Firepit rolling base

A quick little project that I knocked out in a couple of hours today…

My wife an I own a Solo Stove Bonfire. And yes, it does work every bit as well as they say.

The problem is the somewhat fickle Seattle weather; we might have a fire and then the firepit would sit outside and get rained on. It’s stainless so it’s supposed to not corrode, but there are a still a few issues. The obvious thing is to put it under cover when you are done, but it’s really really hot and I’m quite lazy.

A few days ago, I came up with a plan. I will start with the Solo Stove:


My original plan was to buy some angle iron to make a frame, but walking around I found an alternative material:

Four pinball legs that I got with the World Cup Soccer ‘94 that I bought last fall, since replaced with pretty new ones. These legs were just waiting to head to the dump.


and four leftover casters from my Glowforge table project. I didn’t take a picture of them.

Leg modifications

The legs need to be converted from their current form into something more like angle iron. The first step is to cut off the feet. Out comes the 4” angle grinder, on goes the accessory handle and a 4” metal cutting disk, and the feet are cut off.


The process is repeated at the other end to cut off the mounting holes. The length is based upon the diameter of the solo stove, which is 19.25”. After a few minutes of cutting and a lot of sparks, we end up with the following:


Next, I need mounting holes in the corner that the casters can go through. The fluted design of the legs made this a significant pain in the ass, even with a drill press. Here’s the first hole drilled with a 1/8” bit IIRC; I would enlarge it with a 2/8” bit on the way to a 3/8” bit. The drill press is a huge help in this sort of work.


Next it is time to do the layout so I can mark the holes where the metal pieces will overlap and connect:


This is really not precision work, though I will note that I realigned this corner because the two pieces should be symmetrical:


Then, it was back to drill 12 more holes (three pass x four pieces), and then it was time for assembly, in which our caters finally make an appearance:


Tighten up all of the nuts, and we have a frame:


I had toyed with the idea of painting a stainless steel color, but I’m cheap and lazy, so it’s like this for now.

Beauty shot of the Solo Stove sitting in its new frame:


Total cost was $2.09 for a new metal cutting blade and about $2.00 for 8 nuts, 4 flat washers, and 4 lockwashers.

An inexpensive glowforge stand…

My glowforge lives in a workshop I have that I’ve been working on fixing up. The workshop was bare studs but now it has plywood walls and some improved electrical.


As you can see, it’s sitting on top of some old and tired cabinets that I don’t use for storage because they don’t work very well, and a counter that sags in the middle. I need something to be better at holding both the glowforge and the other stuff I want to do down here (in particular, I need a place I can put a reflow oven for some electronics projects).

My initial thought was to price out some replacement cabinets and a countertop, but that quickly started looking like $800 – $1000 for the cheap stuff. So, what other alternatives could I use?

I was inspired by Mike’s table in this forum post:

That’s just a cheap home depot storage rack, only using part of it. I found a rack that was like it at Home Depot, and it was only $60:

But… It was only four feet wide, and I wanted some space to put my laptop and other stuff next to the glowforge. So, I started looking for racks that were wider but still 24” deep. The ones I found were a lot pricier; something like $150 or so.

Time passed, and I ended up on Costco’s website, and decided to search there.


What have we here? 60” wide, 24” deep, and a full 72” tall. $170, so not super cheap, but pretty close to what I wanted. I could put four shelves at the bottom for flat goods, and then one shelf at the top, and the glowforge would be at waist height. And wheels if I wanted them.

It took about a week to ship, and the box it showed up in was heavy. 104 pounds heavy. I dragged it off the front porch and into the garage, opened it up, and found that it was just what I expected. 5 shelves, and – to save on shipping costs – the corner posts come as two sections that screw together. I did some measurements, and realized that if I didn’t use the casters (it comes with both casters and normal feet), the length of he bottom posts was almost exactly counter height, which meant I could do a build that was pretty much at counter height.

And… if I only used 3 shelves on that, I could use the remaining parts – the upper posts and other two shelves – and build a second countertop-height system to go next to the first:


So, that $170 got me two counters – one to hold the glowforge, and one to hold whatever else I want to put next to it. But if you didn’t want the second counter unit, you could easily put the other two shelves on the glowforge part and get a lot of storage for flat materials. And have it on wheels if that is useful for you.

