Gradient Reference for the 25 Watt Laser Cutter

A map of how deep and/or dark the laser cutter etches based on the percentage of power and percentage of speed.

So, I was just getting in to the ‘Space when Jason G. and I started talking about the laser cutter.  I had planned on doing some simple tests to determine the level of shading that I could get for an as-yet unnamed project when he mentioned that he (and others) were talking about doing a full map of different settings and the results.

I thought that I might as well give it a shot.  The set up was interesting.  I created a grid of rectangles in CorelDraw (oh, how I hate you!) and then used the preferences dialogue in the laser cutter driver to adjust the speed and power for each little square.

I should explain that the driver recognizes 8 colors and for each color in your image you can assign different settings.  It was a little trying given that the grid is 10×10 but, eight at a time, I assigned the appropriate colors, then settings and let it cut.

After the charring became significant on the low speed/high power settings, I decided to omit the rest of them because, honestly, who wants their project to turn into charcoal?  If you can’t read the Olde English font, it says, “Here Be Fire! (not suitable for etching).”

As you can see, there is a very nice gradient that results from many of these settings used in conjunction with one another.  I also left the tar/smoke-damage on because I wanted people to know what their project would look like immediately after using these settings.  I suspect that most of that can simply be sanded off.

I had forgotten my camera, but a big thanks to Kevin B. for taking a few shots and emailing them to me via his phone.

Next, a cutting template similar to this one.  Oh, and a gradient rainbow.  Yeah, a monochromatic, smells-like-a-forest-fire rainbow should do the trick.  Maybe I’ll even make it a double. :)

Makers, assemble!

Yeah.  Having access to a laser cutter is pretty boss.  I’m planning to wear this to the premiere of a certain movie this weekend.  Four layers of acrylic; two diffuse, two opaque.  11 LEDs, 11 100 Ohm resistors, some phone cord, some solder, and a 9V battery.  There’s no lack of great pages on Instructables about how to make your own.

PCB with Lasered Paint Resist and Fast Sponge Etching

TomG shows how he etches PCB boards using paint, a 25W laser cutter, Muratic Acid, 30% H2O2 and a sponge. Much frothing ensues.

The technique is a neat one, given the presence of a laser cutter, because it can take you from copper clad to etched board in a pretty quick amount of time.

One note, the Muratic Acid is actually from a pool supply store, not Home Depot. It is, of course, dangerous. Wear safety goggles, use gloves, use in a well ventilated area. (The acid smells like a punch to the nose, don’t inhale it)

Fun with Lasers!

Just about the only thing I don’t love about the Open ReVolt motor controller is the case.

As cool as an Open Source Motor Controller is, it’s just not shown off with a basic metal cover. In fact, I actually drilled through the original cover (and put clear packaging tape over the holes!) to see the power and troubleshooting LEDs through the lid.

Recently, the Milwaukee Makerspace got itself a laser cutter. It’s not all that powerful, but more than capable for cutting plastics. One of the Makers posted a blog entry about making a wood box on the laser. He used a program called BOXMAKER which helps you layout the size of your box, including overlapping cut edges to put the whole thing together.

This got me started on the idea of building a clear plastic case for my 500 amp Open ReVolt controller. But I had never even used the laser before. I sat down with the member who owns the laser, and he took me through the basics of importing files, exporting to the laser, and modifying power and speed settings. With that, I was able to start making a few test items on the laser. I figured that since I already had the Open ReVolt logo as a vector file, it couldn’t be easier to try out etching some plastic with it.

I used the laser to make a few small test pieces on various materials. The two logos turned out pretty well. They were both etched AND cut out with the laser. On the orange medallion, I mirrored the image, so it would be a design on the “back” of the piece. That keeps the upside nice and shiny and clean.

Plastics cut on the laser

 

After practicing a bit on the laser, I started wondering what else I could cut, mark, or etch with the laser. Last night, I forgot something at the Makerspace, so I had to return there this morning to retrieve it. And I am NOT a morning person, so I had my trusty travel coffee mug with me. It’s stainless steel with an anodized dark gun metal finish to it. “I bet that would laser engrave nice!” I though to myself. Sure enough, it only took a little tinkering to figure out how to keep the mug from rolling sideways inside the laser before I could engrave it.

Also, when I came in this morning, all the lights were off, except for one – Tom’s LED lit plexiglass desk drawer. I asked him for some advice last night about how to engrave and then edge-light in clear plastic. He plugged in his project to show me a sample, and had left it on. It was eerily awesome to see the Makerspace lab lit up by green LED power! It’s a good example of how I would like to engrave the top of the controller case and light it up.

Well, that’s it for now. Next, I’ll have to take careful measurements of the controller, lay out the box, find some material to work with, and figure out where and how big the cuts in the end plates will need to be for the bus bars.

