Messages

4751

Mach4 General Discussion / Re: Mach4 Printer Port Discussions

« on: June 19, 2014, 10:21:59 AM »

Hi Art,

Thank you for the information and taking the time to look at the problem.

I have now found that it has nothing to do with the spindle and think I can confirm what you have said. The following runs with rough motion until the M9 is encountered then it runs just fine (so it looks like it's a Mach4 problem).

code
m7
code
m9
code

Tweakie.

4752

Mach4 General Discussion / Re: Mach4 Printer Port Discussions

« on: June 19, 2014, 07:29:40 AM »

Hi Art,

I am having troubles running a simple code such as:-

G1 F300
M3
X10
Y10
X0
Y0
M5
%

I had to delete the M3, M5 macros from the Mach4 macros folder on order to get these commands to operate the spindle but now the motion is lumpy (almost single step mode). If I leave out the M5 then it runs just fine (starting the spindle at the M3) but of course the spindle is not stopped at program end.
I have a similar problem if ending a program with M30 (for the last few lines it runs lumpy) and I put this down to my PC being antique but now I am not so sure.

Does using the M3 / M5 combination alter the output stream from Mach4 in some way?

Any advice greatly appreciated as this issue has me stumped at the present.

Tweakie.

4753

Mach4 General Discussion / Re: Laser Cutting.

« on: June 19, 2014, 04:36:12 AM »

Thanks Brett.

A few of the challenges I encountered with Mach4 v.1767 which may be of interest to others…
 
Initially my machine PC graphics card was not up to the task and had to be replaced with one that makes a better job of handling OpenGL. It’s a 10 year old PC and getting hold of a suitable AGP card was not that easy but where there is a will…

I work in metric so selected Metric Units in Mach4. As it turned out the Counts per Unit / Acceleration and Velocity for the X,Y & Z axes all had to be entered in Imperial units in motor tuning in order to get correct operation and axis movement distance. The A axis behaves differently and settings for this were entered in metric units.

Overall, setting up Mach4 is very easy to do but getting the M3 / M5 commands to talk to my VFD control was, to say the least, a real challenge. I got it working fine in about 5 minutes but did not record the settings, changed something else, it stopped working and then took me a few hours to get it working again (I have now written down my settings for future reference).

I forgot (read about it often enough on the forum but still forgot) to delete the M6 macro and the tool change ‘dance of honour’ tested my reactions – God bless E-Stop.

My old PC does not appear to have the computing power to handle the M30 command (stalling all motors during the GCode rewind operation) so M30 had to be deleted from my GCode programs to get them to run correctly towards the end. This needs further investigation on my part.

The Imperial / Metric bug, mentioned above, may have already been rectified in v.1817 but overall Mach4 v.1767 is just brilliant to use and it operated faultlessly during the couple of test runs I have been able to do so far.

Art’s ‘Darwin’, parallel port driver, performed beautifully during the tests with no faults or bugs to report. It is very easy to set-up and the motion produced is just so smooth it is difficult to describe the difference from Mach3.

As yet we do not have a dedicated control method for laser switching (the old M11P1/M10P1 commands have gone) but Art is working on it and I am sure he will think up something good once he starts using his Synrad. 

As soon as I get more ‘play time’ I will delve a bit deeper and see what I can and can’t do with the new toy. 

Tweakie.

4754

Mach4 General Discussion / Laser Cutting.

« on: June 18, 2014, 10:05:09 AM »

I have said it before but I just can’t say it enough – my congratulations go out to the Mach4 team and of course, Art for the excellent Darwin driver.

Just couldn't resist making a short video of Mach4 (build.1767) with Darwin laser cutting.  http://www.graytel.talktalk.net/Mach4.wmv

Tweakie.

Addition;

This is the video of the latest test engraving and cutting  http://www.graytel.talktalk.net/Darwin 2.wmv

4755

Mach4 General Discussion / Re: Mach4 Printer Port Discussions

« on: June 18, 2014, 02:18:57 AM »

Thanks Art.

Another issue which is probably just M4 v.1767 related and maybe not of interest here but I am just reporting as I find.

In Imperial mode everything is OK but in Metric mode G00 X1 Y1 Z1 moves X,Y,Z axis 1mm whereas G00 A1 moves the A axis 25.4mm (all DRO’s reflect the correct physical movement).

Tweakie.

4756

Mach4 General Discussion / Re: Mach4 Printer Port Discussions

« on: June 17, 2014, 01:58:26 PM »

Just thought I should mention this...

