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Messages - WoodyCam

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Quick update. I've solved my issue after further forum hunting and found two significant sensitivities. All with version x.66 I've found that with mm units, Stop CV on angle >90 deg, no backlash and CV Dist Tollerance set to 0.02mm I could achieve smooth motion if I set the feedrate override to 50%. The little jerk on every line went away. When I increased the tollerance to 0.05mm I could set to 150% feedrate before it came back. The feedrate in the code is quite varied (90 to 300), and well below the motor max speed. So, as is noted in other posts, feedrate overide does have an influence on behaviour. Also, its obvious small CV tollerances would be difficult to achieve as speedrates increase, but this is a small part and fairly slow feed and this issue was with no change in path (a split straight line). Anyway, the tollerance is a much more sensitive parameter than I expected and very small changes make quite a big difference to smoothness.

Anyway, very happy my new machine is able to be smooth.

Does anyone know if it is normal to adjust this for different GCodes each time? What is the best way to do this?

Gobbya, I'd be really interested to know what CV Dist Tollerance you used when you tested with 66?


Just to say, I've discovered exactly the same problem with version 3.043.066 using Parallel Port today. Maybe its not your USB controller?

Trying lots of CV settings and motor tuning makes no improvement with my new machine build. I've been running an old GCode file that worked fine on my old CNC mill (running an older Mach 3). So, I think this post helped me work out the issue, I will try an older version of Mach3 and report back. I've read stacks of posts on CV and I think it should be smooth with CV tuned, certainly others have said they achieve smooth motion after tweaking these settings, but its not always clear what Mach3 version they are using.

Surprising (if so) to see such a fundamental issue with this "final" version? Hasn't anyone else seen this issue?  Hence, I'm still not sure that isn't me doing something wrong, but as Gobbya found, the settings don't seem to change this behaviour. It feels like CV is not on, but it certainly says it is.  Any advice gratefully received.

Just to be clear, in my case, Mach3 is pausing ever so slightly at the end of every straight line even when it is a straight line, just split for no reason by the CAM programme. Surely this should be smooth with CV on? I'm going to test 360 deg circles next. I'm guessing its going to slightly pause at each node... No backlash and quite high acceleration motor settings.


General Mach Discussion / Re: True 4 Axis Simultaneous on Mach3
« on: November 24, 2012, 02:09:37 AM »
Hello Mauri,

If its any use, here is a 4th axis gear cutting file written by hand. Its for a really small watch gear replacement.

I found the machine set-up G codes important.

G17 G21 G40 G64 G90 G49
(Winding Gear Cutting Path)
(48 teeth cutter)
(No Z Motion - set to wheel centre line)
(X0 = 6mm out from front face of gear, cutter touching blank,Y0,Z0)
M03 S500

G1 A90.0 F300 (take up any lash - assuming starting at 0deg)
G0 X1.87 Y6.71
M98 P48 L48 (do roughing cycle 48 48 times)

M05 (Stop Spindle)
M30 (End and Rewind)

O48 (Gear Path Subroutine)
G1 X-0.72 Y6.71 F30
X-2.0 Y8.79
X-2.0 Y11.24
X-7.64 Y11.24
X-7.64 Y13.41
G0 X1.87 Y13.41
X1.87 Y6.71
G91 (INC MODE!!)
G1 A7.5 F300
G90 (ABS MODE!!)
M99 (Subroutine Return)

The Mach3 path is attached (I hope).

Does that help a little?

By the way, if anyone finds a free 4th axis code generator for milling radial shapes from a 3D model, please share!!


General Mach Discussion / Re: Mach 3 turn constant sfm?
« on: December 09, 2010, 07:52:40 AM »
I have had problems with G95 only (no CSS) with PP and Vn 40.

First run would be fine, second would be stepper commands outputted at max computer speed (no reference to feedrate or max velocity at all) (10 mins file executed in 5 seconds)! Steppers screaming and massive lost steps. Next would be fine, next same as above.

Went back to version 22 which works fine except for long, deep threads and finished my work.

However, I had some time and went back to version 40 AFTER changing my parallel port in BIOS from ECP or EPP mode to "Bidirectional Parallel" (for other reasons) and I've not had that problem with version 40 since. All G95 code I've tried so far is fine and ran same piece 6 times with no issues. (Was it a corruped install or does the parallel port make a difference, I don't know.)

With Vn40, I also found the MDI would not accept inputs until G-Code was run. I found this was due to the initialising strings in the Config page being empty after upgrade.

I did a quick check with G95 and G96 and it seems OK. So, at the moment, happy with Vn 40...

