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Messages - WoodyCam

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31
General Mach Discussion / Re: thread problem
« on: February 13, 2009, 05:52:18 AM »
Not yet Keith, I have some homework to do to give Hood a little more info on my setup and a few experiements. Itching to get into the workshop... Day job just always seems to get in the way!

Woody.

32
General Mach Discussion / Re: thread problem
« on: February 10, 2009, 10:39:41 AM »
Hi Hood, yep, that's checked and working - doesn't work without that - its all over the place without that checked. Z axis is near perfect no matter what happens with the spindle speed when checked, so I know that is working well.

Keith, I can't add that delay specifically as I'm using G76 (unless I change the macro??), however, this already has about 1 or 2 secs delay before each cut. Also, I feel the problem starts at the point the spindle slows, not before the start of the next thread cut. Its really counter-intuitive!

I'm starting to think it may be a bug in this version, either of the macro or Mach3...

As I said, everything is fine until the spindle slows more than about 5%. 3% or 4%, no issues but when the cut is sufficiently deep to slow it 5% then the very next cut exhibits this change in X axis, totally repeatably, in the next cut, and the next and the next but with no loss in actual position and no loss in steps. So it must be being commanded under Mach3 control otherwise the X DRO would be wrong, but it is absolutely accurate.

This is with and ORAC lathe and a 1/3hp motor (2000rpm) with VFD down to about 400rpm, so there is not much torque and no closed loop control of spindle speed - that is a future project...! With that in place I think this problem would not show up.  But, it should not be moving the X axis during a cut.

Thanks for your input!

Woody.

33
General Mach Discussion / Re: thread problem
« on: February 09, 2009, 05:00:51 PM »
Hi Hood,

Thanks for looking - well, I checked carefully, and taper was set to 0, and its cuts perfectly on very light cuts but anything that slows the spindle more than 5% on a cut then on the next cut, the X-axis moves in slowly over the cut - its totally repeatable for me. I think this is coming from mach3 because when it does this strange behaviour with the X axis, it does not miss any steps at all. It comes right back on the next cut to the right place, then repeats exactly the same behaviour. I'll see if I can make a video of it.

I wonder if its linked to the index pulse timing signal, but the rpm info is perfectly smooth as far as I can see.

I'll dig out my xml and Gcode when it stops raining and I can reach the workshop!

Thanks Rich -grateful for your experiment (how did you do that!??). Yes, it only seems to do it with real cutting on the lathe under load. Its OK air-cutting too.

tubular2000 - what version did you use that worked OK for you in the end and do you think it was just the light cuts that fixed it?

Thanks, really appreciate it.

Woody.

34
General Mach Discussion / Re: thread problem
« on: February 07, 2009, 03:37:09 AM »
Hi there,

I've just had exactly this problem cutting a M14 x 2 thread. As soon as the cut reach sufficient force to slow the spindle by more than 20rpm (from 400) then the next cut would advance the X axis into the work giving a taper to the thread, and the next cut would do the same if I left it. I'd then stop it, rewind the code and run again. It would then do loads more cuts until again the depth was sufficient to slow by more than 20rpm and then the X axis would start advancing in again, making the spindle slow more...

My lathe is small so I ended up with 0.04mm deep cuts and about 40 passes! But got there in the end. However, it shouldn't really do this so I wonder where am I going wrong?

Parallel port operation
No missed steps that I've ever noticed
Mach3 R3.042.020
Single index pulse with very clean signal - never seen any glitches

No problems at all air cutting 40 passes, the macro seems fine
No problem with very very light cuts
Just X axis moving (in the DRO and in practice) in G76 threading when the cut slows the spindle more than 20rpm

So, why would the X axis move if the spindle slows >5%? Its doesn't make sense?

Also, the pitch is perfect. The Z axis copes fine with the change in speed as Hood mentioned. Just that X axis move - I don't get it.

Thanks if you can point me in the right direction, otherwise, threads take soooo many passes!

I'll try the "turn diag" and version ..43.0 when I get the chance.

I also found feed-hold during threading a little hit and miss. Is there guidance when you can and can't use this - obviously not during the cut!

Thanks for your help!

Woody.

35
General Mach Discussion / Re: Help with G-Code?
« on: January 27, 2009, 10:51:12 AM »
OK, thanks Hood.

The fact that I've got threading working well more than outweighs it :D

Any idea on G41 and G42 - I'm assuming they are not working any time soon in Turn?

Cheers.

36
General Mach Discussion / Re: Help with G-Code?
« on: January 27, 2009, 07:38:55 AM »
Yep, thats what I thought, but I've tried it on three machines now with similar response. I think it may be the zoom level. But you can also see it's got the end of the work wrong, it should be a flat face. How does it look on yours? I'm in Diameter mode by the way.

