Messages

3831

General Mach Discussion / Re: CS Labs CSMIO/P-A

« on: August 16, 2018, 02:47:05 PM »

Hi,
remember one of those two figures of merit, one in particular Ka, the torque constant. Your 200V servos are likely to have a Ka
of about 1 Nm/A whereas your DC servos might, on a good day, have a Ka of 0.5 Nm/A.

So for the same current the new AC servo will produce twice the torque.

Craig

3832

General Mach Discussion / Re: What kind of bit/end mill should I be using?

« on: August 15, 2018, 08:10:26 PM »

Hi,
on a conventional lathe or a mill with ordinary hand wheels if you wind the wheel clockwise the axis
will move to the right, say. If you now wind the wheel counter-clockwise there will be a small zone
where the axis does not move until the 'backlash' is taken up and then starts to move to the left.
If you like backlash is the slack in the thread of the leadscrew. Just about all conventional machines
have it, more as they wear.

Modern CNC machines with preloaded ballscrews can be called zero-backlash, although an engineer might question
your definition, and as such have no measurable slack between the axis moving right  or left. Such machines
often use 'climb milling' toolpaths.

Craig

3833

General Mach Discussion / Re: What kind of bit/end mill should I be using?

« on: August 15, 2018, 06:19:29 PM »

Hi,
the tool rotates in one direction, the vast majority are Right Hand.

As to the direction around the perimeter that you traverse the cut is the difference between 'conventional
milling' and 'climb milling'. With older mills which have backlash you must use conventional milling only whereas
CNC mills with no backlash can use either. For various reasons climb milling is preferred IF your mill has the rigidity
and ZERO backlash.

Most CAM programs allow you to chose either conventional or climb milling toolpaths.

There is plenty on the net about climb/conventional milling.

Craig

3834

General Mach Discussion / Re: Mach3 2-sided pcb milling. Centering with Y-axis width from G-code pattern.

« on: August 15, 2018, 03:45:16 AM »

Hi,
that is unusual. The only thing I can think of that would displace the hole is if Mach were displacing it by making an allowance for the diameter
of the tool.

The example board I posted is 100 x 80 mm. The outline is shown with a zero width line. The board mill path places the tooplath
outside of the line so that the finished dimension is 100 x 80 mm. I use a 1.5mm two flute endmill to mill the outline. The toolpath allows
for my standard etch tool of 0.5mm. Consequently my board will end up about 1mm undersize because I'm using the larger diameter tool
while the Gcode had made allowance for the smaller diameter tool.

When I drill the registration holes I use MDI and therefore can be absolutely assured that Mach has not made an allowance for the diameter of the drill,
if such allowance is required I do it. I do not offset the holes, I MDI to centres. For instance if I have just zeroed the X any Y axes at the lower left corner
and I MDI G0 Y-5 to drill the first registration hole its center is 0,-5   If I then MDI G0 X100 for the second registration hole its center is 100,-5 Thus the centers
are perfectly aligned.

I agree that the spindle would have to be badly off vertical for the displacement you describe. I think it unlikely.

May I suggest some experimentation. Either with some spare PCB blank or other suitably thin and stable plastic sheet or cardboard drill four holes in a rectangular
pattern with the drill going into the baseboard so you can try flipping it and see whether the holes line up. Its not inconceivable that the X and Y axes are not
90 degrees to each other. That will cause a nominally rectangular drill pattern to come out as a parallelogram. If you flip a parallelogram the holes won't line up.
Should say the X to Y axis be 89.5 degrees rather than 90 degrees the displacement of a hole would be 0.9mm over a 100mm rectangle. If you flipped it the
misalignment would be double at 1.8mm, and this occurs with a half a degree of error between the axes. In short the alignment between the upper and lower
traces of a PCB are very sensitive to the assumed 'squareness' of the axes.

Craig

3835

General Mach Discussion / Re: Mach3 with Win7 Laptop USB Controller.