There was only one problem. Wire shelves aren’t the nicest things to put stuff on as small items fall through the openings, and you can’t write on them either. What I needed was a countertop to go on top. There are a few options:

  • Buy one of the ikea countertops – like this or this – and trim them down. I would need two in this case, and that would be another $120. Decent idea, and I like the black look. So yes for fancy, but no for this setting.
  • Buy a full sheet of melamine. My lumberyard will sell me a 48” x 96” sheet for $35, and that would do both counters with some left over. Downside is that the 1/2” sheets are about 65 pounds and a bit of a pain to transport. And the exposed edges aren’t white.
  • Buy some pre-drilled shelf panels. These are meant to be used for the sides of cabinets with shelves in them. $38 each, and I would need two of them.

I was going to go with the big sheet for $35, but then I got to looking around and remembered that we had some extra Ikea shelves hanging around. They are about 29” x 24“, so I’ll just need to trim a bit off of them to make them the right depth (if they are trimmed to 23.5” they will fit between the front and back wire sections and not slide around). When I went and did that, I found that two of the shelves are almost perfect in length between the posts, and everything looks quite tidy. Here it is.


Plenty of space for a laptop on the right side, lots of storage for stock underneath. I might build some vertical storage on the left side; not sure yet.


The shelf is plenty deep; I have mine towards the front to make the exhaust fit better. What I really need to do is trim a couple inches off the duct.

If you are going two countertop-high units, you’ll want to drop the first one down one inch so that everything is level. It looks like this.


Building the Globe of Fire (Dodecahedral Light Engine)…

This guide will describe how to build the Globe of fire. You will need the right tools and good soldering skills to build it successfully.

Please read through the entire guide before you start assembly.

The kit comes with the following parts:


  • 12 polygonal face circuit boards, each with 3 WS2812 LEDs already mounted (you will only use 11 of these)
  • 1 bottom face with a big hole in it
  • Connecting wire that will be used to connect power and a control signal to the globe.
  • 4 assembly jibs to hold the polygonal faces at the proper angle
  • 1 1/4″ bolt and nut to serve as a base
  • 1 stand to hold the completed globe up
  • Approximately 50 tiny half-circle wires, used to connect the polygonal faces together.

11 pentagonal faces with WS2812 (aka “neopixel”) LEDs already soldered on. There is an additional face without LEDs with a hole for mounting the DLE.

To build the kit, you will need the following tools:


A good soldering iron with a fine tip.


Fine tipped tweezers.


A third hand




The globe consists of two rings composed of 5 faces each plus a top and a bottom. We will be joining together the power (VCC) and ground connections so that the LEDs all get power and ground. In addition, we will be connecting the data output from one face (DOUT) to the data input of one adjacent face so that the signals will travel correctly to all of the faces.

It will likely take a couple of hours of soldering to complete the assembly.

If you would like a refresher on how WS2812 LEDs work, there’s a good discussion on StackExchange here.

Building a ring

Five of the pentagonal faces are used to build a ring.


Every face of the pentagon has identical connections so the orientation of an individual face is not important.

The alignment clamps are used to hold the boards together at the correct angle (116 degrees):


Note that the two boards are parallel and there is only a small space between them. Also note that the left and right boards are aligned horizontally; the two VCC holes are aligned with each other.

Here are two wrong ways to do it:


In the left one, the two boards are misaligned vertically; the two VCC holes are not aligned horizontally. In the right one, the boards edges are not parallel.

The board alignment doesn’t have to be perfect, but it helps to have them pretty close.

For the faces in the ring, we will connect both VCC and GND, and then we will connect the data output from the left face (DOUT) to the data input (DIN) on the right face. We will start with VCC.


We will be using a connection wire to make the connection. I have tried a few different ways of doing this, and the following is what I recommend:

  1. Add solder to the hole on one side of the connection (the right side in these pictures). It should stick out slightly above the level of the board.
  2. Hold the connecting wire and place one end of the wire in the hole without solder, and hold the other end against the hole with solder in it.
  3. Touch the soldering iron against the end with solder and lightly press the wire into the solder. It will melt and the wire will sink into the solder. Remove the iron, and hold the wire in position until the solder solidifies.
  4. Solder the other end normally
  5. Verify that both solder joints are shiny and have enough solder. If the joints aren’t shiny, heat one at a time until it just goes liquid.

It’s going to take a little time to get the hang of this. Don’t worry, you will get faster.

After the VCC is connected, connect one of the GNDs to one of the others. It doesn’t matter which one you choose.

After VCC and GND are soldered, remove the assembly jigs so that you can solder DIN and DOUT.


In this detail, the right side (DIN) has been soldered, and left side is in the DOUT hole. The next step is to solder the DOUT end.

