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Fórum » Only in English » Technologies » Diode Lasers. (Using Diode Lasers with CNC Machines.)
Diode Lasers.
JJWMACHINECO Dátum/Date: Vasárnap, 2013-01-27, 21:51 | Üzenet/Post # 381
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John, are you trying to sabotage my laser work purposely? biggrin biggrin biggrin

I found this on ebay and it's for sale. http://www.ebay.com/itm....8.l2649

Jeff


Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver
 
picengraver Dátum/Date: Hétfő, 2013-01-28, 02:00 | Üzenet/Post # 382
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Well, when you're not burning images, you could cook with it biggrin

John


I paint with a blue light beam.
 
Dave Dátum/Date: Hétfő, 2013-01-28, 04:29 | Üzenet/Post # 383
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ebay also has "FAP800-50W-808nm 50 W @ 58 A" lasers... no clue what kind of a driver this would need, or if the beam can be focused to a point.... hmmmm 58 amps is about 15 of my current driver in parallel???....

Jeff, since your setup uses the z-axis for laser control, I'm wondering if the grayscale mirror is burning a wider path where it burns the most, kinda like pvc does with controling the width of the cut for v-bits?

Dave
 
tweakie Dátum/Date: Hétfő, 2013-01-28, 07:47 | Üzenet/Post # 384
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Hi Guys,

The forum threads to keep an eye on are here;

http://hobbycncart.com/forum/17-204-1

http://hobbycncart.com/forum/46-133-1

Tweakie.


Success consists of going from failure to failure without loss of enthusiasm.
 
JJWMACHINECO Dátum/Date: Hétfő, 2013-01-28, 15:03 | Üzenet/Post # 385
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Idézet (Dave)
Jeff, since your setup uses the z-axis for laser control, I'm wondering if the grayscale mirror is burning a wider path where it burns the most, kinda like pvc does with controling the width of the cut for v-bits?


Dave,

my laser is focused down to .007" diameter and by using a .007" pixel resolution, there are no lines in between the burnt passes even when the laser powers up and down. My Z axis is only moving .00825" doing a mirror because of my 2-1 ratio to the Z axis screw. That would not change the diameter of the focused beam enough to have any un-burnt lines in between either. I have lost shades by using a minimum depth of Z-.009" with a full depth of Z-.0255, which only gives me a theoretical 165 shades between white and mirror, if that can even be considered a shade.

Here is a picture of the back of it and since I used Lithophane code, you can see it looks like a photo negative. There allot more shade differences between B&W then there are between white and mirror. So by the naked eye, I'm guessing you may only see 20-30 shades. If you look closely at the original engraving I posted, there are definitely shade differences. When I laser engrave on Birch Ply, how many shades are there between light brown to dark brown, is a good question also. There are no true Black to White 8bit shading when engraving on Birch Ply either, but I have found is closer when using the white stain.



Tweakie,

I have looked at those threads and is hard to follow by Google translation and it may be just as hard for them to follow this thread for the same reason.

John,

I noticed you started a thread and posted some pictures on the Mach forum with some of your mirror engravings. Would it help you if I posted my results over there also? I am the only one that can honestly say, this can be done with your PEP4 version you sell on eBay. How-ever I can not state that I can TTL a mirror with that version, unless you have changed the code generation in it also. When are you going to release your Laser Edition to the public?

Jeff
Csatolások/Attachments: 5209175.jpg(70Kb)


Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver

Az üzenetet módosította/Modified by JJWMACHINECO - Hétfő, 2013-01-28, 20:41
 
JJWMACHINECO Dátum/Date: Hétfő, 2013-01-28, 21:25 | Üzenet/Post # 386
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I figured out the ultimate setting for my system to do the greyscale laser engraved mirrors. Z-.0095 minimum depth and 40IPM. I engraved my dogs picture again at that setting and put a light behind it and it looks just like the original photo. I also back lit the Spirit photo.

Jeff


Csatolások/Attachments: 4141820.jpg(130Kb) · 8053245.jpg(138Kb)


Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver
 
picengraver Dátum/Date: Hétfő, 2013-01-28, 23:18 | Üzenet/Post # 387
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Sweet Jeff,

Uh - meant the mirrors - not you smile

By all means, please post your work on the Mach forum. You deserve much attention and credit for your analog laser development and work. If it happens to help PEP, all the better and appreciated.

With Dave's DAC it is easy to do TTL with PEP4 gray scale code - that's how I'm doing it with dithered images. I'm not having much success with true gray scale though, and I think it is the mirrors (12" tiles) that I'm using. The silvering seems to burn off too easily. I will get some of the cheap mirrors with the gray backing from Dollar Tree later to try.

I'm not decided yet on selling the PEP laser version. If any who purchase PEP4 from eBay want it, I will send it to them. There are several reasons for this. Primarily, sale's volume is too low to justify the amount of personal time I would need for supporting new users (I get lots of emails from a few), and there is not enough interest to set up a Yahoo Group forum.

