / Re: How to correct losing steps?

« on: November 24, 2019, 06:33:31 PM »

Hi,
I did read that and still believe the stepper is not up to it.

May I suggest as an experiment that you swap the drive from X to Y and see if the problem changes axis as well, ie a drive fault, or alternately
the fault stays on the original axis ie a stepper fault.

Craig

1915

General Mach Discussion / Re: How to correct losing steps?

« on: November 24, 2019, 06:27:54 PM »

Hi,

I have a few ideas but i cannot test these without spending more money.
try another PC.
try a UPS.

The testing you have done suggests that its not the PC or UPS, nor is it likely to be Mach......how many people use it successfully......and yet
its faulty just for you alone? I suspect the the stepper motor is too small for the task being asked of it.

My recommendation is up-rate the stepper/steppers on that axis.

You are looking for a stepper with more torque but equally important low inductance. What is the make and model of steppers you
have currently?

Craig

1916

Mach4 General Discussion / Re: Mach4 touch module malfunctioning. Mach4, or ESS, or PMDX126 causing?

« on: November 22, 2019, 10:08:06 PM »

Hi,
looking at the photo suggests to me that there are only four wires (terminations) in use. One in and one out
for each of the two coils. Note that the iron core has two windows thus the flux from one winding will propagate through
the other two limbs, only one of which will have a coil on it. Any flux passing through that (occupied) limb will generate a voltage
in a manner identical to a transformer. As soon as any load is placed on that coil however the flux will preferentially flow though the
center limb WITHOUT a coil, ie the flux takes the path of least resistance.

What it amounts to is that you can consider the two coils to be independent of each other. Having said that there will be one
where the flux due to the current in one coil will cancel the flux from the other coil, and the net result is that it
equivalent to having NO reactor at all.

All that would be required is to reverse the current in one winding  and then the full advantage of the reactor will be obtained.

Can you post a pic of the connection diagram on the top of the reactor?

I have attached a diagram of a single 230VAC supply passing through the two coils of the reactor in series.
The other diagram is two 120VAC phases feeding the 230V VFD each passing through one coil of the reactor.
Electrically they are identical, you don't need two coils for 120V dual phase operation but you can if you wish.
As I said you can hook up a coil backwards, all that happens is that they cancel each other out....no smoke or any
other histrionics. If you realize that no change has happened just reverse the terminations on one winding and your in
business.

Craig

1917

Mach4 General Discussion / Re: Mach4 touch module malfunctioning. Mach4, or ESS, or PMDX126 causing?

« on: November 22, 2019, 06:15:48 PM »

Hi,

Is it possible to use a 3 phase reactor on single phase lines?

Yes you can, just use one coil of the three.

Is it safe to assume a line reactor would install between my line filter and the VFD vs. between the incoming line and the filter?

The reactor goes on the line side (input supply) of the VFD. It may well be that you don't need a line filter if you use a reactor.
UNDER NO CIRCUMSTANCES do you put a filter/reactor or whatever on the output side of the VFD, that is the three phase
line between the VFD and motor UNLESS IT IS SPECIFICALLY PROVIDED FOR BY THE VFD MANUFACTURER.

The single phase reactors I found Ebay appear to have two wires, one for incoming and one out.  So, here in the US, they would only work with 120v.  To work with 240v, a reactor would need connections for 2 in and 2 out.

No, that is incorrect. Remember this is just a series inductance. It has an insulation rating between the coil and the iron core
but it does not have a voltage rating per se. Any well made reactor will work with a 230V input. Remember also that the
switched discontinuous current demanded by a VFD will cause large voltage excursions within the reactor and that any reactor
must withstand several times the input voltage.

May I suggest that any two wire reactor will work. Test the insulation resistance to the iron core with a Megger set to 1000V,
if it can't handle 1000V don't use it.

Craig

1918

Mach4 General Discussion / Re: Servo Spindle Question

« on: November 22, 2019, 03:39:31 PM »

Hi,

I will make sure to include a command to set the motor to OB1 every time Mach loads. I think this would get me around the issue?

Yes, that is exactly the sort of precaution that you need to adopt.

I wish I had your depth of knowledge on Mach 4. I am working hard to get there, but there is a lot to learn.

I assure that my apparent 'depth of knowledge' is not nearly as deep as it might appear.

I have observed the progression of your posts over the year, or so, time that you have been using Mach4 and your knowledge has
increased vastly and in certain areas far exceeds my own.

In this particular case I have some experience of my own but the foundation of what I know about programmatically changing
motor/axis assignments came from a thread where I was trying to help some other bloke do something not dissimilar. The thread
is over a year old, I'll try to find it. Smurph weighed in at one stage of it....and he clears up misunderstandings quicker than my
mother used to tidy my room! (with a continual diatribe re my personal habits!!)

Craig

1919

Mach4 General Discussion / Re: Servo Spindle Question

« on: November 22, 2019, 03:21:01 PM »

Hi,

Do I need to do a profile save or anything silly to get the changes to apply after I call that mc.mcAxisMapMotor()?

Yes, if you want the change to stick.

I imagine that in most circumstances that you will run in free running mode ie OB1 and only occasionally run in C axis mode.
Thus you are likely to switch mode during a session, rigid tap those holes, and then switch back to free running mode.
Thus there is no need to flush the change to the profile.

The only fly-in-the-ointment is if you change mode to C axis mode and then finish your session or Mach crashes and effectively
ends your session, Mach will detect the mode change and flush that change to the profile when it executes the screen un-load script.
This may well have destructive consequences when you next fire up Mach without realizing that the C axis mode was 'left over'
from last time.

Craig

1920

Mach4 General Discussion / Re: Mach4 touch module malfunctioning. Mach4, or ESS, or PMDX126 causing?

« on: November 22, 2019, 03:11:37 PM »

Hi Gary,
electrics and electronics is my thing.

Yes a 250V 30A line filter will certainly work at 120V. It may well not be optimized for use at 120V but it will work.

Line filters are a combination of inductors and capacitors. Generally large inductors are expensive requiring many turns of
large diameter wire on a magnetic core. Manufacturers try to minimize the size of the inductance while providing a certain
level of filtering to stay cost competitive.

This works pretty well but is in fact a poor substitute for line reactors.

A line reactor is just a great big coil, 5mH or more. They are particularly useful in conjunction with VFDs.

You may have noted a quoted specification on your VFD called power factor. Without line reactors its like to be in the range
of 0.5 to 0.6. Thus if your VFD is consuming 10A only about 50% to 60% is actually going to be converted into 'real work' at the
spindle motor. Because of the switching nature of the VFD and the simple and fairly crude input circuit and filtering they are
renowned for poor power factor and 'polluting' the power supply. With a good line reactor the power factor could be 0.85 and
maybe as high as 0.95, a huge improvement, and a tenfold reduction in 'pollution' products.

A line filter will help reduce the electrical noise of a VFD to your PC for instance but it wont do squat for your power factor nor
much for an already 'polluted' power supply.

For the same money as a new line filter you could buy a second hand single phase line reactor of 5mH or so. That would be my
recommendation.

In New Zealand, especially rural New Zealand, many farmers are using 100kW level down-hole pumps (VFD controlled) for
irrigation. The power supply has become so badly polluted that in many rural areas running a PC or stereo is risky.
The power supply companies have been insisting that farmers follow the rules and fit line reactors or their electronic
equivalent. The farmers are screaming blue murder (when don't they??) about the expense, these devices approach the price
of the VFD, tens of thousands.

Craig