If the second end takes too long to solder, it may heat up the first end and the connecting wire may come loose. If that happens, just hold the wire to one end and heat it and wait for the heat to conduct down to the other end and melt the solder there.

That’s one face connected. There are a lot more, but it will get easier with practice.

We next add a third face using the same approach. It looks like this:


Once we have three faces, assemble two more faces together. We will assemble the three and two face pieces to make a full ring. 

Make the ring


Use the alignment clamps to hook the three-face section to the two-face section, and solder one set of connections between the two section and three section.


The last set of connections is different. Note that only the GND and VCC parts are connected; the data lines are unconnected. This is so that data can come into the ring and go out of it.

Looking at the left face, we notice that there is a connection to DOUT but not to DIN; for this face, the data will come in from the other ring that will be under this one and then head out the left side of the face.

Looking at the right face, we notice that there is a connection to DIN for the data that has travelled around the ring, but no connection to DOUT. The data coming into the right face will head out the top to the top face.

Adding the top


We need to add wires to the top so it doesn’t fall through the middle of the ring, and each side will connect either VCC or GND. Start by adding solder to three VCC faces and two GND faces (one arrangement is shown above, but it doesn’t have to look exactly like this).

We need to prepare one connector on each side of the board with solder; either GND or VCC. Do three faces with VCC and two with GND.


To keep the top face from falling through, we need to put connections on it ahead of time. Note that each of these touches the surface; that will give us roughly the angle we need.


The top face is just sitting there. Check that all the connections align properly with the connections from the ring. Solder all the VCC and GND connections to the ring. You may need to heat the already soldered wires to get them to align correctly with the holes on the ring.


Next, we need to make the data connection from the ring to the top. Find the face on the ring that does not have a connection to DOUT, and make a connection from the DOUT on that face to the DIN connection on the top face.


Finally, we find that face that has a DOUT connection but no DIN connections. This is the face that will connect across to the other ring. I have marked the two DIN connections with marker so we can find them later; ONE of these will be connected to the other ring.

If you have a controller than can drive these LEDs, it’s a good idea to test what you have built so far. Connect VCC to 5 volts, GND to ground, and DIN your microcontroller, and run a program that can drive 33 LEDs. They should all light up. If they don’t, examine your solder connections and make sure that you don’t have DOUT/DIN connected all the way around the ring.

Building the second ring

The second ring is built using the same method as the first one. Do not add a top piece. 


This is the bottom ring and is actually upside down at this point. Eventually, we will need to make power, ground, and data connections for the whole globe. They are marked in blue on this face. Why did we choose this face? It’s the only one on the ring that has a DOUT connection but no DIN connection.

It’s a good idea to test the ring at this time.


This is the output face of the second ring. I have put marks on the two DOUT connections; one of them will hook up to the input face on the other ring.


Put the first ring and the second one together, making sure to align the rings so the face that has DOUT marked on the bottom ring is aligned with the DIN that is marked on the upper ring. Tape the two rings together. Connect those two pins together, then attach the top and bottom by connect VCC between three faces and GND between the other two.

At this point, the LED part of the globe is complete. Hook it up to your controller and verify that all of the faces light up. It should look like this:


Attaching the base

The base is purely used for mechanical support; the connections that are made do not carry electricity.


We will use the special bottom pentagon; it has a hole in the middle and no other connections. Attach 5 wires to it on the GND connections, and make sure that you use a variety of GND connections.


Find the spot on the bottom ring where you will attach the wires – you should have marked it before. Rotate the bottom until one of the grounds lines up with the gap between the grounds on the wire-attachment face, as shown in the above picture.

Don’t solder the bottom on yet.


Take the 1/4 screw and put in through the bottom face from the backside, and then put a nut on the outside face. You will want to tighten this out pretty well so that it doesn’t come loose. And then solder the wires to hold the bottom on.


Next, solder on the wires; red to VCC, black to GND, and purple to VIN.


Finally, screw the base onto the 1/4 bolt, and you’re done.

Hook it up, and it should look something like this:


If you’d like, you can put an acrylic plastic globe over it


Both of these pictures are with full lights on and with the globe powered by an underpowered USB source.

Finishing touches–USB charging station part 4

I spent a bit of time tuning all of the joints, cleaning out the dog bones so that they would look nice, and doing an overall sanding of all the plywood. Then it was on to gluing. This was done in sections so that it could be easily clamped together:



The top and back had to be glued all at once, and then clamped. I used a lot of clamps

Finishing was next. I decided to use a water-based polyurethane that I already had:


If you look closely, you will see the base hovering above the platform. I build a little stand using the incorrect base piece I built earlier and some standoffs made of machine screws and nuts. That way, I could finish the bottom, flip it over, and finish the parts of the top that were not done. Finishing the inside of the cubbies was a significant pain in the butt.

