Messages

2001

General Mach Discussion / Re: Constant velocity

« on: October 02, 2007, 10:51:25 AM »

is there no further interest in this from the forum?

2002

General Mach Discussion / Re: edge finding/2.5D probing

« on: October 01, 2007, 09:16:17 AM »

Thanks TP

SOme of us have written simple macros to do simple Probing.

Could you point me at a couple of examples please?

The real problem is that Mach cannot correct itself for probe tip radius compensation or probe touch/trip movement error before it recorded the data so it makes it impossible to know what the true touch position is.

Could you expand on this a little please?

Are these shortfalls restricted only to 2.5D probing? if so, why do they not affect 3D probing in the same way?

Might want to help remind him from time to time.

Hmmmmm - I may be on his back pretty soon about CV - don't want to be too heavy on the man

Ian

2003

General Mach Discussion / edge finding/2.5D probing

« on: October 01, 2007, 06:49:54 AM »

Hi - As I understand it there are no macros/wizards/plugins currently available in Mach for this - i.e. you're on your own with G31. Is this correct?

2004

General Mach Discussion / Re: A Long Sad Story

« on: September 29, 2007, 04:55:04 AM »

Hi mt.man

As far as the 2 (2.5)D is concerned, you're 99.9% there. I don't know about Illutrator - but when you export to .DXF there is often/usually a way to taylor the output, (there's DXF and then there's DXF). What you want is a .DXF exported as AutoCAD Release 12 format (which doesn't contain splines). If not and you're happy with illustrator (someone must be) then google for DXF filters. The point is you're so close. Once you've got such a .DXF, load it into LazyCAM and POST some gcode into Mach3. Job done.

3D - you say you're a handy guy - look at this - it's one of many.
http://www.artsoftcontrols.com/forum/index.php?topic=3857.0

Do not give up - you don't need to draw anything if you don't want to.

2005

General Mach Discussion / Re: Constant velocity

« on: September 28, 2007, 08:39:49 AM »

Brian

I think I've found the problem.

Just to make sure we're on the same page, when we say "Stop CV on angles > 90 degrees. The angle we're referring to as being greater than 90 degrees is the obtuse angle.

Note: We've used 90 degrees as our limit in our discussion but the following holds true for any angle we care to use.

If we refer to the direction of the obtuse angle as being from the first line to the second line then:

For clockwise angles Mach succeeds. i.e. it blends when it should and doesn't blend when it shouldn't.

BUT For anti-clockwise angles Mach fails. i.e. it doesn't blend when it should and does blend when it shouldn't.

If you run the code fragment you posted to me you'll see that it blends (when it shouldn't) but if you cut exactly the same two lines starting from the other end, Mach works fine. I've tried it with loads of examples and the above seems to hold.

The attached pic might help.

Thanks

Ian

2006

General Mach Discussion / Re: Constant velocity

« on: September 28, 2007, 03:34:38 AM »

Jim - you tell me to keep it simple. I thought that's what I was doing when I sent the two short examples to Brian. I have not undertaken this post lightly - I NEED CV to work for me. I spent several hours yesterday doing nothing else but testing the "Stop CV on angles >" and I've done all the simple stuff like you've suggested.

Let me nail my colurs to the mast here. I think that the way that "Stop CV on angles >" has been implemented in the latest version of Mach (R2.45 as of the 5th Sep) is wrong and does NOT do what Art intended.

Brian gave me a code snippet in his last post, told me to set "Stop CV on angles >" to 90, and asked me what I saw. Well, I saw rounding with CV on and a sharp point when CV was off.

So let me ask you to test it and see what you get. I'd be very interested in your results. Note that units are in mm.

2007

General Mach Discussion / Re: Constant velocity

« on: September 27, 2007, 01:02:08 PM »

Sorry Brian - strike that last answer - it's NOT what I'd expect - but I DO get rounding. I'm getting confused now!!!!

2008

General Mach Discussion / Re: Constant velocity

« on: September 27, 2007, 12:58:21 PM »

Hi Brian

I ran your code with angle set to 90°.
With CV mode on I get rounding. With CV mode off I get no rounding which is exactly what I'd expect. Why do you say I shouldn't see any rounding?

Ian

2009

General Mach Discussion / Re: Constant velocity

« on: September 27, 2007, 12:14:01 PM »

Hi Brian

Sorry - had a customer taking up my time all afternoon...
Now back to the REAL work. I'm not sure what you mean by make the file into two line moves.

Hi Brett

Thanks - I've read Arts post but I think my question with Brian at the moment is that CV may be meant to work like that, but I don't think it actually does. I'm sure Brian will correct me though if I'm wrong

Ian

2010

General Mach Discussion / Re: Constant velocity

« on: September 27, 2007, 09:49:28 AM »

Thanks Brian

I'm afraid I'm still having trouble getting things to work as I'd like - would you walk me through a couple of things please?

As I understand it there are the following settings with regard to CV tuning (ignoring things like plasma cutting etc.)

On the Config/General config dialog: two items:

 a)  CV Dist Tolerance (units)
 b)  Stop CV on angles > (degrees)

On the Settings screen: two items:

  c) CV Distance
  d) CV Feedrate

a) and c) seem to be the same thing i.e. when you change one it automatically reflects this in the other.

Concentrating for the moment just on "Stop CV on angles >". Let's set it to 90°.

Please see the attached two short gcode files. Both describe 5 pairs of lines describing different angles - approx 10°, 45°, 90° 135° and approx 170°.
 
The only difference between the two files is that cvtest1 starts at bottom left and cvtest2 starts at bottom right.

For the sake of discussion, if we now call the 90° quadrant between 12 oclock and 9 oclock quadrant 1, and the 90° quadrant between 12 oclock and 3 oclock quadrant two - we'll see that all blending for BOTH files ONLY occurs in quadrant 1. i.e. it seems that the "Stop CV on angles >" refers to the "global" 360° and takes no account of the angle at the actual line intersection. Surely this is wrong?