Tag: wood

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Measure Twice, Laser Once…

Pegs and Pieces

I’ve been working on a project that involves stacking of laser cut pieces of wood to create blocks. In theory the laser cutter is a precise CNC machine that has an (almost) negligible kerf. (The kerf is the part that gets cut away. With a saw it’s the width of the saw blade, and you need to account for it.)

Height Difference

Typically I’ve been using this 3mm Baltic Birch plywood from Woodcraft, and it’s been pretty darn close to 3mm, at least within 0.1mm. For most projects this is fine. Even at 3.2mm things will fit together, though perhaps a bit snug. You can always sand things a bit to make them fit.

Stacking presents a new problem though, because the extra height adds up and throws everything off. For the last batch of blocks I assembled I wasn’t aware of the issue, even when the pegs wouldn’t fit. I assumed I screwed up the peg slots, so I just sanded the pegs down a bit until they fit. Even then, they were not the right height in the other direction.

Height Difference

After assembly I noticed that the blocks were different heights than the first batch I created! I went back and measured the sheet of wood and it was 3.4mm. I checked a few more and got ranges between 3.0mm and 3.4mm. The image above shows what happens if you use 3mm wood and 3.3mm wood to construct the same block. At just four layers you’re already off by 1.2mm. For small things that can make a huge difference.

So what’s the solution? I can attempt to sand the sheets before cutting, or partially assemble the blocks and sand them to the proper height before the final step. A colleague suggested getting one large sheet of wood assuming the height would be consistent across one piece. I may try all three solutions, but will probably start with the first, and apply the second solution if required.

So yeah, even with digital fabrication, and laser cutters with almost no kerf… Measure twice so you only have to cut once!

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Printing Plates v2.0

My last attempt at printmaking didn’t turn out as well as I had hoped it would, so I figured it was time to try again. And actually, the main reason I wanted to try again is because I saw the work of Jenie Gao at Milwaukee MakerFest, and after I took over her table so she could take a break, I asked her a few questions about printmaking, and the most important thing I learned is that I should seal the wood. With that small bit of advice, I was ready to try again…

Laser cutting the plate

Rather than do the same thing I did last time, I decided to start fresh. I once again used the laser cutter, but this time I didn’t want to use a raster etch, but instead opted for a vector cut to create the plate. (A raster etch works quite well of course, as Bret recently demonstrated, but they are time consuming, and tie up the laser for a long time. Vector cuts are much faster.)

Sanding the plate

Once I had my pieces cut from 3mm Baltic Birch, I used the piece of wood I cut them from as a guide to glue them down. After the glue dried I sanded it to make the surface nice and smooth. I’m not sure I needed to do this, but sanding always feels like the right thing to do in these situations.

Sealing the plate

I then coated the piece with polyurethane, sanded it down a bit, and repeated that process two more times. (I’m just doing what is recommended on the can. I don’t know if multiple coats are really needed, but it can’t hurt, right?) I let the whole thing dry for at least 24 hours.

Inking the plate

Ready to print! I inked up the plate and slapped down some paper, did a bit of rubbing, and I actually got a decent looking print! One thing I should do next time is create a larger backing piece, as it was hard to hold the plate in place while inking it, and I got a good amount of ink on my fingers and the table. (And yes, that is a mirror I am rolling the ink on. It’s from a 3D printing experiment long ago.)

MKE Print

The final print. There’s a few spots that could use more ink, but as I wasn’t doing a large run, I didn’t use a lot of ink. I also printed on crappy paper and it turned out good. (Supposedly the suggestion of using ‘Rives BFK’ can be ignored. Regular drawing paper can be used instead.)

Ultimately, my plan is to sort of merge the concept of printmaking with letterpress to make a weird combination of the two… but, you know, using a laser cutter and cheap Baltic Birch plywood.

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Raspberry Pi case (with Camera!)

Raspberry Pi with Camera

I really like the Stacking Pi Case and I’ve laser cut a bunch of them at Milwaukee Makerspace, including the one I used for my Radio Milwaukee Radio, but when I got a Raspberry Pi Camera, there was no easy way to include it…

Raspberry Pi with Camera

I ended up making a derivative of the Stacking Pi Case and calling it the Raspberry Pi Case (with Camera) because, that’s what it is. I just made the Stacking Case taller and added in some holes to mount the camera.

Raspberry Pi with Camera

So if you’ve got a Raspberry Pi and Camera Module, this case might do well for you, since it’ll hold them both. Grab it from Thingiverse!

I’ll get into what I’m doing with this thing in a future post… obviously it will be related to images, time lapses, web stuff, etc.

Oh, and if you’re wondering why the top of the case is purple, it’s due to some crazy experiment I did with dying wood last time I dyed a bunch of t-shirts. And yes, you can totally dye wood.

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Two Square Feet of Art

M

Our story of the M begins when my friend Tiffany from While You Were Out Pet Sitting Service mentioned she was doing a charity event called Red, White & Black: 100 Square Feet of Art. If you remember the old “250 Square Feet of Art” event the Eisner used to hold (and I took part in) it’s like that. Artists create 12″x12″ boards, and they get auctioned off. So I volunteered.