After the finish dried, I sanded down the raised grain that water-based poly gives you and then put on… well, I was going to put on a second coat and then realized that I didn’t need the protection, so I called the finishing done.

I wanted to have some padding for the cubbies to help hold the devices in, so I bought some felt at the fabric store. The pieces needed to be cut into simple rectangles – which would have been pretty easy to do with an x-acto knife, but when you have a laser cutter hanging out under the garage, there’s an easier way.


Felt is pretty light and the laser cutter has air assist to clear away the smoke from the cutting, so you need to hold it down. The magnets are carefully aligned so they don’t overlap any of the cuts.


An action shot of the cut.


And the result. Somewhat surprising to me, there was absolutely no charring at all on the felt; it looks like it was just cut with a very accurate knife.


And here we are with the felt installed. There is no felt in the bottom since that part is just a pass-through for the cables (yes, it could have been more elegant). Putting the felt in was *interesting*. I’d peel of the backing, put it adhesive-side up on the appropriately-sized piece of cardboard from a Digi-Key box, and then, with the unit upside down, carefully lift it up to align the felt with the edge, and then press it down. It worked pretty well.


And finally, it was time for installation. The first shelf peg fit perfectly, the second one was offset by a bit, which means my measurements were off a bit. I enlarged the holes and it was fine. The bottom holes… well, they were off by about 1/4 inch. Which is a bit embarrassing. I did a bit of modification to two of the shelf pins with a grinding wheel in my Dremel to make the cylindrical part a bit longer so they would stick farther into the shelve, drilled a hole through the shelf below to add a grommet, and installed the hub. Here you see it charging my cell phone. I bought some more cables to use but they’re currently all in use for another project, so that’s why there is only one device.

Overall, I’m pretty happy about it; the project looks decent (if you like through-tab designs; I could have done a hidden tab design but chose not to for my first project) and I learned a lot about how to do the design and how to use the Shaper Origin.

A few cutting remarks–USB charging station part 3

In our previous episode, we had just finished cutting the hub portion of the station.

Now, it’s time to cut the remaining parts. I started by cutting the biggest part – the base. It’s about 8″ x 10″, and it has 17 slots in it and 4 holes, and each of those need to be cut in two passes. I decided to cut all the interior holes first in two passes, and then cut the outline. So, I started at the bottom and cut about 13 slots, and then I found that there were four slots missing.

When somebody added shelves to the design, he forgot to do the cut operation with the new shelves, so there were no holes there. Which means that the design needs to be redone, and since shaper doesn’t support an “update my design” operation, I had to abandon that section, though I did manage to cut a shelve out of it so it wasn’t a total loss.

The rest of the cutting was pretty repetitive. The shaper mostly worked okay, though it crashed a number of times and hung a few times as well. The back has 7 holes and a bunch of tabs and the shaper crashed on the last cut. Then I rebooted and found that both the workspace and the placement information is stored in non-volatile memory, so as long as the crash doesn’t damage your workpiece, you can continue.

Eventually, I finished cutting all the pieces, and started cleaning them up:


The shaper uses an upcut spiral bit so that it can easily pull the sawdust out; that cuts well, but leaves a fuzzy edge to the cut. I tried an offset technique where you do the initial cut a bit to the outside of the final line and the second cut right on the line, but the results weren’t any better. I’m going to explore whether a nicer bit would give a better result, but the result here is really worse than it looks. A couple of minutes with some 220 grit sandpaper and it cleans up nicely.


A bit more time for cleanup, and I had a bit pile of parts:


So, is this going to actually work, or was all that effort for naught?

Well, guess what?


The fit of the tabs was very nice and it looks pretty good even without any glue to hold the parts together. Success!


Next up is to look at all the joints and do a bit more tuning on the fit, especially on the hub holder in the left of the last picture.

Givin’ the dog a bone–USB charging station part 2

One of the realities of doing CAD work is that the real world sometimes intrudes…

Your laser cutter – for example – is limited to cutting a given size of material, and only in one plane. And it isn’t a perfectly thin cut, there is a little width to the laser beam.

