Messages

4871

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« 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.

4872

G-Code, CAD, and CAM discussions / Re: I am missing a simple g-code for an engraving program.

« on: February 20, 2012, 07:56:18 AM »

doomcuroe,

Please don't make multiple postings of the same question.

Thank you.

Tweakie.

4873

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« 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.

4874

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« 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.

4875

G-Code, CAD, and CAM discussions / Re: Milling the table

« on: February 19, 2012, 11:59:04 AM »

Hi Michel,

As all my work is done with a vacuum table or double sided sticky to hold the work I fitted a sacrificial plastic sheet onto the machine's aluminium table then milled that flat and parallel. Made a lot of mess but was easier than milling the alloy.

Tweakie.

4876

Show"N"Tell ( What you have made with your CNC machine.) / Re: Mechanical engineer and craftsman

« on: February 14, 2012, 05:56:35 AM »

Hi Ed,

That is just incredible, such detail and precision. Thanks for sharing.

Mind you, I think he would have a fit if he saw the inside of my workshop 

Tweakie.

4877

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« 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.

4878

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: February 13, 2012, 08:46:00 AM »

Hi Greg,

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

Tweakie.

4879

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: February 13, 2012, 04:36:35 AM »

Hi Greg,

No worries, you know me, I am always happy to post my thoughts and opinions.

I have carried out extensive testing of Artsoft's corrected / modified M10 P1 / M11 P1 command set and can honestly say that I have had no problems with the M10 P1 command and the way in which it operates with a laser. IMO it is just perfect.

Perhaps it is common for us to blame tools for not working in the way which we want them to work rather than learn how to use these tools to our best advantage. (I have read far too many posts, on this forum, mentioning a bug within Mach which subsequently turns out to be a bug within the user).
The most important thing here is to understand the way Mach behaves, once this is understood then code and post processors can be tailored to suit. We all have our own preferences but my post processors always end the code with an M10P1 prior to the home move.
If you are having problems you could, if you wish, set your spindle to Output #1 then use the M5 command or, as an end command configure Mach to turn off all outputs then use M30 followed by a CR or %, which most post processors use as a standard program ending anyway.

If you could post a code sample of just where you are having difficulties or detail the problem I would be happy to investigate and suggest a solution.

Tweakie.

4880

G-Code, CAD, and CAM discussions / Re: Laser

« on: February 12, 2012, 07:25:10 AM »

Hi Gordon,

For turning a laser on / off the best solution is now the M10P1 / M11P1 (P# determines Output#) command set.
Brian and the Artsoft team have gone to a lot of trouble recently to get this just right and it now works beautifully (there some more details here http://www.cooperman.talktalk.net/files/27_files/Page652.htm)

The other functions you mention can be handled by the standard G and M codes.

Tweakie.