I started with this letter M, in the typeface Umbra BT. I liked the 3D quality of it, and since I also love using the laser cutter at Milwaukee Makerspace, I had a plan.

M

The Photoshop mock-up was just an idea, so I re-created the letter M in Inkscape to prepare it to be laser cut. You’ll notice right now that the M in the first image and second image don’t match exactly. (I wish I had noticed at the time!)

I cut the shapes out of 1/8″ Baltic Birch plywood. My plan was to cut one board like this, and I’d the use the pieces to attach to another board, and the template piece as an assembly guide. Good idea, right? Right.

M

My next thought was, “Why waste full boards to get more pieces?” and I arranged the pieces to minimize waste. This works well for general assembly of things, but for art, maybe not so much. The pieces cut fine, but I did have to deal with kerfs, some scorching, the grain of the wood, etc. None of those things were huge deals, but they’re things to be aware of in the future.

M

At this point it was just a matter of assembly. A bit of glue, and bit of wood stain, what could go wrong?

M

There was a lot of time spent with the glue and the clamps. Well, most of the time was spent waiting for glue to dry. I obviously need another 20 spring clamps. Just for fun, this is about the time I got sick and had a work overload, so I started getting really concerned about completing this on time. (It gets worse.)

M

Here it is done! I call it “M1” by the way. An “M” for “Milwaukee” or “Mike” or “Mary” or whatever you like… or you could flip it over and make it a “W” for “Wisconsin”, etc.

I also had a nightmare time with the wood stain, though I managed to recover that by changing the piece. I learned everything I’d forgotten about staining wood in the 20 years since I’ve last done it.

M

Here’s a side view of M1 showing the dimensionality of the piece. The M is about 3/8″ thick.

M

But wait, what’s that? I still have that leftover piece that I used as an assembly template! Hmmm…

M

Yeah, here’s “M2” as it were. I figured that a perfectly nice piece of laser cut wood should not go to waste, so I came up with another idea. I reversed the color scheme of the stains on the two pieces of wood, attached the front piece to a back piece, and blammo! Another wonderful(?) piece of laser cut art.

M

I think I may actually like M2 better than M1, maybe just because of the process that created it, but hey, you be the judge, or the critic, or the bidder, or whatever. Cheers!

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(Additional) Nerdy Derby Cars

Great White

There’s a great post over on the Milwaukee Makerspace site about Milwaukee’s First Nerdy Derby, including some sweet video, but I’m mainly going to talk about my own cars here. :)

I spent a lot of time before BarCampMilwaukee7 getting ready for the event, but I also found a bit of time to fabricate a bunch of parts for people to build cars with, so I was down to the wire when it was time for me to make more cars. I already had Poundin’ Sand, my fully laser-cut car, but I wasn’t content to just have one car. (I had heard Jim R. from the Makerspace had five cars. He didn’t race that many, as I think one or two of them exploded during testing.)

My second car was titled “Great White” and was a 3D print of Mr. Jaws. I ended up kicking out some quick axle mounts in OpenSCAD and just hot gluing them to the bottom of Mr. Jaws. They probably weren’t on straight, but I didn’t take the time to care. In the category of 3D printed cars… I still came in second! Ed managed to build an amazing 3D printed car, and the worst (best?) part is, he pretty much had the same idea as I did, but he managed to succeed. (Print time and print failure were the two biggest concerns for both of us.) I ended up using stock wheels instead of the 3D printed wheels I made a few weeks earlier, which seems silly as I could have gone for a full-on 3D printed car… oh well.

RasterMobile!

My third car was the RasterMobile! which actually consisted of a block of wood from a real Pinewood Derby kit, turned sideways, with two holes drilled all the way through, and 5/16″ threaded rod with inline skate wheels attached. I had skate bearings that seemed to turn well, I had some weight and mass, and it was painted black with RasterWeb! stickers on it. What could go wrong!?

So how did my cars do? I didn’t expect much out of Great White, as it was really light, and the wheels were probably not completely straight. It rolled down the track, so that’s all I can report on that one. I still think it looked cool and was a neat idea. The RasterMobile! didn’t do as well as I expected. I thought it would fly down the track, and I suppose it did, but the mass of it probably slowed things down too much at the bottom. I did get a some satisfaction that Gary saw the skate wheels, ran to his car and ripped apart his inline skates just to try to beat me with my own idea. :) Oh, the RasterMobile! also had an accident where it jumped out of its lane, so that certainly didn’t help things.

So which car did the best? Surprisingly it was Poundin’ Sand that performed the best out of my three cars. I wasn’t sure the laser-cut wheels would be up to the task, and I questioned whether not gluing the 3 layers that comprised each wheel together was a good idea or not, but it did alright!

Poundin' Sand

There’s been talk of doing another race in the future, so I may not be done building tiny cars…