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bluehash

What are you doing right now..?

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LQFP-64, 0.25mm tracks - PCB outline is around 0.1mm. Now, if I only can figure out a good way to align layers then prototyping double sided boards should be within reach.

 

Since KiCAD is open source it should be possible add code to plot directly to the board - after a quick glance through the sources this seems doable...

 

post-45966-0-12341500-1440840504_thumb.jpg

 

To build the "printer" one needs a CNC mill/router to make the parts (and drill the pcbs), so maybe it is a bit too demanding to post as a project?

 

 

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This looks awesome @@terjeio. I really like diy CNC machines and would like to see your machine.

I've machined a couple of 2 sided pcb's and had good luck re-aligning the 2nd side.

When I layout the pcb I put in mounting holes for a small fixture I made. Then I bolt the pcb

to the fixture run the 1st side, pull the fixture out flip the boad and reload the fixture. It works

pretty well.

post-36-0-65198800-1440867576_thumb.jpg

1st side

post-36-0-57292500-1440867606_thumb.jpg

2nd side through holes line up pretty well!

post-36-0-51827800-1440867637_thumb.jpg

finished!

post-36-0-52180500-1440867822_thumb.jpg

heres a shot of my robot

thanks for posting your project, you've got me thinking about putting a laser on my printer.

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@@timotet - nice result from isolation milling.

 

The first machine I made is a fairly standard CNC mill, ballscrews, linear rails & steppers, using Mach3 and Vectric Cut2D & VCarve in the toolchain. The design was inspired by Neo7CNCs machines. This is my main workhorse and vital for my projects. It is mainly used for milling aluminium parts and drilling/milling PCBs.

 

post-45966-0-43820100-1440879614_thumb.jpg

 

The PCB printer was inspired by a youtube video "PCB Laserprinter Version 2" by "Hobby Elektronik" - he has not published any design details so I had to start from the information provided in the video.

 

The reason for doing this was that toner transfer did not work for me, and I think isolation milling not well suited for SMD components (IMO). I could have used my main mill by adding a laser to it - but it has a fairly heavy gantry/Z-assembly so not well suited for high speed laser "printing".

 

The "printer" is designed for PCBs up to Eurocard size (100 x 160 mm) and has a moving table mounted on a THK KR33A actuator. The laser sledge is from an old 3.5" disc drive - I thought I needed to control the focus so I choose that because the assemby contains a small stepper. This is not needed in practice - once the focus it set I have found there is no need to adjust it.

 

I am using GT2 belt for the X-axis, combined with 17 teeth pulleys and microstepping gives it a mechanical resolution of 1196 dpi - very close to the standard 1200 dpi.

 

The software renders bmp images directly (no conversion to G-code) so it is "pixel perfect". The PCB outline on the board above is only 5 pixels wide - a tad over 0.1mm, not bad I think. It is my first attempt at double sided printing - this was not my initial design goal so I need to add some way of achieving layer alignment. Since the table has well defined inside edges I think I can utilize that. What I will try is to mill the board slightly oversized so it aligns perfectly with the home position of the laser when I turn it. A complicating factor is that I have to accelerate the laser to max speed before I start exposing the PCB - this to ensure I do not overexpose the board on the edges.

 

post-45966-0-77340500-1440882226_thumb.jpg

 

post-45966-0-52042300-1440882235_thumb.jpg

 

post-45966-0-55188300-1440882243_thumb.jpg

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Revisiting a project I intended to complete last fall for my coworker... a "reptile cage monitor" for one of his reptiles that is particularly cold sensitive (a "bearded dragon").  It will periodically sample the MSP430G2533's internal temperature and send it out via SI24R1 (nRF24L01+ compatible) radio to a base station I will configure for him eventually, but also a threshold temperature is configured at which point the buzzer will go off.

 

Not sure if the buzzer is loud enough for them to hear it from their bedroom, but this is a POC (proof of concept) anyhow.  We could always have the "base station" send him or his wife a text message as an alternate contact.

 

Using straight C with my mspuartcli and msprf24 libraries, but Tag-Connect is the really awesome piece of this IMO.  MSP-FET programming and reading the serial port's debugging messages via holding the tag-connect connector up against the footprint on the PCB.  Such an elegant way to add the FET & UART interface to a tiny board.

 

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One thing I want to visit with this is the concept of sending a packet, then sitting in RX mode for a short interval so we can "talk back" to the device from the base station but without holding the RF transceiver spun up and drinking power all the time.

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@@terjeio very nice build,cute pretty much says it all :)

 

What are the specs of the laser? And at what speed does it move while "printing"?

 

The laser is a 100mW blu-ray diode, speed is a bit above 200 mm/s. The board in my post above is 3813 by 3109 pixels so it takes a little while to render it.

 

@@timotet the actuator I used is a second hand one and badly worn - but perfectly good for the printer, I bought it from Korea (ebay). It should be fairly easy to adapt the design to employ a cheaper ballscrew or a belt and pulley drive.

 

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Assembling and testing my custom EasyDriver-MSP430 board. The MSP430G2452 is powered by the 3.3V output of the EasyDriver, so only one power supply is needed. Push button to start/stop/reverse the motor.

