Combined CNC Engraving Technologies. Spindle + Laser

We tried something new that has been planned by us now for quite some time. Me and my son 3D spindle engraved a Laurel & Hardy height map greyscale with a 1/32" Ball End Mill with a 1/8" depth. We then laser engraved shades on it with analog modulation from the original image afterwards. We combined the gcode movements generated from Picengrave Pro 4 + Laser using both images to accomplish this. Our Dual 445nm Laser Diode's intersecting focal points follows the spindle engraving's contours up and down to maintain focus on the surface. This is the very first time ever trying to do this.

​PicEngrave CNC Image Engraving Software

Picengrave Pro 4 CAD Cam CNC Software Image to Gcode Lithophane Laser Engraving | eBay

http://www.youtube.com/watch?v=rUIrS3Ot1I4

Now that's what I call a laser ! it takes pyrography to a new level :thumsup:

Thank you,

It was a fun build and project, that's for sure. We can actually laser engrave shades on wood, mirrors, artist canvas, leather and something painted white with our 445nm laser diodes. The white paint and white leather gives us the closest to 8bit shading. We are experimenting all the time on different kinds of materials and processes.

Jeff

Hi

did you build the head on this ? any plans.

Amy very impressed, have you tried it on stone.

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Originally Posted by george uk

Hi

did you build the head on this ? any plans.

Amy very impressed, have you tried it on stone.

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Thank you. Yes, me and my son built the laser head using two 9mm Nichia 445nm diodes with two Flexmod P3 drivers. It has a total of 4.5W max power, but does not have enough power to engrave on stone. It was a one off build, so no plans are available.

Hi, some questions, if you can shed some light:

-what goggles you use for adjusting and looking at whats going on? i have been looking at Eagle Pair® 190-540nm OD4+, what exactly would i need to see when adjusting and working with the laser?

-Is this driver ok? I am considering it, cause its here in Europe
http://www.ebay.es/itm/161353680119?...84.m1423.l2649

-How to adjust the driver to 2.4A so it would not burn the diode, cause it can output up to 3A. i searched for this, but as am really not into electronics :panda:


- i am looking at the Nichia NDB7875, very roughly maybe equivalent to your 2 diodes. is it better to buy a double driver and in the future fix 2 of them and achieve ~5-6W. I mean is there any real benefit, for engraving in general and gray scale engraving?

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Originally Posted by silyavski

Hi, some questions, if you can shed some light:

-what goggles you use for adjusting and looking at whats going on? i have been looking at Eagle Pair® 190-540nm OD4+, what exactly would i need to see when adjusting and working with the laser?

-Is this driver ok? I am considering it, cause its here in Europe
http://www.ebay.es/itm/161353680119?...84.m1423.l2649

-How to adjust the driver to 2.4A so it would not burn the diode, cause it can output up to 3A. i searched for this, but as am really not into electronics :panda:


- i am looking at the Nichia NDB7875, very roughly maybe equivalent to your 2 diodes. is it better to buy a double driver and in the future fix 2 of them and achieve ~5-6W. I mean is there any real benefit, for engraving in general and gray scale engraving?

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Those laser safety glasses will be fine for adjusting and watching progress of the engraving. That is a good analog/TTL driver and I would recommend it. The driver should have instructions for setting the threshold and maximum output amps. That is what the potentiometers are for on the driver board. The Nichia NDB7875 is what we are using. The advantage of engraving greyscale is it gives you better shading results compared to pulsing the laser and creating allot of dots to get shades.

Thanks! Now i read a bit more into this but still have some things unclear:

-how many amps you drive the each Nichia NDB7875? it seems it should be much less than 2.4A i thought, for continuous use i mean. If much less, couldnt i use in series 2 diodes with say 4A driver, or i still need the more expensive 2 channel driver?
-do you have Lasorb fitted on your set up?

-The DAC still puzzles me. now having to fabricate the DAC converter as per the PDf, i start to think- is there any schematic to make all by my self, including the driver?


