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Laser etching/PCB maker jig Mark 2

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Conundrum

Sun May 01 2011, 01:05PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

H all.

I just acquired a very nice laser scan module from a discarded Apple printer vintage 1980.
Printer was a lost cause due to extended storage, but snagged some very nice 1.7A/phase monster steppers as well as the optics.

This one differs from the more modern type by having solid glass optics, direct beam path, front surface mirrors as well as a monster laser diode normally only seen on bad sci-fi movies or in museums.

Needless to say the first thing I did is locate the datasheet, and found the chip is stll current, see

for someone else using one.

I also found an equally massive scanner which appears to use a scan mechanism that looks more at home in a printer.

This is going to get used for the laser etcher, as the glass optics ought to be able to take 1w+ of optical power.
The plan is to buffer the data in a pair of 23K256's or 23K640's so that one can write while the other is being read.

Active focus is going to work by mounting the glass lens on a small galvo with feedback from the spinning motor so that as the beam scans it corrects itself. (may not be needed as I tried it and it seems to work fine)

As you may know, I previously attempted this but was put off by the high losses in the plastic optics which attenuated the UV light far too much.
Measured 30% loss in just the first of two plastic lenses

Pics and more details soon!

BTW thanks Justin & friends for this, I owe you one.

-A

hboy007

Mon May 02 2011, 08:28AM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 373

Conundrum wrote ...
As you may know, I previously attempted this

You're kidding me. I started a laser scanner PCB project last year but was thrown back because I couldn't get the damn polygon motor controller to work (perhaps that was the part that broke). In the meantime I built a linear stage and a few days ago I was offered another scanner unit which is still on its way to me. I'm pretty sure you'll get to build one first because my free time is very limited. It is funny how sometimes the same crops up at different places at the same time.

James

Mon May 02 2011, 06:53PM

Registered Member #3610 Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506

The Apple Laserwriter is newer than 1980, it came out for the Macintosh which was released in 1984, I believe the original Laserwriter appeared in 1986. I still have one over at my mom's place, I wonder if it still works.

Polygon scanner assemblies are available from Surplus Shed. Last time I ordered some stuff they had two different types in stock. Usually they require 24V and a 5V enable line. There are also outputs for speed and positional timing but you don't need those to make it spin. You should be able to find the datasheet for the control IC if you have trouble figuring out how to wire it.

That said, I think you will have problems trying to etch anything with a raster scan. 1W is not nearly enough power for the speed it will be moving, unless you are actually making a photo plotter to expose UV sensitive etch resist. Laser engraving machines use X-Y positioning galvos to draw vectors.

hboy007

Mon May 02 2011, 07:55PM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 373

I've tried my luck with the datasheet search. I've kept the pcb the scanner unit connects to for this purpose and there are 24V, 5V, GND and three other signals I know nothing about and since the rest of the controller is gone by now I won't have a chance to hook it up to a scope.

I do not see restrictions originating from the scan speed since the total flux per pixel can be controlled by adjusting the feed velocity of the linear guide.

James

Tue May 03 2011, 06:20PM

Registered Member #3610 Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506

You are still moving the spot rapidly on one axis, and with only a Watt or so to deal with, that's painting a very wide effective spot. Even laser cutting machines utilizing 20-40W CO2 lasers move the spot far more slowly, and high speed engraving machines can be up in the kilowatts.

I have a few 1W blue lasers and while the stationary beam easily sets fire to cardboard and dark paper, when passed through a scanner for beam effects, the resulting line doesn't even begin to char.

Conundrum

Tue May 03 2011, 08:08PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Interesting.

Would make sense, spreading the 1W output into a 20cm wide line would decrease it by a factor of 100 or so.

That said, this would be more than enough to expose a photosensitive PCB or cause sensitive materials to react.

Pinky's Brain

Tue May 03 2011, 08:18PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837

I still say it makes more sense to simply use an old pen plotter.

hboy007

Wed May 04 2011, 06:27AM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 373

We'll have to convince you then

James

Wed May 04 2011, 07:56AM

Registered Member #3610 Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506

Well sure, even a 50mW blu-ray or HD-DVD laser would be fine for exposing UV sensitive stuff, but I thought we were talking about actually cutting or etching material?

hboy007

Wed May 04 2011, 12:44PM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 373

Conundrum wrote ...
Needless to say the first thing I did is locate the datasheet, and found the chip is stll current, see

for someone else using one.

oh look, it's me in the comments section. Maybe I'll give my scanner unit another try.

James, pardon me for not making this clear. Conundrum and I are just planning to shine some nice light on the photoresist.

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