For router-based machining, one of the problems is that the cutter is round, and often the cuts you would like to make are square. Here’s an example:

Image result for cnc dog bones

The part on the left is what you designed, and the part on the right is what you got when you cut it. There are a few approaches to deal with this; you can cut the corners out with a knife or saw, you can just pound the parts together and hope the material yields, or you can change your design so that the corners are cut out. It looks like this:

Image result for cnc dog bone examples

Hence the name “dog bone”. With the Shaper, there are a few ways to do this; you can either modify your design to include the dog bones, or you can do them on the tool, one at a time, kind of by hand. Since there are hundreds in this design, doing them on the tool did not seem very exciting.

There is an add-in for Fusion 360 that does dog bones, so I installed it and tried it on a few designs. Like lots of freeware, it’s a bit challenging; you either have to pick every corner where you want the dog bone, or you can let it pick the corners that need to be modified but this only works if the corners are vertical.

Oh, and it takes a long time. A *long* time. Like 5 minutes for a panel with just a few cuts if you mark them by hand, or 20+ minutes for one with lots of holes (19) where it figures out which corners to modify. This is made much more annoying because Fusion 360 does something that I thought wasn’t supposed to be allowed under Windows UI guidelines any more; the status bar that it shows brings the window to the foreground and selects it. Since this is happening about every second, you can’t do anything else on your computer while the dog-boneification process is underway. Which kindof gets in the way of making good progress, since you need to go and do something else.

About this time I needed to get some wood for the shelf, and I needed to know how much and how I would arrange it the cut pieces on the board. I found this tutorial to be very useful in understanding how to do that, and ended up with a nice layout on a 24” x 48” sheet that used a bit more more than half of the space.

Went to add the dogbones by selecting all 13 pieces in the and kicking off the add-in. An hour later it was still running. Two hours later is was still running, much more slowly. Left it overnight and came back to the autodesk crash dialog.

About this time I was really thinking of just using the Glowforge and forgetting about dogbones, but the whole point was to use the shaper, so I pressed on.

Went out for lunch, picked up some stock (birch plywood that was 4.7mm thick), rolled back to my 3-d layout, set the thickness of the stock, and went through and did each of the dogbones by hand-selecting each corner. After that was done, I ran the Fusion 360 plug-in for the Shaper Origin, which generated SVG files that I uploaded to their website (you can use a USB key if you’d rather). I was going to do the bottom part of the design; the last wide shelf and then the pieces that hang the hub underneath that, four pieces in total.


At some point, Fusion lost the material selection for the one piece, and I was too lazy to fix it.


Here is the setup. Sitting on the router table portion of my BT3000 table saw, I have an extra ikea shelf (melamine and very flat), a sacrificial piece of MDF on top of that (you need to cut just through the material), and then the birch plywood on top (that piece was about $8). Across the wood you can see the “shaper tape”; this is how the vision system on the router knows where it is. The basic process to cut is:

  1. Move the router around so that it locates all of the domino-shaped shapes on the shaper tape.
  2. Load a design (in this case, from the online pieces I uploaded)
  3. Set the cut parameters (the size of the cutter you have in the router (1/8” in this case), how deep you want to cut on this pass (I did two passes, one at 0.125” and one at 0.2”)
  4. Do a “z – touch” so that the router knows where the top of the material is and can therefore judge depth.
  5. Move the router so that the line you want to cut is inside the circle.
  6. Turn the router on (using the physical switch on the head)
  7. Press the cut button (green button on the right handle), and wait for the bit to plunge into the work.
  8. Navigate the router around the cut.
  9. Press the retract button (orange button on the left handle), and wait for it to retract.

At that point, you can move to another cut that needs to be made or change parameters and recut the same line (deeper, for example).

This worked really well, except for two issues. The first was that on my second cut, something went wrong, and on the cut, the router plunged the bit as deep as it could and then the software crashed (you can see the burned hole near the bottom of the workpiece). I had to turn off the router, pull it carefully out, and cycle the power on the shaper to get back. The second was my fault; I cut all the way through an outline before forgetting that the piece I cut had a cutout. Oh, and the software crashed again when it was just sitting there; the image on the display is a static one before I moved it to make the picture nicer.

And the result is…



What do we see? Well, the first thing you’ll notice is that there is a lot of fuzziness on some of the cuts. The shaper uses an upcut bit, so that’s pretty common. The fix is to do the first cut at a bit of an offset back from the line and then do the final cut without the offset. Overall, the lines look really straight, which is remarkable given that a human is moving the router around.

What else do we see? Well, the joints don’t look very good, and there is a distinct lack of dogbones on them.