-why you say at many places that the encoder gives better resolution than the circuit. I can not understand that. I was also thinking as my machine will be servo driven, could i somehow use the servo encoder /2500ppr / or even somehow use the analogue 0-5v output of my 8 axis Galil board

We only drive each Nichia at 1.7a each. That is the max the Data sheet recommends. We never tried wiring 2 diodes in series to one driver, so I can not answer that question. LD's are expensive to replace, so experiment at your own risk. We only have used a dual driver or two single drivers for driving the two Nichia's.

We have Lasorbs on all of our Laser Diode engravers.

Here is our new updated PDF if it will help you any. It has a schematic for the DAC and where to buy the Digital Potentiometer.

http://www.picengrave.com/Pic%20Prog...r%20Setups.pdf

Search here for Laser Diode driver schematics. There is allot of information in the Sam's Laser FAQ.

http://lmgtfy.com/?q=analog+modulati...iver+schematic

The DAC is 8bit (256) resolution for modulation voltage change between the 0-5v. The encoder is 10bit (1024) That's four times finer incremental voltage changes. It must be one of these US Digital MA3 absolute magnetic shaft encoders. We are not familiar with the Galil board, but if it has step and direction pins/ports, a DAC can be wired to it or another stepper/servo motor and controller to drive a MA3 encoder.

Hi,
thanks for the info. I bought almost all of the necessary parts. I will go by the digital pot way.

Edited:
ok i have it clear now why the step up converter. To provide +- and ground to the opamp. Just figured that if using PC ATX power supply to power everything it has +-12V so the step up converter is not needed.
I think of powering the diode and the DAC from the same ATX PSU. Will see how it works. Will use Lasorb of course.

Hi,
some help here please. I am not very good with electronics.

I am looking at the pdf and i see some difference between the 2 drawings

some questions:

-the caps on the 1st /hand/ drawing go to ground and on the second not? I started soldering like the first, then saw the difference, so which one is correct?

-there are 2 more caps on the second drawing /DIR , STEP/ ??

-i will use +-12v from PC ATX instead of 7-9v do i need to change something? UA741CN

http://www.mycncuk.com/attachment.ph...id=14735&stc=1
http://www.mycncuk.com/attachment.ph...id=14736&stc=1

It's difficult to answer the question about capacitors as it's so difficult to follow the second diagram, but it looks to me as if they are doing a different job. However, I think that they should all have one end to ground. You can probably use the capacitors in both diagrams - in the first, they are power supply decoupling caps which are a good idea, and in the second probably to reduce noise and small random fluctuations on the output which you often get when a variable resistor is involved.

As for power supply - the original diagram shows +7V and -7V. You could replace these with +12V and -12V from an ATX supply. That should work fine and is well within the 741 ratings. You can't use just +12V and ground; the 741 would be happy but the output would not go right down to zero.

Thanks Neale,
Meanwhile I have soldered everything as per second diagram.

Now i wonder how to test and adjust everything without burning my BOB or the laser driver. I still dont have the diodes. It seems i have to install the program and start from there.

I still don't understand what these pots do. The one at the output seems to adjust the max voltage output, right? I mean its still not clear how to adjust them.

I am frustrated at the point of freelancing sb to make PCB drawing and even revising all and making me a PCB where double laser driver and this is integrated in one so its very simple to connect and operate. Not sure if there would be enough public for this but i am ready to jump and sale it slowly later or some kickstarter campain.

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Originally Posted by silyavski

I still don't understand what these pots do. The one at the output seems to adjust the max voltage output, right? I mean its still not clear how to adjust them.

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The pot connected to the input of the 741 is to adjust the output to zero, and the pot at the output is (as you say) to reduce the nominal 0-5V output range to 0-something less, that is, reduce the output swing. I assume that the "digital pot" device has an output range of 0-5V and the output of the 741 will follow this.