However, as per my previous post, G95 does not respond to spindle speed changes. I'm sure it used to in previous (very early) Mach3 versions as I remember being a little impressed with it... Seems that is broken now unless I remember badly.


General Mach Discussion / Re: Mach 3 turn constant sfm?
« on: December 02, 2010, 11:06:12 AM »
Related Turn question in Vn 40. with parallel port. Say I'm doing:

M3 S1500 (rpm)
G95 (constant feed per revolution)
F 0.2 (mm/rev)
G01 Z blah

and its cutting, the STrue is 1500 rpm (finally got that working) and its too fast so I turn down the spindle speed (via the VFD by hand), the STrue drops and the S speed stays the same as expected but the feed (mm/rev) goes up and the rate the Z axis moves does not change. So its not reducing the feed rate so mm/rev calculated goes up. Is this normal? Is there a setting I can adjust so it keeps a constant mm/rev when speed changes? Even if I try to change the "S" via override, makes no difference.

Do I need to be in G96 mode for this interaction or is the feedrate fixed once the command is running and actual spindle speed has no input? I have the box "Use Spindle Feedback in Sync modes" ticked.

Next, I've played with G96 and found it messed up the "STrue" number as soon as this command was reached. 0 to 1500 rpm would read 2035 to 2355 or something like that. I must be doing something wrong. Can someone post a successful G-Code snippet with G96 used please - would be really helpful. In the meantime, I'll experiment some more.

(G96 is not in the Turn documentation I have.)



General Mach Discussion / Re: Jog slows down
« on: November 28, 2010, 01:42:53 AM »
Maybe you have to click to it from the top of the downloads page. First blue link:

"For previous versions of Mach and LazyCam, XML's, and other Extra Information: Click Here"

I think that does an auto guest login - sorry, I maybe shouldn't have posted a link to the actual ftp site.


General Mach Discussion / Re: Jog slows down
« on: November 27, 2010, 03:37:21 PM »

I'd suggest downloading version .38 from here: ftp://machsupport.com/Mach/

I'm having loads of trouble with many things in version .40 using parallel port, "std. PC" and Win 2000. Actually I've totally given up on version .40.

I did experience what you have with .40. I found only way to get it working again was to stop Mach and open it up again. Also, it would get stuck in other jog modes also. And if you feed hold, often jog would get stuck when you least want it to.

Also, when you re-start from freehold, if it does manage to let you jog, the restart moves to get back to the path would be totally wrong. Use with great care! Not loosing any steps though.

Also, I get no spindle speed (with started spindle) using vn.40 and nothing I can adjust will get it back. Works fine with vn 38 and older.

But, there don't seem to be many other complaints out there for this version so there must be something with our set ups.

Vn. .38 seems generally better but has feed rate and re-start problems in Turn that I'm just trying to understand now.

Give it a try. I'd be very interested to know if .38 is better for you as well. There was a change to the driver in vn. .39 according to the log.

For me Vn 22 is good for Turn (not for threading) and vn.38 is mostly good for Mill but definitely not for Turn.


General Mach Discussion / Re: Swarf in Keyboard and Mouse!! Ahhhh!
« on: November 24, 2010, 08:09:13 AM »
Hood, that would be great when you have a moment. I've not messed with screens, but looks like you are giving me the motivation!

The std Turn screens seem to take a lot of clicking around to get set up and turning. Never quite worked out why they separated manual and auto operation...



General Mach Discussion / Re: Swarf in Keyboard and Mouse!! Ahhhh!
« on: November 24, 2010, 07:34:23 AM »
Now that is cool! Yeh, I did look out for those, there is one on eBay now for £425... I guess you have to be lucky and persistant.

Hood, any chance you can share your Lathe Screen set pls? ;)

Thanks, Woody.

General Mach Discussion / Re: Swarf in Keyboard and Mouse!! Ahhhh!
« on: November 24, 2010, 04:00:10 AM »
I guess I should reply to my original post. I went with the silicone keyboard. Its OK and I've had no swarf problems since. BUT, the feel is terrible (the one I have anyway) and so jogging can be hit and miss sometimes. The keys need a lot of pressure to be sure to bite. Occasionally I put the original keyboard back just for the feel of it, but its not suitable when there is heavy swarf production going on.

Must get an MPG rigged up for the mill - its on the list. Works great on the lathe.

I've tried USB and PS/2, not have any issues with either.

Only thing I've not got to work is a separate numerical keypad. Ok for very short jogs but on long key presses for long distance jog, some kind of auto repeat interupts the jogging. Not figured that out yet.

Optical mouse seems to have survived so far.

Thanks all for your advice. Woody.

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