I am also not completely happy with the gcode functions as written. I want to try to rewrite them so solid color backgrounds, regardless of color value, will not generate axis moves. This will speed up engraving time for some images.

John


I paint with a blue light beam.
 
JJWMACHINECO Dátum/Date: Hétfő, 2013-01-28, 23:48 | Üzenet/Post # 388
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Thanks John, yea I know I'm a sour puss. tongue

Idézet (picengraver)
With Dave's DAC it is easy to do TTL with PEP4 gray scale code - that's how I'm doing it with dithered images.


So you fixed the code so you don't get the lines ramping off when you TTL with your standard PEP4 version also, or just in your laser version?

I wonder what ever happened to Tweakie's idea of using a PIC microprocessor?

Jeff


Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver

Az üzenetet módosította/Modified by JJWMACHINECO - Kedd, 2013-01-29, 13:38
 
picengraver Dátum/Date: Kedd, 2013-01-29, 01:26 | Üzenet/Post # 389
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Jeff,

The code that was causing the lines was the 'laser' gcode, which is generated anytime the 'Output Laser Gcode' checkbox is selected. When not selected, the gcode should be essentially the same as that generated by PEP4 non-laser version, except some laser-helpful features (Min. Depth, etc.) are missing from PEP4 non-laser. When I added the rotary engraving features back in to the Laser Edition, I copy/pasted them from the non-laser version.

The 'Laser Grayscale' / 'Laser TTL' / 'Rotary Engrave' selection buttons only preselect the settings that are used, not the two gcode formats.

The 'line' problem was the result of skipping white background moves to reduce engraving time, and was 'fixed' by the addition of rapid retract to the laser code before 'any white color' moves, as are found in TTL (B/W) images.

Sorry, I know it is somewhat confusing (it even confuses me sometimes / most times ? confused ).

Bottom line is: PEP4 eBay version should do the same as you are doing now for gray scale mirrors. HOWEVER, I will verify this tomorrow . ok

John


I paint with a blue light beam.
 
tweakie Dátum/Date: Csütörtök, 2013-01-31, 10:02 | Üzenet/Post # 390
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Idézet
I wonder what ever happened to Tweakie's idea of using a PIC microprocessor?


There is a lot more work that needs to be put into this idea before it can become a practical proposition. Although the PIC microprocessor side of things works OK there are issues with the actual laser output power control. Whereas a 1 Watt laser could produce the desired results with an output power variation of say +/- 40% with my laser I am looking for less than +/- 1% variation in output power level.

Basically there are two ways to control the CO2 laser PSU…
The first method is by PWM (or analogue via the internal ADC) to control maximum current. This is OK for relatively large step changes but the internal digital electronics will not handle 256 discrete steps within a +/- 1% variation of output power.
The second method is to pulse the trigger input and again the PWM modulation of the pulse width was not producing the required results. Changing to a pre-set pulse width and then varying the PRF (pulse repetition frequency) produced much more accurate results and this is my current line of investigation.

I will get there in the end – it just requires time.

Tweakie.


Success consists of going from failure to failure without loss of enthusiasm.
 
JJWMACHINECO Dátum/Date: Csütörtök, 2013-01-31, 19:46 | Üzenet/Post # 391
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Tweakie,

I may have another idea. Since you know how to program a PIC Microprocessor, how about using a PIC12F683 and a digital potentiometer to vary the power of your laser. You have a potentiometer to change the output power on your laser now, so can't you tie into this circuit somehow to vary the power to your CO2? You could use Dave's DAC circuit with John's additions to take the step and direction pins to vary the resistance which will vary the intensity of the output power.

http://pdfserv.maximintegrated.com/en/an/AN4051.pdf

This digital potentiometer has 256 increments.

http://www.maximintegrated.com/datashe....051.pdf

The only limitation I can see with your setup is the mechanics of your machine to be able to run at a high enough feed rate with the power of your laser. A rack and pinion or timing belt drive on at least the one axis that travels back and forth would improve the speed considerably. Power increase should be proportional to speed increase to get correct shading results.

It's just a thought and here may be more to it that I am not aware of because I don't have a CO2 laser. I sure would like to have one some day so I can speed up my shaded engravings considerably. cool

Jeff


Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver
 
picengraver Dátum/Date: Péntek, 2013-02-01, 01:49 | Üzenet/Post # 392
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Idézet (JJWMACHINECO)
I have lost shades by using a minimum depth of Z-.009" with a full depth of Z-.0255, which only gives me a theoretical 165 shades between white and mirror,


Jeff,

I was reading back a bit through the recent posts, and realized that I had overlooked replying to you about the number of shades available in PEP4. There are, in fact, always 256 shade values calculated for each image, regardless of the minimum depth you set. In the program coding I calculate a depth factor by subtracting the minimum depth from the maximum depth and dividing the result by 255. While theoretically this calculation will give 256 Z axis increments, rounding to 4 decimals may reduce this by a little bit (yep, pun intended smile ).

