Come on Dave, keep up 

They fit in place of the coin but have been specially designed (for our sort of trolleys) so that they can be weaselled out and this lets you become a real vandal and set free all the trolleys that have been imprisoned in the trolley park. 

Tweakie.

Actually I knew that (used to try this as a kid), but never in a million years thought the pure and honest heart of Tweakie would ever do this.  

We also used to regrind blanks from electrical boxes to use as well  

Dave

Sorry Dave - perhaps I am not quite as white as white. 

Incidentally, my CNC programmed car park cards were a real hit last month. 

Tweakie.

I've now lost all respect for you, my friend - 

Dave

I've now lost all respect for you, my friend - 

Dave

Hi Dave,

I have been having sleepless nights about this - Could I possibly redeem my position if I sent you some free samples of the 'infinite trolley token' and the 'car park entry card' ??

Tweakie.

Those of you that have been following this (never ending) thread will know that between Andrea in Italy and myself in the UK we have spent quite a lot of time putting the Mach Impact / Laser engraving plugin through it’s paces. Although there are still some improvements that could be made to the plugin and it still has a lot of mileage left in it, the legacy issue of it’s requirement for a parallel port are starting to show and it is perhaps time to start looking at alternatives.

In the Eastern European countries, for many years, it has been common practice for black marble monuments and remembrance plaques to display an engraved ‘photographic style’ of image and this has inevitably prompted the development of CNC software to complete the task. One such software is “DotG” a Hungarian program which has just had an English translation version released. It is completely ‘free of charge’ and can be downloaded from here http://dotg.weebly.com/download.html

DotG works in an entirely different way to the Mach plugin insofar as it creates GCode from a pre-processed 1 Bit image and although I haven’t quite got my postprocessor completely sorted everything looks extremely promising so far.
It is early days yet but I will keep you posted of my experience with this software as I learn more.

This example image of Audry Hepburn with the glamour of the 1950/1960’s was laser cut into some scrap MDF whilst I was testing various settings and it would, I think, look quite stunning cut into some mirror tile (project awaiting).

Tweakie.

Hi Tweakie,

This sounds interesting. Can you please explain how it works or post a Gcode snippet? How is the modulation done in the Gcode?

Thanks,
Dan

Hi Dan,

The image has to be pre-processed until it is essentially a 1 bit halftone which is really just a collection of dots. DotG then scans this image in raster fashion and creates the GCode as a series of ON or OFF instructions for the laser or impact magnet.
For some time now I have used the B Axis as my laser control with B1 to turn the laser on and B0 to turn the laser off  and for me, this has two major advantages. Firstly the on or off commands can be synchronised with the start or finish of axis movement and secondly the G01 federate can be used to control the laser burn time.
I have attached the GCode used for the previously posted image which you will see is pretty basic stuff with just two lines per dot (or dash). I haven’t quite got my post-processor right yet so the code is still a bit messy but this can only improve  

Tweakie.

Hi Tweakie,

Thanks for the description. So it isn't as smooth as it is with the plugin. The axis has to stop and then the laser comes on and off and then it proceeds to the next point. Seems to be slower also.

It is the direction line of the B axis that you're using, right?

Is there any meaning for this in this Gcode:

T1
S8000 M3 f1500

Dan

Hi Dan,

Yes I think it is slower than the plugin but the jury’s still out on this one for the moment because it does not make any unnecessary line scans or unnecessary increased length of scan lines. More comparative testing is necessary before I know for sure.
As far as magnet impact is concerned it should be a lot faster but I think Andrea will have more information on this.

Yes I am using the B Axis direction signal and only the F1500 is being used from those other commands.

Tweakie.