I don’t know if this is a Mach4 v.1767 issue or a Darwin issue but for those like me, that work in metric, the motors Counts per Unit : Velocity and Acceleration all have to be entered in Imperial units irrespective if metric is selected in general config. Not a problem once you know but it was puzzling initially.

Tweakie.

4757

Mach4 General Discussion / Re: Mach4 Printer Port Discussions

« on: June 17, 2014, 12:05:29 PM »

Hi Art,

I have been searching my PC but cannot find the link to it - The Synrad UC2000 controller data sheet gives a lot more information on Duty Cycle and Pulse Repetition Frequencies and how they should be managed - perhaps may be worth looking for it if it is still available on the Synrad site.

I have no practical experience of mounting a tube vertically I am just going on the manufacturer's advice trusting that they are correct.

Tweakie.

4758

Mach4 General Discussion / Re: Mach4 Printer Port Discussions

« on: June 17, 2014, 11:32:37 AM »

@ Craig,

I understand what you say, however, the logic gates invert the signal - connecting another gate in series restores the state. As there are 4 'and gates' in a package it makes sense to use one of them this way rather than use a separate inverter chip.
The output shown from the tickle pulse generator is signal 1 and GND. Signal 2 is fed from the Mach PWM or a stand alone PWM generator then the output goes to the laser control circuitry. Hope this makes sense. 

@ Art,

I think the Synrad CW operation may only apply to the relatively new models of their RF lasers. I don’t know for sure but I suspect that externally we can apply 100% duty cycle while internally the electronics is still pulsing at a reduced duty cycle and I would be concerned that older models do not have this safeguard. Perhaps we need to contact Synrad for more information.

As far as I am aware the grey scaling was not incorporated into the version of the plugin that you released.
If it’s any help this is typical of the shades of grey that can be achieved from the plugin as it stands http://openbuilds.com/attachments/a1-jpg.1862/

Tweakie.

4759

Mach4 General Discussion / Re: Mach4 Printer Port Discussions

« on: June 17, 2014, 08:20:34 AM »

Hi Art,

For the Synrad I use an external tickle pulse generator. It is a very simple circuit and has approx 10% of adjustment for both the frequency and pulse width – this enables it to be set to just below the point of lase. The Mach PWM and the tickle pulse are then switched in or out by a separate trigger circuit (diagrams attached).

In order to get the best laser versatility (never know what we will want to do tomorrow) I think you need as many different individual levels of power as you can achieve (I believe Synrad use 5% step variation of the duty cycle between 0% and 95%).

You will have to be careful if operating the Synrad above the recommended 5kHz PRF – for example at 20kHz then a 95% duty cycle will exceed the maximum recommended internal photon density for the tube (overheating the output coupler and / or the rear mirror). The Synrad controllers software limit the maximum available duty cycle as PRF is increased thereby negating the problem.

I am no expert here but it is my understanding that the Mach3 engraving plugin allocates a set number of ‘dots’ per each individual pixel value and because for high pixel values the dots overlap each other many times during one X axis scan it produces ‘dot-gain’ and thus a shade of burn in accordance with actual pixel value. In my opinion this process works extremely well and I think I am able to get results that are up there with the professional laser systems. Overall the engraving plugin is going to take a lot to better but you are the expert and I am really looking forward to trying the Mk II.

On the other side of the coin those using diode lasers have found that DC variation in actual laser output power level in accordance with pixel value is the way to go.
I can actually do this with my DC excited laser but I still prefer to vary the output power level by varying the PWM in the same way as the Synrad is controlled.

Tweakie.

4760

Mach4 General Discussion / Re: Mach4 Printer Port Discussions

« on: June 17, 2014, 06:04:25 AM »

My first laser test with Mach4 and Darwin (using a well trusted GCode toolpath that has been run many times before). Although this is not a method I would prefer to use the laser switching was done by using the A axis direction pin (A1=on and A0=off) and everything ran exactly as expected with no errors.

The problem mentioned in my earlier post regarding the final G00 X0,Y0 home move has now been identified as being the M30 command which, on my old and perhaps rather slow PC causes, both motors to stall during the GCode rewind. Removing the M30 cures this problem.

The ‘run today and not tomorrow’ problem I was experiencing has also been cured so it’s onwards and upwards with perhaps some more adventurous testing. 

You need to get that Synrad hooked up and running Art. 

Tweakie.