It turns out that I outsmarted myself. One of the tricks with dogbones in wood is to set the cutter size slightly smaller than the actual size of the cutter; that makes the dogbone a bit smaller but it still works since the wood has a little give to it. But… the Shaper knows the size of the cut you are asking it to do and the size of the cutter, so it just avoids cutting the dogbone path. I cut them by hand with a utility knife, but I was short of time so this is the result I got.

Finally, a couple of action shots with the hub in place:



Up next is to redo the dogbones for the remaining pieces *again*, and the cut them using the offset to see if I can get nicer joints.

Fusion 360: USB Charging station part 1

With a new Shaper Origin joining my Glowforge in the workshop, I decided it was finally time to break down and learn a real 3D modelling program. Autodesk provide a free year’s subscription to Fusion 360 and it looks like I can keep using it for hobby use, so I decided to learn it.

It took a few days, but I finally understand what I’m doing and can make decent progress. The really cool part about fusion is that your design is created from a series of steps and that series of steps is preserved in a timeline; if you discover that you made a mistake in how you defined a shape (fusion calls them “bodies”) two hours ago, you can go back to that step in the timeline and either modify the step that is there or add in a new one. This is a hugely powerful paradigm once you get used to it. It also lets you define parameters such as the width or height of a design, and when you change them it walks through all the steps and updates things. Or, you can say that you want to do a project in 1/4” plywood, but when you measure it it turns out to be actually 0.23” thick.

After watching a few tutorials, I decided I needed to do a project for the shaper origin, and that project would be a USB charging station to go in our walk-in closet. We have a shelf with predrilled 5mm holes that I am going to mount the charging station on.

The first step was to order a hub, and I picked up a RavPower Nexus 6 charger; it will spread 60 watts of power across 6 ports.

I did two different designs before I settled on one that I liked.

I started with four holes that should line up with the holes in the cabinet side:


Basically, the location of the holes is constrained by the measurements, and then the rectangle around it gives a given border.

The first shelf is added, along with tabs that will connect it to the other components. To get these views I’m rewinding the timeline to show what the design was at a certain point of time.


Now it’s time to duplicate the shelves.


A singled command called “pattern” did that; I selected a 1×8 pattern and the offset between each of the shelves.

A view from the back farther along:


I added a top and a back to the shelves. There are now a series of cubbies which is where the devices to be charged will rest. There are holes in the top and back where the tabs from the shelves will stick through, and holes in the back for the charging cables. This is done by subtraction one body from another, using the “cut” operation.

The section for shelves is completed. Now we need a spot for the usb hub. It will live in a box under the shelves, with a hole in the back for the power cord. The size of the hub was measured with a set of calipers, and then I entered it directly as a parameter for the design.


It looks like I perfectly sized the base for what I wanted, but in reality I did the shelves and usb hub box and then went back and changed the number of pins that the design covered.

The reasons that the tool is called “Fusion” is that it is a combination of design, rendering, and analysis tools. Since it’s going to be made out of wood, here’s a nice render of the result done in pine:


Basically the hub lives at the bottom, the wires from the hub go out the back through the bottom cubby, and then back through the individual cubby holes. The cubby bottoms will have felt in the bottom, which I’m sure I could define if I wanted to.

To build this, there are different ways to proceed. Shaper provides an add-in that lets me select on component and export it as an SVG that the tool will understand. There are 7 parts that are unique, and then 7 shelves that are identical.

I’ll write more when I’ve had a chance to get some material and do some cutting. I’m going to start with 1/4” plywood and use the shaper, but I could also use the glowforge to make this from as well.

With a bill of materials add-in, I can get an export that I can turn into a parts list. If everything fit perfectly, it would take 2.68 square feet for the whole thing, so if I go with a 2×2 piece, things will *probably* work out.


More when I have some wood cut. My plan is to start with a cheap wood (maybe mdf) first.

WPC Driver board Upgrade

I finished the upgrade of my WPC driver board today. It was fairly simple despite Williams using a crappy circuit design; instead of using vias to carry power from one side of the board to the other, they rely on component leads to do that, presumably to save cost.

If you do this yourself, after you remove the component make sure to tin the ring on the component side with solder and overdo the amount of solder you use if you can’t see the component side; I had to redo several of the big capacitors because they had great solder joints on the bottom but not enough solder to grab onto the other side. So, on those components, jam more solder in there than you would normally do, and I also recommend grabbing the schematics, an ohmmeter, and checking for continuity through the hole.

WCS Power Driver Board Voltages

I measured the board voltage for future reference, both with only the input power connected to the board and the game in attract mode, using a quality Fluke voltmeter.

