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Fórum » Only in English » Technologies » Diode Lasers. (Using Diode Lasers with CNC Machines.)
Diode Lasers.
picengraver Dátum/Date: Csütörtök, 2012-03-22, 02:41 | Üzenet/Post # 41
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Thanks guys, I appreciate your kind words.

I'm still learning to post here, so my apologies if I reply in the wrong place.

Peter, Krylon Fusion is a spray paint formulated to paint plastics and other materials. See here: http://www.krylon.com/products/fusion_for_plastic/

It dries to a hard, durable finish. I have tried a couple of other brands of spray enamel, and this is best so far. I would think that any spray enamel that dries rather quickly might be usable. I used a black satin only to minimize the laser beam reflecting and not burning well, but I haven't done any testing to prove whether it would or not. Maybe a gloss paint will work, too. I suggest you first try what is easily available there.

Today I experimented more and made four more boards, similar to the first one. They are for a LED flasher circuit for my friends model airplanes and cars so he can play at night with his radio control toys. He also owns a local hobby shop, so we do, and have, played a lot together over the past 50 years with our "toys." Our first radio controlled planes used vacuum tube receivers and transmitters .

I have simplified my method, and actually got better results. Instead of using steel wool and a brass brush to clean the traces, I discovered that making a paste of a powdered kitchen pot cleanser (Bon Ami brand - http://www.bonami.com/ ), and scrubbing the boards after burning with a soft toothbrush, the burned paint cleans from the traces very well and ready for etching. I imagine similar paint and cleanser must be available to you there.

Tweakie, I will experiment more later with M10/M11. I haven't given up. I thought that I had my gcode correct, but I got erratic firing, delayed on AND off timing of the laser diode, as well as completely missed laser firings. I have changed computers, diode drivers, stepper drivers, power supply, Mach3 versions, gcode files, and even wiring. Nothing fixes the problem. So far a resolution escapes me, and also puzzles me since you and others are getting such good results. Next week I will hand code a file using your example above and see how the diode reacts. My gcode is the only other thing that it can be.

By the way, have any of you tried burning leather? It does burn nicely.

John Champlain
www.picengrave.com

Csatolások/Attachments: 1135173.jpg(147Kb)


I paint with a blue light beam.

Az üzenetet módosította/Modified by picengraver - Csütörtök, 2012-03-22, 02:52
 
tweakie Dátum/Date: Csütörtök, 2012-03-22, 07:25 | Üzenet/Post # 42
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Hi John,

Yes, I tried Leather - the smell was so bad (obnoxious) I will never try it again. sad

Tweakie.


Success consists of going from failure to failure without loss of enthusiasm.
 
picengraver Dátum/Date: Péntek, 2012-03-23, 22:27 | Üzenet/Post # 43
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Ha Ha. Yes, it is that, but also one reason why my machine is in a screened-in room on the back of my home, and with an overhead ceiling fan (keeps the BOSS happier, too).

JohnC


I paint with a blue light beam.
 
tweakie Dátum/Date: Szombat, 2012-09-01, 08:42 | Üzenet/Post # 44
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For those who have not seen his work - some extremely interesting results (by varying the laser diode intensity) producing shades of gray, (as opposed to half-tone) are now starting to be achieved by Jeff on the Vectric forum.

He is basically taking an image and slightly embossing (Photoshop or similar) to enhance the edges then using PhotoVCarve to produce a lithophane toolpath.

He has fitted a rotary shaft encoder to his Z Axis which outputs a 0 – 5 Volt analog voltage which is then fed into a FlexMod P3 driver.

The small amount of Z Axis movement then controls the laser diode intensity which produces the shades of gray.

Not all materials will accept shades but this method seems to be ideally suited to wood.

There is further information in his thread here

Tweakie.

Csatolások/Attachments: 9922241.jpg(102Kb)


Success consists of going from failure to failure without loss of enthusiasm.
 
Béni Dátum/Date: Szombat, 2012-09-01, 20:28 | Üzenet/Post # 45
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tweakie, Excellent result. Excellent method.
( and beautiful model. ) ok


http://dotg.weebly.com/
http://benishare.weebly.com/
 
Amatőr Dátum/Date: Vasárnap, 2012-09-02, 09:50 | Üzenet/Post # 46
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tweakie, that is awesome. Seems a new method without points, the laser works "on fly". Really nice results.Please pass our congrats to Jeff!

H1i.hu
 
tweakie Dátum/Date: Vasárnap, 2012-09-02, 11:25 | Üzenet/Post # 47
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Hi Guys,

Just ‘thinking out loud’ - as a development idea and because not everyone would necessarily want to fit a rotary encoder to their Z Axis.