Unexpected Detour

When I arrived at the space Sunday, I had planned to work on a circuit board design in DipTrace.  After I left, I had spent six hours rewiring a golf cart.  Allow me to explain…

It all started when I went to take the trash out.  I used the golf cart with the flatbed to ferry the cans out to the dumpster.  After emptying the cans, I rode back and decided to charge the cart’s batteries.  Tom and Rich had just returned from lunch and Tom suggested we swap out batteries instead.  While swapping them out, we decided to also rewire them.  While rewiring them, part of the cart broke.  There’s a small white plate under the driver’s seat.  It’s about 4″ x 6″, likely made of asbestos, and holds a series of copper contacts that a lever attached to the gas pedal slides over to select the speed of the cart.  And it broke in two when we tried to tighten fix a wire on it.

We had a few options: try to mend the old, brittle plate, replace it with something new, rewire the whole thing, or scrap everything out for a solid state motor controller.  Not wanting to adopt a new project or sacrifice a motor controller that could be better used elsewhere, I volunteered to try and fabricate a replacement for the broken part.

First I documented everything just the way it was.  I labeled wires, took photos, scribbled down notes, etc.  Next I went about removing the broken plate.  There was probably more rust than metal on those bolts.  Then I took a pair of digital calipers and a ruler and measured the locations and sizes of holes for each component.  I considered using the CNC router or drilling a plate by hand, but the laser cutter seemed to be a much faster and precise approach.  I drew up my replacement plate in CorelDraw and found a scrap of 1/4″ acrylic that matched the size and thickness of the old plate.  After some tinkering with the printer driver and a dozen passes with the laser, I had a copy of the original in plastic form.

The next few hours were spent migrating the old parts over to the new one and wiring it back in.  Right around 7:00 PM, I tied some batteries together and the thing leaped forward.  A few more tests and it should be as good as new.  Someone suggested that maybe the plate was asbestos to avoid heating issues so we’ll keep an eye on that too.

Easter at the Makerspace

eggs

As we think about Easter, we can’t help but think about all the cool stuff we could do at the Makerspace. Oh sure, we’ve got the Egg-Bot, to plot art onto eggs (and other spherical objects) but hey, that’s almost too easy, right? What else can we do?

wood bunnies

Maybe some laser-cut bunnies! We could use the Laser Cutter to cut out some bunnies and do something interesting with them. (Or the CNC Router could be used for bigger pieces.) Hmmm, I bet we could even make some sort of crazy laser-cut Easter baskets, maybe using living hinges.

Speaking of bunnies, what is Easter without chocolate, put them together and you’ve got chocolate bunnies, which I’d consider the pinnacle of Easter treats.

bunny

With the Makerbot we could print these awesome chocolate bunny molds and kick out our own chocolate bunnies!

So… what will you be making for Easter?

My neverending quest for quick turnaround prototype PCBs

For years I have dreamed of a fast way to prototype PCB for projects I am designing.

20 years ago I was using rub on drafting tape and stencils – slow and spotty results.

I tried to modify a plotter to plot resist directly to a PCB – no luck.

Magic markers – I’m no artist.

5 years ago I hacked a laminate router by tapping into the stepper controllers and adding a better Z axis – It can rout boards ok, but takes some tweaking.  It only does fairly wide traces.  But its great at drilling holes!

2 years ago I tried the inkjet printing systems – lots of smeared wet ink and poor registration, not very effective.

I opened up a laser printer and tried to get a board to go through it – almost worked, but the fuser was to narrow to take the board.

Although I haven’t found a fast system yet, I get by with the PNP Blue material and a good laminator.  Although I am regularly disappointed when dust, not quite clean boards, minor wrinkles and other issues leave gaps in traces that need touching up.

Which brings us to the latest attempt:

Now that the maker space has a small laser cutter I am trying to find something I can coat a board with and either burn away or melt onto the board to act as an etch resist.

Early attempts with paint had moderate results – our laser cutters on only 25W so it didn’t burn it cleanly.  I have heard that using flat black paint and a more powerful laser works.

Paste wax and markup fluid weren’t dark enough for the laser to vaporize (thinking of trying black crayons)

The latest attempt uses laser printer toner (just like the PNP only skipping the printing and iron on steps.)

The problem is how to get an even coat on a board without it blowing around.  Static electricity has potential (just like what they do inside a laser printer) but I don’t like the idea of a 5KV power supply exposed and handling powered toner is an automatic mess.

So for the first attempt I mixed the toner with rubbing alcohol (30% water).

Messy stuff!

I painted it on with the tongue depressor but it seemed to coat evenly and took only a few minutes to dry:

It mixes well and paints on fairly easily, here are some sample prints I did at various power and speed settings.  I cleaned the board fairly aggressively with paper towel and rubbing alcohol.

None are quite clean enough to become PCBs but they are getting close.

Although the toner paint looked dry, it may still have had some water in it.  I plan on trying a batch with denatured alcohol (100% – no water) and see if it works better.

 

2/16/2012

Updated progress

I have been trying a number of materials and methods to make my fast turn circuit boards.

