Topics

1

General Mach Discussion / Constant velocity vs Exact stop

« on: May 21, 2020, 01:55:37 PM »

So, I am once again confused. I have been running my machine in constant velocity mode, which seems to be the default. I had a little issue with corners rounding off and corrected this by altering the acceleration and deceleration settings.

Then I saw a YouTube vid which introduced me to the wonders of ‘exact stop’. This works well and creates really sharp corners but is a bit weird when cutting circles. So I tried the option to turn off CV on an angle greater than 89 degrees. I assumed that this would make the machine run in CV mode until it encountered a 90-degree corner and would switch to exact stop mode. But it doesn’t. No matter what angle is set, it stays in CV mode.

What am I doing wrong?

2

General Mach Discussion / Set for mm but moving in inches.

« on: May 14, 2020, 10:58:47 AM »

Hello

I have been using mach 3 for several months now and had good results. I have a home made machine that moved on the X&Y axis using a timing belt and toothed pulley system. This worked well, but the belt tension was difficult to maintain and sometimes led to poor results, so I have upgraded to a leadscrew system for both axis. This required retuning of the motors. I used the axis calibration in the settings tab and got readings of around 5200, which seems about right and was close to the steps needed on the Z axis which was already on a lead screw system.

I created a test file using Vectric Vcarve to simply make a straight cut 300mm along the X axis, but despite the mach 3 being set to mm in the settings page, G21 being indicated on the program run screen and the Vcarve project being set to mm, the machine moved in inches.

When I first ran the machine after the upgrade I used the automatic axis calculation tool, but this seems to only work in inches. i.e. despite being set to mm, when using MDI a value of X1 this resulted in a movement of 25.4mm i.e. 1 inch, not 1mm. I got the same result whether the units were set to mm or inches.

What is puzzling is that the Z axis also now moves in inches and I had only fine-tuned this axis using the automatic calculation tool.
What have I done wrong?

Cheers

Peter

3

General Mach Discussion / Saved axis settings

« on: May 01, 2020, 03:44:58 PM »

I will put my hand up and say that I am embarrassed to be asking this, but....

With my machine, the Y axis is driven by two motors which are 180 degrees from each other. I have slaved the A axis off the Y axis, with the A direction reversed. Everything works well but I am making a change to the machine that requires the slaved axis to not be reversed. But when I looked at motor configuration, I noticed that the settings for A are significantly different to Y settings. I have not noticed this before and had not to as all was well.

So my question is: if an axis is slaved, does it automatically use the settings from the axis that it is slaved from?

4

General Mach Discussion / Not cutting circles neatly

« on: April 08, 2020, 08:33:10 AM »

Advice needed again.

I noticed that circles on my machine don't cut nicely and seem to have an odd shape where the Y axis reverses direction - see attached pic.

The CRV file is just a test to return to X Y zero for a tool change and reset Z zero.

Cheers

Peter

5

General Mach Discussion / Unable to reset

« on: April 03, 2020, 11:34:24 AM »

Hi all

My home made CNC is working just fine - or at least it was. Yesterday I was using it, and fortunately I was only doing a test cut to check tangency, but then it started to stop functioning with no predictable pattern, and the reset button on the screen was flashing red. I was able to reset from the PC screen as normal and it would work for a while then stop. This was regardless of whether a G Code file was running, or I was moving the gantry manually using the L/R, F/B, Page up/down keys. Again, with no predictable pattern.

The gantry was nowhere near any of the safety limit switches.

I turned it all off and went to ponder as to whether I had done something stupid or not. I'm pretty sure I haven't, all I had done prior to this problem manifesting itself was to edit the Code file to lift the cutter, return to zero so I could change the tool, reset Z zero and continue on. i.e.

Z10
X0 Y0
M0
(reset Z zero)
Z10

Not the most elegant bit of code, but it worked.

This morning all was working fine, until this afternoon. I now can't reset at all. I get a scrolling message saying 'Emergency mode active" and below that in the status box it says "External E Stop requested" I can't say that I've ever noticed this message before.

I checked the limit switches and the LED's on the interface board go out indicating that these are working correctly (board is CNC interface board LV3.3 - pretty much the same one everyone uses).

Has anyone else had this issue?

All suggestions will be appreciated.

Cheers

Peter

6

General Mach Discussion / Setting Z height with a manual tool change

« on: March 07, 2020, 01:01:13 PM »

Hi

I have a home-made CNC machine – surprisingly accurate – but it doesn’t have an auto tool changer. So far, I have been setting the Z height between different tools using the ‘bit of paper’ method, then resetting Z zero in Mach 3.

This works well enough for my purposes, but I felt that there has to be a more sophisticated way. So I tied into my emergency stop circuit and with a connection to the cutter and another to a 0.0015” feeler gauge. I can lower the Z manually and the machine stops instantly when the cutter touches the gauge then I zero Z. But 0.0015 is a bit flimsy and I want to use something more rigid.

I have a piece of Aluminium which is 1.77mm thick. How can I use this to set Z zero?

7

General Mach Discussion / Program pause command?

« on: January 19, 2020, 03:16:59 AM »

Hi

Is there a G command that will pause a running program. I don't have option for an automatic tool change and want to use different tools on one piece, so I will have to manually change the tools. The G4 dwell code could give me a period of delay of however long I needed, but that is far too dangerous as it would start again once the time was up.

I could hit the 'Pause' button in Mach3, but a line of code would be far more elegant.

I have looked through the G and M code lists, but can't see a pause option.

8

General Mach Discussion / Open vectors

« on: January 11, 2020, 03:43:45 PM »

Hi

I appreciate that the may not be the right forum, but here goes.

I'm using VCarve and I have created a stylised line drawing of a dog and I want to engrave this onto a bit of MDF with a 60 degree V bit. I have selected the image and set the tool, but when I hit 'Calculate' to get the tool path I get a message saying:

"Ignoring Unsuitable Open Vectors. 19 open vectors in the selection are being ignored. There are 0 remaining vectors."

No tool paths are created.

What am I doing wrong?

9

General Mach Discussion / Non repeatable movement

« on: December 26, 2019, 07:17:22 AM »

Hi, I'm having some issues with non repeatability. I shall explain:

X0 (Ref 0 in the software)
X15 (In inches)
X0

Cutter head moves 15" to the right, stops and returns to zero, but it doesn't. It says 0 in the software but the cutter head stops short by about 0.25". Similar situation with the Y and Z axis.

Hema 23 motors, standard driver boards, Mach 3 software (obviously), timing belt for X/Y axis, lead screw for Z axis.

So what am I doing wrong?

10

General Mach Discussion / Code snippets

« on: December 21, 2019, 07:15:20 AM »

Where can I find G Code examples? e.g. interpolation of a 6mm cutter to cut a 10mm hole.

I haven't done programming for a while and that was VB, but when I was doing it I found the best way for me to learn was to download a code snippet then read it, make changes etc... and see what worked.

Cheers