« on: August 15, 2018, 03:04:01 AM »

Hi,
you have bought a USB connected external motion controller of dubious origin with no manufacturer support.
The issues you are having are not Mach3 issues and unless you are fortunate enough to find someone on the forum who
has extensive experience with that particular board then you will get exactly what you paid for.....not much.

Should you consider replacing what you have or want another unit then carefully consider products by Warp9 Tech Design, CNCDrive
and PoKeys. All three enjoy industry leading reputation for support.

Craig

3836

General Mach Discussion / Re: RefAllHome issues

« on: August 13, 2018, 09:05:49 PM »

Hi,
the direction ans speed that an axis attains during homing is set on Config/Homing and Limits page.
The speed is a percentage of G0 speed, commonly 20%

craig

3837

Mach4 General Discussion / Re: PCID

« on: August 13, 2018, 09:01:44 PM »

Hi,
did you reload the OS? That will change the PCID.

Craig

3838

General Mach Discussion / Re: Mach3 2-sided pcb milling. Centering with Y-axis width from G-code pattern.

« on: August 13, 2018, 06:26:00 PM »

Hi,
you need to outline your board in layer 46, the milling layer. That will give you a Gcode file for outline
milling.

I used to follow the same idea, that is to say the mid-line approach, but I gave it away with the simple
expedient of re-locating the 0,0 point the width of the board when flipping it, so much simpler.

Craig

3839

Mach4 General Discussion / Re: Tool Path Window Blank

« on: August 13, 2018, 05:58:02 AM »

Hi,
I'm still no closer to the answer but:

More info that may help is if I change the Bg Colour in Screen Edit mode, the new colour is applied whilst still in Edit Mode, but when I save the change and exit Screen Edit, the new colour is not applied!

Note that in the pic I attached the window has a background colour of silver. But when I exit Edit mode the window turns to regular blue. Thus the colour settings made
in Machs Toolpath tab overwrite the background colour. Its not that Mach has ignored a setting but in use that setting is overwritten, its not what I'd call a fault and I don't
think is going to give us a great deal of insight into your problem.

Craig

3840

General Mach Discussion / Re: Mach3 2-sided pcb milling. Centering with Y-axis width from G-code pattern.

« on: August 13, 2018, 03:42:33 AM »

Hi,
I use Eagle and PCB-GCode and have done for several years.

I follow the same general idea you do however I flip the board in the X axis not the Y. You can setup PCB-GCode to do either.

One thing I've got in the habit of doing is defining an outline with a zero width line, both in the dimension layer (20) AND the milling layer (46).
When I draw the outline I set the grid at 5mm. This means that my boards all come out in 5mm increments, this makes it easier to manipulate
so that the top and bottom layer coincide. The pic attached shows that the 0,0 point is at the lower left hand corner Note also that once you
have drawn the frame around your board you can shift the entirety of the traces by highlighting all and using MoveGroup (at a suitably fine grid)
to shift within the frame.

I have also attached a pic of a piece of circuit board blank. Note how the two registration holes (1.6mm, as I use short lengths of 1.6mm welding wire for pins)
are outside of my intended finished board. I stick the board down with double sided tape, it works so much better than any other technique with Autoleveller,
jog to my anticipated 0,0 point and zero the X and Y axes.

Then MDI G0 Y-5 to drill my 1.6mm hole and put in a pin through the board and into the baseboard
Then MDI G0 X100 and drill the second 1.6mm hole and put a pin in it.

Now you can run the top etch file.
When you go to flip it:
G0 X0 Y0 and retract Z out of the way. Flip the board on the pins.
Then G0 X100
Now <zero X> This has now effectively redefined the 0,0 point at the lower right hand corner and now the bottom etch file can be run.

The only real difference between you method and mine, aside from flipping in X rather than Y, is choosing a defined frame with a nicely rounded
number, and the corner of the frame is the 0,0 reference for the board.