It would not be too difficult to program a PIC microprocessor to accept Step and Direction input and then output a 0 to 100% PWM signal. Just a couple of extra components (forming a DAC) could be added to then convert this to a 0 to 5 Volt analog voltage, if required.
If it was configured as, say, the B Axis then the GCode could be easily edited in Notepad to replace the ‘Z’ with ‘B’.

This should enable any diode laser controller which has a ‘modulation input’ to be used with variable output power and produce ‘shades of gray’ on wood, or similar, materials.

Tweakie.


Success consists of going from failure to failure without loss of enthusiasm.
 
Amatőr Dátum/Date: Vasárnap, 2012-09-02, 14:27 | Üzenet/Post # 48
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tweakie, I think that it would be good to create a circuit what can do this.
Why should be the outout between 0 and 5V? Do You know a laser circuit wht can recieve this signal? Is it a standard in laser related circuits?
Wouldn't it be simplier to use the PWM signal directly for the laser? (just thinking loud too)


H1i.hu
 
tweakie Dátum/Date: Vasárnap, 2012-09-02, 15:31 | Üzenet/Post # 49
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Hi Amator,

I think you are quite right. Certainly my laser controller (PSU) accepts 0 – 100% PWM at 5 Volts but I do not know if that applies to all laser controllers.

Do you think that a Step / Direction controlled PWM generator such as this would be useful to forum members ??

Tweakie.


Success consists of going from failure to failure without loss of enthusiasm.
 
Amatőr Dátum/Date: Vasárnap, 2012-09-02, 16:26 | Üzenet/Post # 50
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Quote (tweakie)
Do you think that a Step / Direction controlled PWM generator such as this would be useful to forum members ??

I don't know what it does to drive 1W laser with PWM. Maybe on lower power (for example under 50%) it does not take effect on wood.
With higher power lasers I think it can increase the engraving speed, because it's real "on fly" engraving without points.
I find Jeff's results really awesome, but the solution is quite difficult.
One way to create PWM signal from the lithophane kind gcode height by steal the step and dir signal and convert with a circuit.
What do You think about Mach's PWM output? Can it be used to simplifi this task?


H1i.hu
 
tweakie Dátum/Date: Hétfő, 2012-09-03, 06:39 | Üzenet/Post # 51
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Quote
What do You think about Mach's PWM output? Can it be used to simplifi this task?


Hi Amator,

Although the Mach3 generated PWM is good, it is adjusted with the S*** command and is not available as a combined axis movement so cannot be adjusted on the fly.

Tweakie.


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Amatőr Dátum/Date: Kedd, 2012-09-04, 17:10 | Üzenet/Post # 52
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tweakie, then the only way to create pwm from step and dir signals is a circuit. How difficult could it be?
What do You think about to use this pwm on an impact engraver's power?


H1i.hu
 
tweakie Dátum/Date: Szerda, 2012-09-05, 07:31 | Üzenet/Post # 53
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Hi Amator,

Quote
then the only way to create pwm from step and dir signals is a circuit. How difficult could it be?


As far as I can see this is very simple and easy to do.

Quote
What do You think about to use this pwm on an impact engraver's power?


If PWM was used to control an impact magnet's power it would vary the size (diameter / depth) of dot produced but I can see no advantage in being able to do this. (I think it would only be of benefit to laser users). Am I missing something ??

Tweakie.


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Amatőr Dátum/Date: Szerda, 2012-09-05, 15:46 | Üzenet/Post # 54
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tweakie,
Quote (tweakie)
As far as I can see this is very simple and easy to do.

How would You solve it?

Normally halftone pictures are made by producing different depth/diameter of dots in material, but it requires to have precise flat surface, it is sensitive for inaccuracy in plain. If You have a g-code for drilling halftone picture, You can use the step to pwm circuit to create different size dots but it can follow the bended surfaces. The circuit generates the pwm from the Z steps taken down, and gives the start signal when the Z axis starts to go up, at this point You have the depth, able to give the correct strenght for impact device, and when Z turns back can strat the stroke. (Just thinking about it, maybe I'm wrong)


H1i.hu
 
tweakie Dátum/Date: Szerda, 2012-09-05, 20:36 | Üzenet/Post # 55
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Hi Amator,

Quote
How would You solve it?


To be totally honest I have not decided yet, mainly because there are still too many unknown’s, but I do have a number of different ideas and with a bit of testing / experimentation and more test data one will come out on top.