I’ve decided that last toner is too messy and there are too many variables to create a repeatable process.  So now I’m trying various other masking materials:

 

Black and white spray paint – it works ok, but the ash left behind by the laser resists the etchant and leaves you with a poor etch.

I also tried tape:  Painters tape, electrical tape, clear and brown box tape.  The masking tape worked ok until the etch was slow and the tape started to dissolve.

I held a few of the boards up to the light so you can see how it etched:

 

 

 

 

 

 

One of the other members of the space found someone who had made the black paint work.  The process is to do 2 passes with the laser – the first burns off the paint, the second burns off the ash!  Then you wipe the board down with rubbing alcohol to clean off any residue.   Here is a set of 3 projects I lasered and etched at once:

This board turned out rather well, I had some trouble with the etchant taking for ever so lost some of the detail on the lettering, but the boards came out nicely.  I should get even better results on the next project.

In an attempt to speed the entire process up I tried to drill holes with the laser cutter from the back of the board:

   Not very good results!  After about 6 passes it still didn’t cut through thin PCB material and stunk and smoked the whole time!

 

 

 

 

 

 

So instead, I used the laser to cut wholes in a small piece of acrylic to use as drill guide:

 

 

 

This gives you a pattern to follow using a Dremel and the holes wind up in the right places and nicely lined up.  I drilled 2 holes in opposite corners of the board and used the leads from resistor to line up the template and board and hold them together while drilling.

 

 

 

This image shows the template attached to the board and about half the holes drilled.  This worked very nicely!  The only problems was small disks of acrylic getting stuck to the drill bit (you can see little craters on the left side of the board where these came from)  I had to clean the drill bit twice to drill the whole thing.  Either bigger holes or a different plastic might fix this.

 

This is first of the 3 boards I put together and it works just fine.  It is a level translator for the encoder you see in the holder.  The encoder will be attached to the drive motor in my electric car and feed back motor position to the controller.  The encoder is 5V and the controller wants a 15V signal.  The test bed uses a 15V power supply and LEDs on the 4 quaderature outputs.

Encoder test video

Wooden Nickels

There’s an old saying “Don’t take any wooden nickels” but I say “Do take some wooden nickels!”

Especially if they’re laser-cut wooden nickels from Milwaukee Makerspace.

Wooden Nickels in CorelDraw

Here’s my file in CorelDraw, with different colors to indicate the front etching, back etching, and the cut.

Laser cutting wooden nickels

I taped down a piece of 1/8″ Baltic Birch plywood to the laser cutter platen so it wouldn’t move, and then I set the laser cutter to etch the front (which is our logo, in blue) and ignore the other parts.

Once I was happy with the front etching, I changed the settings to cut the outline (in red) and ignore the black and blue. After the cut was complete, I pulled out the pieces and flipped them over for the back etching.

(Here’s a tip for you: I mentioned that I taped down the piece of wood so it would not move, but the other trick I have it to use a piece of tape to check if the cut is all the way through. I just stick a piece to the cut piece and see if it will lift out.)

Laser cutting wooden nickels

Our nickels have the front etched, have been cut out, and now they’ve been flipped over and put back in place to etch the back.

Laser-cut wooden nickels

And here are our completed wooden nickels! Ready to be handed out at any event we might be attending, or to guests of the Makerspace.

I’m not 100% happy with them, mainly due to some weird file formatting issued between creating them in Inkscape and importing them into CorelDraw as DXF files, but those are all minor issues we can tackle next time.

BoxMaker

We’ve got a Laser Cutter! We can cut things… like boxes. So head on over to BoxMaker and make a box!

As far as materials, that’s a little trickier. I tried wood, but currently the laser cutter can’t handle cutting your standard 1/4″ plywood. (Update: 3mm Baltic Birch plywood works great though!) Here you can see the results of me trying.

Wood

No matter… I moved on to acrylic, since we’ve got a lot of acrylic scrap to play with…

Acrylic

That worked much better! Hopefully once we do some laser maintenance (cleaning and what not) it might be able to cut wood. Of course you could always use BoxMaker to create your box and cut it on the CNC Router instead.

So here’s my laser-cut acrylic box. Notice anything? The tabs are way too big! In my frustration of not being able to cut wood, I switched to the acrylic, but didn’t measure the thickness and create a new file, and since it was not as thick as the wood, I got the tabs all wrong.

Box

Still, BoxMaker is an awesome tool, and I look forward to getting the cutting part right next time.

The “wife is right” sign

Dana is right.

For Christmas I made my lovely wife this lovely sign that lets me (and everyone else in the room) know that she is right.

She can easily point at it to end any disagreement we may be having.

I think I’m going to call it the “wife is right” sign, and I’ll be taking orders from wives to make them signs soon. I’ll also be taking orders from husbands to prevent me from taking orders from their wives. Either way, I see it as a great business opportunity.

In all honesty, the sign comes from a joke my wife and I had a few months back. When we got the laser cutter at the space, this was one of the first things I made with it.