Laser cutter, part II

Welcome to my nightmare - Laser cutter, part II

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[Feb. 4th, 2011|09:22 pm]

[	Tags	\|	electronics, lasers	]
[	Current Location	\|	Purcellville, VA	]
[	mood	\|	accomplished	]
[	music	\|	purring cat	]

I didn't get a reply to my email for a couple of days, I assume because they were celebrating the New Year. Then I got a note reading:

1. NOw we comfirm your machine is 110V

2. Please check the laser tube has the broken or not inside.  and then tell us, because we think it is mostly the laser tube broken

Much apprecaite

I explained that the laser tube was intact, and I was convinced that the laser power supply was broken. They replied:

Can you please return the problem laser power supply and we will send you a new one

OK?

So I removed laser power supply from the unit, and figured it was worth a look before sending it halfway around the world for replacement. Since the supply appeared totally dead, not even the fan running, I suspected the problem was something pretty basic, and perhaps something I could fix.

So I took the cover off the power supply, and found this:

It's unplugged!

The power supply had an internal connector that was unplugged! It is a locking connector too, so it had never been fully engaged at the factory. I plugged it in firmly, buttoned up the supply, re-installed it in the cutter, powered it on, and the fan spun! Thus encouraged, I fired up the cooling pump and hit the test button. Nothing. Maybe the tube doesn't strike at minimum power. I turned up the power a little and tried again.

It worked!

CO2 tube lit

I did a few other tests, and determined that the laser was emitting plenty of power (even unfocussed, the beam burns through a sheet of paper immediately).

I wrote the manufacturer and explained that I had repaired the power supply and wouldn't need a replacement.

Next step is to replace the control electronics with something more useful. The existing controller only works with nasty ancient software on an MS-DOS PC with a parallel port. Originally posted at Dreamwidth.org comments

link

Comments:

From:

randomdreams
2011-02-05 02:43 am (UTC)

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SO COOL. I AM ADROOL.

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From:

perspicuity
2011-02-05 03:21 am (UTC)

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i was expecting to read something like "found dead rat in interlock, removed rat; also found 2 lb brick of illegal somethingsomething and the vendor replying "keep complimentary rat, send something something back please"

#

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From:

neuro42
2011-02-05 04:31 am (UTC)

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Dead Rat Interlock would be a good name for a band.

Hey,

madbodger, dare I ask what you paid for this beast?

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From:

madbodger
2011-02-05 04:42 am (UTC)

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I agree on the band name!

$618 plus $340 (yeek!) for shipping halfway around the world. Gotta love an eBay vendor who calls themselves love-happyshopping (I chose them mostly because other bloggers had bought stuff from them with decent results).

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From:

keith_m043
2011-02-05 04:24 am (UTC)

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I think the traditional response to the results of the burn test is "Groovy!"

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From:

madbodger
2011-02-05 04:44 am (UTC)

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You can actually see the results in the picture - the piece of paper in the upper left has a hole on the lower edge, toward the right - that's what the laser did to it.

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From:

keith_m043
2011-02-05 04:51 am (UTC)

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The spot next to the [what looks like a coil] in the baby schematic there?
Awesome!

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From:

madbodger
2011-02-05 01:27 pm (UTC)

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Yep (it's a fuse in this case)! That schematic was from when I suspected the laser power supply wasn't getting power, so I was tracing out the wiring in the engraver. The wire colours aren't much help (ground is blue, +5 is blue, +24 is blue, etc.). I'm tempted to rewire it with more appropriate colours, since I'll be replacing some of the guts of it anyway.

I'm planning on using IEC colour codes for the AC wiring, the usual PC power supply codes for DC power, and whatever's left for everything else. For your reference and mine, here's what I have in mind:

function	colour
AC hot	brown
AC neutral	blue
safety ground	green
logic ground	black
+5VDC	red
+24VDC	yellow
laser enable	violet
laser on	orange
laser power	grey

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From:

dglenn
2011-02-05 11:33 am (UTC)

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Hey, just how small a hole will this thing make in, say, a very thin sheet of brass? Or aluminium foil? I've been trying to make very small, very round holes by purely mechanical means for a while, with consistently fuzzy results.

But sure enough, everything at every distance is equally fuzzy, so I do at least get the advertised infinite depth-of-fuzziness.

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From:

madbodger
2011-02-05 01:33 pm (UTC)

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While it's a treat for paper, cardboard, wood, rubber, and (some) plastic, it's not so good for metal cutting. A Nd:YAG laser is a better choice for that sort of thing. I'm guessing from context that you want a nice round pinhole. You could ask your artist friend to make one with a needle and aluminum foil. Or you could use a very tiny drill, like I did.

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From:

dglenn
2011-02-10 12:30 pm (UTC)

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I've tried with various sizes of pins and needles, and a few materials (mostly aluminium foil, but also thicker aluminium cut from a V8 can, and a couple thicknesses of brass), as well as different approaches to stabilizing the material I'm punching through and keeping the pin straight. I have yet to achieve an actually round hole. :-( And my smallest drill bit is way too big.

I'll keep trying. (Or break down and buy one from Lenox Laser with birthday money, but the prices there are just high enough to give me pause.)

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