Brett

Tweakie,
From what I have seen of your projects and designs these past few years, I'm convinced that you have to be a descendant of Merlin.
John Champlain 

Thanks guys you are far too kind. 

As I learn more from others it is nice to re-visit the things I have done in the past and see if improvements in my techniques can be made.

This is only my second attempt at laser etching photographic images into the rear surface of a mirror and thought you may like to see the result.

It’s a bit on the dark side (too much contrast) but I think I can improve that for the next attempt.

I used 'PicEngravePro' to create the Mach3 toolpath - thanks John (Picengraver) for such excellent software and all the time and effort you have put into making it what it is today.

Tweakie.

As usual, very Nice Tweakie!  The whole lot of you guys have made a lot of progress and are turning out some very impressive results. 

Brett

Tweakie,
Very nicely done, as is usual with all your work.  Thank you for the kind words and all your support.

Brett,
Thanks, too, for your very appreciated comments.  Still waiting for you to join us.  Must be some way you could justify a laser for your business.   

John

Although there are still only a handful of us worldwide that are using the Mach3 Impact / Laser Engraving plugin I thought you may all be interested in the latest update.

Because the output from the plugin is bi-directional, the exact registration of the horizontal lines produced is dependant on device activation speed and from version 1.1 to date this line registration had been set to a compromise between the speed of a laser trigger and the speed of an impact magnet trigger.

Arising out of necessity, I have recently had to adjust this line timing to better reproduce some fine detail work with Lithophanes and in order to preserve the plugin’s compatibility between Laser and Magnet operation I thought it would be wise to include a user adjustable horizontal alignment feature.
To this end I have now added a group of 4 buttons to the GUI - these new buttons will allow the registration of the raster lines to be advanced by +1 or retarded by up to -2 image pixel widths (with the default being zero) and this should now be sufficient adjustment to cater for the correct operation of both devices.

I still have a bit of tidying-up to do (I always seem to get into a terrible mess between the manual coding and the automatic coding from the wizards when using Microsoft’s Visual C++), and I need to do some more testing but the latest version of the plugin (1.2c) will shortly be freely available to any that are interested.

Tweakie.

Nicely done, Tweakie.

Would it also be possible to alter (or make user selectable) the pulse timing of the output for possible use with laser diodes?
 
John Champlain

Hi John,

Thanks, that is a very good suggestion and something I will look into.
Basically, my initial thoughts are that for diode laser operation (slower feed-rate) changing the calculation ratio between output power (amount of ‘dot-gain’) and feed-rate will achieve the desired result (a bit like the way in which the ‘greyscale compression’ function currently works for the CO2 laser). Anyway this is something I will investigate, as time permits and report back.

Tweakie.

Well, after a bit of experimentation, I think I can now safely say that the Mach3 Impact / Laser plugin can be used with low power diode lasers.

My design criteria was for a 1 Watt, blue-ray diode laser using a feed-rate of 1000mm/min but as I only have a 100mW, 655nm diode laser available for my tests I scaled back the feed-rate and the following work was produced at just 100mm/min. The results are, I think, acceptable and demonstrate that, in principle, it is possible and that the system works but like my school reports always used to say – “could do better”.

I have used this particular .jpg image many times before (for testing purposes) as using the same image helps me with comparisons between different settings and methods etc. The .jpg has been dithered (using John’s excellent software PicDither), my diode laser was triggered using the TTL method and the total job time was around 3 hours for this 50mm x 50mm example.

The Mach3 plugin basically works by a system which has been termed ‘dot gain’ - firing individual dots on the digital trigger output at up to 12,500 times per second. A great many of these dots appear on top of one another (overlapping) and the more dots that occur in any one place the darker the work is burned.

The maximum duty-cycle for the digital trigger output from Mach3 is 50% (pulse on time / pulse off time) and although this is just fine for a higher powered CO2 laser it was necessary to increase this duty-cycle to around 90% for diode laser operation.

If there is any interest in this, I would be pleased to provide the details of just how it was accomplished.

Tweakie.

As usual, excellent work from the house of Tweakie.