Thank you for the explanation of a possible application (which I had not considered at all). The work material would have to be relatively soft (wood perhaps) or else the magnet would need to be quite powerful for the larger dots to be produced. In any event, your suggestion could work very well indeed.

Do we actually use halftone though ??

DotG, for example uses 'dot dithering' where equal sized dots are arranged in varying density to form the illusion of shade. What software would you have in mind to create halftone GCode ??

Tweakie.


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Amatőr Dátum/Date: Szerda, 2012-09-05, 21:22 | Üzenet/Post # 56
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tweakie,
Quote (tweakie)
Do we actually use halftone though ??

No. Just I was playing with the possibilities in my mind.
Halftoner 1.4 would be used to generate the gcode but I have a doubt that the impact force is not linear with the desired dot diameter.

Do You think to give the job for an mcu? Avr or Pic, perhaps Arduino? I suppose You don't plan with TTL elements smile


H1i.hu
 
tweakie Dátum/Date: Csütörtök, 2012-09-06, 06:50 | Üzenet/Post # 57
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Hi Amator,

I did some tests last night with varying the voltage applied to my impact magnet in an attempt to produce different sized dots.
It sort of works but the results are very disappointing. I suspect that this is a process better suited to drilling than it is to impact.

Regarding the PWM - I think I will be using a 16f627 PIC microprocessor (or similar). This is capable of producing the HPWM signal as a background task, freeing the processor time for detecting the step / direction signals and calculating the appropriate changes to the % PWM output.

Tweakie.


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Amatőr Dátum/Date: Csütörtök, 2012-09-06, 18:10 | Üzenet/Post # 58
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tweakie,
Quote (tweakie)
the results are very disappointing

semms that finished with my theory smile

Quote (tweakie)
I will be using a 16f627 PIC microprocessor (or similar).

The first asm program I wrote was created for 16f628A, nearly the same processor. I made an optimized heat distribution system for the underfloor heating and radiators. I found programming in asm is very uncomfortable.


H1i.hu
 
elektron Dátum/Date: Péntek, 2012-09-07, 07:00 | Üzenet/Post # 59
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With ARDUINO to make PWM signals is very simple in C language, if I remember correctly this line can solve the job:

analogWrite(pwmPin, pwmVal);

or something similar but a full program is more complicated.


Az üzenetet módosította/Modified by elektron - Péntek, 2012-09-07, 07:03
 
tweakie Dátum/Date: Hétfő, 2012-09-10, 17:59 | Üzenet/Post # 60
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Quote
Just ‘thinking out loud’ - as a development idea and because not everyone would necessarily want to fit a rotary encoder to their Z Axis.
It would not be too difficult to program a PIC microprocessor to accept Step and Direction input and then output a 0 to 100% PWM signal. Just a couple of extra components (forming a DAC) could be added to then convert this to a 0 to 5 Volt analog voltage, if required. If it was configured as, say, the B Axis then the GCode could be easily edited in Notepad to replace the ‘Z’ with ‘B’.
This should enable any diode laser controller which has a ‘modulation input’ to be used with variable output power and produce ‘shades of grey’ on wood, or similar, materials.


Hi Guys,

Giving this idea a little more thought and looking at available options the PIC 12F683 microprocessor seems to be an ideal candidate. This little chip is quite big in features and will run the PWM as a background task and allow the processor to spend it’s time receiving the Step transitions, comparing the Direction state and updating the PWM output accordingly. The command set comprises only 35 instructions so programming is no big deal.

For the initial testing I have programmed a linear response, requiring 255 Step transitions to increase the PWM output from 0 to 100%.
When connected to the breakout board and configured within Mach3 as the B Axis the PWM output is adjusted up or down by the B*** command so, for example, B127 will produce a 50%PWM, B000 will produce 0%PWM and be off , B255 will produce 100%PWM and be on continuously (CW mode) and pro-rata for any steps in-between.

If a lithophane creation software such as PicEngrave or PhotoVCarve is set up so that the maximum cut depth is equal to 255 machine steps (with Z zero at the top surface of the work) and it’s generated GCode is then edited to replace the ‘Z****’ with a ‘B****’ then the power output of any laser controller (which accepts PWM input for it’s current control) can be used to create shades of grey.

The prototype is not much to look at but it works surprisingly well. I still have a bit more work to do on the software side as initial tests showed a ‘rollover’ from 100% to 0% but it is nothing that can’t be solved.

Tweakie.

Csatolások/Attachments: 6709260.jpg(53Kb)


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