Despite my poor PCB designing skills it works good so far :) Initially I planned to turn the EasyDriver board upside down to get a smaller package (large cap facing towards MSP430 board), but the A3967 IC is getting really warm/hot, so I did it this way just to be on the safe side...

 

post-31435-0-07428600-1441007506_thumb.jpg
 

 

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Assembling and testing my custom EasyDriver-MSP430 board. The MSP430G2452 is powered by the 3.3V output of the EasyDriver, so only one power supply is needed. Push button to start/stop/reverse the motor.

Despite my poor PCB designing skills it works good so far :) Initially I planned to turn the EasyDriver board upside down to get a smaller package (large cap facing towards MSP430 board), but the A3967 IC is getting really warm/hot, so I did it this way just to be on the safe side...

 

 

Hi @@yosh, this is great. What is the notch is the top left for?

 

Also.. a project page would be awesome, either in the projects section or your own blog :)

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Hi @@yosh, this is great. What is the notch is the top left for?

 

Hi @@bluehash

This notch isn't really necessary but I thought it could provide an easy access to the motor cable pins (see image). If I use the EasyDriver board with screw terminals, I have easy access to the screws. If I use an EasyDriver board with pins, there is enough space to connect stepper motors with standard female dupont connectors. In the prototyping stage I found this a convenient way as I want to test different stepper motors.

 

 

post-31435-0-16361200-1441024858_thumb.jpg

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While waiting for 0.3mm PCB drills so I can finish and test my prototype PCBs I have now managed to get most systems running on my (high-end?) stereo multimedia center.

 

Specs:

 

Remote control (RC5, MSP430G2312).

 

Rasperry Pi 2 running OSMC, internal SSD for music (I am using FLAC compression) - network storage of other media.

 

Power control for Raspberry Pi (MSP430G2553), PC-like startup/shutdown. I2C and button based. Daemon running on Pi handles shutdown requests.

 

Audio DAC (Chinese made).

 

Pre-amp board, 5 input channels including RIAA (optional), digital switching and VCA based volume control. MSP430G2553 on daugther board provides I2C control of input switches, I2C DAC on same for volume control.

 

KeyStone DAB/FM-radio, prototype on MonkeyBoard - new version of pre-amp board will include this and MCU for I2C-control.

 

Main controller powered by Tiva C for now, will move to custom board when drills arrive. 2.2" TFT-display and old stepper motor behind navigator button. I will try to implement selection buttons (on each side of navigator button) by using Atmel AT42QT1012 touch sensors - not sure if that will work...

 

post-45966-0-98820100-1441526389_thumb.jpg

 

 

 

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Experimenting with stencil cutting in my CO2 Laser. KiCad -> HPGL -> G-code so using vector cutting, can adjust cutout size for beam width. I am using PPI-mode (Pulses Per Inch) and adjustable pulse width in order to deliver relatively constant energy to the cut. PPI-mode is implemented by two CPLDs for counting stepper pulses and a 2553 for handling calculations and pulsing the laser. This kind of circuitry may be retrofitted to chinese lasers that only uses simple on/off switching resulting in uneven cutting in the corners (in vector mode).

 

post-45966-0-64133200-1448047767_thumb.jpg

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@@terjeio your PCB laser plotter looks great! I've been trying to do the same thing with my CO2 laser, but it just puts out too much power.

 

 

Rendering bit maps directly is an interesting idea. Does your custom software stream the data to the printer in real time?

 

You can use metal alignment pins in the table to align a double sided board, the drawback being you need to mill holes in the PCB prior to plotting.

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@@greeeg PPI/pulse length control is a must (IMO) - it is then possible to very finely control the power delivered. I have seen some references on the net about using car paint and stripping that with a CO2 laser. A problem with the CO2 laser beam is its wavelength, you will not be able to get the same resolution as with a blu-ray diode - 10.9 um vs 0.4um. Real resolutions above 300 dpi for CO2 is not easy to achieve...

 

My software streams data in real time, I pack seven pixels per byte - the 2553 handles this just fine. With only 512 bytes of RAM available there is not much room for buffering. I am currently working on the laser controller, I want to upgrade this to a TMC1231 (Tiva C) - my plan is to integrate my bitmap rendering code with grbl and to extend the bitmap code to support grayscale engraving (4-6 bits?). The PCB-design is ready - will start coding soon. I will still use the CPLDs and a 2553 for PPI/pulse width control - if anyone are interested in this as a way to "upgrade" a chinese laser I will be happy to share the design and code used.

I know I can buy a DSP way cheaper, but then the fun (and challenges) making it myself is lost.

 

The solution for aligning double sided boards was to pre-mill the boards slightly oversized, there is an edge around the table that then can be used for alignment. So, now I am at the mercy of the repeatability of the optical homing sensors - good enough for prototyping.

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Making a stencil for my new Tiva based CO2 Laser controller, got the boards from China today. I have ported grbl to Tiva, I am going to integrate it into my own code so will make it into a library.

 

Here is a video of the laser in action if you have nothing better to do:

 

https://youtu.be/nkeuVN_bmTo

 

Terje

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