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Author Topic: The Laser Project.  (Read 821529 times)

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Offline Greolt

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Re: The Laser Project.
« Reply #610 on: February 13, 2012, 05:59:02 AM »
OK it sounds like you feel I am off track .  :D

If I use code as follows,

M11P1  'turn laser on
G1 X25 F1000
M10P1  'turn laser off
M30
%

After running this code the laser does not turn off, it remains on.

I guess knowing that should be sufficient. 

I must remember to place a movement command after the M10 so as the laser will turn off.  Such as,

M11P1 'turn laser on
G1 X25 F1000
M10P1  'turn laser off
X0
M30
%

If I am correct in this, and that is certainly not guaranteed, I might call it acceptable, but not perfect.

Greolt

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #611 on: February 13, 2012, 08:46:00 AM »
Hi Greg,

Try checking the 'Turn off all outputs' on the general config page.  ;)

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Greolt

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Re: The Laser Project.
« Reply #612 on: February 13, 2012, 07:04:40 PM »
Thanks Tweakie

Two options then;

1.  Follow the M10P1 with a move command so that the laser turns off.

2.  Follow the M10P1 with an M30 so that the laser turns off. (if it is set in config to do so)

The second option is not so good, as there is a delay before the laser turns off.  So the first option may be the only one.

Thanks for clearing that up,

Greolt
« Last Edit: February 13, 2012, 07:19:03 PM by Greolt »

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #613 on: February 14, 2012, 05:32:18 AM »
Hi Greg,

Yes, I think that is about the size of it - always follow the commands with an axis movement (which would normally always be the case anyway).

There may be some occasions when it is necessary to ‘fire’ the laser for a short period when an axis is stationary, as would be the case when using DotG in ‘dot’ mode but as it’s post processor if fully configurable a ‘dummy’ axis movement can easily be included. This was tested yesterday for the attached image and it works well.

As mentioned in the earlier post we do need the ‘turn off all outputs’ checked for safety reasons this way the laser will be turned off with ‘feed hold’, ‘limit switches triggered’, ‘estop’, M30, etc.

Tweakie.

Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #614 on: February 20, 2012, 04:59:21 AM »
The recent period of cold weather has rather slowed things up a bit but spring is now on the way.

Another forum member ‘PicEngraver’ has sent me an advance beta copy of his new program ‘PicDither’ which will convert a bmp, jpg, etc image to halftone. This is capable of applying a number of different industry standard algorithms which in their own way produce differing results but the overall effect is extremely similar to the, rather overpriced, commercial program ‘PhotoGrav’.

These are my first tests made from a standard .jpg image which was then laser engraved onto MDF  using the Mach3 Impact / Laser plugin. It is early days and I have not yet tried a photographic image but that is next on my list.

Further details of ‘PicDither’ can be obtained by contacting John through his website  http://picengrave.com/

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #615 on: February 20, 2012, 07:25:53 AM »
Exactly the same technique as previously used but this time with a photographic image.

I really don't know if all CO2 lasers behave in the same way but, as mentioned in way back postings, when using the Mach plugin directly I am only able to achieve a maximum of 5 shades of grey which, I suspect, may be a function of my high voltage power supply operating in a digital rather than an analogue way. Converting an image to half-tone seems to overcome this limitation by introducing the visual effect of many more shades.

My congratulations on an excellent program John.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Dan13

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Re: The Laser Project.
« Reply #616 on: February 20, 2012, 09:20:27 AM »
Can you explain please, Tweakie? The power supply still operates in digital mode so how does the image conversion help?

In the image the program outputs, are all the dots equal in size?

Dan

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #617 on: February 20, 2012, 11:14:18 AM »
Hi Dan,

A very good question (you always ask good questions) – as far as I can tell, yes the dots are all the same size so this would indicate that the laser has been fired at exactly the same power level throughout the whole image. The thing that varies is the dot density and this is the clever part which gives the illusion of shade.
In some areas of the image the dots actually merge because the burn marks on the wood are larger in diameter than the laser spot that created them. So, in theory, if I could increase my axis speed and reduce the burn time of each dot they would be smaller in diameter and I could increase my resolution. But, as said before, everything is a compromise.  :'(

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Dan13

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Re: The Laser Project.
« Reply #618 on: February 20, 2012, 11:52:36 AM »
Hi Tweakie,

So how does it vary from the Impact plugin which still fires the laser at the same power each time? Roughly speaking, if I understand correctly the way the plugin works, it does internally the same thing as that program does, but following a different algorithm.

Dan

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #619 on: February 20, 2012, 12:22:00 PM »
Hi Dan,

I think you have got me there, because I just don't know the answer.

On it's own, the plugin will not always smooth a gradient of tone without producing 'steps' as can be seen in the background of this image which is a smooth transition from light to dark. I have spoken with Art about this and he feels that the cause is mathematical in nature.



Once an image has been 'halftoned' this does not happen, the gradient is much smoother.

As for why ? hopefully I will eventually discover the reason but for the moment it illudes me.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.