AC is measured to look for poor filtering by the large capacitors on the board; as the capacitors degrade there will be more AC present on the voltages.

Test point Input DC Input AC Attract DC Attract AC Description
TP1 15.83 0.002 13.8 0.1 +12V filtered but not regulated
TP2 5.02 0 5.01 0 +5V regulated Digital supply
TP3 12.03 0 11.7 0 +12V regulated digital supply
TP4 0.393 0.6 3.80 0.06 zero cross
TP5 Board ground
TP6 77 0 76.2 0 +50V for solenoids, flippers
TP7 22.26 0.003 21.8 0.01 +20v flash lamps
TP8 18.52 0 13.9 – 15.1 0 – 2 +18 to lamp columns

When and where do I burn fat and carbs?

I’ve been having a repeated online discussion about fat and carbohydrate burning, and therefore decided to write a post that goes into it in detail.

There is a very common – perhaps even famous – graph in exercise physiology that looks like this:


The explanation that goes along with says that at low intensities, our bodies get most of their energy from burning fat, but that as we get to higher intensities, the percentage gradually changes, until at the top intensities, we get pretty much all of our energy from carbohydrate (CHO in the diagram). This explanation led to a lot of advice; there was a lot of advice that people should exercise at low intensities because that is where they would burn the most fat, and then contrary advice that said that while the fat burn was a smaller percentage at higher intensities, it was larger in absolute values and therefore to burn more fat you should work out at higher intensities.

What this discussions missed was something very simple…

This graph cannot be true for the vast majority of the population.

And it is wrong for a very simple reason; our bodies adapt their energy sources based on the diets we eat.

To illustrate why, let me discuss two different people:

  • Chris eats a very low fat diet of about 2000 calories per day; of these, she gets 10% from fat, 25% from protein, and 65% from carbohydrates.
  • Felicia eats a low carb diet of about 2000 calories per day, of these, she gets 65% from fat, 25% from protein, and 10% from carbohydrates.
  • Both have stable weight and body composition; they are neither gaining nor losing weight.

    Let’s explore how the graph might relate to Chris, starting at the left side. If Chris is getting 80% of her calories from fat, then she needs 2000 * 0.8 = 1600 calories a day from fat. But she is only eating about 200 calories per day in fat and her body composition is stable, so there is no place that she could be getting an extra 1400 calories a day in fat. If she had that big of a fat deficit, she would be losing about 2.7 pounds a week (1400 * 7 = 9800 calories / 3600 is about 2.7 pounds). Further, if she is only getting 20% of her calories from carbs, that would be 400 calories per day, but she is eating 1300 calories per day, so she has an extra 900 calories per day of carbs. Those carbs need to go someplace, but the only big carb sink in our bodies is to store those calories as fat.

    This graph simply cannot be true for Chris. Given that she has a stable weight and body composition, the energy she gets has to come in the same proportions as the food that she eats.

    On to Felicia. The left side of the graph can work okay for her; she eats a lot of fat calories and those could provide the bulk of her energy at rest. It doesn’t work well for her at the right side; she is only eating about 200 calories per day of carbs, and let’s say that she goes on a one-hour run every day at moderate intensity. On that one-hour run, she burns around 500 calories, and half is 250 calories from carbs. But she is only eating 200 calories per day of carbs, and there are other tissues (the brain and red blood cells) that need some glucose to survive, so she doesn’t eat enough carbs to make this graph a reality.

    In neither of these cases is the graph a realistic depiction of what is going on. So what really happens?

    Well, here’s some research from back in 1997 where they played around with the amount of fat in the diet, and this is what they found:

    “The results of the present study show that, in situations in which energy balance is reached, substrate oxidation can be adjusted to substrate intake. After 7 d(ays) on a high-fat diet, fat oxidation was, on average, equal to fat intake.”  (Discussion section, first paragraph)

    In other words, the amount of fat that the subjects burned adjusted to be the same as the amount of fat the subjects ate.

    Or this study. From the abstract:

    Diet composition did not affect total daily energy expenditure but did affect daily nutrient oxidation by rapidly shifting substrate oxidation to more closely reflect the composition of the diet.

    The same result as the other study. Our bodies adapt to burn the mixture of food that we provide it.

    So, what does the graph really look like?

    Here is some data gathered from testing a couple of athletes; the full article is here. Basically, you put them through a VO2max testing protocol, and you measure their fat and carbohydrate metabolism along the way.

    Here is the first athlete:

    This is athlete burns a small amount of fat even at very low intensities, and it only gets worse from there. Based on what I wrote about adaptation, what kind of diet is this athlete on?