Also, the G2 G3 info in this post is very helpful as Tom says!

Thanks for looking.

G21 G18 G61 G90 G95 G40
T0101 M06
M03 S1400
(Rough out with 0.4mm deep cuts with 0.4mm nose rad tip)
G0 X20.0 Z1.0
G0 X18.8 Z0.0
G1 Z-79.0 F0.15
G0 X19.0 Z0.0
X18.0 Z0.0
G1 Z-64.8 F0.15
G0 X18.5 Z0.0
X17.2
G1 Z-48.8 F0.15
G0 X17.7 Z0.0
X16.4
G1 Z-32.8 F0.15
G0 X16.9 Z0.0
X15.6
G1 Z-16.8 F0.15
G0 X16.1 Z0.0
X14.8
G1 Z-10.8 F0.15
G0 X15.3 Z0.0
X14.0
G1 Z-10.4 F0.15
G0 X14.5 Z0.0
X13.2
G1 Z-10 F0.15
G0 X13.7 Z0.0
X12.4
G1 Z-9.6 F0.15
G0 X12.9 Z0.0
X11.6
G1 Z-9.6 F0.15
G0 X12.1 Z0.0
X10.8
G1 Z-9.6 F0.15
G0 X11.3 Z0.0
X9.7
G1 X10.8 Z-0.55 F0.15
G0 X11 Z0.0

(Rough Profile 1)
X8.57
G1 X10.8 Z-1.1 F0.15
Z-9.6
X12.39
X15.3 Z-11
X18.6 Z-76.4
X18.6 Z-78.9
X19.1 Z-79.2
G0 Z0.0

(Rough Profile 2 0.4MM Deep)
X7.72
G1 X10.2 Z-1.24 F0.15
Z-9.90
X12.14
X14.72 Z-11.19
X17.98 Z-76.45
Z-79.01
X19.04 Z-79.56
G0 X20 Z0.0

(Cut final profile 0.1MM Deep)
G1 X7.44 Z0.0 F0.11
X10.0 Z-1.28
Z-10
X12.06
X14.52 Z-11.23
X17.78 Z-76.46
Z-79.06
X19.0 Z-79.67
Z-97.0 (end of profile)
G0 X20
Z1
M05
M30

37
General Mach Discussion / Re: Help with G-Code?
« on: January 27, 2009, 05:06:37 AM »
I'm using the same - see attached. This is 14mm dia and 100mm long.


Thanks!

38
General Mach Discussion / Re: Help with G-Code?
« on: January 26, 2009, 04:16:09 PM »
TurnerTom - how do you get your display to be so smooth? Mine is always jagged and not quite following the path? Sorry its off topic.

Thanks!

39
General Mach Discussion / Re: G41 and G42 Help Request! Example given
« on: January 19, 2009, 04:19:36 AM »
Thanks Rich and Hood,

I'll try and learn a little more on this, try out a few different approaches and keep watching this forum on G41. If I discover anything, I'll let you know.

At the moment, yes, I don't think G41 and G42 are working in Turn, at least, not as I've read they might. If anyone knows otherwise, please share how!

Richard.


40
General Mach Discussion / Re: G41 and G42 Help Request! Example given
« on: January 18, 2009, 03:45:15 PM »
Thanks for your help Hood and jimpinder,

I updated to 3.043.000 and shortened my test a little:

(Diameter Mode)
g21 (metric)
g18 (xz)
G61 (exact)
g90 (absolute)
g95 (mm per revolution feed mode)

T0101 M06
M03 S1000
g0 x0.0 z0.0

g41
g1 x8.0 z0.0 F1.0
x10.0 z-1.0
x10.0 z-10
x12.53 z-10.0
x14.53 z-11.0
x14.53 z-15
g0 x14.53 z0
g0 x0
g40

M05 (Stop Spindle)
M30 (End and Rewind)

I ran this without the G41 first and tried various Tip Directions and this provided a fixed offset as per the "LatheOffsetsSystem.doc" that I had. So, the Tip Direction seems to work. But I set this to zero to not confuse things.

With G41 set and with zero tip radius, no problems (but obviously no offset).

With 0.4 tip radius in the tool table, it stops just before finishing the G0 X8 ... In fact, any tip radius over 0.01 crashes it.

Does G41 and G42 work yet in Mach3Turn vn. '42 and '43?

Is anyone using them in Turn? I'd be really grateful to see some working examples of G-code - I'm sure its probably an error in my set-up somewhere.

Or, is there a better way? I want to try and do it in G-code with the off-set calculated in Mach3 and I assume G41 and G42 is the way?

Thanks, Richard.

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