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Author Topic: The Laser Project.  (Read 806560 times)

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Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #570 on: January 30, 2012, 08:48:09 AM »
 ;D ;D

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 #571 on: January 31, 2012, 04:08:37 AM »
Tweakie

How do I set up for M10P1 / M11P1 and or E1P0 / E1P1?

"Output 1" or "Digital Trigger" or something else?

And is it different for vector cutting and the engraving plugin?

I have the laser firing manually and got the mirror alignment fairly good.  So I am dead keen to try it out.

Greolt

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #572 on: January 31, 2012, 05:30:31 AM »
Hi Greg,

I use two different Mach profiles;
For Raster and the Mach plugin the Digital Trigger is mapped to the LPT parallel port pin that is used to fire the laser.
For Vector my GCode has M11P1 to turn the laser ON and M10P1 to turn the laser OFF then Output #1 is mapped to the LPT parallel port pin that is used to fire the laser (the P# relates to the Output Pin#).

You have probably seen this already but the schematic of my laser control is here http://www.cooperman.talktalk.net/circuit2aa.jpg  and the LPT parallel port pin (referred to above) connects to the TTL input. (The two, series TTL gates I am using are there just as a buffer and to ensure a proper 5 Volt logic switching, for the laser PSU, from the parallel port output which could possibly be 3.3 Volts).

Hope this helps.

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 #573 on: January 31, 2012, 06:17:35 AM »
Tweakie

Just got in from the shed. (its getting late)   Been cutting and engraving.    Woo Hoo!!!  ;D ;D

I worked it out before seeing your post.  I am using Output1, not Digital Trigger, for both vector cutting and engraving (with the plugin).  Only one profile.  I hope this is right.  It works anyway.

Using M10P1 / M11P1 for vector cutting.  Had them around the wrong way at first.  Doh!   :o

The Vectric PP worked fine so far.

"............Output #1 is mapped to the LPT parallel port pin that is used to fire the laser (the P# relates to the Output Pin#)"

Output Pin# is confusing.  Don't you mean Output#, which can be mapped to any output pin on the LPT?


"............. buffer and to ensure a proper 5 Volt logic switching, for the laser PSU, from the parallel port output which could possibly be 3.3 Volts)."

I am using one of Peter Homman's BoBs which buffers the outputs, so no worries there.

Anyway I am very happy.   Engraving results are not great yet.  Lots to learn.  But at least it works.

Thanks for the help,

Greolt

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #574 on: January 31, 2012, 07:46:59 AM »
Hi Greg,

That's great news, I am really pleased you have it all working OK.

Don't forget to post some pictures.  ;)

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 #575 on: February 03, 2012, 12:49:05 AM »
Tweakie

Cutting acrylic, it cuts great but I am getting lines on the cut.  I think you call them striations.

Can you suggest a strategy to eliminate them?

Tried a combination of power and speed settings, but to no avail.

Greg

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #576 on: February 03, 2012, 02:39:15 AM »
Hi Greg,

I went through this a while back, tried various speed / power settings with no improvement.

Thanks to Sam, who looked closely at my toolpath, he found that my circles / curves were not smooth so the cut was not smooth and the results were rubbish.

This was typical of the problem - note how the true horizontals have been cut perfectly yet all other angles are poor.


After cleaning up the dxf the results were much improved.


Hope this helps,

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 #577 on: February 03, 2012, 04:29:25 AM »
Tweakie
I don't believe that is my problem.  I am cutting test circles using G2 and G3 commands.  So movement, in theory, should be as good as it gets.

I would love to have a go at those bicycles.  Do you have a DXF or similar?

I have tried to take a picture but it is poor.

Greolt

By the way I am not referring to the one large mark.  That is where the cut starts and stops.  I can use strategies to minimise that.
« Last Edit: February 03, 2012, 04:31:28 AM by Greolt »

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #578 on: February 03, 2012, 07:43:12 AM »
Hi Greg,

The problem I have is knowing where to start because the cause could be so many things.

You need to be using true Acrylic (Plexiglas / Perspex) and not Polycarbonate. Cast acrylic is best.
Practice initially with rectangles (single axis movements rather than compound) this will eliminate the issue I mentioned earlier.
You need air assist to protect your focus lens from contamination but not so much air that the vaporised acrylic is blown back into the kerf.
The acrylic needs to be supported above a non-reflective surface (I use a home made grid with glass base).
Do not use too much power, just enough to cut through and no more.(Cutting acrylic is a bit like machining metal – there is an ideal speed and feed – put in too much energy and the results will be poor).
Remove any protective film before cutting (some protective film is OK and some is bad so at this stage it is best to remove it).
I achieve best results by setting my focal point about 1/3 of the thickness into the material.

Does this help at all ??

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 #579 on: February 03, 2012, 05:05:12 PM »
Thanks Tweakie

I will continue to play around with different power and speed settings.

And I will cut rectangles rather than circles.

I had read that plastic film should be removed before cutting and paper should be left on.

Do you have that bicycle file?

Greolt