    Yes, it’s a high carb one; in fact, the athlete said that he had a sweet tooth and ate lots of sugar. Even at rest, he is burning a lot of carbs, and it only gets higher from there. As part of the study, this athlete modified his diet to reduce the amount of carbs and increase the amount of fat, by minimizing sugar and eating rice/break/pasta/potatoes only once or twice a week. After 10 weeks of training on the new diet, he looked like this:

    He now gets a lot more energy from fat across the board, though he still gets a lot of calories from carbs. His body adapted to use the kind of diet that he now eats.

    Here’s a second athlete:

    What kind of diet was he on? Well, there’s no description of that in the linked article, but my guess is it’s a pretty standard athlete diet, and he doesn’t eat a lot of sugar. He is decent at burning fat, burning 40-50% over most intensities, but most of his energy still comes from carbs.

    He switched his diet to take out grains and fruit (a break from the study goal, which was a low-carb ketogenic diet), and trained for 10 weeks. Here’s his second graph:

    He now burns a ton of fat *everywhere*, regardless of intensity. Even at 4.5 watts per kilogram – a very high energy output – the fat and carbohydrate burn are about equal. The contrast of this graph to the first athlete’s “before” graph is huge.

    Note that none of these graphs look like the one at the beginning of this post; what we see is that the poor fat burners stay poor fat burners as intensity rises, and the same for the good fat burners. We do see that at the high end fat burning goes down and carb burning goes up, but the overall graph shape doesn’t look like what we are told it should be.

    So, where does the graph come from? Not being in the field and having not researched this thoroughly, I do not have a definitive answer, but following a reference led to this article which has this graph in it:


    Digging a bit into the article, it is about how training effects the relative use of fats and carbs during exercise. I followed a few of the cited articles, but did not find the ones I wanted for free. I *did* find that the article cited Phinney’s early research on exercise and ketosis, which to me implies that the author knew about the adaptation due to different diets.

    Anyway, I didn’t find any support for the idea that this graph was intended to be a representation of different sources of fuel *in general*.

    So how do I burn more fat?

    The whole concept of a fat burning zone and different intensities is not supported by studies. What *is* supported is that humans adapt to be good at burning the kind of fuel that they have available over time after a short adjustment period.

    If you want to burn more fat *in general*, the answer is pretty simple; if you eat fewer carbohydrates – especially simple carbohydrates with high glycemic load – you will get better at burning fat during the day. Whether you lose weight will depend on your overall energy balance – you will still need to eat fewer calories than you burn to lose weight – but that puts you in a better position to be burning fat.

    If you want to burn more fat during exercise – which can be a great way to burn fat – there are a few approaches:

    1. You can change your base diet to eat fewer carbohydrates – especially the simple ones.
    2. You can reduce the amount of carbohydrate that you take in during exercise. If your exercise is of a long enough duration, you will burn off enough carbohydrate to encourage your body to shift to better fat metabolism.
    3. You can exercise fasted. You start in your best fat-burning state, so the exercise will have more of an effect on changing how your body generates energy.

    You can mix and match these at will to see which one works the best for you.

    There are a few caveats when it comes to exercise:

    • To become a better fat burner, we need to train as if we were already a better fat burner – without as much available carbohydrate – and if we train for a significant duration, we can exhaust our carbohydrate stores and bonk. So, my advice is to have a source of carbs with you in case you start getting hungry or feeling really tired, and if this happens, to have a few of those carbs.

    • When you start, your body is poor at fueling your exercise from fat. That means that you are going to have less power overall than you are used to. If you continue to push hard, you push your metabolism over to burning more carbs, losing the adaptation that you are trying to get. So, you will need to slow down to get the best adaptation, and remember that it’s going to take a little while (ie weeks) to become decently adapted.

    Workshop finishing update

    I’ve done a fair bit of work to update the workshop, but have been terrible at taking pictures. So, here’s the current state:



    There’s a pretty new window in the bottom picture to bring some natural light into the space. The walls are all insulated with Roxul rock wool, which was a significant pain in the ass because the long wall has studs 12” on center and it doesn’t come in those widths, so I had to take 23” batts and split them. Ick. There are three new boxes for outlets, but the circuits aren’t hooked up yet. The wall is 1/2” CDX plywood, chosen because I want to have a wall I can hang things on.


    Here is a pretty picture with the wall painted white to make the whole room lighter.

    Up next will be doing the electrical, moving the cabinets back, and working on the rest of the room.