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

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.

But is it Art?

My Completed Art Deco Wall HangingI sketch quite a bit and I’ve been doodling things like this for years without realizing that, technically, they fall under the “Art Deco” category.  If I were content with that, I’d paint it blue, pink, and silver.  However, because cerulean blue belongs in the sky and not on your wall, pink belongs in distant sunsets and not on your wall, and why the hell would you paint wood silver?  I decided that to bring this piece into the 21st century I’d need to radically rethink the colors.

At first, I had intended to only paint 3 elements of the composition.  After picturing it in my mind, I decided on the single yellow piece that you see here.  I’m quite pleased with the end result.  Unfortunately, the spray-acrylic sealer that I used was very old and I suspect that it was this that led to the strange patina you see on the main circle here.  No matter what I tried, I kept getting glossy parts and flat parts.

The primary material is MDF, some of which was cut with our very own CNC router, with hardboard being used for the yellow part, and split pine dowels (thanks to my own rig, clamped to our band-saw) for the 3 extending pieces.

*Note: When cutting a perfectly cylindrical piece length-wise on a band-saw, the piece will have a tendency to rotate as you’re cutting.  I’d have done a better job had I thought to clamp the piece to the jig that I set up.

The preliminary sketch of the art deco wall-hanging.This is the rough sketch of what I had planned on making.  Things change in a wonderfully organic way when you go from sketch to completed project.

The wall-hanging before painting and glueing.The piece before painting and assembly.

I laid the pieces out separately and hit them with flat-black spray paint.  This took very well to the MDF.  After painting and clear-coating everything, I waffled about how to assemble the many into the whole.  I first toyed with the notion of pre-drilling, then screwing everything in from the backside of the piece; I also realized what a pain it would be to try to locate each hole without being able to see the front first.

Next, I thought I’d use a brad-nailer and just pop everything in, but ours doesn’t take anything shorter than 5/8″ and this entire project is just under 1/2″ in depth and I didn’t want to bother cutting the ends of the brads flush with the back, plus, they could scratch the wall that it hangs on.

I finally decided on some epoxy that one of our makers had brought in.  It’s proven very workable and durable, as I found out when I used it to make the spools for our Makerbot ABS plastic filament.  I put several pieces on at a time, weighting them down with some paving bricks (covered in cloth, as I didn’t wish to scratch the paint).  After letting it cure for 24 hours, the project was more-or-less done.

All that’s left is to figure out how to mount it to a wall.  I think I might use a plunge router and hollow out a portion of the back for that.  Another idea has been brewing in the back of my mind, but it’s too cool to mention unless I actually do it.  Rest assured, if I use that idea, I’ll be posting about it here and on Instructables.

UPDATE: I found that it’s about the same weight as a moderately sized picture, so I picked up some picture-wire and attached it via two screws in the back.  It is now hanging on my bedroom wall.

Laser Cutter Venting System Progress

The laser cutter is now connected to the new vacuum pump!  I’d still like to do some endurance testing on it to fully put it through it’s paces, and we need to finish the last leg of the vent pipes up in the loft, but otherwise you can use it to cut wood and such just as you did before.  I wouldn’t suggest cutting any plastic just yet as the vent pipe is just discharging over the hallway by the bathrooms.  There’s an instruction sheet on how to turn the vacuum pump on and off taped to the machine and my contact number if you run into problems.

You can see pictures here:

http://www.flickr.com/groups/milwaukeemakerspace/pool/with/6471649899/

Holiday Make-A-Thon 2011 Photos

Wow! We had a great turnout at the Holiday Make-A-Thon, and besides teaching people to solder, and providing blank ornaments to decorate, we just generally had a good time.

Here’s some photos from the event:

Soldering

Here’s Royce teaching someone to solder with our Tie Pin Kit. We plan to have these at all the events we participate in so we can show people how easy it is to get into soldering.

Ornaments

Here’s Brant working on some ornaments. We used the CNC Router to cut out a bunch of different shapes for people to decorate.

Ornaments

Here’s a collection of finished ornaments.

Penguin

Here’s a dried gourd that was transformed into an awesome penguin.

Some crazy looking reindeer Brant made out of scraps from one of my projects…

And finally… Starclops. (Does Starclops really need any sort of explanation? I think not.)

Thanks to everyone who came out to make this event awesome!

First DIY CNC Club Meeting

Today marked the first monthly meeting of The DIY CNC Club at Milwaukee Makerspace.  Ron Bean and Tom Gondek, the creators of the router, guided members and guests through the use of CamBam CAD software to generate G-code and Mach3 software to operate and control the router.  The day before, Tom and Mike tested the machine’s ability to cut aluminum.  On Sunday, Rich created a decorative wooden sign and Brant began making plastic shapes for a project enclosure. As Ron pointed out, in less than 24 hours we had worked in three different materials: wood, metal, and plastic.

Several items were also crossed off our wish list.  Two emergency stop buttons were added to the front of the machine and wired together in series.  Hitting either one stops all motion in the X, Y, and Z planes and pauses the program.  We also built a relay-controlled receptacle box that when wired into the CNC computer, will be able to stop the spindle so hitting the E-stop will kill all motion in all axes and the router.  For some reason the pins we’re using on the parallel port are only producing 1.6 volts instead of the 3 or 5 we expected and the relays won’t turn on.  All in all, a very productive weekend.

Screeching Cat Railing

CNC Cutout of screeching cat inserted into porch railing

Recently we completely re-built our aging 2nd story porch. During the process I took the opportunity to add a little flair courtesy of the makerspace’s CNC Router. The idea was to place an emblem into the railing of the porch as decoration. After thinking about the emblem I’d want I decided that I’d never be happy with just one, so I incorporated spring hinges (look carefully below the cat in the photo) that allow me to pull back and replace the emblem at will with ease. With that done the only thing to do was decide on the first emblem. I decided on seasonal/occasion emblems.

Rich showed me a great site with free CNC artwork, some of which was Halloween themed. I downloaded that artwork, selected the screeching cat and had the CNC router cut the cat out of a 2’x2′ plywood. I installed the cat as part of the porch railing as you can see in the photo.  I’m now looking to round up a turkey for Thanksgiving, a snow man for winter, etc.

During the design process TomG had the bright idea to shine a light through the cutout. So I took a high brightness LED out of a malfunctioning flashlight and attached it to some sheet metal on a malleable aluminium boom. The result is that I now have a screeching cat projected down onto the sidewalk below. (It’s too dim for me to capture on camera)

I’m really looking forward to cutting out more shapes on the CNC Router!