I did this last November when the minimum depth setting was added, and I realized that color shades would be lost with the use of any minimum depth other than zero.

John


I paint with a blue light beam.
 
Dave Dátum/Date: Péntek, 2013-02-01, 04:16 | Üzenet/Post # 393
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The maxim 5450-5455 series of digital pots give 256 steps and have an up/down input, looks like they could use the step and direction lines directly. Might be easier than programming a pic... hmmm might have been easier than using a counter and dac too... sigh...

http://www.mouser.com/ds/2/256/MAX5450-MAX5455-105439.pdf

Dave
 
picengraver Dátum/Date: Péntek, 2013-02-01, 04:44 | Üzenet/Post # 394
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Dave,
Nah, your DAC circuit is easier - I can understand it biggrin

How's the rebuild going?

John


I paint with a blue light beam.
 
Dave Dátum/Date: Péntek, 2013-02-01, 05:03 | Üzenet/Post # 395
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Hi John,
The max545* has a built in up/down counter to select which tap of the virtual pot gets selected. I had looked at those earlier, but at the time was looking for something with 1024 or more steps. All of those had a serial data interface instead of step and direction, so I opted to build the counter/dac instead.

Machine rebuild turned ugly... the ballnut decided to gradually shred itself, with metal chips from it showing up on the ballscrew. Mcmaster sent a new one that came yesterday. While I was waiting for it to arrive, I decided to do some more mods to the machine to stiffen the gantry, etc... Most of that's finished today. Tomorrow I'll square up the gantry, and try the new ballnut. I want to be sure there's no residual metal chips anywhere first though. I'm hoping to have it running again over the weekend.
Dave
 
JJWMACHINECO Dátum/Date: Péntek, 2013-02-01, 13:43 | Üzenet/Post # 396
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Idézet (picengraver)
While theoretically this calculation will give 256 Z axis increments, rounding to 4 decimals may reduce this by a little bit (yep, pun intended).


That's interesting John. If I remember correctly you added the option of selecting 5 decimal places at the same time also. With me using my Z axis stepper to rotate the encoder, I'm limited to .0001" incremental moves. With Dave and your circuits, there would be 256 increments.

Dave, I'm glad I posted that digital pot information so it got you thinking about another way to do it also. If you do try it with one of those maxim 5450-5455, please post how you hooked everything up to make it work. It looks like a good way for Tweakie to vary the power on his laser also without using a PIC.

Jeff


Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver
 
picengraver Dátum/Date: Péntek, 2013-02-01, 15:20 | Üzenet/Post # 397
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Jeff,

You have a good memory thumb .

Unfortunately I discovered that Mach3 does not handle 5 decimal gcode properly. Understandable, since it is doubtful that there are any cnc machines that can handle that resolution anyway. I have deleted that option and settled on using the same settings as you use.

I have added the relay that I recently bought to my setup and use spindle M commands to turn the diode on and off now to avoid unwanted burn marks. Works good using the beam suppression feature of the Denmark controller by simply removing the input control signal. FWIW, the Denmark controller is working flawlessly for me, and I highly recommend it.

http://www.ebay.com/itm....f7c795c

John


I paint with a blue light beam.
 
Dave Dátum/Date: Péntek, 2013-02-01, 15:34 | Üzenet/Post # 398
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Hi Jeff,
After re-reading that datasheet, I now remember the other reason that I didn't go that way - they don't come in regular DIP packages and I have enough trouble seeing the pins on a dip package wink . To use it though, I'd tie the CS1 pin to ground, the direction line to the up/down pin, the step line to the inc pin, +5 to the H1 pin, ground to the L1 pin, and use the W1 pin to drive the laser modulator.

Dave
 
JJWMACHINECO Dátum/Date: Péntek, 2013-02-01, 15:48 | Üzenet/Post # 399
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Great John,

That's good to know. The only draw back on the Denmark driver is the max amps. The Flexmod P3 is 4A max where the Demark driver is 2.5A. If I wanted to drive a higher watt laser diode, the Denmark driver would be limited. The Flexmod still shows out of stock on there site. fudge

Dave,

Thanks for that info. My eyes are bad too, maybe from to much lasering. laugh I would have to get my son to build it

Jeff


Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver
 
picengraver Dátum/Date: Péntek, 2013-02-01, 22:39 | Üzenet/Post # 400
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Made some simple mirror stands today. Oak with clear lacquer.

(For some reason, the 'Image' button is not showing to allow me to place pics in the message box.)

John

OK, sorry, I had pics in wrong format.

I will laser a logo on them tomorrow.



Csatolások/Attachments: 4157425.jpg(23Kb) · 1009348.jpg(25Kb)


I paint with a blue light beam.

Az üzenetet módosította/Modified by picengraver - Péntek, 2013-02-01, 22:49
 
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